another safety belt

[lyx.git] / src / support / lyxstring.C

/**
 * \file lyxstring.C
 * This file is part of LyX, the document processor.
 * Licence details can be found in the file COPYING.
 *
 * \author Lars Gullik Bjønnes
 *
 * Full author contact details are available in file CREDITS
 */

#ifdef HAVE_CONFIG_H
#include <config.h>
#endif

#ifdef __GNUG__
#pragma implementation "lyxstring.h"
#endif

#include "lyxstring.h"
#include <cstdlib>
#include <cctype>
#include <algorithm>

#include "LAssert.h"

#include "debug.h"

using std::min;
using std::istream;
using std::ostream;

// This class is supposed to be functionaly equivalent to a
// standard conformant string. This mean among others that we
// are useing the same requirements. Before you change anything
// in this file consult me and/or the standard to discover the
// right behavior.

// Asserts with a STD! are required by the standard.
// Asserts with a OURS! are added by me.
// Some asserts could still be missing and some of the existing
// ones might be wrong or not needed.

// Reference count has been checked, empty_rep removed and
// introduced again in a similar guise. Where is empty_rep _really_
// needed?

// We are missing a couple of imporant things from the standard:
// reverse iterators and methods taking InputIterators as paramters.
// Also the methods returning iterators is returning the wrong value.

// All the different find functions need a good look over.
// I have so far not tested them extensively and would be
// happy if others took the time to have a peek.

// Space allocation of string.
// I have tried to do this very simple without using any special tricks.
// Earlier we used a fixed value to enlarge the string with this would
// cause a lot of reallocations with large strings (especially if
// push_back was used) and wasting space for very small strings.
// I have now changed the allocation to use a doubling of reserved
// space until it is large enough. So far tests show a small speed
// increase and a noticable memory saving.

// Lgb.


///////////////////////////////////////
// The internal string representation
///////////////////////////////////////

struct lyxstring::Srep {
        /// size
        size_t sz;
        /// Reference count
        size_t ref;
        /// The total amount of data reserved for this representaion
        size_t res;
        /// Data. At least 1 char for trailing null.
        lyxstring::value_type * s;

        ///
        Srep(lyxstring::size_type nsz, const lyxstring::value_type * p);
        ///
        Srep(lyxstring::size_type nsz, lyxstring::value_type ch);
        ///
        ~Srep() { delete[] s; }
        ///
        Srep * get_own_copy() {
                if (ref == 1) return this;
                --ref;
                return new Srep(sz, s);
        }

        ///
        void assign(lyxstring::size_type nsz, const lyxstring::value_type * p);
        ///
        void assign(lyxstring::size_type nsz, lyxstring::value_type ch);
        ///
        void append(lyxstring::size_type asz, const lyxstring::value_type * p);
        ///
        void push_back(lyxstring::value_type c);
        ///
        void insert(lyxstring::size_type pos,
                    const lyxstring::value_type * p,
                    lyxstring::size_type n);
        ///
        void resize(lyxstring::size_type n, lyxstring::value_type c);
        ///
        void reserve(lyxstring::size_type res_arg);
        ///
        void replace(lyxstring::size_type i, lyxstring::size_type n,
                     lyxstring::value_type const * p, lyxstring::size_type n2);
private:
        Srep(const Srep &);
        Srep & operator=(const Srep &);
};


lyxstring::Srep::Srep(lyxstring::size_type nsz, const value_type * p)
{
        // can be called with p == 0 by
        // lyxstring::assign(const value_type *, size_type)

        sz = nsz;
        ref = 1;
        res = sz ? sz : 1;
        s = new value_type[res + 1]; // add space for terminator
        if (p && sz) {
                // if sz = 0 nothing gets copied and we have an error
                memcpy(s, p, sz);
        } else {
                // possibly allows for large but empty string
                sz = 0;  // this line should be redundant
                s[0] = '\0';
        }
}


lyxstring::Srep::Srep(lyxstring::size_type nsz, value_type ch)
{
        sz = nsz;
        ref = 1;
        res = sz ? sz : 1;
        s = new value_type[res + 1]; // add space for terminator
        memset(s, ch, sz);
        if (!ch) {
                // if ch == '\0' strlen(lyxstring.c_str()) == 0 so sz = 0
                // allows for large but empty string
                sz = 0;
        }
}


void lyxstring::Srep::assign(lyxstring::size_type nsz, const value_type * p)
{
        // can be called with p == 0
        // by lyxstring::assign(const value_type *, size_type)

        if (res < nsz) {
                delete[] s;
                sz = nsz;
                res = sz ? sz : 1;
                s = new value_type[res + 1]; // add space for terminator
        } else {
                sz = nsz;
        }
        if (p && sz) {
                // if sz = 0 nothing gets copied and we have an error
                memcpy(s, p, sz);
        } else {
                // stops segfaults
                sz = 0;  // this line should be redundant
                s[0] = '\0';
        }
}


void lyxstring::Srep::assign(lyxstring::size_type nsz, value_type ch)
{
        sz = nsz;
        if (res < nsz) {
                delete[] s;
                res = sz ? sz : 1;
                s = new value_type[res + 1]; // add space for terminator
        }
        memset(s, ch, sz);
        if (!ch) {
                // if ch == '\0' strlen(lyxstring.c_str()) == 0 so sz = 0
                // allows for a large empty string
                sz = 0;
        }
}


void lyxstring::Srep::append(lyxstring::size_type asz, const value_type * p)
{
        register unsigned int const len = sz + asz;
        if (res < len) {
                do {
                        res *= 2;
                } while (res < len);
                value_type * tmp = new value_type[res + 1];
                memcpy(tmp, s, sz);
                memcpy(tmp + sz, p, asz);
                sz += asz;
                delete[] s;
                s = tmp;
        } else {
                memcpy(s + sz, p, asz);
                sz += asz;
        }
}


void lyxstring::Srep::push_back(value_type c)
{
        s[sz] = c; // it is always room to put a value_type at the end
        ++sz;
        if (res < sz) {
                do {
                        res *= 2;
                } while (res < sz);
                value_type * tmp = new value_type[res + 1];
                memcpy(tmp, s, sz);
                delete[] s;
                s = tmp;
        }
}


void lyxstring::Srep::insert(lyxstring::size_type pos, const value_type * p,
                             lyxstring::size_type n)
{
        if (res < n + sz) {
                do {
                        res *= 2;
                } while (res < n + sz);
                value_type * tmp = new value_type[res + 1];
                memcpy(tmp, s, pos);
                memcpy(tmp + pos, p, n);
                memcpy(tmp + pos + n, &s[pos], sz - pos);
                sz += n;
                delete[] s;
                s = tmp;
        } else {
                memmove(s + pos + n, &s[pos], sz - pos);
                memcpy(s + pos, p, n);
                sz += n;
        }
}


void lyxstring::Srep::resize(size_type n, value_type c)
{
        // This resets sz to res_arg
        res = min(n, npos - 2); // We keep no xtra when we resize
        value_type * tmp = new value_type[res + 1];
        memcpy(tmp, s, min(sz, res));
        if (res > sz)
                memset(tmp + sz, c, res - sz);
        delete[] s;
        sz = res;
        s = tmp;
}


void lyxstring::Srep::reserve(lyxstring::size_type res_arg)
{
        // This keeps the old sz, but
        // increases res with res_arg
        res += res_arg;
        value_type * tmp = new value_type[res + 1];
        memcpy(tmp, s, sz);
        delete[] s;
        s = tmp;
}


void lyxstring::Srep::replace(lyxstring::size_type i, lyxstring::size_type n,
                              value_type const * p, size_type n2)
{
// can be called with p= 0 and n2= 0
        n = min(sz - i, n);
        sz -= n;
        if (res >= n2 + sz) {
                memmove(s + i + n2, &s[i + n], sz - i);
                memcpy(s + i, p, n2);
                sz += n2;
        } else {
                do {
                        res *= 2;
                } while (res < n2 + sz);
                value_type * tmp = new value_type[res + 1];
                memcpy(tmp, s, i);
                memcpy(tmp + i, p, n2);
                memcpy(tmp + i + n2, &s[i + n], sz - i);
                delete[] s;
                s = tmp;
                sz += n2;
        }
}


///////////////////////////////////////
// The lyxstring Invariant tester
///////////////////////////////////////

// There are no know bugs in lyxstring now, and it have been
// tested for a long time. so we disable the invariant checker. (Lgb)
#undef ENABLE_ASSERTIONS
#ifdef ENABLE_ASSERTIONS

/** Testing of the lyxstring invariant
 * By creating an object that tests the lyxstring invariant during its
 * construction *and* its deconstruction we greatly simplify our code.
 * Calling TestlyxstringInvariant() upon entry to an lyxstring method
 * will test the invariant upon entry to the code.  If the Asserts fail
 * then we know from the stack trace that the corruption occurred *before*
 * entry to this method.  We can also be sure it didn't happen in any of
 * the tested lyxstring methods.  It is therefore likely to be due to some
 * other external force.
 * Several lyxstring methods have multiple exit points which would otherwise
 * require us to insert a separate test before each return.  But since we
 * created an object its destructor will be called upon exit (any exit!).
 * We thus get testing at both start and end of a method with one line of
 * code at the head of a method.  More importantly,  we get good testing
 * everytime we run the code.
 * NOTE:  just because we test the invariant doesn't mean we can forget
 * about testing pre and post conditions specific to any given method.
 * This test simply proves that the lyxstring/Srep is in a valid state it
 * does *not* prove that the method did what it was supposed to.
 */
class lyxstringInvariant {
public:
        lyxstringInvariant(lyxstring const *);
        ~lyxstringInvariant();
private:
        void helper() const;
        lyxstring const * object;
};


// To test if this scheme works "as advertised" uncomment the printf's in
// the constructor and destructor below and then uncomment the printf and the
// call to TestlyxstringInvariant() in lyxstring::operator=(char const *).
// The correct output when LyX has been recompiled and run is:
//     lyxstringInvariant constructor
//     lyxstring::operator=(char const *)
//     lyxstringInvariant constructor
//     lyxstringInvariant destructor completed
//     lyxstringInvariant destructor completed
// NOTE: The easiest way to catch this snippet of the output is to wait for
//       the splash screen to disappear and then open and close Help->Credits
//
lyxstringInvariant::lyxstringInvariant(lyxstring const * ls) : object(ls)
{
        // printf("lyxstringInvariant constructor\n");
        helper();
}


lyxstringInvariant::~lyxstringInvariant()
{
        helper();
        // printf("lyxstringInvariant destructor completed\n");
}


void lyxstringInvariant::helper() const
{
        // Some of these tests might look pointless but they are
        // all part of the invariant and if we want to make sure
        // we have a bullet proof implementation then we need to
        // test every last little thing we *know* should be true.
        // I may have missed a test or two, so feel free to fill
        // in the gaps.  ARRae.
        using lyx::Assert;
        Assert(object);
        Assert(object->rep);
        Assert(object->rep->s);    // s is never 0
        Assert(object->rep->res);  // res cannot be 0
        Assert(object->rep->sz <= object->rep->res);
        Assert(object->rep->ref >= 1);  // its in use so it must be referenced
        Assert(object->rep->ref < 1UL << (8UL * sizeof(object->rep->ref) - 1));
        // if it does ever == then we should be generating a new copy
        // and starting again.  (Is char always 8-bits?)
}
#define TestlyxstringInvariant(s) lyxstringInvariant lyxstring_invariant(s);
#else
#define TestlyxstringInvariant(s)
#endif /* ENABLE_ASSERTIONS */


///////////////////////////////////////
// Constructors and Deconstructors.
///////////////////////////////////////

lyxstring::size_type const lyxstring::npos =
static_cast<lyxstring::size_type>(-1);


lyxstring::lyxstring()
{
        static Srep empty_rep(0, "");
        ++empty_rep.ref;
        rep = &empty_rep;
}


lyxstring::lyxstring(lyxstring const & x, size_type pos, size_type n)
{
        lyx::Assert(pos <= x.rep->sz); // STD!
        if (pos == 0 && n >= x.length()) { // this is the default
                x.rep->ref++;
                rep = x.rep;
        } else {
                rep = new Srep(min(n, x.rep->sz - pos), &(x.rep->s[pos]));
        }
}


lyxstring::lyxstring(value_type const * s, size_type n)
{
        lyx::Assert(s && n < npos); // STD!
        static Srep empty_rep(0, "");
        if (n) { // n > 0
                rep = new Srep(n, s);
        } else {
                ++empty_rep.ref;
                rep = &empty_rep;
        }
}


lyxstring::lyxstring(value_type const * s)
{
        lyx::Assert(s); // STD!
        static Srep empty_rep(0, "");
        if (*s) { // s is not empty string
                rep = new Srep(strlen(s), s);
        } else {
                ++empty_rep.ref;
                rep = &empty_rep;
        }
}


lyxstring::lyxstring(size_type n, value_type c)
{
        lyx::Assert(n < npos); // STD!
        rep = new Srep(n, c);
}


lyxstring::lyxstring(const_iterator first, const_iterator last)
{
        rep = new Srep(last - first, first);
}


lyxstring::~lyxstring()
{
        if (--rep->ref == 0) delete rep;
}

///////////////////////
// Iterators
///////////////////////

lyxstring::iterator lyxstring::begin()
{
        rep = rep->get_own_copy();
        return rep->s;
}


lyxstring::const_iterator lyxstring::begin() const
{
        return rep->s;
}


lyxstring::iterator lyxstring::end()
{
        rep = rep->get_own_copy();
        return rep->s + rep->sz;
}


lyxstring::const_iterator lyxstring::end() const
{
        return rep->s + rep->sz;
}

#if 0
reverse_iterator lyxstring::rbegin()
{
        return reverse_iterator( end() );
}


const_reverse_iterator lyxstring::rbegin() const
{
        return const_reverse_iterator( end() );
}


reverse_iterator lyxstring::rend()
{
        return reverse_iterator( begin() );
}


const_reverse_iterator lyxstring::rend() const
{
        return const_reverse_iterator( begin() );
}
#endif


///////////////////////
// Size and Capacity
///////////////////////

lyxstring::size_type lyxstring::size() const
{
        return rep->sz;
}


void lyxstring::resize(size_type n, value_type c)
{
        lyx::Assert(n <= npos); // STD!
        TestlyxstringInvariant(this);

        // This resets sz to res_arg
        rep = rep->get_own_copy();
        rep->resize(n, c);
}


lyxstring::size_type lyxstring::capacity() const
{
        return rep->res;
}


void lyxstring::reserve(size_type res_arg)
{
        TestlyxstringInvariant(this);

        rep = rep->get_own_copy();
        rep->reserve(res_arg);
}


////////////////
// Assignment
////////////////

lyxstring & lyxstring::operator=(lyxstring const & x)
{
        TestlyxstringInvariant(this);

        return assign(x);
}


lyxstring & lyxstring::operator=(value_type const * s)
{
        lyx::Assert(s); // OURS!
        TestlyxstringInvariant(this);
//      printf("lyxstring::operator= (value_type const *)\n");

        return assign(s);
}


lyxstring & lyxstring::operator=(value_type c)
{
        TestlyxstringInvariant(this);

        value_type s[1];
        s[0] = c;
        if (rep->ref == 1) // recycle rep
                rep->assign(1, s);
        else {
                rep->ref--;
                rep = new Srep(1, s);
        }
        return *this;
}


lyxstring & lyxstring::assign(lyxstring const & x)
{
        TestlyxstringInvariant(this);

        x.rep->ref++; // protect against ``st = st''
        if (--rep->ref == 0) delete rep;
        rep = x.rep; // share representation
        return *this;
}


lyxstring & lyxstring::assign(lyxstring const & x, size_type pos, size_type n)
{
        lyx::Assert(pos <= x.rep->sz); // STD!
        TestlyxstringInvariant(this);

        return assign(x.substr(pos, n));
}


lyxstring & lyxstring::assign(value_type const * s, size_type n)
{
        lyx::Assert(s && n < npos); // STD!
        TestlyxstringInvariant(this);

        if (rep->ref == 1) // recycle rep
                rep->assign(n, s);
        else {
                --rep->ref;
                rep = new Srep(n, s);
        }
        return *this;
}


lyxstring & lyxstring::assign(value_type const * s)
{
        lyx::Assert(s); // OURS!
        TestlyxstringInvariant(this);

        return assign(s, strlen(s));
}


lyxstring & lyxstring::assign(size_type n, value_type ch)
{
        TestlyxstringInvariant(this);

        rep = rep->get_own_copy();
        rep->assign(n, ch);
        return *this;
}


lyxstring & lyxstring::assign(const_iterator first, const_iterator last)
{
        TestlyxstringInvariant(this);

        rep = rep->get_own_copy();
        rep->assign(last - first, first);
        return *this;
}


////////////////////
// Element Access
////////////////////

lyxstring::const_reference lyxstring::operator[](size_type pos) const
{
#if 0
        // This is actually what the standard requires,
        lyx::Assert(pos <= rep->sz); // OURS!
        static char const helper = '\0';
        return pos == rep->sz ? helper : rep->s[pos];
#else
        // but we use this one since it is stricter
        // and more according to the real intent of std::string.
        lyx::Assert(pos < rep->sz); // OURS!
        return rep->s[pos];
#endif
}


lyxstring::reference lyxstring::operator[](size_type pos)
{
        lyx::Assert(pos < rep->sz); // OURS!
        TestlyxstringInvariant(this);

        rep = rep->get_own_copy();
        return rep->s[pos];
}


lyxstring::const_reference lyxstring::at(size_type n) const
{
        lyx::Assert(n < rep->sz); // STD!
        return rep->s[n];
}


lyxstring::reference lyxstring::at(size_type n)
{
        lyx::Assert(n < rep->sz); // STD!
        TestlyxstringInvariant(this);

        rep = rep->get_own_copy();
        return rep->s[n];
}


/////////////
// Insert
/////////////

lyxstring & lyxstring::operator+=(lyxstring const & x)
{
        TestlyxstringInvariant(this);

        return append(x);
}


lyxstring & lyxstring::operator+=(value_type const * x)
{
        lyx::Assert(x); // OURS!
        TestlyxstringInvariant(this);

        return append(x);
}


lyxstring & lyxstring::operator+=(value_type c)
{
        TestlyxstringInvariant(this);

        push_back(c);
        return *this;
}


void lyxstring::push_back(value_type c)
{
        TestlyxstringInvariant(this);

        rep = rep->get_own_copy();
        rep->push_back(c);
}


lyxstring & lyxstring::append(lyxstring const & x)
{
        TestlyxstringInvariant(this);

        if (x.empty()) return *this;
        rep = rep->get_own_copy();
        rep->append(x.length(), x.rep->s);
        return *this;
}


lyxstring & lyxstring::append(lyxstring const & x, size_type pos, size_type n)
{
        lyx::Assert(pos <= x.rep->sz); // STD!
        TestlyxstringInvariant(this);

        return append(x.substr(pos, n));
}


lyxstring & lyxstring::append(value_type const * p, size_type n)
{
        lyx::Assert(p); // OURS!
        TestlyxstringInvariant(this);

        if (!*p || !n) return *this;
        rep = rep->get_own_copy();
        rep->append(n, p);
        return *this;
}


lyxstring & lyxstring::append(value_type const * p)
{
        lyx::Assert(p); // OURS!
        return append(p, strlen(p));
}


lyxstring & lyxstring::append(size_type n, value_type c)
{
        TestlyxstringInvariant(this);

        value_type * tmp = new value_type[n];
        memset(tmp, c, n);
        rep = rep->get_own_copy();
        rep->append(n, tmp);
        delete[] tmp;
        return *this;
}


lyxstring & lyxstring::append(iterator first, iterator last)
{
        TestlyxstringInvariant(this);

        rep = rep->get_own_copy();
        rep->append(last - first, first);
        return *this;
}

// insert characters before (*this)[pos]

lyxstring & lyxstring::insert(size_type pos, lyxstring const & x)
{
        TestlyxstringInvariant(this);

        return insert(pos, x, 0, x.rep->sz);
}


lyxstring & lyxstring::insert(size_type pos, lyxstring const & x,
                              size_type pos2, size_type n)
{
        lyx::Assert(pos <= rep->sz && pos2 <= x.rep->sz); // STD!
        TestlyxstringInvariant(this);

        rep = rep->get_own_copy();
        rep->insert(pos, &(x.rep->s[pos2]), min(n, x.rep->sz));
        return *this;
}


lyxstring & lyxstring::insert(size_type pos, value_type const * p, size_type n)
{
        lyx::Assert(p); // OURS!
        TestlyxstringInvariant(this);

        if (*p && n) {
                // insert nothing and you change nothing
                rep = rep->get_own_copy();
                rep->insert(pos, p, n);
        }
        return *this;
}


lyxstring & lyxstring::insert(size_type pos, value_type const * p)
{
        lyx::Assert(p); // OURS!
        return insert(pos, p, strlen(p));
}


lyxstring & lyxstring::insert(size_type pos, size_type n, value_type c)
{
        TestlyxstringInvariant(this);

        rep = rep->get_own_copy();
        value_type * tmp = new value_type[n];
        memset(tmp, c, n);
        rep->insert(pos, tmp, n);
        delete[] tmp;
        return *this;
}


lyxstring::iterator lyxstring::insert(iterator p, value_type c)
{
        TestlyxstringInvariant(this);

        // what iterator is this supposed to return??
        size_type tmp = p - begin();
        insert(p - begin(), 1, c);
        return begin() + tmp + 1; // ??
}


void lyxstring::insert(iterator p, size_type n , value_type c)
{
        TestlyxstringInvariant(this);

        insert(p - begin(), n , c);
}


void lyxstring::insert(iterator p, iterator first, iterator last)
{
        TestlyxstringInvariant(this);

        insert(p - begin(), first, last - first);
}


////////////////
// Find
////////////////

         // All the below find functions should be verified,
         // it is very likely that I have mixed up or interpreted
         // some of the parameters wrong, also some of the funcs can surely
         // be written more effectively.

lyxstring::size_type lyxstring::find(lyxstring const & a, size_type i) const
{
        if (!rep->sz || i >= rep->sz) return npos;

        TestlyxstringInvariant(this);

        size_type n = a.length();
        if (!n) return npos;
        for (size_type t = i; rep->sz - t >= n; ++t) {
                // search until (*this)[i] == a[0]
                if (rep->s[t] == a[0]) {
                        // check if the rest of the value_types match
                        bool equal = true;
                        for (size_type j = 1; j < n; ++j) {
                                if (rep->s[t + j] != a[j]) {
                                        equal = false;
                                        break;
                                }
                        }
                        if (equal) return t;
                }
        }
        return npos;
}


lyxstring::size_type lyxstring::find(value_type const * ptr, size_type i,
                                     size_type n) const
{
        lyx::Assert(ptr); // OURS!
        if (!rep->sz || !*ptr || i >= rep->sz) return npos;

        TestlyxstringInvariant(this);

        // What is "n" here? is it the number of value_types to use in ptr
        // or does "i" and "n" togeter form a substring to search
        // for ptr in? For now I will assume that "n" tells the length
        // of ptr. (Lgb)
        n = min(n, strlen(ptr));
        if (!n) return npos;
        for (size_type t = i; rep->sz - t >= n; ++t) {
                // search until (*this)[i] == a[0]
                if (rep->s[t] == ptr[0]) {
                        // check if the rest of the value_types match
                        bool equal = true;
                        for (size_type j = 1; j < n; ++j) {
                                if (rep->s[t + j] != ptr[j]) {
                                        equal = false;
                                        break;
                                }
                        }
                        if (equal) return t;
                }
        }
        return npos;
}


lyxstring::size_type lyxstring::find(value_type const * s, size_type i) const
{
        lyx::Assert(s); // OURS!
        if (!rep->sz || i >= rep->sz) return npos;

        TestlyxstringInvariant(this);

        if (!s || !*s) return npos;
        return find(s, i, strlen(s));
}


lyxstring::size_type lyxstring::find(value_type c, size_type i) const
{
        if (!rep->sz || i >= rep->sz) return npos;

        TestlyxstringInvariant(this);

        for (size_type t = 0; t + i < rep->sz; ++t) {
                if (rep->s[t + i] == c) return t + i;
        }
        return npos;
}


lyxstring::size_type lyxstring::rfind(lyxstring const & a, size_type i) const
{
        TestlyxstringInvariant(this);

        size_type n = a.length();
        if (!n || rep->sz < n)
                return npos;

        size_type t = min(rep->sz - n, i);
        do {
                if (rep->s[t] == a[0]) {
                        // check if the rest of the value_types match
                        bool equal = true;
                        for (size_type j = 1; j < n; ++j) {
                                if (rep->s[t + j] != a[j]) {
                                        equal = false;
                                        break;
                                }
                        }
                        if (equal) return t;
                }
        } while (t-- > 0);
        return npos;
}


lyxstring::size_type lyxstring::rfind(value_type const * ptr, size_type i,
                                      size_type n) const
{
        lyx::Assert(ptr); // OURS!
        TestlyxstringInvariant(this);

        n = min(n, strlen(ptr));
        if (!n || rep->sz < n)
                return npos;

        size_type t = min(rep->sz - n, i);
        do {
                if (rep->s[t] == ptr[0]) {
                        // check if the rest of the value_types match
                        bool equal = true;
                        for (size_type j = 1; j < n; ++j) {
                                if (rep->s[t + j] != ptr[j]) {
                                        equal = false;
                                        break;
                                }
                        }
                        if (equal) return t;
                }
        } while (t-- > 0);
        return npos;
}


lyxstring::size_type lyxstring::rfind(value_type const * ptr,
                                      size_type i) const
{
        lyx::Assert(ptr); // OURS!

        if (!ptr || !*ptr) return npos;
        return rfind(ptr, i, strlen(ptr));
}


lyxstring::size_type lyxstring::rfind(value_type c, size_type i) const
{
        TestlyxstringInvariant(this);

        size_type const sz = rep->sz;
        if (sz < 1) return npos;
        size_type ii = min(sz - 1, i);
        do {
                if (rep->s[ii] == c) return ii;
        } while (ii-- > 0);
        return npos;
}


lyxstring::size_type lyxstring::find_first_of(lyxstring const & a,
                                              size_type i) const
{
        lyx::Assert(i <= rep->sz); // OURS!
        TestlyxstringInvariant(this);

        for (size_type t = i; t < rep->sz; ++t) {
                if (a.find(rep->s[t]) != npos) return t;
        }
        return npos;
}


lyxstring::size_type lyxstring::find_first_of(value_type const * ptr,
                                              size_type i,
                                              size_type n) const
{
        lyx::Assert(ptr && i <= rep->sz); // OURS!
        TestlyxstringInvariant(this);
        if (!n) return npos;

        for (size_type t = i; t < rep->sz; ++t) {
                if (memchr(ptr, rep->s[t], n) != 0) return t;
        }
        return npos;
}


lyxstring::size_type lyxstring::find_first_of(value_type const * ptr,
                                              size_type i) const
{
        lyx::Assert(ptr && i <= rep->sz); // OURS!
        TestlyxstringInvariant(this);

        for (size_type t = i; t < rep->sz; ++t) {
                if (strchr(ptr, rep->s[t]) != 0) return t;
        }
        return npos;
}


lyxstring::size_type lyxstring::find_first_of(value_type c, size_type i) const
{
        lyx::Assert(i <= rep->sz); // OURS!
        TestlyxstringInvariant(this);

        for (size_type t = i; t < rep->sz; ++t) {
                if (rep->s[t] == c) return t;
        }
        return npos;
}


lyxstring::size_type lyxstring::find_last_of(lyxstring const & a,
                                             size_type i) const
{
        TestlyxstringInvariant(this);

        size_type ii = min(rep->sz - 1, i);
        for (int t = ii; t >= 0; --t) {
                if (a.find(rep->s[t]) != npos) return t;
        }
        return npos;
}


lyxstring::size_type lyxstring::find_last_of(value_type const * ptr,
                                             size_type i,
                                             size_type n) const
{
        lyx::Assert(ptr); // OURS!
        TestlyxstringInvariant(this);
        if (!n) return npos;

        size_type ii = min(rep->sz - 1, i);
        for (int t = ii; t >= 0; --t) {
                if (memchr(ptr, rep->s[t], n) != 0) return t;
        }
        return npos;
}


lyxstring::size_type lyxstring::find_last_of(value_type const * ptr,
                                             size_type i) const
{
        lyx::Assert(ptr); // OURS!
        TestlyxstringInvariant(this);

        size_type ii = min(rep->sz - 1, i);
        for (int t = ii; t >= 0; --t) {
                if (strchr(ptr, rep->s[t]) != 0) return t;
        }
        return npos;
}


lyxstring::size_type lyxstring::find_last_of(value_type c, size_type i) const
{
        TestlyxstringInvariant(this);

        if (!rep->sz) return npos;
        size_type ii = min(rep->sz - 1, i);
        for (int t = ii; t >= 0; --t) {
                if (rep->s[t] == c) return t;
        }
        return npos;
}


lyxstring::size_type lyxstring::find_first_not_of(lyxstring const & a,
                                                  size_type i) const
{
        TestlyxstringInvariant(this);

        if (!rep->sz) return npos;
        lyx::Assert(i <= rep->sz);
        for (size_type t = i; t < rep->sz; ++t) {
                if (a.find(rep->s[t]) == npos) return t;
        }
        return npos;
}


lyxstring::size_type lyxstring::find_first_not_of(value_type const * ptr,
                                                  size_type i,
                                                  size_type n) const
{
        lyx::Assert(ptr && i <= rep->sz); // OURS!
        TestlyxstringInvariant(this);

        if (!n) return (i < rep->sz) ? i : npos;
        for (size_type t = i; t < rep->sz; ++t) {
                if (memchr(ptr, rep->s[t], n) == 0) return t;
        }
        return npos;
}


lyxstring::size_type lyxstring::find_first_not_of(value_type const * ptr,
                                                  size_type i) const
{
        lyx::Assert(ptr && i <= rep->sz); // OURS!
        TestlyxstringInvariant(this);

        for (size_type t = i; t < rep->sz; ++t) {
                if (strchr(ptr, rep->s[t]) == 0) return t;
        }
        return npos;
}


lyxstring::size_type lyxstring::find_first_not_of(value_type c,
                                                  size_type i) const
{
        if (!rep->sz) return npos;
        lyx::Assert(i <= rep->sz); // OURS!
        TestlyxstringInvariant(this);

        for (size_type t = i; t < rep->sz; ++t) {
                if (rep->s[t] != c) return t;
        }
        return npos;
}


lyxstring::size_type lyxstring::find_last_not_of(lyxstring const & a,
                                                 size_type i) const
{
        TestlyxstringInvariant(this);

        size_type ii = min(rep->sz - 1, i);
        for (int t = ii; t >= 0; --t) {
                if (a.find(rep->s[t]) == npos) return t;
        }
        return npos;
}


lyxstring::size_type lyxstring::find_last_not_of(value_type const * ptr,
                                                 size_type i,
                                                 size_type n) const
{
        lyx::Assert(ptr); // OURS!
        TestlyxstringInvariant(this);

        if (!n) return npos;
        size_type ii = min(rep->sz - 1, i);

        for (int t = ii; t >= 0; --t) {
                if (memchr(ptr, rep->s[t], n) == 0) return t;
        }
        return npos;
}


lyxstring::size_type lyxstring::find_last_not_of(value_type const * ptr,
                                                 size_type i) const
{
        lyx::Assert(ptr); // OURS!
        TestlyxstringInvariant(this);

        size_type ii = min(rep->sz - 1, i);
        for (int t = ii; t >= 0; --t) {
                if (strchr(ptr, rep->s[t]) == 0) return t;
        }
        return npos;
}


lyxstring::size_type lyxstring::find_last_not_of(value_type c,
                                                 size_type i) const
{
        TestlyxstringInvariant(this);

        size_type ii = min(rep->sz - 1, i);
        for (int t = ii; t >= 0; --t) {
                if (rep->s[t] != c) return t;
        }
        return npos;
}


/////////////////
// Replace
/////////////////

lyxstring & lyxstring::replace(size_type i, size_type n, lyxstring const & x)
{
        lyx::Assert(i <= rep->sz); // OURS!
        TestlyxstringInvariant(this);

        return replace(i, n, x, 0, x.rep->sz);
}


lyxstring & lyxstring::replace(size_type i, size_type n, lyxstring const & x,
                               size_type i2, size_type n2)
{
        lyx::Assert(i <= rep->sz && i2 <= x.rep->sz); // STD!
        TestlyxstringInvariant(this);

        rep = rep->get_own_copy();
        rep->replace(i, min(n, rep->sz), &(x.rep->s[i2]), min(n2, x.rep->sz));
        return *this;
}


lyxstring & lyxstring::replace(size_type i, size_type n,
                               value_type const * p, size_type n2)
{
        lyx::Assert(p && i <= rep->sz); // OURS!
        TestlyxstringInvariant(this);

        rep = rep->get_own_copy();
        rep->replace(i, min(n, rep->sz), p, min(n2, strlen(p)));
        return *this;
}


lyxstring & lyxstring::replace(size_type i, size_type n, value_type const * p)
{
        lyx::Assert(p && i <= rep->sz); // OURS!
        TestlyxstringInvariant(this);

        return replace(i, min(n, rep->sz), p, (!p) ? 0 : strlen(p));
}


lyxstring & lyxstring::replace(size_type i, size_type n,
                               size_type n2, value_type c)
{
        lyx::Assert(i <= rep->sz);  // OURS!
        TestlyxstringInvariant(this);

        rep = rep->get_own_copy();
        value_type * tmp = new value_type[n2];
        memset(tmp, c, n2);
        rep->replace(i, min(n, rep->sz), tmp, n2);
        delete[] tmp;
        return *this;
}


/// FY! FY! FY! go away !
lyxstring & lyxstring::replace(size_type i, size_type n, value_type c)
{
        return replace(i, n, 1, c);
}


lyxstring & lyxstring::replace(iterator i, iterator i2, const lyxstring & str)
{
        TestlyxstringInvariant(this);

        return replace(i - begin(), i2 - i, str);
}


lyxstring & lyxstring::replace(iterator i, iterator i2,
                               value_type const * p, size_type n)
{
        lyx::Assert(p); // OURS!
        TestlyxstringInvariant(this);

        return replace(i - begin(), i2 - i, p, n);
}


lyxstring & lyxstring::replace(iterator i, iterator i2, value_type const * p)
{
        lyx::Assert(p); // OURS!
        TestlyxstringInvariant(this);

        return replace(i - begin(), i2 - i, p);
}


lyxstring & lyxstring::replace(iterator i, iterator i2,
                               size_type n , value_type c)
{
        TestlyxstringInvariant(this);

        return replace(i - begin(), i2 - i, n, c);
}


lyxstring & lyxstring::replace(iterator i, iterator i2,
                               iterator j, iterator j2)
{
        TestlyxstringInvariant(this);

        return replace(i - begin(), i2 - i, j, j2 - j);
}


void lyxstring::swap(lyxstring & str)
{
        if (rep == str.rep) return;
        Srep * tmp = str.rep;
        str.rep = rep;
        rep = tmp;
}


lyxstring & lyxstring::erase(size_type i, size_type n)
{
        lyx::Assert(i <= rep->sz); // STD!
        TestlyxstringInvariant(this);

        rep = rep->get_own_copy();
        if (i == 0 && n >= rep->sz) {
                rep->sz = 0;
        } else {
                n = min(n, rep->sz - i);
                memmove(&(rep->s[i]), &(rep->s[i + n]), rep->sz - i - n);
                rep->sz -= n;
        }
        return *this;
}


lyxstring::iterator lyxstring::erase(iterator i)
{
        TestlyxstringInvariant(this);

        // what iterator is this supposed to return?
        // the iterator after the one erased
        erase(i - begin(), 1);
        return begin(); // BUG
}


lyxstring::iterator lyxstring::erase(iterator first, iterator last)
{
        TestlyxstringInvariant(this);

        erase(first - begin(), last - first);
        return begin(); // BUG
}


/////////////////////////////////////
// Conversion to C-style Strings
/////////////////////////////////////

lyxstring::value_type const * lyxstring::c_str() const
{
        rep->s[length()] = '\0';
        return rep->s;
}


lyxstring::value_type const * lyxstring::data() const
{
        return rep->s;
}


lyxstring::size_type lyxstring::copy(value_type * buf, size_type len,
                                     size_type pos) const
{
        lyx::Assert(buf); // OURS!
        lyx::Assert(pos <= rep->sz); // STD!
        TestlyxstringInvariant(this);

        register int nn = min(len, length() - pos);
        memcpy(buf, &(rep->s[pos]), nn);
        return nn;
}


////////////////////
// Comparisons
////////////////////

// Compare funcs should be verified.

int lyxstring::internal_compare(size_type pos, size_type n,
                                value_type const * s,
                                size_type slen, size_type n2) const
{
        if ((rep->sz == 0 || n == 0) && (!*s || n2 == 0)) return 0;
        if (!*s) return 1;
        // since n > n2, min(n, n2) == 0, c == 0 (stops segfault also)

        // remember that n can very well be a lot larger than rep->sz
        // so we have to ensure that n is no larger than rep->sz
        n = min(n, rep->sz);
        n2 = min(n2, slen);
        if (n == n2)
                return memcmp(&(rep->s[pos]), s, n);
        int c = memcmp(&(rep->s[pos]), s, min(n, n2));
        if (c)
                return c;
        if (n < n2)
                return -1;
        return 1;
}


int lyxstring::compare(lyxstring const & str) const
{
        TestlyxstringInvariant(this);
        return internal_compare(0, rep->sz, str.rep->s,
                                str.rep->sz, str.rep->sz);
}


int lyxstring::compare(value_type const * s) const
{
        lyx::Assert(s); //OURS!
        TestlyxstringInvariant(this);
        int n = (!s) ? 0 : strlen(s);
        return internal_compare(0, rep->sz, s, n, n);
}


int lyxstring::compare(size_type pos, size_type n,
                       lyxstring const & str) const
{
        lyx::Assert(pos <= rep->sz); // OURS!
        TestlyxstringInvariant(this);
        return internal_compare(pos, n, str.rep->s, str.rep->sz, str.rep->sz);
}


int lyxstring::compare(size_type pos, size_type n, lyxstring const & str,
                       size_type pos2, size_type n2) const
{
        lyx::Assert(pos <= rep->sz); // OURS!
        lyx::Assert(pos2 <= str.rep->sz); // OURS!
        TestlyxstringInvariant(this);
        return internal_compare(pos, n,
                                str.rep->s + pos2,
                                str.rep->sz - pos2, n2);
}


int lyxstring::compare(size_type pos, size_type n, value_type const * s,
                       size_type n2) const
{
        lyx::Assert(s && pos <= rep->sz); // OURS!
        TestlyxstringInvariant(this);
        return internal_compare(pos, n, s, (!s) ? 0 : strlen(s), n2);
}


/////////////////
// Substrings
/////////////////

// i = index, n = length
lyxstring lyxstring::substr(size_type i, size_type n) const
{
        lyx::Assert(i <= rep->sz); // STD!
        TestlyxstringInvariant(this);

        return lyxstring(*this, i, n);
}


/////////////////////////////////////////////
// String operators, non member functions
/////////////////////////////////////////////

bool operator==(lyxstring const & a, lyxstring const & b)
{
        return a.compare(b) == 0;
}


bool operator==(lyxstring::value_type const * a, lyxstring const & b)
{
        lyx::Assert(a); // OURS!
        return b.compare(a) == 0;
}


bool operator==(lyxstring const & a, lyxstring::value_type const * b)
{
        lyx::Assert(b); // OURS!
        return a.compare(b) == 0;
}


bool operator!=(lyxstring const & a, lyxstring const & b)
{
        return a.compare(b) != 0;
}


bool operator!=(lyxstring::value_type const * a, lyxstring const & b)
{
        lyx::Assert(a); // OURS!
        return b.compare(a) != 0;
}


bool operator!=(lyxstring const & a, lyxstring::value_type const * b)
{
        lyx::Assert(b); // OURS!
        return a.compare(b) != 0;
}


bool operator>(lyxstring const & a, lyxstring const & b)
{
        return a.compare(b) > 0;
}


bool operator>(lyxstring::value_type const * a, lyxstring const & b)
{
        lyx::Assert(a); // OURS!
        return b.compare(a) < 0; // since we reverse the parameters
}


bool operator>(lyxstring const & a, lyxstring::value_type const * b)
{
        lyx::Assert(b); // OURS!
        return a.compare(b) > 0;
}


bool operator<(lyxstring const & a, lyxstring const & b)
{
        return a.compare(b) < 0;
}


bool operator<(lyxstring::value_type const * a, lyxstring const & b)
{
        lyx::Assert(a); // OURS!
        return b.compare(a) > 0; // since we reverse the parameters
}


bool operator<(lyxstring const & a, lyxstring::value_type const * b)
{
        lyx::Assert(b); // OURS!
        return a.compare(b) < 0;
}


bool operator>=(lyxstring const & a, lyxstring const & b)
{
        return a.compare(b) >= 0;
}


bool operator>=(lyxstring::value_type const * a, lyxstring const & b)
{
        lyx::Assert(a); // OURS!
        return b.compare(a) <= 0; // since we reverse the parameters
}


bool operator>=(lyxstring const & a, lyxstring::value_type const * b)
{
        lyx::Assert(b); // OURS!
        return a.compare(b) >= 0;
}


bool operator<=(lyxstring const & a, lyxstring const & b)
{
        return a.compare(b) <= 0;
}


bool operator<=(lyxstring::value_type const * a, lyxstring const & b)
{
        lyx::Assert(a); // OURS!
        return b.compare(a) >= 0; // since we reverse the parameters
}


bool operator<=(lyxstring const & a, lyxstring::value_type const * b)
{
        lyx::Assert(b); // OURS!
        return a.compare(b) <= 0;
}


lyxstring operator+(lyxstring const & a, lyxstring const & b)
{
        lyxstring tmp(a);
        tmp += b;
        return tmp;
}


lyxstring operator+(lyxstring::value_type const * a, lyxstring const & b)
{
        lyx::Assert(a); // OURS!
        lyxstring tmp(a);
        tmp += b;
        return tmp;
}


lyxstring operator+(lyxstring::value_type a, lyxstring const & b)
{
        lyxstring tmp;
        tmp += a;
        tmp += b;
        return tmp;
}


lyxstring operator+(lyxstring const & a, lyxstring::value_type const * b)
{
        lyx::Assert(b); // OURS!
        lyxstring tmp(a);
        tmp += b;
        return tmp;
}


lyxstring operator+(lyxstring const & a, lyxstring::value_type b)
{
        lyxstring tmp(a);
        tmp += b;
        return tmp;
}


void swap(lyxstring & str1, lyxstring & str2)
{
        str1.swap(str2);
}


#include <iostream>

istream & operator>>(istream & is, lyxstring & s)
{
#if 0
        // very bad solution
        char * nome = new char[1024];
        is >> nome;
        lyxstring tmp(nome);
        delete [] nome;
        if (!tmp.empty()) s = tmp;
#else
        // better solution
        int w = is.width(0);
        s.clear();
        char c = 0;
        bool skipspace = true;
        while (is.get(c)) {
                if (isspace(c)) {
                        if (!skipspace) {
                                is.putback(c);
                                break;
                        }
                } else {
                        s += c;
                        skipspace = false;
                }
                if (--w == 1) break;
        }
        if (s.empty()) is.setstate(std::ios::failbit);
#endif
        return is;
}


ostream & operator<<(ostream & o, lyxstring const & s)
{
        return o.write(s.data(), s.length());
}


istream & getline(istream & is, lyxstring & s,
                  lyxstring::value_type delim)
{
        // very bad solution
        char tmp = 0;
        s.erase();
        while (is) {
                is.get(tmp);
                if (tmp != delim) {
                        s += tmp;
                } else {
                        break;
                }
        }
        return is;
}

#ifdef TEST_MAIN
int main() {
        lyxstring a = "abcac";
        cout << a.rfind("ab") << endl;
        cout << a.rfind("c") << endl;
        cout << a.rfind("d") << endl;
}
#endif