[lyx.git] / src / Paragraph.cpp

/**
 * \file Paragraph.cpp
 * This file is part of LyX, the document processor.
 * Licence details can be found in the file COPYING.
 *
 * \author Asger Alstrup
 * \author Lars Gullik Bjønnes
 * \author Richard Heck (XHTML output)
 * \author Jean-Marc Lasgouttes
 * \author Angus Leeming
 * \author John Levon
 * \author André Pönitz
 * \author Dekel Tsur
 * \author Jürgen Vigna
 *
 * Full author contact details are available in file CREDITS.
 */

#include <config.h>

#include "Paragraph.h"

#include "LayoutFile.h"
#include "Buffer.h"
#include "BufferParams.h"
#include "Changes.h"
#include "Counters.h"
#include "BufferEncodings.h"
#include "InsetList.h"
#include "Language.h"
#include "LaTeXFeatures.h"
#include "Layout.h"
#include "Font.h"
#include "FontList.h"
#include "LyXRC.h"
#include "OutputParams.h"
#include "output_latex.h"
#include "output_xhtml.h"
#include "output_docbook.h"
#include "ParagraphParameters.h"
#include "SpellChecker.h"
#include "xml.h"
#include "texstream.h"
#include "TextClass.h"
#include "TexRow.h"
#include "Text.h"
#include "WordLangTuple.h"
#include "WordList.h"

#include "frontends/alert.h"

#include "insets/InsetBibitem.h"
#include "insets/InsetLabel.h"
#include "insets/InsetSpecialChar.h"
#include "insets/InsetText.h"

#include "mathed/InsetMathHull.h"

#include "support/debug.h"
#include "support/docstring_list.h"
#include "support/ExceptionMessage.h"
#include "support/gettext.h"
#include "support/lassert.h"
#include "support/Length.h"
#include "support/lstrings.h"
#include "support/textutils.h"
#include "output_docbook.h"

#include <atomic>
#include <sstream>
#include <vector>

using namespace std;
using namespace lyx::support;

// OSX clang, gcc < 4.8.0, and msvc < 2015 do not support C++11 thread_local
#if defined(__APPLE__) || (defined(__GNUC__) && __GNUC__ == 4 && __GNUC_MINOR__ < 8)
#define THREAD_LOCAL_STATIC static __thread
#elif defined(_MSC_VER) && (_MSC_VER < 1900)
#define THREAD_LOCAL_STATIC static __declspec(thread)
#else
#define THREAD_LOCAL_STATIC thread_local static
#endif

namespace lyx {

/////////////////////////////////////////////////////////////////////
//
// SpellResultRange
//
/////////////////////////////////////////////////////////////////////

class SpellResultRange {
public:
        SpellResultRange(FontSpan range, SpellChecker::Result result)
        : range_(range), result_(result)
        {}
        ///
        FontSpan const & range() const { return range_; }
        ///
        void range(FontSpan const & r) { range_ = r; }
        ///
        SpellChecker::Result result() const { return result_; }
        ///
        void result(SpellChecker::Result r) { result_ = r; }
        ///
        bool contains(pos_type pos) const { return range_.contains(pos); }
        ///
        bool covered(FontSpan const & r) const
        {
                // 1. first of new range inside current range or
                // 2. last of new range inside current range or
                // 3. first of current range inside new range or
                // 4. last of current range inside new range
                //FIXME: is this the same as !range_.intersect(r).empty() ?
                return range_.contains(r.first) || range_.contains(r.last) ||
                        r.contains(range_.first) || r.contains(range_.last);
        }
        ///
        void shift(pos_type pos, int offset)
        {
                if (range_.first > pos) {
                        range_.first += offset;
                        range_.last += offset;
                } else if (range_.last >= pos) {
                        range_.last += offset;
                }
        }
private:
        FontSpan range_ ;
        SpellChecker::Result result_ ;
};


/////////////////////////////////////////////////////////////////////
//
// SpellCheckerState
//
/////////////////////////////////////////////////////////////////////

class SpellCheckerState {
public:
        SpellCheckerState()
        {
                needs_refresh_ = true;
                current_change_number_ = 0;
        }

        void setRange(FontSpan const & fp, SpellChecker::Result state)
        {
                Ranges result;
                RangesIterator et = ranges_.end();
                RangesIterator it = ranges_.begin();
                for (; it != et; ++it) {
                        if (!it->covered(fp))
                                result.push_back(SpellResultRange(it->range(), it->result()));
                        else if (state == SpellChecker::WORD_OK) {
                                // trim or split the current misspelled range
                                // store misspelled ranges only
                                FontSpan range = it->range();
                                if (fp.first > range.first) {
                                        // misspelled area in front of WORD_OK
                                        range.last = fp.first - 1;
                                        result.push_back(SpellResultRange(range, it->result()));
                                        range = it->range();
                                }
                                if (fp.last < range.last) {
                                        // misspelled area after WORD_OK range
                                        range.first = fp.last + 1;
                                        result.push_back(SpellResultRange(range, it->result()));
                                }
                        }
                }
                ranges_ = result;
                if (state != SpellChecker::WORD_OK)
                        ranges_.push_back(SpellResultRange(fp, state));
        }

        void increasePosAfterPos(pos_type pos)
        {
                correctRangesAfterPos(pos, 1);
                needsRefresh(pos);
        }

        void decreasePosAfterPos(pos_type pos)
        {
                correctRangesAfterPos(pos, -1);
                needsRefresh(pos);
        }

        void refreshLast(pos_type pos)
        {
                if (pos < refresh_.last)
                        refresh_.last = pos;
        }

        SpellChecker::Result getState(pos_type pos) const
        {
                SpellChecker::Result result = SpellChecker::WORD_OK;
                RangesIterator et = ranges_.end();
                RangesIterator it = ranges_.begin();
                for (; it != et; ++it) {
                        if(it->contains(pos)) {
                                return it->result();
                        }
                }
                return result;
        }

        FontSpan const & getRange(pos_type pos) const
        {
                /// empty span to indicate mismatch
                static FontSpan empty_;
                RangesIterator et = ranges_.end();
                RangesIterator it = ranges_.begin();
                for (; it != et; ++it) {
                        if(it->contains(pos)) {
                                return it->range();
                        }
                }
                return empty_;
        }

        bool needsRefresh() const
        {
                return needs_refresh_;
        }

        SpellChecker::ChangeNumber currentChangeNumber() const
        {
                return current_change_number_;
        }

        void refreshRange(pos_type & first, pos_type & last) const
        {
                first = refresh_.first;
                last = refresh_.last;
        }

        void needsRefresh(pos_type pos)
        {
                if (needs_refresh_ && pos != -1) {
                        if (pos < refresh_.first)
                                refresh_.first = pos;
                        if (pos > refresh_.last)
                                refresh_.last = pos;
                } else if (pos != -1) {
                        // init request check for neighbour positions too
                        refresh_.first = pos > 0 ? pos - 1 : 0;
                        // no need for special end of paragraph check
                        refresh_.last = pos + 1;
                }
                needs_refresh_ = pos != -1;
        }

        void needsCompleteRefresh(SpellChecker::ChangeNumber change_number)
        {
                needs_refresh_ = true;
                refresh_.first = 0;
                refresh_.last = -1;
                current_change_number_ = change_number;
        }
private:
        typedef vector<SpellResultRange> Ranges;
        typedef Ranges::const_iterator RangesIterator;
        Ranges ranges_;
        /// the area of the paragraph with pending spell check
        FontSpan refresh_;
        /// spell state cache version number
        SpellChecker::ChangeNumber current_change_number_;
        bool needs_refresh_;


        void correctRangesAfterPos(pos_type pos, int offset)
        {
                RangesIterator et = ranges_.end();
                Ranges::iterator it = ranges_.begin();
                for (; it != et; ++it) {
                        it->shift(pos, offset);
                }
        }

};

/////////////////////////////////////////////////////////////////////
//
// Paragraph::Private
//
/////////////////////////////////////////////////////////////////////

class Paragraph::Private
{
        // Enforce our own "copy" constructor
        Private(Private const &) = delete;
        Private & operator=(Private const &) = delete;
        // Unique ID generator
        static int make_id();
public:
        ///
        Private(Paragraph * owner, Layout const & layout);
        /// "Copy constructor"
        Private(Private const &, Paragraph * owner);
        /// Copy constructor from \p beg  to \p end
        Private(Private const &, Paragraph * owner, pos_type beg, pos_type end);

        ///
        void insertChar(pos_type pos, char_type c, Change const & change);

        /// Output the surrogate pair formed by \p c and \p next to \p os.
        /// \return the number of characters written.
        int latexSurrogatePair(BufferParams const &, otexstream & os,
                               char_type c, char_type next,
                               OutputParams const &);

        /// Output a space in appropriate formatting (or a surrogate pair
        /// if the next character is a combining character).
        /// \return whether a surrogate pair was output.
        bool simpleTeXBlanks(BufferParams const &,
                             OutputParams const &,
                             otexstream &,
                             pos_type i,
                             unsigned int & column,
                             Font const & font,
                             Layout const & style);

        /// This could go to ParagraphParameters if we want to.
        int startTeXParParams(BufferParams const &, otexstream &,
                              OutputParams const &) const;

        /// This could go to ParagraphParameters if we want to.
        bool endTeXParParams(BufferParams const &, otexstream &,
                             OutputParams const &) const;

        ///
        void latexInset(BufferParams const &,
                                   otexstream &,
                                   OutputParams &,
                                   Font & running_font,
                                   Font & basefont,
                                   Font const & outerfont,
                                   bool & open_font,
                                   Change & running_change,
                                   Layout const & style,
                                   pos_type & i,
                                   unsigned int & column,
                                   bool const fontswitch_inset,
                                   bool const closeLanguage,
                                   bool const lang_switched_at_inset);

        ///
        void latexSpecialChar(
                                   otexstream & os,
                                   BufferParams const & bparams,
                                   OutputParams const & runparams,
                                   Font const & running_font,
                                   string & alien_script,
                                   Layout const & style,
                                   pos_type & i,
                                   pos_type end_pos,
                                   unsigned int & column);

        ///
        bool latexSpecialT1(
                char_type const c,
                otexstream & os,
                pos_type i,
                unsigned int & column);
        ///
        bool latexSpecialTU(
                char_type const c,
                otexstream & os,
                pos_type i,
                unsigned int & column);
        ///
        bool latexSpecialT3(
                char_type const c,
                otexstream & os,
                pos_type i,
                unsigned int & column);

        ///
        void validate(LaTeXFeatures & features) const;

        /// Checks if the paragraph contains only text and no inset or font change.
        bool onlyText(Buffer const & buf, Font const & outerfont,
                      pos_type initial) const;

        /// a vector of speller skip positions
        typedef vector<FontSpan> SkipPositions;
        typedef SkipPositions::const_iterator SkipPositionsIterator;

        void appendSkipPosition(SkipPositions & skips, pos_type const pos) const;

        Language * getSpellLanguage(pos_type const from) const;

        Language * locateSpellRange(pos_type & from, pos_type & to,
                                    SkipPositions & skips) const;

        bool hasSpellerChange() const
        {
                SpellChecker::ChangeNumber speller_change_number = 0;
                if (theSpellChecker())
                        speller_change_number = theSpellChecker()->changeNumber();
                return speller_change_number > speller_state_.currentChangeNumber();
        }

        bool ignoreWord(docstring const & word) const ;

        void setMisspelled(pos_type from, pos_type to, SpellChecker::Result state)
        {
                pos_type textsize = owner_->size();
                // check for sane arguments
                if (to <= from || from >= textsize)
                        return;
                FontSpan fp = FontSpan(from, to - 1);
                speller_state_.setRange(fp, state);
        }

        void requestSpellCheck(pos_type pos)
        {
                if (pos == -1)
                        speller_state_.needsCompleteRefresh(speller_state_.currentChangeNumber());
                else
                        speller_state_.needsRefresh(pos);
        }

        void readySpellCheck()
        {
                speller_state_.needsRefresh(-1);
        }

        bool needsSpellCheck() const
        {
                return speller_state_.needsRefresh();
        }

        void rangeOfSpellCheck(pos_type & first, pos_type & last) const
        {
                speller_state_.refreshRange(first, last);
                if (last == -1) {
                        last = owner_->size();
                        return;
                }
                pos_type endpos = last;
                owner_->locateWord(first, endpos, WHOLE_WORD, true);
                if (endpos < last) {
                        endpos = last;
                        owner_->locateWord(last, endpos, WHOLE_WORD, true);
                }
                last = endpos;
        }

        int countSkips(SkipPositionsIterator & it, SkipPositionsIterator const et,
                            int & start) const
        {
                int numskips = 0;
                while (it != et && it->first < start) {
                        long skip = it->last - it->first + 1;
                        start += skip;
                        numskips += skip;
                        ++it;
                }
                return numskips;
        }

        void markMisspelledWords(pos_type const & first, pos_type const & last,
                                                         SpellChecker::Result result,
                                                         docstring const & word,
                                                         SkipPositions const & skips);

        InsetCode ownerCode() const
        {
                return inset_owner_ ? inset_owner_->lyxCode() : NO_CODE;
        }

        /// Which Paragraph owns us?
        Paragraph * owner_;

        /// In which Inset?
        Inset const * inset_owner_;

        ///
        FontList fontlist_;

        ///
        ParagraphParameters params_;

        /// for recording and looking up changes
        Changes changes_;

        ///
        InsetList insetlist_;

        /// end of label
        pos_type begin_of_body_;

        typedef docstring TextContainer;
        ///
        TextContainer text_;

        typedef set<docstring> Words;
        typedef map<string, Words> LangWordsMap;
        ///
        LangWordsMap words_;
        ///
        Layout const * layout_;
        ///
        SpellCheckerState speller_state_;
        ///
        int id_;
};


Paragraph::Private::Private(Paragraph * owner, Layout const & layout)
        : owner_(owner), inset_owner_(nullptr), begin_of_body_(0), layout_(&layout), id_(-1)
{
        text_.reserve(100);
}


//static
int Paragraph::Private::make_id()
{
        // The id is unique per session across buffers because it is used in
        // LFUN_PARAGRAPH_GOTO to switch to a different buffer, for instance in the
        // outliner.
        // (thread-safe)
        static int next_id(0);
        return next_id++;
}


Paragraph::Private::Private(Private const & p, Paragraph * owner)
        : owner_(owner), inset_owner_(p.inset_owner_), fontlist_(p.fontlist_),
          params_(p.params_), changes_(p.changes_), insetlist_(p.insetlist_),
          begin_of_body_(p.begin_of_body_), text_(p.text_), words_(p.words_),
          layout_(p.layout_), id_(make_id())
{
        requestSpellCheck(p.text_.size());
}


Paragraph::Private::Private(Private const & p, Paragraph * owner,
        pos_type beg, pos_type end)
        : owner_(owner), inset_owner_(p.inset_owner_),
          params_(p.params_), changes_(p.changes_),
          insetlist_(p.insetlist_, beg, end),
          begin_of_body_(p.begin_of_body_), words_(p.words_),
          layout_(p.layout_), id_(make_id())
{
        if (beg >= pos_type(p.text_.size()))
                return;
        text_ = p.text_.substr(beg, end - beg);

        FontList::const_iterator fcit = fontlist_.begin();
        FontList::const_iterator fend = fontlist_.end();
        for (; fcit != fend; ++fcit) {
                if (fcit->pos() < beg)
                        continue;
                if (fcit->pos() >= end) {
                        // Add last entry in the fontlist_.
                        fontlist_.set(text_.size() - 1, fcit->font());
                        break;
                }
                // Add a new entry in the fontlist_.
                fontlist_.set(fcit->pos() - beg, fcit->font());
        }
        requestSpellCheck(p.text_.size());
}


void Paragraph::addChangesToToc(DocIterator const & cdit, Buffer const & buf,
                                bool output_active, TocBackend & backend) const
{
        d->changes_.addToToc(cdit, buf, output_active, backend);
}


bool Paragraph::isDeleted(pos_type start, pos_type end) const
{
        LASSERT(start >= 0 && start <= size(), return false);
        LASSERT(end > start && end <= size() + 1, return false);

        return d->changes_.isDeleted(start, end);
}


bool Paragraph::isChanged(pos_type start, pos_type end) const
{
        LASSERT(start >= 0 && start <= size(), return false);
        LASSERT(end > start && end <= size() + 1, return false);

        return d->changes_.isChanged(start, end);
}

// FIXME: Ideally the diverse isChanged() methods should account for that!
bool Paragraph::hasChangedInsets(pos_type start, pos_type end) const
{
        LASSERT(start >= 0 && start <= size(), return false);
        LASSERT(end > start && end <= size() + 1, return false);

        for (auto const & icit : d->insetlist_) {
                if (icit.pos < start)
                        continue;
                if (icit.pos >= end)
                        break;
                if (icit.inset && icit.inset->isChanged())
                        return true;
        }
        return false;
}

bool Paragraph::isChanged() const
{
        return d->changes_.isChanged();
}


bool Paragraph::isMergedOnEndOfParDeletion(bool trackChanges) const
{
        // keep the logic here in sync with the logic of eraseChars()
        if (!trackChanges)
                return true;

        Change const & change = d->changes_.lookup(size());
        return change.inserted() && change.currentAuthor();
}

Change Paragraph::parEndChange() const
{
        return d->changes_.lookup(size());
}


void Paragraph::setChange(Change const & change)
{
        // beware of the imaginary end-of-par character!
        d->changes_.set(change, 0, size() + 1);

        /*
         * Propagate the change recursively - but not in case of DELETED!
         *
         * Imagine that your co-author makes changes in an existing inset. He
         * sends your document to you and you come to the conclusion that the
         * inset should go completely. If you erase it, LyX must not delete all
         * text within the inset. Otherwise, the change tracked insertions of
         * your co-author get lost and there is no way to restore them later.
         *
         * Conclusion: An inset's content should remain untouched if you delete it
         */

        if (!change.deleted()) {
                for (pos_type pos = 0; pos < size(); ++pos) {
                        if (Inset * inset = getInset(pos))
                                inset->setChange(change);
                }
        }
}


void Paragraph::setChange(pos_type pos, Change const & change)
{
        LASSERT(pos >= 0 && pos <= size(), return);
        d->changes_.set(change, pos);

        // see comment in setChange(Change const &) above
        if (!change.deleted() && pos < size())
                if (Inset * inset = getInset(pos))
                        inset->setChange(change);
}


Change const & Paragraph::lookupChange(pos_type pos) const
{
        LBUFERR(pos >= 0 && pos <= size());
        return d->changes_.lookup(pos);
}


void Paragraph::acceptChanges(pos_type start, pos_type end)
{
        LASSERT(start >= 0 && start <= size(), return);
        LASSERT(end > start && end <= size() + 1, return);

        for (pos_type pos = start; pos < end; ++pos) {
                switch (lookupChange(pos).type) {
                        case Change::UNCHANGED:
                                // accept changes in nested inset
                                if (Inset * inset = getInset(pos))
                                        inset->acceptChanges();
                                break;

                        case Change::INSERTED:
                                d->changes_.set(Change(Change::UNCHANGED), pos);
                                // also accept changes in nested inset
                                if (Inset * inset = getInset(pos))
                                        inset->acceptChanges();
                                break;

                        case Change::DELETED:
                                // Suppress access to non-existent
                                // "end-of-paragraph char"
                                if (pos < size()) {
                                        eraseChar(pos, false);
                                        --end;
                                        --pos;
                                }
                                break;
                }

        }
}


void Paragraph::rejectChanges(pos_type start, pos_type end)
{
        LASSERT(start >= 0 && start <= size(), return);
        LASSERT(end > start && end <= size() + 1, return);

        for (pos_type pos = start; pos < end; ++pos) {
                switch (lookupChange(pos).type) {
                        case Change::UNCHANGED:
                                // reject changes in nested inset
                                if (Inset * inset = getInset(pos))
                                                inset->rejectChanges();
                                break;

                        case Change::INSERTED:
                                // Suppress access to non-existent
                                // "end-of-paragraph char"
                                if (pos < size()) {
                                        eraseChar(pos, false);
                                        --end;
                                        --pos;
                                }
                                break;

                        case Change::DELETED:
                                d->changes_.set(Change(Change::UNCHANGED), pos);

                                // Do NOT reject changes within a deleted inset!
                                // There may be insertions of a co-author inside of it!

                                break;
                }
        }
}


void Paragraph::Private::insertChar(pos_type pos, char_type c,
                Change const & change)
{
        LASSERT(pos >= 0 && pos <= int(text_.size()), return);

        // track change
        changes_.insert(change, pos);

        // This is actually very common when parsing buffers (and
        // maybe inserting ascii text)
        if (pos == pos_type(text_.size())) {
                // when appending characters, no need to update tables
                text_.push_back(c);
                // but we want spell checking
                requestSpellCheck(pos);
                return;
        }

        text_.insert(text_.begin() + pos, c);

        // Update the font table.
        fontlist_.increasePosAfterPos(pos);

        // Update the insets
        insetlist_.increasePosAfterPos(pos);

        // Update list of misspelled positions
        speller_state_.increasePosAfterPos(pos);
}


bool Paragraph::insertInset(pos_type pos, Inset * inset,
                                   Font const & font, Change const & change)
{
        LASSERT(inset, return false);
        LASSERT(pos >= 0 && pos <= size(), return false);

        // Paragraph::insertInset() can be used in cut/copy/paste operation where
        // d->inset_owner_ is not set yet.
        if (d->inset_owner_ && !d->inset_owner_->insetAllowed(inset->lyxCode()))
                return false;

        d->insertChar(pos, META_INSET, change);
        LASSERT(d->text_[pos] == META_INSET, return false);

        // Add a new entry in the insetlist_.
        d->insetlist_.insert(inset, pos);

        // Some insets require run of spell checker
        requestSpellCheck(pos);
        setFont(pos, font);
        return true;
}


bool Paragraph::eraseChar(pos_type pos, bool trackChanges)
{
        LASSERT(pos >= 0 && pos <= size(), return false);

        // keep the logic here in sync with the logic of isMergedOnEndOfParDeletion()

        if (trackChanges) {
                Change change = d->changes_.lookup(pos);

                // set the character to DELETED if
                //  a) it was previously unchanged or
                //  b) it was inserted by a co-author

                if (!change.changed() ||
                      (change.inserted() && !change.currentAuthor())) {
                        setChange(pos, Change(Change::DELETED));
                        // request run of spell checker
                        requestSpellCheck(pos);
                        return false;
                }

                if (change.deleted())
                        return false;
        }

        // Don't physically access the imaginary end-of-paragraph character.
        // eraseChar() can only mark it as DELETED. A physical deletion of
        // end-of-par must be handled externally.
        if (pos == size()) {
                return false;
        }

        // track change
        d->changes_.erase(pos);

        // if it is an inset, delete the inset entry
        if (d->text_[pos] == META_INSET)
                d->insetlist_.erase(pos);

        d->text_.erase(d->text_.begin() + pos);

        // Update the fontlist_
        d->fontlist_.erase(pos);

        // Update the insetlist_
        d->insetlist_.decreasePosAfterPos(pos);

        // Update list of misspelled positions
        d->speller_state_.decreasePosAfterPos(pos);
        d->speller_state_.refreshLast(size());

        return true;
}


int Paragraph::eraseChars(pos_type start, pos_type end, bool trackChanges)
{
        LASSERT(start >= 0 && start <= size(), return 0);
        LASSERT(end >= start && end <= size() + 1, return 0);

        pos_type i = start;
        for (pos_type count = end - start; count; --count) {
                if (!eraseChar(i, trackChanges))
                        ++i;
        }
        return end - i;
}

// Handle combining characters
int Paragraph::Private::latexSurrogatePair(BufferParams const & bparams,
                otexstream & os, char_type c, char_type next,
                OutputParams const & runparams)
{
        // Writing next here may circumvent a possible font change between
        // c and next. Since next is only output if it forms a surrogate pair
        // with c we can ignore this:
        // A font change inside a surrogate pair does not make sense and is
        // hopefully impossible to input.
        // FIXME: change tracking
        // Is this correct WRT change tracking?
        Encoding const & encoding = *(runparams.encoding);
        docstring latex1 = encoding.latexChar(next).first;
        if (runparams.inIPA) {
                string const tipashortcut = Encodings::TIPAShortcut(next);
                if (!tipashortcut.empty()) {
                        latex1 = from_ascii(tipashortcut);
                }
        }
        docstring latex2 = encoding.latexChar(c).first;

        if (bparams.useNonTeXFonts || docstring(1, next) == latex1) {
                // Encoding supports the combination:
                // output as is (combining char after base char).
                os << latex2 << latex1;
                return latex1.length() + latex2.length();
        }

        os << latex1 << "{" << latex2 << "}";
        return latex1.length() + latex2.length() + 2;
}


bool Paragraph::Private::simpleTeXBlanks(BufferParams const & bparams,
                                       OutputParams const & runparams,
                                       otexstream & os,
                                       pos_type i,
                                       unsigned int & column,
                                       Font const & font,
                                       Layout const & style)
{
        if (style.pass_thru || runparams.pass_thru)
                return false;

        if (i + 1 < int(text_.size())) {
                char_type next = text_[i + 1];
                if (Encodings::isCombiningChar(next)) {
                        // This space has an accent, so we must always output it.
                        column += latexSurrogatePair(bparams, os, ' ', next, runparams) - 1;
                        return true;
                }
        }

        if (runparams.linelen > 0
            && column > runparams.linelen
            && i
            && text_[i - 1] != ' '
            && (i + 1 < int(text_.size()))
            // same in FreeSpacing mode
            && !owner_->isFreeSpacing()
            // In typewriter mode, we want to avoid
            // ! . ? : at the end of a line
            && !(font.fontInfo().family() == TYPEWRITER_FAMILY
                 && (text_[i - 1] == '.'
                     || text_[i - 1] == '?'
                     || text_[i - 1] == ':'
                     || text_[i - 1] == '!'))) {
                os << '\n';
                os.texrow().start(owner_->id(), i + 1);
                column = 0;
        } else if (style.free_spacing) {
                os << '~';
        } else {
                os << ' ';
        }
        return false;
}


void Paragraph::Private::latexInset(BufferParams const & bparams,
                                    otexstream & os,
                                    OutputParams & runparams,
                                    Font & running_font,
                                    Font & basefont,
                                    Font const & outerfont,
                                    bool & open_font,
                                    Change & running_change,
                                    Layout const & style,
                                    pos_type & i,
                                    unsigned int & column,
                                    bool const fontswitch_inset,
                                    bool const closeLanguage,
                                    bool const lang_switched_at_inset)
{
        Inset * inset = owner_->getInset(i);
        LBUFERR(inset);

        if (style.pass_thru) {
                odocstringstream ods;
                inset->plaintext(ods, runparams);
                os << ods.str();
                return;
        }

        // FIXME: move this to InsetNewline::latex
        if (inset->lyxCode() == NEWLINE_CODE || inset->lyxCode() == SEPARATOR_CODE) {
                // newlines are handled differently here than
                // the default in simpleTeXSpecialChars().
                if (!style.newline_allowed) {
                        os << '\n';
                } else {
                        if (open_font) {
                                bool needPar = false;
                                column += running_font.latexWriteEndChanges(
                                        os, bparams, runparams,
                                        basefont, basefont, needPar);
                                open_font = false;
                        }

                        if (running_font.fontInfo().family() == TYPEWRITER_FAMILY)
                                os << '~';

                        basefont = owner_->getLayoutFont(bparams, outerfont);
                        running_font = basefont;

                        if (runparams.moving_arg)
                                os << "\\protect ";

                }
                os.texrow().start(owner_->id(), i + 1);
                column = 0;
        }

        if (owner_->isDeleted(i)) {
                if( ++runparams.inDeletedInset == 1)
                        runparams.changeOfDeletedInset = owner_->lookupChange(i);
        }

        if (inset->canTrackChanges()) {
                column += Changes::latexMarkChange(os, bparams, running_change,
                        Change(Change::UNCHANGED), runparams);
                running_change = Change(Change::UNCHANGED);
        }

        bool close = false;
        odocstream::pos_type const len = os.os().tellp();

        if (inset->forceLTR(runparams)
            && running_font.isRightToLeft()
            // ERT is an exception, it should be output with no
            // decorations at all
            && inset->lyxCode() != ERT_CODE) {
                if (runparams.use_polyglossia) {
                        os << "\\LRE{";
                } else if (running_font.language()->lang() == "farsi"
                           || running_font.language()->lang() == "arabic_arabi")
                        os << "\\textLR{" << termcmd;
                else
                        os << "\\L{";
                close = true;
        }

        if (open_font && (!inset->inheritFont() || fontswitch_inset)) {
                bool lang_closed = false;
                // Close language if needed
                if (closeLanguage) {
                        // We need prev_font here as language changes directly at inset
                        // will only be started inside the inset.
                        Font const prev_font = (i > 0) ?
                                                owner_->getFont(bparams, i - 1, outerfont)
                                              : running_font;
                        Font tmpfont(basefont);
                        tmpfont.setLanguage(prev_font.language());
                        bool needPar = false;
                        unsigned int count = tmpfont.latexWriteEndChanges(os, bparams, runparams,
                                                                          basefont, basefont,
                                                                          needPar, closeLanguage);
                        column += count;
                        lang_closed = count > 0;
                }
                // Update the running_font, making sure, however,
                // to leave the language as it was.
                // FIXME: probably a better way to keep track of the old
                // language, than copying the entire font?
                Font const copy_font(running_font);
                basefont = owner_->getLayoutFont(bparams, outerfont);
                running_font = basefont;
                if (!closeLanguage)
                        running_font.setLanguage(copy_font.language());
                OutputParams rp = runparams;
                rp.encoding = basefont.language()->encoding();
                // For these, we use switches, so they should be taken as
                // base inside the inset.
                basefont.fontInfo().setSize(copy_font.fontInfo().size());
                basefont.fontInfo().setFamily(copy_font.fontInfo().family());
                basefont.fontInfo().setSeries(copy_font.fontInfo().series());
                // Now re-do font changes in a way needed here
                // (using switches with multi-par insets)
                InsetText const * textinset = inset->asInsetText();
                bool const cprotect = textinset
                        ? textinset->hasCProtectContent(runparams.moving_arg)
                          && !textinset->text().isMainText()
                        : false;
                unsigned int count2 = basefont.latexWriteStartChanges(os, bparams,
                                                      rp, running_font,
                                                      basefont, true,
                                                      cprotect);
                column += count2;
                if (count2 == 0 && (lang_closed || lang_switched_at_inset))
                        // All fonts closed
                        open_font = false;
                if (closeLanguage)
                        runparams.local_font = &basefont;
        }

        size_t const previous_row_count = os.texrow().rows();

        try {
                runparams.lastid = id_;
                runparams.lastpos = i;
                inset->latex(os, runparams);
        } catch (EncodingException & e) {
                // add location information and throw again.
                e.par_id = id_;
                e.pos = i;
                throw(e);
        }

        if (close)
                os << '}';

        if (os.texrow().rows() > previous_row_count) {
                os.texrow().start(owner_->id(), i + 1);
                column = 0;
        } else {
                column += (unsigned int)(os.os().tellp() - len);
        }

        if (owner_->isDeleted(i))
                --runparams.inDeletedInset;
}


void Paragraph::Private::latexSpecialChar(otexstream & os,
                                          BufferParams const & bparams,
                                          OutputParams const & runparams,
                                          Font const & running_font,
                                          string & alien_script,
                                          Layout const & style,
                                          pos_type & i,
                                          pos_type end_pos,
                                          unsigned int & column)
{
        char_type const c = owner_->getUChar(bparams, runparams, i);

        if (style.pass_thru || runparams.pass_thru
            || contains(style.pass_thru_chars, c)
            || contains(runparams.pass_thru_chars, c)) {
                if (c != '\0') {
                        Encoding const * const enc = runparams.encoding;
                        if (enc && !enc->encodable(c))
                                throw EncodingException(c);
                        os.put(c);
                }
                return;
        }

        // TIPA uses its own T3 encoding
        if (runparams.inIPA && latexSpecialT3(c, os, i, column))
                return;
        // If T1 font encoding is used, use the special
        // characters it provides.
        // NOTE: Some languages reset the font encoding internally to a
        //       non-standard font encoding. If we are using such a language,
        //       we do not output special T1 chars.
        if (!runparams.inIPA && !running_font.language()->internalFontEncoding()
            && !runparams.isFullUnicode() && bparams.main_font_encoding() == "T1"
            && latexSpecialT1(c, os, i, column))
                return;
        // NOTE: "fontspec" (non-TeX fonts) sets the font encoding to "TU" (untill 2017 "EU1" or "EU2")
        else if (!runparams.inIPA && !running_font.language()->internalFontEncoding()
                 && runparams.isFullUnicode() && latexSpecialTU(c, os, i, column))
                     return;

        // Otherwise, we use what LaTeX provides us.
        switch (c) {
        case '\\':
                os << "\\textbackslash" << termcmd;
                column += 15;
                break;
        case '<':
                os << "\\textless" << termcmd;
                column += 10;
                break;
        case '>':
                os << "\\textgreater" << termcmd;
                column += 13;
                break;
        case '|':
                os << "\\textbar" << termcmd;
                column += 9;
                break;
        case '-':
                os << '-';
                if (i + 1 < static_cast<pos_type>(text_.size()) &&
                    (end_pos == -1 || i + 1 < end_pos) &&
                    text_[i+1] == '-') {
                        // Prevent "--" becoming an en dash and "---" an em dash.
                        // (Within \ttfamily, "---" is merged to en dash + hyphen.)
                        os << "{}";
                        column += 2;
                }
                break;
        case '\"':
                os << "\\textquotedbl" << termcmd;
                column += 14;
                break;

        case '$': case '&':
        case '%': case '#': case '{':
        case '}': case '_':
                os << '\\';
                os.put(c);
                column += 1;
                break;

        case '~':
                os << "\\textasciitilde" << termcmd;
                column += 16;
                break;

        case '^':
                os << "\\textasciicircum" << termcmd;
                column += 17;
                break;

        case '*':
        case '[':
        case ']':
                // avoid being mistaken for optional arguments
                os << '{';
                os.put(c);
                os << '}';
                column += 2;
                break;

        case ' ':
                // Blanks are printed before font switching.
                // Sure? I am not! (try nice-latex)
                // I am sure it's correct. LyX might be smarter
                // in the future, but for now, nothing wrong is
                // written. (Asger)
                break;

        case 0x2013:
        case 0x2014:
                // XeTeX's dash behaviour is determined via a global setting
                if (bparams.use_dash_ligatures
                    && owner_->getFontSettings(bparams, i).fontInfo().family() != TYPEWRITER_FAMILY
                    && !runparams.inIPA
                        // TODO #10961: && not in inset Flex Code
                        // TODO #10961: && not in layout LyXCode
                    && (!bparams.useNonTeXFonts || runparams.flavor != OutputParams::XETEX)) {
                        if (c == 0x2013) {
                                // en-dash
                                os << "--";
                                column +=2;
                        } else {
                                // em-dash
                                os << "---";
                                column +=3;
                        }
                        break;
                }
                // fall through
        default:
                if (c == '\0')
                        return;

                Encoding const & encoding = *(runparams.encoding);
                char_type next = '\0';
                if (i + 1 < int(text_.size())) {
                        next = text_[i + 1];
                        if (Encodings::isCombiningChar(next)) {
                                column += latexSurrogatePair(bparams, os, c, next, runparams) - 1;
                                ++i;
                                break;
                        }
                }
                pair<docstring, bool> latex = encoding.latexChar(c);
                docstring nextlatex;
                bool nexttipas = false;
                string nexttipashortcut;
                if (next != '\0' && next != META_INSET && !encoding.encodable(next)) {
                        nextlatex = encoding.latexChar(next).first;
                        if (runparams.inIPA) {
                                nexttipashortcut = Encodings::TIPAShortcut(next);
                                nexttipas = !nexttipashortcut.empty();
                        }
                }
                bool tipas = false;
                if (runparams.inIPA) {
                        string const tipashortcut = Encodings::TIPAShortcut(c);
                        if (!tipashortcut.empty()) {
                                latex.first = from_ascii(tipashortcut);
                                latex.second = false;
                                tipas = true;
                        }
                }
                // eventually close "script wrapper" command (see `Paragraph::latex`)
                if (!alien_script.empty()
                        && alien_script != Encodings::isKnownScriptChar(next)) {
                        column += latex.first.length();
                        alien_script.clear();
                        os << latex.first << "}";
                        break;
                }
                if (latex.second
                         && ((!prefixIs(nextlatex, '\\')
                               && !prefixIs(nextlatex, '{')
                               && !prefixIs(nextlatex, '}'))
                             || (nexttipas
                                 && !prefixIs(from_ascii(nexttipashortcut), '\\')))
                         && !tipas) {
                        // Prevent eating of a following space or command corruption by
                        // following characters
                        if (next == ' ' || next == '\0') {
                                column += latex.first.length() + 1;
                                os << latex.first << "{}";
                        } else {
                                column += latex.first.length();
                                os << latex.first << " ";
                        }
                } else {
                        column += latex.first.length() - 1;
                        os << latex.first;
                }
                break;
        }
}


bool Paragraph::Private::latexSpecialT1(char_type const c, otexstream & os,
        pos_type i, unsigned int & column)
{
        switch (c) {
        case '>':
        case '<':
                os.put(c);
                // In T1 encoding, these characters exist
                // but we should avoid ligatures
                if (i + 1 >= int(text_.size()) || text_[i + 1] != c)
                        return true;
                os << "\\textcompwordmark" << termcmd;
                column += 19;
                return true;
        case '|':
                os.put(c);
                return true;
        case '\"':
                // soul.sty breaks with \char`\"
                os << "\\textquotedbl" << termcmd;
                column += 14;
                return true;
        default:
                return false;
        }
}


bool Paragraph::Private::latexSpecialTU(char_type const c, otexstream & os,
        pos_type i, unsigned int & column)
{
        // TU encoding is currently on par with T1.
        return latexSpecialT1(c, os, i, column);
}


bool Paragraph::Private::latexSpecialT3(char_type const c, otexstream & os,
        pos_type /*i*/, unsigned int & column)
{
        switch (c) {
        case '*':
        case '[':
        case ']':
        case '\"':
                os.put(c);
                return true;
        case '|':
                os << "\\textvertline" << termcmd;
                column += 14;
                return true;
        default:
                return false;
        }
}


void Paragraph::Private::validate(LaTeXFeatures & features) const
{
        if (layout_->inpreamble && inset_owner_) {
                // FIXME: Using a string stream here circumvents the encoding
                // switching machinery of odocstream. Therefore the
                // output is wrong if this paragraph contains content
                // that needs to switch encoding.
                Buffer const & buf = inset_owner_->buffer();
                otexstringstream os;
                os << layout_->preamble();
                size_t const length = os.length();
                TeXOnePar(buf, *inset_owner_->getText(int(buf.getParFromID(owner_->id()).idx())),
                          buf.getParFromID(owner_->id()).pit(), os,
                          features.runparams(), string(), 0, -1, true);
                if (os.length() > length)
                        features.addPreambleSnippet(os.release(), true);
        }

        if (features.runparams().flavor == OutputParams::HTML
            && layout_->htmltitle()) {
                features.setHTMLTitle(owner_->asString(AS_STR_INSETS | AS_STR_SKIPDELETE));
        }

        // check the params.
        if (!params_.spacing().isDefault())
                features.require("setspace");

        // then the layouts
        features.useLayout(layout_->name());

        // then the fonts
        fontlist_.validate(features);

        // then the indentation
        if (!params_.leftIndent().zero())
                features.require("ParagraphLeftIndent");

        // then the insets
        InsetList::const_iterator icit = insetlist_.begin();
        InsetList::const_iterator iend = insetlist_.end();
        for (; icit != iend; ++icit) {
                if (icit->inset) {
                        features.inDeletedInset(owner_->isDeleted(icit->pos));
                        if (icit->inset->lyxCode() == FOOT_CODE) {
                                // FIXME: an item inset would make things much easier.
                                if ((layout_->latextype == LATEX_LIST_ENVIRONMENT
                                     || (layout_->latextype == LATEX_ITEM_ENVIRONMENT
                                         && layout_->margintype == MARGIN_FIRST_DYNAMIC))
                                    && (icit->pos < begin_of_body_
                                        || (icit->pos == begin_of_body_
                                            && (icit->pos == 0 || text_[icit->pos - 1] != ' '))))
                                        features.saveNoteEnv("description");
                        }
                        icit->inset->validate(features);
                        features.inDeletedInset(false);
                        if (layout_->needprotect &&
                            icit->inset->lyxCode() == FOOT_CODE)
                                features.require("NeedLyXFootnoteCode");
                }
        }

        // then the contents
        BufferParams const bp = features.runparams().is_child
                ? features.buffer().masterParams() : features.buffer().params();
        for (pos_type i = 0; i < int(text_.size()) ; ++i) {
                char_type c = text_[i];
                CharInfo const & ci = Encodings::unicodeCharInfo(c);
                if (c == 0x0022) {
                        if (features.runparams().isFullUnicode() && bp.useNonTeXFonts)
                                features.require("textquotedblp");
                        else if (bp.main_font_encoding() != "T1"
                                 || ((&owner_->getFontSettings(bp, i))->language()->internalFontEncoding()))
                                features.require("textquotedbl");
                } else if (ci.textfeature() && contains(ci.textpreamble(), '=')) {
                        // features that depend on the font or input encoding
                        string feats = ci.textpreamble();
                        string fontenc = (&owner_->getFontSettings(bp, i))->language()->fontenc(bp);
                        if (fontenc.empty())
                                fontenc = features.runparams().main_fontenc;
                        while (!feats.empty()) {
                                string feat;
                                feats = split(feats, feat, ',');
                                if (contains(feat, "!=")) {
                                        // a feature that is required except for the spcified
                                        // font or input encodings
                                        string realfeature;
                                        string const contexts = ltrim(split(feat, realfeature, '!'), "=");
                                        // multiple encodings are separated by semicolon
                                        vector<string> context = getVectorFromString(contexts, ";");
                                        // require feature if the context matches neither current font
                                        // nor input encoding
                                        if (std::find(context.begin(), context.end(), fontenc) == context.end()
                                            && std::find(context.begin(), context.end(),
                                                         features.runparams().encoding->name()) == context.end())
                                                features.require(realfeature);
                                } else if (contains(feat, '=')) {
                                        // a feature that is required only for the spcified
                                        // font or input encodings
                                        string realfeature;
                                        string const contexts = split(feat, realfeature, '=');
                                        // multiple encodings are separated by semicolon
                                        vector<string> context = getVectorFromString(contexts, ";");
                                        // require feature if the context matches either current font
                                        // or input encoding
                                        if (std::find(context.begin(), context.end(), fontenc) != context.end()
                                            || std::find(context.begin(), context.end(),
                                                         features.runparams().encoding->name()) != context.end())
                                                features.require(realfeature);
                                }
                        }
                } else if (!bp.use_dash_ligatures
                           && (c == 0x2013 || c == 0x2014)
                           && bp.useNonTeXFonts
                           && features.runparams().flavor == OutputParams::XETEX)
                        // XeTeX's dash behaviour is determined via a global setting
                        features.require("xetexdashbreakstate");
                BufferEncodings::validate(c, features);
        }
}

/////////////////////////////////////////////////////////////////////
//
// Paragraph
//
/////////////////////////////////////////////////////////////////////

namespace {
        Layout const emptyParagraphLayout;
}

Paragraph::Paragraph()
        : d(new Paragraph::Private(this, emptyParagraphLayout))
{
        itemdepth = 0;
        d->params_.clear();
}


Paragraph::Paragraph(Paragraph const & par)
        : itemdepth(par.itemdepth),
        d(new Paragraph::Private(*par.d, this))
{
        registerWords();
}


Paragraph::Paragraph(Paragraph const & par, pos_type beg, pos_type end)
        : itemdepth(par.itemdepth),
        d(new Paragraph::Private(*par.d, this, beg, end))
{
        registerWords();
}


Paragraph & Paragraph::operator=(Paragraph const & par)
{
        // needed as we will destroy the private part before copying it
        if (&par != this) {
                itemdepth = par.itemdepth;

                deregisterWords();
                delete d;
                d = new Private(*par.d, this);
                registerWords();
        }
        return *this;
}


Paragraph::~Paragraph()
{
        deregisterWords();
        delete d;
}


namespace {

// this shall be called just before every "os << ..." action.
void flushString(ostream & os, docstring & s)
{
        os << to_utf8(s);
        s.erase();
}

} // namespace


void Paragraph::write(ostream & os, BufferParams const & bparams,
        depth_type & dth) const
{
        // The beginning or end of a deeper (i.e. nested) area?
        if (dth != d->params_.depth()) {
                if (d->params_.depth() > dth) {
                        while (d->params_.depth() > dth) {
                                os << "\n\\begin_deeper";
                                ++dth;
                        }
                } else {
                        while (d->params_.depth() < dth) {
                                os << "\n\\end_deeper";
                                --dth;
                        }
                }
        }

        // First write the layout
        os << "\n\\begin_layout " << to_utf8(d->layout_->name()) << '\n';

        d->params_.write(os);

        Font font1(inherit_font, bparams.language);

        Change running_change = Change(Change::UNCHANGED);

        // this string is used as a buffer to avoid repetitive calls
        // to to_utf8(), which turn out to be expensive (JMarc)
        docstring write_buffer;

        int column = 0;
        for (pos_type i = 0; i <= size(); ++i) {

                Change const & change = lookupChange(i);
                if (change != running_change)
                        flushString(os, write_buffer);
                Changes::lyxMarkChange(os, bparams, column, running_change, change);
                running_change = change;

                if (i == size())
                        break;

                // Write font changes
                Font font2 = getFontSettings(bparams, i);
                if (font2 != font1) {
                        flushString(os, write_buffer);
                        font2.lyxWriteChanges(font1, os);
                        column = 0;
                        font1 = font2;
                }

                char_type const c = d->text_[i];
                switch (c) {
                case META_INSET:
                        if (Inset const * inset = getInset(i)) {
                                flushString(os, write_buffer);
                                if (inset->directWrite()) {
                                        // international char, let it write
                                        // code directly so it's shorter in
                                        // the file
                                        inset->write(os);
                                } else {
                                        if (i)
                                                os << '\n';
                                        os << "\\begin_inset ";
                                        inset->write(os);
                                        os << "\n\\end_inset\n\n";
                                        column = 0;
                                }
                                // FIXME This can be removed again once the mystery
                                // crash has been resolved.
                                os << flush;
                        }
                        break;
                case '\\':
                        flushString(os, write_buffer);
                        os << "\n\\backslash\n";
                        column = 0;
                        break;
                case '.':
                        flushString(os, write_buffer);
                        if (i + 1 < size() && d->text_[i + 1] == ' ') {
                                os << ".\n";
                                column = 0;
                        } else
                                os << '.';
                        break;
                default:
                        if ((column > 70 && c == ' ')
                            || column > 79) {
                                flushString(os, write_buffer);
                                os << '\n';
                                column = 0;
                        }
                        // this check is to amend a bug. LyX sometimes
                        // inserts '\0' this could cause problems.
                        if (c != '\0')
                                write_buffer.push_back(c);
                        else
                                LYXERR0("NUL char in structure.");
                        ++column;
                        break;
                }
        }

        flushString(os, write_buffer);
        os << "\n\\end_layout\n";
        // FIXME This can be removed again once the mystery
        // crash has been resolved.
        os << flush;
}


void Paragraph::validate(LaTeXFeatures & features) const
{
        d->validate(features);
        bool fragile = features.runparams().moving_arg;
        fragile |= layout().needprotect;
        if (inInset().getLayout().isNeedProtect())
                fragile = true;
        if (needsCProtection(fragile))
                features.require("cprotect");
}


void Paragraph::insert(pos_type start, docstring const & str,
                       Font const & font, Change const & change)
{
        for (size_t i = 0, n = str.size(); i != n ; ++i)
                insertChar(start + i, str[i], font, change);
}


void Paragraph::appendChar(char_type c, Font const & font,
                Change const & change)
{
        // track change
        d->changes_.insert(change, d->text_.size());
        // when appending characters, no need to update tables
        d->text_.push_back(c);
        setFont(d->text_.size() - 1, font);
        d->requestSpellCheck(d->text_.size() - 1);
}


void Paragraph::appendString(docstring const & s, Font const & font,
                Change const & change)
{
        pos_type end = s.size();
        size_t oldsize = d->text_.size();
        size_t newsize = oldsize + end;
        size_t capacity = d->text_.capacity();
        if (newsize >= capacity)
                d->text_.reserve(max(capacity + 100, newsize));

        // when appending characters, no need to update tables
        d->text_.append(s);

        // FIXME: Optimize this!
        for (size_t i = oldsize; i != newsize; ++i) {
                // track change
                d->changes_.insert(change, i);
                d->requestSpellCheck(i);
        }
        d->fontlist_.set(oldsize, font);
        d->fontlist_.set(newsize - 1, font);
}


void Paragraph::insertChar(pos_type pos, char_type c,
                           bool trackChanges)
{
        d->insertChar(pos, c, Change(trackChanges ?
                           Change::INSERTED : Change::UNCHANGED));
}


void Paragraph::insertChar(pos_type pos, char_type c,
                           Font const & font, bool trackChanges)
{
        d->insertChar(pos, c, Change(trackChanges ?
                           Change::INSERTED : Change::UNCHANGED));
        setFont(pos, font);
}


void Paragraph::insertChar(pos_type pos, char_type c,
                           Font const & font, Change const & change)
{
        d->insertChar(pos, c, change);
        setFont(pos, font);
}


void Paragraph::resetFonts(Font const & font)
{
        d->fontlist_.clear();
        d->fontlist_.set(0, font);
        d->fontlist_.set(d->text_.size() - 1, font);
}

// Gets uninstantiated font setting at position.
Font const & Paragraph::getFontSettings(BufferParams const & bparams,
                                         pos_type pos) const
{
        if (pos > size()) {
                LYXERR0("pos: " << pos << " size: " << size());
                LBUFERR(false);
        }

        FontList::const_iterator cit = d->fontlist_.fontIterator(pos);
        if (cit != d->fontlist_.end())
                return cit->font();

        if (pos == size() && !empty())
                return getFontSettings(bparams, pos - 1);

        // Optimisation: avoid a full font instantiation if there is no
        // language change from previous call.
        static Font previous_font;
        static Language const * previous_lang = nullptr;
        Language const * lang = getParLanguage(bparams);
        if (lang != previous_lang) {
                previous_lang = lang;
                previous_font = Font(inherit_font, lang);
        }
        return previous_font;
}


FontSpan Paragraph::fontSpan(pos_type pos) const
{
        LBUFERR(pos <= size());

        if (pos == size())
                return FontSpan(pos, pos);

        pos_type start = 0;
        FontList::const_iterator cit = d->fontlist_.begin();
        FontList::const_iterator end = d->fontlist_.end();
        for (; cit != end; ++cit) {
                if (cit->pos() >= pos) {
                        if (pos >= beginOfBody())
                                return FontSpan(max(start, beginOfBody()),
                                                cit->pos());
                        else
                                return FontSpan(start,
                                                min(beginOfBody() - 1,
                                                         cit->pos()));
                }
                start = cit->pos() + 1;
        }

        // This should not happen, but if so, we take no chances.
        LYXERR0("Paragraph::fontSpan: position not found in fontinfo table!");
        LASSERT(false, return FontSpan(pos, pos));
}


// Gets uninstantiated font setting at position 0
Font const & Paragraph::getFirstFontSettings(BufferParams const & bparams) const
{
        if (!empty() && !d->fontlist_.empty())
                return d->fontlist_.begin()->font();

        // Optimisation: avoid a full font instantiation if there is no
        // language change from previous call.
        static Font previous_font;
        static Language const * previous_lang = nullptr;
        if (bparams.language != previous_lang) {
                previous_lang = bparams.language;
                previous_font = Font(inherit_font, bparams.language);
        }

        return previous_font;
}


// Gets the fully instantiated font at a given position in a paragraph
// This is basically the same function as Text::GetFont() in text2.cpp.
// The difference is that this one is used for generating the LaTeX file,
// and thus cosmetic "improvements" are disallowed: This has to deliver
// the true picture of the buffer. (Asger)
Font const Paragraph::getFont(BufferParams const & bparams, pos_type pos,
                                 Font const & outerfont) const
{
        LBUFERR(pos >= 0);

        Font font = getFontSettings(bparams, pos);

        pos_type const body_pos = beginOfBody();
        FontInfo & fi = font.fontInfo();
        if (pos < body_pos)
                fi.realize(d->layout_->labelfont);
        else
                fi.realize(d->layout_->font);

        fi.realize(outerfont.fontInfo());
        fi.realize(bparams.getFont().fontInfo());

        return font;
}


Font const Paragraph::getLabelFont
        (BufferParams const & bparams, Font const & outerfont) const
{
        FontInfo tmpfont = d->layout_->labelfont;
        tmpfont.realize(outerfont.fontInfo());
        tmpfont.realize(bparams.getFont().fontInfo());
        return Font(tmpfont, getParLanguage(bparams));
}


Font const Paragraph::getLayoutFont
        (BufferParams const & bparams, Font const & outerfont) const
{
        FontInfo tmpfont = d->layout_->font;
        tmpfont.realize(outerfont.fontInfo());
        tmpfont.realize(bparams.getFont().fontInfo());
        return Font(tmpfont, getParLanguage(bparams));
}


char_type Paragraph::getUChar(BufferParams const & bparams,
                              OutputParams const & rp,
                              pos_type pos) const
{
        char_type c = d->text_[pos];

        // Return unchanged character in LTR languages
        // or if we use poylglossia/bidi (XeTeX).
        if (rp.useBidiPackage()
            || !getFontSettings(bparams, pos).isRightToLeft())
                return c;

        // Without polyglossia/bidi, we need to account for some special cases.
        // FIXME This needs to be audited!
        // Check if:
        // * The input is as expected for all delimiters
        //   => checked for Hebrew!
        // * The output matches the display in the LyX workarea
        //   => checked for Hebrew!
        // * The special cases below are really necessary
        //   => checked for Hebrew!
        // * In arabic_arabi, brackets are transformed to Arabic
        //   Ornate Parentheses. Is this is really wanted?

        string const & lang = getFontSettings(bparams, pos).language()->lang();
        char_type uc = c;

        // 1. In the following languages, parentheses need to be reversed.
        //    Also with polyglodia/luabidi
        bool const reverseparens = (lang == "hebrew" || rp.use_polyglossia);

        // 2. In the following languages, brackets don't need to be reversed.
        bool const reversebrackets = lang != "arabic_arabtex"
                        && lang != "arabic_arabi"
                        && lang != "farsi";

        // Now swap delimiters if needed.
        switch (c) {
        case '(':
                if (reverseparens)
                        uc = ')';
                break;
        case ')':
                if (reverseparens)
                        uc = '(';
                break;
        case '[':
                if (reversebrackets)
                        uc = ']';
                break;
        case ']':
                if (reversebrackets)
                        uc = '[';
                break;
        case '{':
                uc = '}';
                break;
        case '}':
                uc = '{';
                break;
        case '<':
                uc = '>';
                break;
        case '>':
                uc = '<';
                break;
        }

        return uc;
}


void Paragraph::setFont(pos_type pos, Font const & font)
{
        LASSERT(pos <= size(), return);

        // First, reduce font against layout/label font
        // Update: The setCharFont() routine in text2.cpp already
        // reduces font, so we don't need to do that here. (Asger)

        d->fontlist_.set(pos, font);
}


void Paragraph::makeSameLayout(Paragraph const & par)
{
        d->layout_ = par.d->layout_;
        d->params_ = par.d->params_;
}


bool Paragraph::stripLeadingSpaces(bool trackChanges)
{
        if (isFreeSpacing())
                return false;

        int pos = 0;
        int count = 0;

        while (pos < size() && (isNewline(pos) || isLineSeparator(pos))) {
                if (eraseChar(pos, trackChanges))
                        ++count;
                else
                        ++pos;
        }

        return count > 0 || pos > 0;
}


bool Paragraph::hasSameLayout(Paragraph const & par) const
{
        return par.d->layout_ == d->layout_
                && d->params_.sameLayout(par.d->params_);
}


depth_type Paragraph::getDepth() const
{
        return d->params_.depth();
}


depth_type Paragraph::getMaxDepthAfter() const
{
        if (d->layout_->isEnvironment())
                return d->params_.depth() + 1;
        else
                return d->params_.depth();
}


LyXAlignment Paragraph::getAlign(BufferParams const & bparams) const
{
        if (d->params_.align() == LYX_ALIGN_LAYOUT)
                return getDefaultAlign(bparams);
        else
                return d->params_.align();
}


LyXAlignment Paragraph::getDefaultAlign(BufferParams const & bparams) const
{
        LyXAlignment res = layout().align;
        if (isRTL(bparams)) {
                // Swap sides
                if (res == LYX_ALIGN_LEFT)
                        res = LYX_ALIGN_RIGHT;
                else if  (res == LYX_ALIGN_RIGHT)
                        res = LYX_ALIGN_LEFT;
        }
        return res;
}


docstring const & Paragraph::labelString() const
{
        return d->params_.labelString();
}


// the next two functions are for the manual labels
docstring const Paragraph::getLabelWidthString() const
{
        if (d->layout_->margintype == MARGIN_MANUAL
            || d->layout_->latextype == LATEX_BIB_ENVIRONMENT)
                return d->params_.labelWidthString();
        else
                return _("Senseless with this layout!");
}


void Paragraph::setLabelWidthString(docstring const & s)
{
        d->params_.labelWidthString(s);
}


docstring Paragraph::expandLabel(Layout const & layout,
                BufferParams const & bparams) const
{
        return expandParagraphLabel(layout, bparams, true);
}


docstring Paragraph::expandParagraphLabel(Layout const & layout,
                BufferParams const & bparams, bool process_appendix) const
{
        DocumentClass const & tclass = bparams.documentClass();
        string const & lang = getParLanguage(bparams)->code();
        bool const in_appendix = process_appendix && d->params_.appendix();
        docstring fmt = translateIfPossible(layout.labelstring(in_appendix), lang);

        if (fmt.empty() && !layout.counter.empty())
                return tclass.counters().theCounter(layout.counter, lang);

        // handle 'inherited level parts' in 'fmt',
        // i.e. the stuff between '@' in   '@Section@.\arabic{subsection}'
        size_t const i = fmt.find('@', 0);
        if (i != docstring::npos) {
                size_t const j = fmt.find('@', i + 1);
                if (j != docstring::npos) {
                        docstring parent(fmt, i + 1, j - i - 1);
                        docstring label = from_ascii("??");
                        if (tclass.hasLayout(parent))
                                label = expandParagraphLabel(tclass[parent], bparams,
                                                      process_appendix);
                        fmt = docstring(fmt, 0, i) + label
                                + docstring(fmt, j + 1, docstring::npos);
                }
        }

        return tclass.counters().counterLabel(fmt, lang);
}


void Paragraph::applyLayout(Layout const & new_layout)
{
        d->layout_ = &new_layout;
        LyXAlignment const oldAlign = d->params_.align();

        if (!(oldAlign & d->layout_->alignpossible)) {
                frontend::Alert::warning(_("Alignment not permitted"),
                        _("The new layout does not permit the alignment previously used.\nSetting to default."));
                d->params_.align(LYX_ALIGN_LAYOUT);
        }
}


pos_type Paragraph::beginOfBody() const
{
        return d->begin_of_body_;
}


void Paragraph::setBeginOfBody()
{
        if (d->layout_->labeltype != LABEL_MANUAL) {
                d->begin_of_body_ = 0;
                return;
        }

        // Unroll the first two cycles of the loop
        // and remember the previous character to
        // remove unnecessary getChar() calls
        pos_type i = 0;
        pos_type end = size();
        bool prev_char_deleted = false;
        if (i < end && (!(isNewline(i) || isEnvSeparator(i)) || isDeleted(i))) {
                ++i;
                if (i < end) {
                        char_type previous_char = d->text_[i];
                        if (!(isNewline(i) || isEnvSeparator(i))) {
                                ++i;
                                while (i < end && (previous_char != ' ' || prev_char_deleted)) {
                                        char_type temp = d->text_[i];
                                        prev_char_deleted = isDeleted(i);
                                        if (!isDeleted(i) && (isNewline(i) || isEnvSeparator(i)))
                                                break;
                                        ++i;
                                        previous_char = temp;
                                }
                        }
                }
        }

        d->begin_of_body_ = i;
}


bool Paragraph::allowParagraphCustomization() const
{
        return inInset().allowParagraphCustomization();
}


bool Paragraph::usePlainLayout() const
{
        return inInset().usePlainLayout();
}


bool Paragraph::isPassThru() const
{
        return inInset().isPassThru() || d->layout_->pass_thru;
}

namespace {

// paragraphs inside floats need different alignment tags to avoid
// unwanted space

bool noTrivlistCentering(InsetCode code)
{
        return code == FLOAT_CODE
               || code == WRAP_CODE
               || code == CELL_CODE;
}


string correction(string const & orig)
{
        if (orig == "flushleft")
                return "raggedright";
        if (orig == "flushright")
                return "raggedleft";
        if (orig == "center")
                return "centering";
        return orig;
}


bool corrected_env(otexstream & os, string const & suffix, string const & env,
        InsetCode code, bool const lastpar, int & col)
{
        string macro = suffix + "{";
        if (noTrivlistCentering(code)) {
                if (lastpar) {
                        // the last paragraph in non-trivlist-aligned
                        // context is special (to avoid unwanted whitespace)
                        if (suffix == "\\begin") {
                                macro = "\\" + correction(env) + "{}";
                                os << from_ascii(macro);
                                col += macro.size();
                                return true;
                        }
                        return false;
                }
                macro += correction(env);
        } else
                macro += env;
        macro += "}";
        if (suffix == "\\par\\end") {
                os << breakln;
                col = 0;
        }
        os << from_ascii(macro);
        col += macro.size();
        if (suffix == "\\begin") {
                os << breakln;
                col = 0;
        }
        return true;
}

} // namespace


int Paragraph::Private::startTeXParParams(BufferParams const & bparams,
                        otexstream & os, OutputParams const & runparams) const
{
        int column = 0;

        bool canindent =
                (bparams.paragraph_separation == BufferParams::ParagraphIndentSeparation) ?
                        (layout_->toggle_indent != ITOGGLE_NEVER) :
                        (layout_->toggle_indent == ITOGGLE_ALWAYS);

        if (canindent && params_.noindent() && !layout_->pass_thru) {
                os << "\\noindent ";
                column += 10;
        }

        LyXAlignment const curAlign = params_.align();

        if (curAlign == layout_->align)
                return column;

        switch (curAlign) {
        case LYX_ALIGN_NONE:
        case LYX_ALIGN_BLOCK:
        case LYX_ALIGN_LAYOUT:
        case LYX_ALIGN_SPECIAL:
        case LYX_ALIGN_DECIMAL:
                break;
        case LYX_ALIGN_LEFT:
        case LYX_ALIGN_RIGHT:
        case LYX_ALIGN_CENTER:
                if (runparams.moving_arg) {
                        os << "\\protect";
                        column += 8;
                }
                break;
        }

        string const begin_tag = "\\begin";
        InsetCode code = ownerCode();
        bool const lastpar = runparams.isLastPar;
        // RTL in classic (PDF)LaTeX (without the Bidi package)
        // Luabibdi (used by LuaTeX) behaves like classic
        bool const rtl_classic = owner_->getParLanguage(bparams)->rightToLeft()
                && !runparams.useBidiPackage();

        switch (curAlign) {
        case LYX_ALIGN_NONE:
        case LYX_ALIGN_BLOCK:
        case LYX_ALIGN_LAYOUT:
        case LYX_ALIGN_SPECIAL:
        case LYX_ALIGN_DECIMAL:
                break;
        case LYX_ALIGN_LEFT: {
                if (rtl_classic)
                        // Classic (PDF)LaTeX switches the left/right logic in RTL mode
                        corrected_env(os, begin_tag, "flushright", code, lastpar, column);
                else
                        corrected_env(os, begin_tag, "flushleft", code, lastpar, column);
                break;
        } case LYX_ALIGN_RIGHT: {
                if (rtl_classic)
                        // Classic (PDF)LaTeX switches the left/right logic in RTL mode
                        corrected_env(os, begin_tag, "flushleft", code, lastpar, column);
                else
                        corrected_env(os, begin_tag, "flushright", code, lastpar, column);
                break;
        } case LYX_ALIGN_CENTER: {
                corrected_env(os, begin_tag, "center", code, lastpar, column);
                break;
        }
        }

        return column;
}


bool Paragraph::Private::endTeXParParams(BufferParams const & bparams,
                        otexstream & os, OutputParams const & runparams) const
{
        LyXAlignment const curAlign = params_.align();

        if (curAlign == layout_->align)
                return false;

        switch (curAlign) {
        case LYX_ALIGN_NONE:
        case LYX_ALIGN_BLOCK:
        case LYX_ALIGN_LAYOUT:
        case LYX_ALIGN_SPECIAL:
        case LYX_ALIGN_DECIMAL:
                break;
        case LYX_ALIGN_LEFT:
        case LYX_ALIGN_RIGHT:
        case LYX_ALIGN_CENTER:
                if (runparams.moving_arg)
                        os << "\\protect";
                break;
        }

        bool output = false;
        int col = 0;
        string const end_tag = "\\par\\end";
        InsetCode code = ownerCode();
        bool const lastpar = runparams.isLastPar;
        // RTL in classic (PDF)LaTeX (without the Bidi package)
        // Luabibdi (used by LuaTeX) behaves like classic
        bool const rtl_classic = owner_->getParLanguage(bparams)->rightToLeft()
                && !runparams.useBidiPackage();

        switch (curAlign) {
        case LYX_ALIGN_NONE:
        case LYX_ALIGN_BLOCK:
        case LYX_ALIGN_LAYOUT:
        case LYX_ALIGN_SPECIAL:
        case LYX_ALIGN_DECIMAL:
                break;
        case LYX_ALIGN_LEFT: {
                if (rtl_classic)
                        // Classic (PDF)LaTeX switches the left/right logic in RTL mode
                        output = corrected_env(os, end_tag, "flushright", code, lastpar, col);
                else
                        output = corrected_env(os, end_tag, "flushleft", code, lastpar, col);
                break;
        } case LYX_ALIGN_RIGHT: {
                if (rtl_classic)
                        // Classic (PDF)LaTeX switches the left/right logic in RTL mode
                        output = corrected_env(os, end_tag, "flushleft", code, lastpar, col);
                else
                        output = corrected_env(os, end_tag, "flushright", code, lastpar, col);
                break;
        } case LYX_ALIGN_CENTER: {
                corrected_env(os, end_tag, "center", code, lastpar, col);
                break;
        }
        }

        return output || lastpar;
}


// This one spits out the text of the paragraph
void Paragraph::latex(BufferParams const & bparams,
        Font const & outerfont,
        otexstream & os,
        OutputParams const & runparams,
        int start_pos, int end_pos, bool force) const
{
        LYXERR(Debug::LATEX, "Paragraph::latex...     " << this);

        // FIXME This check should not be needed. Perhaps issue an
        // error if it triggers.
        Layout const & style = inInset().forcePlainLayout() ?
                bparams.documentClass().plainLayout() : *d->layout_;

        if (!force && style.inpreamble)
                return;

        bool const allowcust = allowParagraphCustomization();

        // Current base font for all inherited font changes, without any
        // change caused by an individual character, except for the language:
        // It is set to the language of the first character.
        // As long as we are in the label, this font is the base font of the
        // label. Before the first body character it is set to the base font
        // of the body.
        Font basefont;

        // If there is an open font-encoding changing command (script wrapper),
        // alien_script is set to its name
        string alien_script;
        string script;

        // Maybe we have to create a optional argument.
        pos_type body_pos = beginOfBody();
        unsigned int column = 0;

        // If we are inside an non inheritFont() inset, the real outerfont is local_font
        Font const real_outerfont = (!inInset().inheritFont()
                                     && runparams.local_font != nullptr)
                        ? Font(runparams.local_font->fontInfo()) : outerfont;

        if (body_pos > 0) {
                // the optional argument is kept in curly brackets in
                // case it contains a ']'
                // This is not strictly needed, but if this is changed it
                // would be a file format change, and tex2lyx would need
                // to be adjusted, since it unconditionally removes the
                // braces when it parses \item.
                os << "[{";
                column += 2;
                basefont = getLabelFont(bparams, real_outerfont);
        } else {
                basefont = getLayoutFont(bparams, real_outerfont);
        }

        // Which font is currently active?
        Font running_font(basefont);
        // Do we have an open font change?
        bool open_font = false;

        Change runningChange = Change(Change::UNCHANGED);

        Encoding const * const prev_encoding = runparams.encoding;

        os.texrow().start(id(), 0);

        // if the paragraph is empty, the loop will not be entered at all
        if (empty()) {
                // For InTitle commands, we have already opened a group
                // in output_latex::TeXOnePar.
                if (style.isCommand() && !style.intitle) {
                        os << '{';
                        ++column;
                }
                if (!style.leftdelim().empty()) {
                        os << style.leftdelim();
                        column += style.leftdelim().size();
                }
                if (allowcust)
                        column += d->startTeXParParams(bparams, os, runparams);
        }

        // Whether a \par can be issued for insets typeset inline with text.
        // Yes if greater than 0. This has to be static.
        THREAD_LOCAL_STATIC int parInline = 0;

        for (pos_type i = 0; i < size(); ++i) {
                // First char in paragraph or after label?
                if (i == body_pos) {
                        if (body_pos > 0) {
                                if (open_font) {
                                        bool needPar = false;
                                        column += running_font.latexWriteEndChanges(
                                                os, bparams, runparams,
                                                basefont, basefont, needPar);
                                        open_font = false;
                                }
                                basefont = getLayoutFont(bparams, real_outerfont);
                                running_font = basefont;

                                column += Changes::latexMarkChange(os, bparams,
                                                runningChange, Change(Change::UNCHANGED),
                                                runparams);
                                runningChange = Change(Change::UNCHANGED);

                                os << "}] ";
                                column +=3;
                        }
                        // For InTitle commands, we have already opened a group
                        // in output_latex::TeXOnePar.
                        if (style.isCommand() && !style.intitle) {
                                os << '{';
                                ++column;
                        }

                        if (!style.leftdelim().empty()) {
                                os << style.leftdelim();
                                column += style.leftdelim().size();
                        }

                        if (allowcust)
                                column += d->startTeXParParams(bparams, os,
                                                            runparams);
                }

                runparams.wasDisplayMath = runparams.inDisplayMath;
                runparams.inDisplayMath = false;
                bool deleted_display_math = false;
                Change const & change = runparams.inDeletedInset
                        ? runparams.changeOfDeletedInset : lookupChange(i);

                char_type const c = d->text_[i];

                // Check whether a display math inset follows
                if (c == META_INSET
                    && i >= start_pos && (end_pos == -1 || i < end_pos)) {
                        if (isDeleted(i))
                                runparams.ctObject = getInset(i)->CtObject(runparams);
        
                        InsetMath const * im = getInset(i)->asInsetMath();
                        if (im && im->asHullInset()
                            && im->asHullInset()->outerDisplay()) {
                                runparams.inDisplayMath = true;
                                // runparams.inDeletedInset will be set by
                                // latexInset later, but we need this info
                                // before it is called. On the other hand, we
                                // cannot set it here because it is a counter.
                                deleted_display_math = isDeleted(i);
                        }
                        if (bparams.output_changes && deleted_display_math
                            && runningChange == change
                            && change.type == Change::DELETED
                            && !os.afterParbreak()) {
                                // A display math in the same paragraph follows.
                                // We have to close and then reopen \lyxdeleted,
                                // otherwise the math will be shifted up.
                                OutputParams rp = runparams;
                                if (open_font) {
                                        bool needPar = false;
                                        column += running_font.latexWriteEndChanges(
                                                os, bparams, rp, basefont,
                                                basefont, needPar);
                                        open_font = false;
                                }
                                basefont = (body_pos > i) ? getLabelFont(bparams, real_outerfont)
                                                          : getLayoutFont(bparams, real_outerfont);
                                running_font = basefont;
                                column += Changes::latexMarkChange(os, bparams,
                                        Change(Change::INSERTED), change, rp);
                        }
                }

                if (bparams.output_changes && runningChange != change) {
                        if (!alien_script.empty()) {
                                column += 1;
                                os << "}";
                                alien_script.clear();
                        }
                        if (open_font) {
                                bool needPar = false;
                                column += running_font.latexWriteEndChanges(
                                                os, bparams, runparams,
                                                basefont, basefont, needPar);
                                open_font = false;
                        }
                        basefont = (body_pos > i) ? getLabelFont(bparams, real_outerfont)
                                                  : getLayoutFont(bparams, real_outerfont);
                        running_font = basefont;
                        column += Changes::latexMarkChange(os, bparams, runningChange,
                                                           change, runparams);
                        runningChange = change;
                }

                // do not output text which is marked deleted
                // if change tracking output is disabled
                if (!bparams.output_changes && change.deleted()) {
                        continue;
                }

                ++column;

                // Fully instantiated font
                Font const current_font = getFont(bparams, i, outerfont);
                // Previous font
                Font const prev_font = (i > 0) ?
                                        getFont(bparams, i - 1, outerfont)
                                      : current_font;

                Font const last_font = running_font;
                bool const in_ct_deletion = (bparams.output_changes
                                             && runningChange == change
                                             && change.type == Change::DELETED
                                             && !os.afterParbreak());
                // Insets where font switches are used (rather than font commands)
                bool const fontswitch_inset =
                                c == META_INSET
                                && getInset(i)
                                && getInset(i)->allowMultiPar()
                                && getInset(i)->lyxCode() != ERT_CODE;

                bool closeLanguage = false;
                bool lang_switched_at_inset = false;
                if (fontswitch_inset) {
                        // Some insets cannot be inside a font change command.
                        // However, even such insets *can* be placed in \L or \R
                        // or their equivalents (for RTL language switches),
                        // so we don't close the language in those cases
                        // (= differing isRightToLeft()).
                        // ArabTeX, though, doesn't seem to handle this special behavior.
                        closeLanguage = basefont.isRightToLeft() == current_font.isRightToLeft()
                                        || basefont.language()->lang() == "arabic_arabtex"
                                        || current_font.language()->lang() == "arabic_arabtex";
                        // We need to check prev_font as language changes directly at inset
                        // will only be started inside the inset.
                        lang_switched_at_inset = prev_font.language() != current_font.language();
                }

                // Do we need to close the previous font?
                if (open_font &&
                    ((current_font != running_font
                      || current_font.language() != running_font.language())
                     || (fontswitch_inset
                         && (current_font == prev_font
                             || current_font.language() == prev_font.language()))))
                {
                        // ensure there is no open script-wrapper
                        if (!alien_script.empty()) {
                                column += 1;
                                os << "}";
                                alien_script.clear();
                        }
                        bool needPar = false;
                        if (in_ct_deletion) {
                                // We have to close and then reopen \lyxdeleted,
                                // as strikeout needs to be on lowest level.
                                os << '}';
                                column += 1;
                        }
                        column += running_font.latexWriteEndChanges(
                                    os, bparams, runparams, basefont,
                                    (i == body_pos-1) ? basefont : current_font,
                                    needPar);
                        if (in_ct_deletion) {
                                // We have to close and then reopen \lyxdeleted,
                                // as strikeout needs to be on lowest level.
                                OutputParams rp = runparams;
                                column += Changes::latexMarkChange(os, bparams,
                                        Change(Change::UNCHANGED), Change(Change::DELETED), rp);
                        }
                        running_font = basefont;
                        open_font = false;
                }

                // if necessary, close language environment before opening CJK
                string const running_lang = running_font.language()->babel();
                string const lang_end_command = lyxrc.language_command_end;
                if (!lang_end_command.empty() && !bparams.useNonTeXFonts
                        && !running_lang.empty()
                        && running_lang == openLanguageName()
                        && current_font.language()->encoding()->package() == Encoding::CJK) {
                        string end_tag = subst(lang_end_command, "$$lang", running_lang);
                        os << from_ascii(end_tag);
                        column += end_tag.length();
                        popLanguageName();
                }

                // Switch file encoding if necessary (and allowed)
                if (!runparams.pass_thru && !style.pass_thru &&
                    runparams.encoding->package() != Encoding::none &&
                    current_font.language()->encoding()->package() != Encoding::none) {
                        pair<bool, int> const enc_switch =
                                switchEncoding(os.os(), bparams, runparams,
                                        *(current_font.language()->encoding()));
                        if (enc_switch.first) {
                                column += enc_switch.second;
                                runparams.encoding = current_font.language()->encoding();
                        }
                }

                // A display math inset inside an ulem command will be output
                // as a box of width \linewidth, so we have to either disable
                // indentation if the inset starts a paragraph, or start a new
                // line to accommodate such box. This has to be done before
                // writing any font changing commands.
                if (runparams.inDisplayMath && !deleted_display_math
                    && runparams.inulemcmd) {
                        if (os.afterParbreak())
                                os << "\\noindent";
                        else
                                os << "\\\\\n";
                }

                // Do we need to change font?
                if ((current_font != running_font ||
                     current_font.language() != running_font.language())
                    && i != body_pos - 1)
                {
                        if (in_ct_deletion) {
                                // We have to close and then reopen \lyxdeleted,
                                // as strikeout needs to be on lowest level.
                                bool needPar = false;
                                OutputParams rp = runparams;
                                column += running_font.latexWriteEndChanges(
                                        os, bparams, rp, basefont,
                                        basefont, needPar);
                                os << '}';
                                column += 1;
                        }
                        otexstringstream ots;
                        if (!fontswitch_inset) {
                                InsetText const * textinset = inInset().asInsetText();
                                bool const cprotect = textinset
                                        ? textinset->hasCProtectContent(runparams.moving_arg)
                                          && !textinset->text().isMainText()
                                        : false;
                                column += current_font.latexWriteStartChanges(ots, bparams,
                                                                              runparams, basefont, last_font, false,
                                                                              cprotect);
                        }
                        // Check again for display math in ulem commands as a
                        // font change may also occur just before a math inset.
                        if (runparams.inDisplayMath && !deleted_display_math
                            && runparams.inulemcmd) {
                                if (os.afterParbreak())
                                        os << "\\noindent";
                                else
                                        os << "\\\\\n";
                        }
                        running_font = current_font;
                        open_font = true;
                        docstring fontchange = ots.str();
                        os << fontchange;
                        // check whether the fontchange ends with a \\textcolor
                        // modifier and the text starts with a space. If so we
                        // need to add } in order to prevent \\textcolor from gobbling
                        // the space (bug 4473).
                        docstring const last_modifier = rsplit(fontchange, '\\');
                        if (prefixIs(last_modifier, from_ascii("textcolor")) && c == ' ')
                                os << from_ascii("{}");
                        else if (ots.terminateCommand())
                                os << termcmd;
                        if (in_ct_deletion) {
                                // We have to close and then reopen \lyxdeleted,
                                // as strikeout needs to be on lowest level.
                                OutputParams rp = runparams;
                                column += Changes::latexMarkChange(os, bparams,
                                        Change(Change::UNCHANGED), change, rp);
                        }
                }

                // FIXME: think about end_pos implementation...
                if (c == ' ' && i >= start_pos && (end_pos == -1 || i < end_pos)) {
                        // FIXME: integrate this case in latexSpecialChar
                        // Do not print the separation of the optional argument
                        // if style.pass_thru is false. This works because
                        // latexSpecialChar ignores spaces if
                        // style.pass_thru is false.
                        if (i != body_pos - 1) {
                                if (d->simpleTeXBlanks(bparams, runparams, os,
                                                i, column, current_font, style)) {
                                        // A surrogate pair was output. We
                                        // must not call latexSpecialChar
                                        // in this iteration, since it would output
                                        // the combining character again.
                                        ++i;
                                        continue;
                                }
                        }
                }

                OutputParams rp = runparams;
                rp.free_spacing = style.free_spacing;
                rp.local_font = &current_font;
                rp.intitle = style.intitle;

                // Two major modes:  LaTeX or plain
                // Handle here those cases common to both modes
                // and then split to handle the two modes separately.
                if (c == META_INSET) {
                        if (i >= start_pos && (end_pos == -1 || i < end_pos)) {
                                // Greyedout notes and, in general, all insets
                                // with InsetLayout::isDisplay() == false,
                                // are typeset inline with the text. So, we
                                // can add a \par to the last paragraph of
                                // such insets only if nothing else follows.
                                bool incremented = false;
                                Inset const * inset = getInset(i);
                                InsetText const * textinset = inset
                                                        ? inset->asInsetText()
                                                        : nullptr;
                                if (i + 1 == size() && textinset
                                    && !inset->getLayout().isDisplay()) {
                                        ParagraphList const & pars =
                                                textinset->text().paragraphs();
                                        pit_type const pit = pars.size() - 1;
                                        Font const lastfont =
                                                pit < 0 || pars[pit].empty()
                                                ? pars[pit].getLayoutFont(
                                                                bparams,
                                                                real_outerfont)
                                                : pars[pit].getFont(bparams,
                                                        pars[pit].size() - 1,
                                                        real_outerfont);
                                        if (lastfont.fontInfo().size() !=
                                            basefont.fontInfo().size()) {
                                                ++parInline;
                                                incremented = true;
                                        }
                                }
                                // We need to restore parts of this after insets with
                                // allowMultiPar() true
                                Font const save_basefont = basefont;
                                d->latexInset(bparams, os, rp, running_font,
                                                basefont, real_outerfont, open_font,
                                                runningChange, style, i, column, fontswitch_inset,
                                                closeLanguage, lang_switched_at_inset);
                                if (fontswitch_inset) {
                                        if (open_font) {
                                                bool needPar = false;
                                                column += running_font.latexWriteEndChanges(
                                                        os, bparams, runparams,
                                                        basefont, basefont, needPar);
                                                open_font = false;
                                        }
                                        basefont.fontInfo().setSize(save_basefont.fontInfo().size());
                                        basefont.fontInfo().setFamily(save_basefont.fontInfo().family());
                                        basefont.fontInfo().setSeries(save_basefont.fontInfo().series());
                                }
                                if (incremented)
                                        --parInline;

                                if (runparams.ctObject == OutputParams::CT_DISPLAYOBJECT
                                    || runparams.ctObject == OutputParams::CT_UDISPLAYOBJECT) {
                                        // Close \lyx*deleted and force its
                                        // reopening (if needed)
                                        os << '}';
                                        column++;
                                        runningChange = Change(Change::UNCHANGED);
                                        runparams.ctObject = OutputParams::CT_NORMAL;
                                }
                        }
                } else if (i >= start_pos && (end_pos == -1 || i < end_pos)) {
                        if (!bparams.useNonTeXFonts)
                          script = Encodings::isKnownScriptChar(c);
                        if (script != alien_script) {
                                if (!alien_script.empty()) {
                                        os << "}";
                                        alien_script.clear();
                                }
                                string fontenc = running_font.language()->fontenc(bparams);
                                if (!script.empty()
                                        && !Encodings::fontencSupportsScript(fontenc, script)) {
                                        column += script.length() + 2;
                                        os << "\\" << script << "{";
                                        alien_script = script;
                                }
                        }
                        try {
                                d->latexSpecialChar(os, bparams, rp, running_font,
                                                                        alien_script, style, i, end_pos, column);
                        } catch (EncodingException & e) {
                                if (runparams.dryrun) {
                                        os << "<" << _("LyX Warning: ")
                                           << _("uncodable character") << " '";
                                        os.put(c);
                                        os << "'>";
                                } else {
                                        // add location information and throw again.
                                        e.par_id = id();
                                        e.pos = i;
                                        throw(e);
                                }
                        }
                }

                // Set the encoding to that returned from latexSpecialChar (see
                // comment for encoding member in OutputParams.h)
                runparams.encoding = rp.encoding;

                // Also carry on the info on a closed ulem command for insets
                // such as Note that do not produce any output, so that no
                // command is ever executed but its opening was recorded.
                runparams.inulemcmd = rp.inulemcmd;

                // These need to be passed upstream as well
                runparams.need_maketitle = rp.need_maketitle;
                runparams.have_maketitle = rp.have_maketitle;

                // And finally, pass the post_macros upstream
                runparams.post_macro = rp.post_macro;
        }

        // Close wrapper for alien script
        if (!alien_script.empty()) {
                os << "}";
                alien_script.clear();
        }

        // If we have an open font definition, we have to close it
        if (open_font) {
                // Make sure that \\par is done with the font of the last
                // character if this has another size as the default.
                // This is necessary because LaTeX (and LyX on the screen)
                // calculates the space between the baselines according
                // to this font. (Matthias)
                //
                // We must not change the font for the last paragraph
                // of non-multipar insets, tabular cells or commands,
                // since this produces unwanted whitespace.

                Font const font = empty()
                        ? getLayoutFont(bparams, real_outerfont)
                        : getFont(bparams, size() - 1, real_outerfont);

                InsetText const * textinset = inInset().asInsetText();

                bool const maintext = textinset
                        ? textinset->text().isMainText()
                        : false;

                size_t const numpars = textinset
                        ? textinset->text().paragraphs().size()
                        : 0;

                bool needPar = false;

                if (style.resfont.size() != font.fontInfo().size()
                    && (!runparams.isLastPar || maintext
                        || (numpars > 1 && d->ownerCode() != CELL_CODE
                            && (inInset().getLayout().isDisplay()
                                || parInline)))
                    && !style.isCommand()) {
                        needPar = true;
                }
#ifdef FIXED_LANGUAGE_END_DETECTION
                if (next_) {
                        running_font.latexWriteEndChanges(os, bparams,
                                        runparams, basefont,
                                        next_->getFont(bparams, 0, outerfont),
                                                       needPar);
                } else {
                        running_font.latexWriteEndChanges(os, bparams,
                                        runparams, basefont, basefont, needPar);
                }
#else
//FIXME: For now we ALWAYS have to close the foreign font settings if they are
//FIXME: there as we start another \selectlanguage with the next paragraph if
//FIXME: we are in need of this. This should be fixed sometime (Jug)
                running_font.latexWriteEndChanges(os, bparams, runparams,
                                basefont, basefont, needPar);
#endif
                if (needPar) {
                        // The \par could not be inserted at the same nesting
                        // level of the font size change, so do it now.
                        os << "{\\" << font.latexSize() << "\\par}";
                }
        }

        column += Changes::latexMarkChange(os, bparams, runningChange,
                                           Change(Change::UNCHANGED), runparams);

        // Needed if there is an optional argument but no contents.
        if (body_pos > 0 && body_pos == size()) {
                os << "}]~";
        }

        if (!style.rightdelim().empty()) {
                os << style.rightdelim();
                column += style.rightdelim().size();
        }

        if (allowcust && d->endTeXParParams(bparams, os, runparams)
            && runparams.encoding != prev_encoding) {
                runparams.encoding = prev_encoding;
                os << setEncoding(prev_encoding->iconvName());
        }

        LYXERR(Debug::LATEX, "Paragraph::latex... done " << this);
}


bool Paragraph::emptyTag() const
{
        for (pos_type i = 0; i < size(); ++i) {
                if (Inset const * inset = getInset(i)) {
                        InsetCode lyx_code = inset->lyxCode();
                        // FIXME testing like that is wrong. What is
                        // the intent?
                        if (lyx_code != TOC_CODE &&
                            lyx_code != INCLUDE_CODE &&
                            lyx_code != GRAPHICS_CODE &&
                            lyx_code != ERT_CODE &&
                            lyx_code != LISTINGS_CODE &&
                            lyx_code != FLOAT_CODE &&
                            lyx_code != TABULAR_CODE) {
                                return false;
                        }
                } else {
                        char_type c = d->text_[i];
                        if (c != ' ' && c != '\t')
                                return false;
                }
        }
        return true;
}


string Paragraph::getID(Buffer const &, OutputParams const &)
        const
{
        for (pos_type i = 0; i < size(); ++i) {
                if (Inset const * inset = getInset(i)) {
                        InsetCode lyx_code = inset->lyxCode();
                        if (lyx_code == LABEL_CODE) {
                                InsetLabel const * const il = static_cast<InsetLabel const *>(inset);
                                docstring const & id = il->getParam("name");
                                return "id='" + to_utf8(xml::cleanID(id)) + "'";
                        }
                }
        }
        return string();
}


pos_type Paragraph::firstWordDocBook(XMLStream & xs, OutputParams const & runparams) const
{
        pos_type i;
        for (i = 0; i < size(); ++i) {
                if (Inset const * inset = getInset(i)) {
                        inset->docbook(xs, runparams);
                } else {
                        char_type c = d->text_[i];
                        if (c == ' ')
                                break;
                        xs << c;
                }
        }
        return i;
}


pos_type Paragraph::firstWordLyXHTML(XMLStream & xs, OutputParams const & runparams)
        const
{
        pos_type i;
        for (i = 0; i < size(); ++i) {
                if (Inset const * inset = getInset(i)) {
                        inset->xhtml(xs, runparams);
                } else {
                        char_type c = d->text_[i];
                        if (c == ' ')
                                break;
                        xs << c;
                }
        }
        return i;
}


bool Paragraph::Private::onlyText(Buffer const & buf, Font const & outerfont, pos_type initial) const
{
        Font font_old;
        pos_type size = text_.size();
        for (pos_type i = initial; i < size; ++i) {
                Font font = owner_->getFont(buf.params(), i, outerfont);
                if (text_[i] == META_INSET)
                        return false;
                if (i != initial && font != font_old)
                        return false;
                font_old = font;
        }

        return true;
}


namespace {

void doFontSwitchDocBook(vector<xml::FontTag> & tagsToOpen,
                  vector<xml::EndFontTag> & tagsToClose,
                  bool & flag, FontState curstate, xml::FontTypes type)
{
        if (curstate == FONT_ON) {
                tagsToOpen.push_back(docbookStartFontTag(type));
                flag = true;
        } else if (flag) {
                tagsToClose.push_back(docbookEndFontTag(type));
                flag = false;
        }
}

class OptionalFontType {
public:
        xml::FontTypes ft;
        bool has_value;

        OptionalFontType(): ft(xml::FT_EMPH), has_value(false) {} // A possible value at random for ft.
        OptionalFontType(xml::FontTypes ft): ft(ft), has_value(true) {}
};

OptionalFontType fontShapeToXml(FontShape fs)
{
        switch (fs) {
        case ITALIC_SHAPE:
                return {xml::FT_ITALIC};
        case SLANTED_SHAPE:
                return {xml::FT_SLANTED};
        case SMALLCAPS_SHAPE:
                return {xml::FT_SMALLCAPS};
        case UP_SHAPE:
        case INHERIT_SHAPE:
                return {};
        default:
                // the other tags are for internal use
                LATTEST(false);
                return {};
        }
}

OptionalFontType fontFamilyToXml(FontFamily fm)
{
        switch (fm) {
        case ROMAN_FAMILY:
                return {xml::FT_ROMAN};
        case SANS_FAMILY:
                return {xml::FT_SANS};
        case TYPEWRITER_FAMILY:
                return {xml::FT_TYPE};
        case INHERIT_FAMILY:
                return {};
        default:
                // the other tags are for internal use
                LATTEST(false);
                return {};
        }
}

OptionalFontType fontSizeToXml(FontSize fs)
{
        switch (fs) {
        case TINY_SIZE:
                return {xml::FT_SIZE_TINY};
        case SCRIPT_SIZE:
                return {xml::FT_SIZE_SCRIPT};
        case FOOTNOTE_SIZE:
                return {xml::FT_SIZE_FOOTNOTE};
        case SMALL_SIZE:
                return {xml::FT_SIZE_SMALL};
        case LARGE_SIZE:
                return {xml::FT_SIZE_LARGE};
        case LARGER_SIZE:
                return {xml::FT_SIZE_LARGER};
        case LARGEST_SIZE:
                return {xml::FT_SIZE_LARGEST};
        case HUGE_SIZE:
                return {xml::FT_SIZE_HUGE};
        case HUGER_SIZE:
                return {xml::FT_SIZE_HUGER};
        case INCREASE_SIZE:
                return {xml::FT_SIZE_INCREASE};
        case DECREASE_SIZE:
                return {xml::FT_SIZE_DECREASE};
        case INHERIT_SIZE:
        case NORMAL_SIZE:
                return {};
        default:
                // the other tags are for internal use
                LATTEST(false);
                return {};
        }
}

struct DocBookFontState
{
        FontShape  curr_fs   = INHERIT_SHAPE;
        FontFamily curr_fam  = INHERIT_FAMILY;
        FontSize   curr_size = INHERIT_SIZE;

        // track whether we have opened these tags
        bool emph_flag = false;
        bool bold_flag = false;
        bool noun_flag = false;
        bool ubar_flag = false;
        bool dbar_flag = false;
        bool sout_flag = false;
        bool xout_flag = false;
        bool wave_flag = false;
        // shape tags
        bool shap_flag = false;
        // family tags
        bool faml_flag = false;
        // size tags
        bool size_flag = false;
};

std::tuple<vector<xml::FontTag>, vector<xml::EndFontTag>> computeDocBookFontSwitch(FontInfo const & font_old,
                                                                                           Font const & font,
                                                                                           std::string const & default_family,
                                                                                           DocBookFontState & fs)
{
        vector<xml::FontTag> tagsToOpen;
        vector<xml::EndFontTag> tagsToClose;

        // emphasis
        FontState curstate = font.fontInfo().emph();
        if (font_old.emph() != curstate)
                doFontSwitchDocBook(tagsToOpen, tagsToClose, fs.emph_flag, curstate, xml::FT_EMPH);

        // noun
        curstate = font.fontInfo().noun();
        if (font_old.noun() != curstate)
                doFontSwitchDocBook(tagsToOpen, tagsToClose, fs.noun_flag, curstate, xml::FT_NOUN);

        // underbar
        curstate = font.fontInfo().underbar();
        if (font_old.underbar() != curstate)
                doFontSwitchDocBook(tagsToOpen, tagsToClose, fs.ubar_flag, curstate, xml::FT_UBAR);

        // strikeout
        curstate = font.fontInfo().strikeout();
        if (font_old.strikeout() != curstate)
                doFontSwitchDocBook(tagsToOpen, tagsToClose, fs.sout_flag, curstate, xml::FT_SOUT);

        // xout
        curstate = font.fontInfo().xout();
        if (font_old.xout() != curstate)
                doFontSwitchDocBook(tagsToOpen, tagsToClose, fs.xout_flag, curstate, xml::FT_XOUT);

        // double underbar
        curstate = font.fontInfo().uuline();
        if (font_old.uuline() != curstate)
                doFontSwitchDocBook(tagsToOpen, tagsToClose, fs.dbar_flag, curstate, xml::FT_DBAR);

        // wavy line
        curstate = font.fontInfo().uwave();
        if (font_old.uwave() != curstate)
                doFontSwitchDocBook(tagsToOpen, tagsToClose, fs.wave_flag, curstate, xml::FT_WAVE);

        // bold
        // a little hackish, but allows us to reuse what we have.
        curstate = (font.fontInfo().series() == BOLD_SERIES ? FONT_ON : FONT_OFF);
        if (font_old.series() != font.fontInfo().series())
                doFontSwitchDocBook(tagsToOpen, tagsToClose, fs.bold_flag, curstate, xml::FT_BOLD);

        // Font shape
        fs.curr_fs = font.fontInfo().shape();
        FontShape old_fs = font_old.shape();
        if (old_fs != fs.curr_fs) {
                if (fs.shap_flag) {
                        OptionalFontType tag = fontShapeToXml(old_fs);
                        if (tag.has_value)
                                tagsToClose.push_back(docbookEndFontTag(tag.ft));
                        fs.shap_flag = false;
                }

                OptionalFontType tag = fontShapeToXml(fs.curr_fs);
                if (tag.has_value)
                        tagsToOpen.push_back(docbookStartFontTag(tag.ft));
        }

        // Font family
        fs.curr_fam = font.fontInfo().family();
        FontFamily old_fam = font_old.family();
        if (old_fam != fs.curr_fam) {
                if (fs.faml_flag) {
                        OptionalFontType tag = fontFamilyToXml(old_fam);
                        if (tag.has_value)
                                tagsToClose.push_back(docbookEndFontTag(tag.ft));
                        fs.faml_flag = false;
                }
                switch (fs.curr_fam) {
                        case ROMAN_FAMILY:
                                // we will treat a "default" font family as roman, since we have
                                // no other idea what to do.
                                if (default_family != "rmdefault" && default_family != "default") {
                                        tagsToOpen.push_back(docbookStartFontTag(xml::FT_ROMAN));
                                        fs.faml_flag = true;
                                }
                                break;
                        case SANS_FAMILY:
                                if (default_family != "sfdefault") {
                                        tagsToOpen.push_back(docbookStartFontTag(xml::FT_SANS));
                                        fs.faml_flag = true;
                                }
                                break;
                        case TYPEWRITER_FAMILY:
                                if (default_family != "ttdefault") {
                                        tagsToOpen.push_back(docbookStartFontTag(xml::FT_TYPE));
                                        fs.faml_flag = true;
                                }
                                break;
                        case INHERIT_FAMILY:
                                break;
                        default:
                                // the other tags are for internal use
                                LATTEST(false);
                                break;
                }
        }

        // Font size
        fs.curr_size = font.fontInfo().size();
        FontSize old_size = font_old.size();
        if (old_size != fs.curr_size) {
                if (fs.size_flag) {
                        OptionalFontType tag = fontSizeToXml(old_size);
                        if (tag.has_value)
                                tagsToClose.push_back(docbookEndFontTag(tag.ft));
                        fs.size_flag = false;
                }

                OptionalFontType tag = fontSizeToXml(fs.curr_size);
                if (tag.has_value) {
                        tagsToOpen.push_back(docbookStartFontTag(tag.ft));
                        fs.size_flag = true;
                }
        }

        return std::tuple<vector<xml::FontTag>, vector<xml::EndFontTag>>(tagsToOpen, tagsToClose);
}

} // anonymous namespace


void Paragraph::simpleDocBookOnePar(Buffer const & buf,
                                    XMLStream & xs,
                                    OutputParams const & runparams,
                                    Font const & outerfont,
                                    bool start_paragraph, bool close_paragraph,
                                    pos_type initial) const
{
        // track whether we have opened these tags
        DocBookFontState fs;

        if (start_paragraph)
                xs.startDivision(allowEmpty());

        Layout const & style = *d->layout_;
        FontInfo font_old =
                        style.labeltype == LABEL_MANUAL ? style.labelfont : style.font;

        string const default_family =
                        buf.masterBuffer()->params().fonts_default_family;

        vector<xml::FontTag> tagsToOpen;
        vector<xml::EndFontTag> tagsToClose;

        // parsing main loop
        for (pos_type i = initial; i < size(); ++i) {
                // let's not show deleted material in the output
                if (isDeleted(i))
                        continue;

                Font const font = getFont(buf.masterBuffer()->params(), i, outerfont);

                // Determine which tags should be opened or closed.
                tie(tagsToOpen, tagsToClose) = computeDocBookFontSwitch(font_old, font, default_family, fs);

                // FIXME XHTML
                // Other such tags? What about the other text ranges?

                vector<xml::EndFontTag>::const_iterator cit = tagsToClose.begin();
                vector<xml::EndFontTag>::const_iterator cen = tagsToClose.end();
                for (; cit != cen; ++cit)
                        xs << *cit;

                vector<xml::FontTag>::const_iterator sit = tagsToOpen.begin();
                vector<xml::FontTag>::const_iterator sen = tagsToOpen.end();
                for (; sit != sen; ++sit)
                        xs << *sit;

                tagsToClose.clear();
                tagsToOpen.clear();

                if (Inset const * inset = getInset(i)) {
                        if (!runparams.for_toc || inset->isInToc()) {
                                OutputParams np = runparams;
                                np.local_font = &font;
                                // If the paragraph has size 1, then we are in the "special
                                // case" where we do not output the containing paragraph info.
                                // This "special case" is defined in more details in output_docbook.cpp, makeParagraphs. The results
                                // of that brittle logic is passed to this function through open_par.
                                if (!inset->getLayout().htmlisblock() && size() != 1) // TODO: htmlisblock here too!
                                        np.docbook_in_par = true;
                                inset->docbook(xs, np);
                        }
                } else {
                        char_type c = getUChar(buf.masterBuffer()->params(), runparams, i);
                        xs << c;
                }
                font_old = font.fontInfo();
        }

        // FIXME, this code is just imported from XHTML
        // I'm worried about what happens if a branch, say, is itself
        // wrapped in some font stuff. I think that will not work.
        xs.closeFontTags();
        if (runparams.docbook_in_listing)
                xs << xml::CR();
        if (close_paragraph)
                xs.endDivision();
}


namespace {

void doFontSwitchXHTML(vector<xml::FontTag> & tagsToOpen,
                  vector<xml::EndFontTag> & tagsToClose,
                  bool & flag, FontState curstate, xml::FontTypes type)
{
        if (curstate == FONT_ON) {
                tagsToOpen.push_back(xhtmlStartFontTag(type));
                flag = true;
        } else if (flag) {
                tagsToClose.push_back(xhtmlEndFontTag(type));
                flag = false;
        }
}

} // anonymous namespace


docstring Paragraph::simpleLyXHTMLOnePar(Buffer const & buf,
                                    XMLStream & xs,
                                    OutputParams const & runparams,
                                    Font const & outerfont,
                                    bool start_paragraph, bool close_paragraph,
                                    pos_type initial) const
{
        docstring retval;

        // track whether we have opened these tags
        bool emph_flag = false;
        bool bold_flag = false;
        bool noun_flag = false;
        bool ubar_flag = false;
        bool dbar_flag = false;
        bool sout_flag = false;
        bool xout_flag = false;
        bool wave_flag = false;
        // shape tags
        bool shap_flag = false;
        // family tags
        bool faml_flag = false;
        // size tags
        bool size_flag = false;

        Layout const & style = *d->layout_;

        if (start_paragraph)
                xs.startDivision(allowEmpty());

        FontInfo font_old =
                style.labeltype == LABEL_MANUAL ? style.labelfont : style.font;

        FontShape  curr_fs   = INHERIT_SHAPE;
        FontFamily curr_fam  = INHERIT_FAMILY;
        FontSize   curr_size = INHERIT_SIZE;

        string const default_family =
                buf.masterBuffer()->params().fonts_default_family;

        vector<xml::FontTag> tagsToOpen;
        vector<xml::EndFontTag> tagsToClose;

        // parsing main loop
        for (pos_type i = initial; i < size(); ++i) {
                // let's not show deleted material in the output
                if (isDeleted(i))
                        continue;

                Font const font = getFont(buf.masterBuffer()->params(), i, outerfont);

                // emphasis
                FontState curstate = font.fontInfo().emph();
                if (font_old.emph() != curstate)
                        doFontSwitchXHTML(tagsToOpen, tagsToClose, emph_flag, curstate, xml::FT_EMPH);

                // noun
                curstate = font.fontInfo().noun();
                if (font_old.noun() != curstate)
                        doFontSwitchXHTML(tagsToOpen, tagsToClose, noun_flag, curstate, xml::FT_NOUN);

                // underbar
                curstate = font.fontInfo().underbar();
                if (font_old.underbar() != curstate)
                        doFontSwitchXHTML(tagsToOpen, tagsToClose, ubar_flag, curstate, xml::FT_UBAR);

                // strikeout
                curstate = font.fontInfo().strikeout();
                if (font_old.strikeout() != curstate)
                        doFontSwitchXHTML(tagsToOpen, tagsToClose, sout_flag, curstate, xml::FT_SOUT);

                // xout
                curstate = font.fontInfo().xout();
                if (font_old.xout() != curstate)
                        doFontSwitchXHTML(tagsToOpen, tagsToClose, xout_flag, curstate, xml::FT_XOUT);

                // double underbar
                curstate = font.fontInfo().uuline();
                if (font_old.uuline() != curstate)
                        doFontSwitchXHTML(tagsToOpen, tagsToClose, dbar_flag, curstate, xml::FT_DBAR);

                // wavy line
                curstate = font.fontInfo().uwave();
                if (font_old.uwave() != curstate)
                        doFontSwitchXHTML(tagsToOpen, tagsToClose, wave_flag, curstate, xml::FT_WAVE);

                // bold
                // a little hackish, but allows us to reuse what we have.
                curstate = (font.fontInfo().series() == BOLD_SERIES ? FONT_ON : FONT_OFF);
                if (font_old.series() != font.fontInfo().series())
                        doFontSwitchXHTML(tagsToOpen, tagsToClose, bold_flag, curstate, xml::FT_BOLD);

                // Font shape
                curr_fs = font.fontInfo().shape();
                FontShape old_fs = font_old.shape();
                if (old_fs != curr_fs) {
                        if (shap_flag) {
                                switch (old_fs) {
                                case ITALIC_SHAPE:
                                        tagsToClose.emplace_back(xhtmlEndFontTag(xml::FT_ITALIC));
                                        break;
                                case SLANTED_SHAPE:
                                        tagsToClose.emplace_back(xhtmlEndFontTag(xml::FT_SLANTED));
                                        break;
                                case SMALLCAPS_SHAPE:
                                        tagsToClose.emplace_back(xhtmlEndFontTag(xml::FT_SMALLCAPS));
                                        break;
                                case UP_SHAPE:
                                case INHERIT_SHAPE:
                                        break;
                                default:
                                        // the other tags are for internal use
                                        LATTEST(false);
                                        break;
                                }
                                shap_flag = false;
                        }
                        switch (curr_fs) {
                        case ITALIC_SHAPE:
                                tagsToOpen.emplace_back(xhtmlStartFontTag(xml::FT_ITALIC));
                                shap_flag = true;
                                break;
                        case SLANTED_SHAPE:
                                tagsToOpen.emplace_back(xhtmlStartFontTag(xml::FT_SLANTED));
                                shap_flag = true;
                                break;
                        case SMALLCAPS_SHAPE:
                                tagsToOpen.emplace_back(xhtmlStartFontTag(xml::FT_SMALLCAPS));
                                shap_flag = true;
                                break;
                        case UP_SHAPE:
                        case INHERIT_SHAPE:
                                break;
                        default:
                                // the other tags are for internal use
                                LATTEST(false);
                                break;
                        }
                }

                // Font family
                curr_fam = font.fontInfo().family();
                FontFamily old_fam = font_old.family();
                if (old_fam != curr_fam) {
                        if (faml_flag) {
                                switch (old_fam) {
                                case ROMAN_FAMILY:
                                        tagsToClose.emplace_back(xhtmlEndFontTag(xml::FT_ROMAN));
                                        break;
                                case SANS_FAMILY:
                                    tagsToClose.emplace_back(xhtmlEndFontTag(xml::FT_SANS));
                                    break;
                                case TYPEWRITER_FAMILY:
                                        tagsToClose.emplace_back(xhtmlEndFontTag(xml::FT_TYPE));
                                        break;
                                case INHERIT_FAMILY:
                                        break;
                                default:
                                        // the other tags are for internal use
                                        LATTEST(false);
                                        break;
                                }
                                faml_flag = false;
                        }
                        switch (curr_fam) {
                        case ROMAN_FAMILY:
                                // we will treat a "default" font family as roman, since we have
                                // no other idea what to do.
                                if (default_family != "rmdefault" && default_family != "default") {
                                        tagsToOpen.emplace_back(xhtmlStartFontTag(xml::FT_ROMAN));
                                        faml_flag = true;
                                }
                                break;
                        case SANS_FAMILY:
                                if (default_family != "sfdefault") {
                                        tagsToOpen.emplace_back(xhtmlStartFontTag(xml::FT_SANS));
                                        faml_flag = true;
                                }
                                break;
                        case TYPEWRITER_FAMILY:
                                if (default_family != "ttdefault") {
                                        tagsToOpen.emplace_back(xhtmlStartFontTag(xml::FT_TYPE));
                                        faml_flag = true;
                                }
                                break;
                        case INHERIT_FAMILY:
                                break;
                        default:
                                // the other tags are for internal use
                                LATTEST(false);
                                break;
                        }
                }

                // Font size
                curr_size = font.fontInfo().size();
                FontSize old_size = font_old.size();
                if (old_size != curr_size) {
                        if (size_flag) {
                                switch (old_size) {
                                case TINY_SIZE:
                                        tagsToClose.emplace_back(xhtmlEndFontTag(xml::FT_SIZE_TINY));
                                        break;
                                case SCRIPT_SIZE:
                                        tagsToClose.emplace_back(xhtmlEndFontTag(xml::FT_SIZE_SCRIPT));
                                        break;
                                case FOOTNOTE_SIZE:
                                        tagsToClose.emplace_back(xhtmlEndFontTag(xml::FT_SIZE_FOOTNOTE));
                                        break;
                                case SMALL_SIZE:
                                        tagsToClose.emplace_back(xhtmlEndFontTag(xml::FT_SIZE_SMALL));
                                        break;
                                case LARGE_SIZE:
                                        tagsToClose.emplace_back(xhtmlEndFontTag(xml::FT_SIZE_LARGE));
                                        break;
                                case LARGER_SIZE:
                                        tagsToClose.emplace_back(xhtmlEndFontTag(xml::FT_SIZE_LARGER));
                                        break;
                                case LARGEST_SIZE:
                                        tagsToClose.emplace_back(xhtmlEndFontTag(xml::FT_SIZE_LARGEST));
                                        break;
                                case HUGE_SIZE:
                                        tagsToClose.emplace_back(xhtmlEndFontTag(xml::FT_SIZE_HUGE));
                                        break;
                                case HUGER_SIZE:
                                        tagsToClose.emplace_back(xhtmlEndFontTag(xml::FT_SIZE_HUGER));
                                        break;
                                case INCREASE_SIZE:
                                        tagsToClose.emplace_back(xhtmlEndFontTag(xml::FT_SIZE_INCREASE));
                                        break;
                                case DECREASE_SIZE:
                                        tagsToClose.emplace_back(xhtmlEndFontTag(xml::FT_SIZE_DECREASE));
                                        break;
                                case INHERIT_SIZE:
                                case NORMAL_SIZE:
                                        break;
                                default:
                                        // the other tags are for internal use
                                        LATTEST(false);
                                        break;
                                }
                                size_flag = false;
                        }
                        switch (curr_size) {
                        case TINY_SIZE:
                                tagsToOpen.emplace_back(xhtmlStartFontTag(xml::FT_SIZE_TINY));
                                size_flag = true;
                                break;
                        case SCRIPT_SIZE:
                                tagsToOpen.emplace_back(xhtmlStartFontTag(xml::FT_SIZE_SCRIPT));
                                size_flag = true;
                                break;
                        case FOOTNOTE_SIZE:
                                tagsToOpen.emplace_back(xhtmlStartFontTag(xml::FT_SIZE_FOOTNOTE));
                                size_flag = true;
                                break;
                        case SMALL_SIZE:
                                tagsToOpen.emplace_back(xhtmlStartFontTag(xml::FT_SIZE_SMALL));
                                size_flag = true;
                                break;
                        case LARGE_SIZE:
                                tagsToOpen.emplace_back(xhtmlStartFontTag(xml::FT_SIZE_LARGE));
                                size_flag = true;
                                break;
                        case LARGER_SIZE:
                                tagsToOpen.emplace_back(xhtmlStartFontTag(xml::FT_SIZE_LARGER));
                                size_flag = true;
                                break;
                        case LARGEST_SIZE:
                                tagsToOpen.emplace_back(xhtmlStartFontTag(xml::FT_SIZE_LARGEST));
                                size_flag = true;
                                break;
                        case HUGE_SIZE:
                                tagsToOpen.emplace_back(xhtmlStartFontTag(xml::FT_SIZE_HUGE));
                                size_flag = true;
                                break;
                        case HUGER_SIZE:
                                tagsToOpen.emplace_back(xhtmlStartFontTag(xml::FT_SIZE_HUGER));
                                size_flag = true;
                                break;
                        case INCREASE_SIZE:
                                tagsToOpen.emplace_back(xhtmlStartFontTag(xml::FT_SIZE_INCREASE));
                                size_flag = true;
                                break;
                        case DECREASE_SIZE:
                                tagsToOpen.emplace_back(xhtmlStartFontTag(xml::FT_SIZE_DECREASE));
                                size_flag = true;
                                break;
                        case INHERIT_SIZE:
                        case NORMAL_SIZE:
                                break;
                        default:
                                // the other tags are for internal use
                                LATTEST(false);
                                break;
                        }
                }

                // FIXME XHTML
                // Other such tags? What about the other text ranges?

                vector<xml::EndFontTag>::const_iterator cit = tagsToClose.begin();
                vector<xml::EndFontTag>::const_iterator cen = tagsToClose.end();
                for (; cit != cen; ++cit)
                        xs << *cit;

                vector<xml::FontTag>::const_iterator sit = tagsToOpen.begin();
                vector<xml::FontTag>::const_iterator sen = tagsToOpen.end();
                for (; sit != sen; ++sit)
                        xs << *sit;

                tagsToClose.clear();
                tagsToOpen.clear();

                Inset const * inset = getInset(i);
                if (inset) {
                        if (!runparams.for_toc || inset->isInToc()) {
                                OutputParams np = runparams;
                                np.local_font = &font;
                                // If the paragraph has size 1, then we are in the "special
                                // case" where we do not output the containing paragraph info
                                if (!inset->getLayout().htmlisblock() && size() != 1)
                                        np.html_in_par = true;
                                retval += inset->xhtml(xs, np);
                        }
                } else {
                        char_type c = getUChar(buf.masterBuffer()->params(),
                                               runparams, i);
                        if (c == ' ' && (style.free_spacing || runparams.free_spacing))
                                xs << XMLStream::ESCAPE_NONE << "&nbsp;";
                        else
                                xs << c;
                }
                font_old = font.fontInfo();
        }

        // FIXME XHTML
        // I'm worried about what happens if a branch, say, is itself
        // wrapped in some font stuff. I think that will not work.
        xs.closeFontTags();
        if (close_paragraph)
                xs.endDivision();

        return retval;
}


bool Paragraph::isHfill(pos_type pos) const
{
        Inset const * inset = getInset(pos);
        return inset && inset->isHfill();
}


bool Paragraph::isNewline(pos_type pos) const
{
        // U+2028 LINE SEPARATOR
        // U+2029 PARAGRAPH SEPARATOR
        char_type const c = d->text_[pos];
        if (c == 0x2028 || c == 0x2029)
                return true;
        Inset const * inset = getInset(pos);
        return inset && inset->lyxCode() == NEWLINE_CODE;
}


bool Paragraph::isEnvSeparator(pos_type pos) const
{
        Inset const * inset = getInset(pos);
        return inset && inset->lyxCode() == SEPARATOR_CODE;
}


bool Paragraph::isLineSeparator(pos_type pos) const
{
        char_type const c = d->text_[pos];
        if (isLineSeparatorChar(c))
                return true;
        Inset const * inset = getInset(pos);
        return inset && inset->isLineSeparator();
}


bool Paragraph::isWordSeparator(pos_type pos, bool const ignore_deleted) const
{
        if (pos == size())
                return true;
        if (ignore_deleted && isDeleted(pos))
                return false;
        if (Inset const * inset = getInset(pos))
                return !inset->isLetter();
        // if we have a hard hyphen (no en- or emdash) or apostrophe
        // we pass this to the spell checker
        // FIXME: this method is subject to change, visit
        // https://bugzilla.mozilla.org/show_bug.cgi?id=355178
        // to get an impression how complex this is.
        if (isHardHyphenOrApostrophe(pos))
                return false;
        char_type const c = d->text_[pos];
        // We want to pass the escape chars to the spellchecker
        docstring const escape_chars = from_utf8(lyxrc.spellchecker_esc_chars);
        return !isLetterChar(c) && !isDigitASCII(c) && !contains(escape_chars, c);
}


bool Paragraph::isHardHyphenOrApostrophe(pos_type pos) const
{
        pos_type const psize = size();
        if (pos >= psize)
                return false;
        char_type const c = d->text_[pos];
        if (c != '-' && c != '\'')
                return false;
        int nextpos = pos + 1;
        int prevpos = pos > 0 ? pos - 1 : 0;
        if ((nextpos == psize || isSpace(nextpos))
                && (pos == 0 || isSpace(prevpos)))
                return false;
        return true;
}


bool Paragraph::needsCProtection(bool const fragile) const
{
        // first check the layout of the paragraph, but only in insets
        InsetText const * textinset = inInset().asInsetText();
        bool const maintext = textinset
                ? textinset->text().isMainText()
                : false;

        if (!maintext && layout().needcprotect) {
                // Environments need cprotection regardless the content
                if (layout().latextype == LATEX_ENVIRONMENT)
                        return true;

                // Commands need cprotection if they contain specific chars
                int const nchars_escape = 9;
                static char_type const chars_escape[nchars_escape] = {
                        '&', '_', '$', '%', '#', '^', '{', '}', '\\'};

                docstring const pars = asString();
                for (int k = 0; k < nchars_escape; k++) {
                        if (contains(pars, chars_escape[k]))
                                return true;
                }
        }

        // now check whether we have insets that need cprotection
        pos_type size = pos_type(d->text_.size());
        for (pos_type i = 0; i < size; ++i) {
                if (!isInset(i))
                        continue;
                Inset const * ins = getInset(i);
                if (ins->needsCProtection(maintext, fragile))
                        return true;
                if (ins->getLayout().latextype() == InsetLayout::ENVIRONMENT)
                        // Environments need cprotection regardless the content
                        return true;
                // Now check math environments
                InsetMath const * im = getInset(i)->asInsetMath();
                if (!im || im->cell(0).empty())
                        continue;
                switch(im->cell(0)[0]->lyxCode()) {
                case MATH_AMSARRAY_CODE:
                case MATH_SUBSTACK_CODE:
                case MATH_ENV_CODE:
                case MATH_XYMATRIX_CODE:
                        // these need cprotection
                        return true;
                default:
                        break;
                }
        }

        return false;
}


FontSpan const & Paragraph::getSpellRange(pos_type pos) const
{
        return d->speller_state_.getRange(pos);
}


bool Paragraph::isChar(pos_type pos) const
{
        if (Inset const * inset = getInset(pos))
                return inset->isChar();
        char_type const c = d->text_[pos];
        return !isLetterChar(c) && !isDigitASCII(c) && !lyx::isSpace(c);
}


bool Paragraph::isSpace(pos_type pos) const
{
        if (Inset const * inset = getInset(pos))
                return inset->isSpace();
        char_type const c = d->text_[pos];
        return lyx::isSpace(c);
}


Language const *
Paragraph::getParLanguage(BufferParams const & bparams) const
{
        if (!empty())
                return getFirstFontSettings(bparams).language();
        // FIXME: we should check the prev par as well (Lgb)
        return bparams.language;
}


bool Paragraph::isRTL(BufferParams const & bparams) const
{
        return getParLanguage(bparams)->rightToLeft()
                && !inInset().getLayout().forceLTR();
}


void Paragraph::changeLanguage(BufferParams const & bparams,
                               Language const * from, Language const * to)
{
        // change language including dummy font change at the end
        for (pos_type i = 0; i <= size(); ++i) {
                Font font = getFontSettings(bparams, i);
                if (font.language() == from) {
                        font.setLanguage(to);
                        setFont(i, font);
                        d->requestSpellCheck(i);
                }
        }
}


bool Paragraph::isMultiLingual(BufferParams const & bparams) const
{
        Language const * doc_language = bparams.language;
        for (auto const & f : d->fontlist_)
                if (f.font().language() != ignore_language &&
                    f.font().language() != latex_language &&
                    f.font().language() != doc_language)
                        return true;
        return false;
}


void Paragraph::getLanguages(std::set<Language const *> & langs) const
{
        for (auto const & f : d->fontlist_) {
                Language const * lang = f.font().language();
                if (lang != ignore_language &&
                    lang != latex_language)
                        langs.insert(lang);
        }
}


docstring Paragraph::asString(int options) const
{
        return asString(0, size(), options);
}


docstring Paragraph::asString(pos_type beg, pos_type end, int options, const OutputParams *runparams) const
{
        odocstringstream os;

        if (beg == 0
            && options & AS_STR_LABEL
            && !d->params_.labelString().empty())
                os << d->params_.labelString() << ' ';

        for (pos_type i = beg; i < end; ++i) {
                if ((options & AS_STR_SKIPDELETE) && isDeleted(i))
                        continue;
                char_type const c = d->text_[i];
                if (isPrintable(c) || c == '\t'
                    || (c == '\n' && (options & AS_STR_NEWLINES)))
                        os.put(c);
                else if (c == META_INSET && (options & AS_STR_INSETS)) {
                        if (c == META_INSET && (options & AS_STR_PLAINTEXT)) {
                                LASSERT(runparams != nullptr, return docstring());
                                getInset(i)->plaintext(os, *runparams);
                        } else {
                                getInset(i)->toString(os);
                        }
                }
        }

        return os.str();
}


void Paragraph::forOutliner(docstring & os, size_t const maxlen,
                            bool const shorten, bool const label) const
{
        size_t tmplen = shorten ? maxlen + 1 : maxlen;
        if (label && !labelString().empty())
                os += labelString() + ' ';
        if (!layout().isTocCaption())
                return;
        for (pos_type i = 0; i < size() && os.length() < tmplen; ++i) {
                if (isDeleted(i))
                        continue;
                char_type const c = d->text_[i];
                if (isPrintable(c))
                        os += c;
                else if (c == META_INSET)
                        getInset(i)->forOutliner(os, tmplen, false);
        }
        if (shorten)
                Text::shortenForOutliner(os, maxlen);
}


void Paragraph::setInsetOwner(Inset const * inset)
{
        d->inset_owner_ = inset;
}


int Paragraph::id() const
{
        return d->id_;
}


void Paragraph::setId(int id)
{
        d->id_ = id;
}


Layout const & Paragraph::layout() const
{
        return *d->layout_;
}


void Paragraph::setLayout(Layout const & layout)
{
        d->layout_ = &layout;
}


void Paragraph::setDefaultLayout(DocumentClass const & tc)
{
        setLayout(tc.defaultLayout());
}


void Paragraph::setPlainLayout(DocumentClass const & tc)
{
        setLayout(tc.plainLayout());
}


void Paragraph::setPlainOrDefaultLayout(DocumentClass const & tclass)
{
        if (usePlainLayout())
                setPlainLayout(tclass);
        else
                setDefaultLayout(tclass);
}


Inset const & Paragraph::inInset() const
{
        LBUFERR(d->inset_owner_);
        return *d->inset_owner_;
}


ParagraphParameters & Paragraph::params()
{
        return d->params_;
}


ParagraphParameters const & Paragraph::params() const
{
        return d->params_;
}


bool Paragraph::isFreeSpacing() const
{
        if (d->layout_->free_spacing)
                return true;
        return d->inset_owner_ && d->inset_owner_->isFreeSpacing();
}


bool Paragraph::allowEmpty() const
{
        if (d->layout_->keepempty)
                return true;
        return d->inset_owner_ && d->inset_owner_->allowEmpty();
}


bool Paragraph::brokenBiblio() const
{
        // There is a problem if there is no bibitem at position 0 in
        // paragraphs that need one, if there is another bibitem in the
        // paragraph or if this paragraph is not supposed to have
        // a bibitem inset at all.
        return ((d->layout_->labeltype == LABEL_BIBLIO
                && (d->insetlist_.find(BIBITEM_CODE) != 0
                    || d->insetlist_.find(BIBITEM_CODE, 1) > 0))
                || (d->layout_->labeltype != LABEL_BIBLIO
                    && d->insetlist_.find(BIBITEM_CODE) != -1));
}


int Paragraph::fixBiblio(Buffer const & buffer)
{
        // FIXME: when there was already an inset at 0, the return value is 1,
        // which does not tell whether another inset has been removed; the
        // cursor cannot be correctly updated.

        bool const track_changes = buffer.params().track_changes;
        int bibitem_pos = d->insetlist_.find(BIBITEM_CODE);

        // The case where paragraph is not BIBLIO
        if (d->layout_->labeltype != LABEL_BIBLIO) {
                if (bibitem_pos == -1)
                        // No InsetBibitem => OK
                        return 0;
                // There is an InsetBibitem: remove it!
                d->insetlist_.release(bibitem_pos);
                eraseChar(bibitem_pos, track_changes);
                return (bibitem_pos == 0) ? -1 : -bibitem_pos;
        }

        bool const hasbibitem0 = bibitem_pos == 0;
        if (hasbibitem0) {
                bibitem_pos = d->insetlist_.find(BIBITEM_CODE, 1);
                // There was an InsetBibitem at pos 0,
                // and no other one => OK
                if (bibitem_pos == -1)
                        return 0;
                // there is a bibitem at the 0 position, but since
                // there is a second one, we copy the second on the
                // first. We're assuming there are at most two of
                // these, which there should be.
                // FIXME: why does it make sense to do that rather
                // than keep the first? (JMarc)
                Inset * inset = releaseInset(bibitem_pos);
                d->insetlist_.begin()->inset = inset;
                // This needs to be done to update the counter (#8499)
                buffer.updateBuffer();
                return -bibitem_pos;
        }

        // We need to create an inset at the beginning
        Inset * inset = nullptr;
        if (bibitem_pos > 0) {
                // there was one somewhere in the paragraph, let's move it
                inset = d->insetlist_.release(bibitem_pos);
                eraseChar(bibitem_pos, track_changes);
        } else
                // make a fresh one
                inset = new InsetBibitem(const_cast<Buffer *>(&buffer),
                                         InsetCommandParams(BIBITEM_CODE));

        Font font(inherit_font, buffer.params().language);
        insertInset(0, inset, font, Change(track_changes ? Change::INSERTED
                                                   : Change::UNCHANGED));

        // This is needed to get the counters right
        buffer.updateBuffer();
        return 1;
}


void Paragraph::checkAuthors(AuthorList const & authorList)
{
        d->changes_.checkAuthors(authorList);
}


bool Paragraph::isChanged(pos_type pos) const
{
        return lookupChange(pos).changed();
}


bool Paragraph::isInserted(pos_type pos) const
{
        return lookupChange(pos).inserted();
}


bool Paragraph::isDeleted(pos_type pos) const
{
        return lookupChange(pos).deleted();
}


InsetList const & Paragraph::insetList() const
{
        return d->insetlist_;
}


void Paragraph::setInsetBuffers(Buffer & b)
{
        d->insetlist_.setBuffer(b);
}


void Paragraph::resetBuffer()
{
        d->insetlist_.resetBuffer();
}


Inset * Paragraph::releaseInset(pos_type pos)
{
        Inset * inset = d->insetlist_.release(pos);
        /// does not honour change tracking!
        eraseChar(pos, false);
        return inset;
}


Inset * Paragraph::getInset(pos_type pos)
{
        return (pos < pos_type(d->text_.size()) && d->text_[pos] == META_INSET)
                 ? d->insetlist_.get(pos) : nullptr;
}


Inset const * Paragraph::getInset(pos_type pos) const
{
        return (pos < pos_type(d->text_.size()) && d->text_[pos] == META_INSET)
                 ? d->insetlist_.get(pos) : nullptr;
}


void Paragraph::changeCase(BufferParams const & bparams, pos_type pos,
                pos_type & right, TextCase action)
{
        // process sequences of modified characters; in change
        // tracking mode, this approach results in much better
        // usability than changing case on a char-by-char basis
        // We also need to track the current font, since font
        // changes within sequences can occur.
        vector<pair<char_type, Font> > changes;

        bool const trackChanges = bparams.track_changes;

        bool capitalize = true;

        for (; pos < right; ++pos) {
                char_type oldChar = d->text_[pos];
                char_type newChar = oldChar;

                // ignore insets and don't play with deleted text!
                if (oldChar != META_INSET && !isDeleted(pos)) {
                        switch (action) {
                                case text_lowercase:
                                        newChar = lowercase(oldChar);
                                        break;
                                case text_capitalization:
                                        if (capitalize) {
                                                newChar = uppercase(oldChar);
                                                capitalize = false;
                                        }
                                        break;
                                case text_uppercase:
                                        newChar = uppercase(oldChar);
                                        break;
                        }
                }

                if (isWordSeparator(pos) || isDeleted(pos)) {
                        // permit capitalization again
                        capitalize = true;
                }

                if (oldChar != newChar) {
                        changes.push_back(make_pair(newChar, getFontSettings(bparams, pos)));
                        if (pos != right - 1)
                                continue;
                        // step behind the changing area
                        pos++;
                }

                int erasePos = pos - changes.size();
                for (size_t i = 0; i < changes.size(); i++) {
                        insertChar(pos, changes[i].first,
                                   changes[i].second,
                                   trackChanges);
                        if (!eraseChar(erasePos, trackChanges)) {
                                ++erasePos;
                                ++pos; // advance
                                ++right; // expand selection
                        }
                }
                changes.clear();
        }
}


int Paragraph::find(docstring const & str, bool cs, bool mw,
                pos_type start_pos, bool del) const
{
        pos_type pos = start_pos;
        int const strsize = str.length();
        int i = 0;
        pos_type const parsize = d->text_.size();
        for (i = 0; i < strsize && pos < parsize; ++i, ++pos) {
                // Ignore "invisible" letters such as ligature breaks
                // and hyphenation chars while searching
                while (pos < parsize - 1 && isInset(pos)) {
                        Inset const * inset = getInset(pos);
                        if (!inset->isLetter())
                                break;
                        odocstringstream os;
                        inset->toString(os);
                        if (!os.str().empty())
                                break;
                        pos++;
                }
                if (cs && str[i] != d->text_[pos])
                        break;
                if (!cs && uppercase(str[i]) != uppercase(d->text_[pos]))
                        break;
                if (!del && isDeleted(pos))
                        break;
        }

        if (i != strsize)
                return 0;

        // if necessary, check whether string matches word
        if (mw) {
                if (start_pos > 0 && !isWordSeparator(start_pos - 1))
                        return 0;
                if (pos < parsize
                        && !isWordSeparator(pos))
                        return 0;
        }

        return pos - start_pos;
}


char_type Paragraph::getChar(pos_type pos) const
{
        return d->text_[pos];
}


pos_type Paragraph::size() const
{
        return d->text_.size();
}


bool Paragraph::empty() const
{
        return d->text_.empty();
}


bool Paragraph::isInset(pos_type pos) const
{
        return d->text_[pos] == META_INSET;
}


bool Paragraph::isSeparator(pos_type pos) const
{
        //FIXME: Are we sure this can be the only separator?
        return d->text_[pos] == ' ';
}


void Paragraph::deregisterWords()
{
        Private::LangWordsMap::const_iterator itl = d->words_.begin();
        Private::LangWordsMap::const_iterator ite = d->words_.end();
        for (; itl != ite; ++itl) {
                WordList & wl = theWordList(itl->first);
                Private::Words::const_iterator it = (itl->second).begin();
                Private::Words::const_iterator et = (itl->second).end();
                for (; it != et; ++it)
                        wl.remove(*it);
        }
        d->words_.clear();
}


void Paragraph::locateWord(pos_type & from, pos_type & to,
        word_location const loc, bool const ignore_deleted) const
{
        switch (loc) {
        case WHOLE_WORD_STRICT:
                if (from == 0 || from == size()
                    || isWordSeparator(from, ignore_deleted)
                    || isWordSeparator(from - 1, ignore_deleted)) {
                        to = from;
                        return;
                }
                // fall through

        case WHOLE_WORD:
                // If we are already at the beginning of a word, do nothing
                if (!from || isWordSeparator(from - 1, ignore_deleted))
                        break;
                // fall through

        case PREVIOUS_WORD:
                // always move the cursor to the beginning of previous word
                while (from && !isWordSeparator(from - 1, ignore_deleted))
                        --from;
                break;
        case NEXT_WORD:
                LYXERR0("Paragraph::locateWord: NEXT_WORD not implemented yet");
                break;
        case PARTIAL_WORD:
                // no need to move the 'from' cursor
                break;
        }
        to = from;
        while (to < size() && !isWordSeparator(to, ignore_deleted))
                ++to;
}


void Paragraph::collectWords()
{
        for (pos_type pos = 0; pos < size(); ++pos) {
                if (isWordSeparator(pos))
                        continue;
                pos_type from = pos;
                locateWord(from, pos, WHOLE_WORD);
                // Work around MSVC warning: The statement
                // if (pos < from + lyxrc.completion_minlength)
                // triggers a signed vs. unsigned warning.
                // I don't know why this happens, it could be a MSVC bug, or
                // related to LLP64 (windows) vs. LP64 (unix) programming
                // model, or the C++ standard might be ambigous in the section
                // defining the "usual arithmetic conversions". However, using
                // a temporary variable is safe and works on all compilers.
                pos_type const endpos = from + lyxrc.completion_minlength;
                if (pos < endpos)
                        continue;
                FontList::const_iterator cit = d->fontlist_.fontIterator(from);
                if (cit == d->fontlist_.end())
                        return;
                Language const * lang = cit->font().language();
                docstring const word = asString(from, pos, AS_STR_NONE);
                d->words_[lang->lang()].insert(word);
        }
}


void Paragraph::registerWords()
{
        Private::LangWordsMap::const_iterator itl = d->words_.begin();
        Private::LangWordsMap::const_iterator ite = d->words_.end();
        for (; itl != ite; ++itl) {
                WordList & wl = theWordList(itl->first);
                Private::Words::const_iterator it = (itl->second).begin();
                Private::Words::const_iterator et = (itl->second).end();
                for (; it != et; ++it)
                        wl.insert(*it);
        }
}


void Paragraph::updateWords()
{
        deregisterWords();
        collectWords();
        registerWords();
}


void Paragraph::Private::appendSkipPosition(SkipPositions & skips, pos_type const pos) const
{
        SkipPositionsIterator begin = skips.begin();
        SkipPositions::iterator end = skips.end();
        if (pos > 0 && begin < end) {
                --end;
                if (end->last == pos - 1) {
                        end->last = pos;
                        return;
                }
        }
        skips.insert(end, FontSpan(pos, pos));
}


Language * Paragraph::Private::locateSpellRange(
        pos_type & from, pos_type & to,
        SkipPositions & skips) const
{
        // skip leading white space
        while (from < to && owner_->isWordSeparator(from))
                ++from;
        // don't check empty range
        if (from >= to)
                return nullptr;
        // get current language
        Language * lang = getSpellLanguage(from);
        pos_type last = from;
        bool samelang = true;
        bool sameinset = true;
        while (last < to && samelang && sameinset) {
                // hop to end of word
                while (last < to && !owner_->isWordSeparator(last)) {
                        Inset const * inset = owner_->getInset(last);
                        if (inset && inset->lyxCode() == SPECIALCHAR_CODE) {
                                // check for "invisible" letters such as ligature breaks
                                odocstringstream os;
                                inset->toString(os);
                                if (os.str().length() != 0) {
                                        // avoid spell check of visible special char insets
                                        // stop the loop in front of the special char inset
                                        sameinset = false;
                                        break;
                                }
                        } else if (inset) {
                                appendSkipPosition(skips, last);
                        } else if (owner_->isDeleted(last)) {
                                appendSkipPosition(skips, last);
                        }
                        ++last;
                }
                // hop to next word while checking for insets
                while (sameinset && last < to && owner_->isWordSeparator(last)) {
                        if (Inset const * inset = owner_->getInset(last))
                                sameinset = inset->isChar() && inset->isLetter();
                        if (sameinset && owner_->isDeleted(last)) {
                                appendSkipPosition(skips, last);
                        }
                        if (sameinset)
                                last++;
                }
                if (sameinset && last < to) {
                        // now check for language change
                        samelang = lang == getSpellLanguage(last);
                }
        }
        // if language change detected backstep is needed
        if (!samelang)
                --last;
        to = last;
        return lang;
}


Language * Paragraph::Private::getSpellLanguage(pos_type const from) const
{
        Language * lang =
                const_cast<Language *>(owner_->getFontSettings(
                        inset_owner_->buffer().params(), from).language());
        if (lang == inset_owner_->buffer().params().language
                && !lyxrc.spellchecker_alt_lang.empty()) {
                string lang_code;
                string const lang_variety =
                        split(lyxrc.spellchecker_alt_lang, lang_code, '-');
                lang->setCode(lang_code);
                lang->setVariety(lang_variety);
        }
        return lang;
}


void Paragraph::requestSpellCheck(pos_type pos)
{
        d->requestSpellCheck(pos);
}


bool Paragraph::needsSpellCheck() const
{
        SpellChecker::ChangeNumber speller_change_number = 0;
        if (theSpellChecker())
                speller_change_number = theSpellChecker()->changeNumber();
        if (speller_change_number > d->speller_state_.currentChangeNumber()) {
                d->speller_state_.needsCompleteRefresh(speller_change_number);
        }
        return d->needsSpellCheck();
}


bool Paragraph::Private::ignoreWord(docstring const & word) const
{
        // Ignore words with digits
        // FIXME: make this customizable
        // (note that some checkers ignore words with digits by default)
        docstring::const_iterator cit = word.begin();
        docstring::const_iterator const end = word.end();
        for (; cit != end; ++cit) {
                if (isNumber((*cit)))
                        return true;
        }
        return false;
}


SpellChecker::Result Paragraph::spellCheck(pos_type & from, pos_type & to,
        WordLangTuple & wl, docstring_list & suggestions,
        bool do_suggestion, bool check_learned) const
{
        SpellChecker::Result result = SpellChecker::WORD_OK;
        SpellChecker * speller = theSpellChecker();
        if (!speller)
                return result;

        if (!d->layout_->spellcheck || !inInset().allowSpellCheck())
                return result;

        locateWord(from, to, WHOLE_WORD, true);
        if (from == to || from >= size())
                return result;

        docstring word = asString(from, to, AS_STR_INSETS | AS_STR_SKIPDELETE);
        Language * lang = d->getSpellLanguage(from);

        if (getFontSettings(d->inset_owner_->buffer().params(), from).fontInfo().nospellcheck() == FONT_ON)
                return result;

        wl = WordLangTuple(word, lang);

        if (word.empty())
                return result;

        if (needsSpellCheck() || check_learned) {
                pos_type end = to;
                if (!d->ignoreWord(word)) {
                        bool const trailing_dot = to < size() && d->text_[to] == '.';
                        result = speller->check(wl);
                        if (SpellChecker::misspelled(result) && trailing_dot) {
                                wl = WordLangTuple(word.append(from_ascii(".")), lang);
                                result = speller->check(wl);
                                if (!SpellChecker::misspelled(result)) {
                                        LYXERR(Debug::GUI, "misspelled word is correct with dot: \"" <<
                                           word << "\" [" <<
                                           from << ".." << to << "]");
                                } else {
                                        // spell check with dot appended failed too
                                        // restore original word/lang value
                                        word = asString(from, to, AS_STR_INSETS | AS_STR_SKIPDELETE);
                                        wl = WordLangTuple(word, lang);
                                }
                        }
                }
                if (!SpellChecker::misspelled(result)) {
                        // area up to the begin of the next word is not misspelled
                        while (end < size() && isWordSeparator(end))
                                ++end;
                }
                d->setMisspelled(from, end, result);
        } else {
                result = d->speller_state_.getState(from);
        }

        if (do_suggestion)
                suggestions.clear();

        if (SpellChecker::misspelled(result)) {
                LYXERR(Debug::GUI, "misspelled word: \"" <<
                           word << "\" [" <<
                           from << ".." << to << "]");
                if (do_suggestion)
                        speller->suggest(wl, suggestions);
        }
        return result;
}


void Paragraph::anonymize()
{
        // This is a very crude anonymization for now
        for (char_type & c : d->text_)
                if (isLetterChar(c) || isNumber(c))
                        c = 'a';
}


void Paragraph::Private::markMisspelledWords(
        pos_type const & first, pos_type const & last,
        SpellChecker::Result result,
        docstring const & word,
        SkipPositions const & skips)
{
        if (!SpellChecker::misspelled(result)) {
                setMisspelled(first, last, SpellChecker::WORD_OK);
                return;
        }
        int snext = first;
        SpellChecker * speller = theSpellChecker();
        // locate and enumerate the error positions
        int nerrors = speller->numMisspelledWords();
        int numskipped = 0;
        SkipPositionsIterator it = skips.begin();
        SkipPositionsIterator et = skips.end();
        for (int index = 0; index < nerrors; ++index) {
                int wstart;
                int wlen = 0;
                speller->misspelledWord(index, wstart, wlen);
                /// should not happen if speller supports range checks
                if (!wlen) continue;
                docstring const misspelled = word.substr(wstart, wlen);
                wstart += first + numskipped;
                if (snext < wstart) {
                        /// mark the range of correct spelling
                        numskipped += countSkips(it, et, wstart);
                        setMisspelled(snext,
                                wstart - 1, SpellChecker::WORD_OK);
                }
                snext = wstart + wlen;
                numskipped += countSkips(it, et, snext);
                /// mark the range of misspelling
                setMisspelled(wstart, snext, result);
                LYXERR(Debug::GUI, "misspelled word: \"" <<
                           misspelled << "\" [" <<
                           wstart << ".." << (snext-1) << "]");
                ++snext;
        }
        if (snext <= last) {
                /// mark the range of correct spelling at end
                setMisspelled(snext, last, SpellChecker::WORD_OK);
        }
}


void Paragraph::spellCheck() const
{
        SpellChecker * speller = theSpellChecker();
        if (!speller || empty() ||!needsSpellCheck())
                return;
        pos_type start;
        pos_type endpos;
        d->rangeOfSpellCheck(start, endpos);
        if (speller->canCheckParagraph()) {
                // loop until we leave the range
                for (pos_type first = start; first < endpos; ) {
                        pos_type last = endpos;
                        Private::SkipPositions skips;
                        Language * lang = d->locateSpellRange(first, last, skips);
                        if (first >= endpos)
                                break;
                        // start the spell checker on the unit of meaning
                        docstring word = asString(first, last, AS_STR_INSETS + AS_STR_SKIPDELETE);
                        WordLangTuple wl = WordLangTuple(word, lang);
                        SpellChecker::Result result = word.size() ?
                                speller->check(wl) : SpellChecker::WORD_OK;
                        d->markMisspelledWords(first, last, result, word, skips);
                        first = ++last;
                }
        } else {
                static docstring_list suggestions;
                pos_type to = endpos;
                while (start < endpos) {
                        WordLangTuple wl;
                        spellCheck(start, to, wl, suggestions, false);
                        start = to + 1;
                }
        }
        d->readySpellCheck();
}


bool Paragraph::isMisspelled(pos_type pos, bool check_boundary) const
{
        bool result = SpellChecker::misspelled(d->speller_state_.getState(pos));
        if (result || pos <= 0 || pos > size())
                return result;
        if (check_boundary && (pos == size() || isWordSeparator(pos)))
                result = SpellChecker::misspelled(d->speller_state_.getState(pos - 1));
        return result;
}


string Paragraph::magicLabel() const
{
        stringstream ss;
        ss << "magicparlabel-" << id();
        return ss.str();
}


} // namespace lyx