From fe31e337c13c4db657a267c7a9cf9869a10db696 Mon Sep 17 00:00:00 2001
From: =?utf8?q?Andr=C3=A9=20P=C3=B6nitz?= <poenitz@gmx.net>
Date: Mon, 10 Dec 2001 10:09:00 +0000
Subject: [PATCH] perhaps a fix for the latest crashes

git-svn-id: svn://svn.lyx.org/lyx/lyx-devel/trunk@3174 a592a061-630c-0410-9148-cb99ea01b6c8
---
 src/mathed/Makefile.am     |   2 +
 src/mathed/formula.C       |   4 +-
 src/mathed/formulamacro.C  |   3 +-
 src/mathed/math_cursor.C   | 154 +++++++++++--------------------------
 src/mathed/math_cursor.h   |  48 +-----------
 src/mathed/math_data.h     |   8 +-
 src/mathed/math_iterator.C |  61 +++++++++++----
 src/mathed/math_iterator.h |  18 +++--
 src/mathed/math_pos.C      |  98 +++++++++++++++++++++++
 src/mathed/math_pos.h      |  47 +++++++++++
 10 files changed, 266 insertions(+), 177 deletions(-)
 create mode 100644 src/mathed/math_pos.C
 create mode 100644 src/mathed/math_pos.h

diff --git a/src/mathed/Makefile.am b/src/mathed/Makefile.am
index a3963baff5..ff6bc1a6e5 100644
--- a/src/mathed/Makefile.am
+++ b/src/mathed/Makefile.am
@@ -96,6 +96,8 @@ libmathed_la_SOURCES = \
 	math_notinset.h \
 	math_parser.C \
 	math_parser.h \
+	math_pos.C \
+	math_pos.h \
 	math_replace.h \
 	math_rootinset.C \
 	math_rootinset.h \
diff --git a/src/mathed/formula.C b/src/mathed/formula.C
index b0bc0c7621..2cd2e7304a 100644
--- a/src/mathed/formula.C
+++ b/src/mathed/formula.C
@@ -346,7 +346,9 @@ void InsetFormula::draw(BufferView * bv, LyXFont const & font,
 	if (lcolor.getX11Name(LColor::mathbg)!=lcolor.getX11Name(LColor::background))
 		pain.fillRectangle(x, y - a, w, h, LColor::mathbg);
 
-	if (mathcursor && mathcursor->formula() == this) {
+	if (mathcursor &&
+			const_cast<InsetFormulaBase const *>(mathcursor->formula()) == this)
+	{
 		mathcursor->drawSelection(pain);
 		pain.rectangle(x, y - a, w, h, LColor::mathframe);
 	}
diff --git a/src/mathed/formulamacro.C b/src/mathed/formulamacro.C
index 4e6739ffb7..01e934b4f4 100644
--- a/src/mathed/formulamacro.C
+++ b/src/mathed/formulamacro.C
@@ -215,7 +215,8 @@ void InsetFormulaMacro::draw(BufferView * bv, LyXFont const & f,
 	pain.fillRectangle(int(x), a , w, h, LColor::mathmacrobg);
 	pain.rectangle(int(x), a, w, h, LColor::mathframe);
 
-	if (mathcursor && mathcursor->formula() == this)
+	if (mathcursor &&
+			const_cast<InsetFormulaBase const *>(mathcursor->formula()) == this)
 		mathcursor->drawSelection(pain);
 
 	pain.text(int(x + 2), y, prefix(), font);
diff --git a/src/mathed/math_cursor.C b/src/mathed/math_cursor.C
index 9aeeafba1e..2d7747052c 100644
--- a/src/mathed/math_cursor.C
+++ b/src/mathed/math_cursor.C
@@ -68,7 +68,7 @@ struct Selection
 			data_.push_back(MathArray(i1.cell(), i1.pos_, i2.pos_));
 		else {
 			std::vector<MathInset::idx_type> indices =
-				i1.par_->idxBetween(i1.idx_, i2.idx_);
+				i1.par_->nucleus()->idxBetween(i1.idx_, i2.idx_);
 			for (MathInset::idx_type i = 0; i < indices.size(); ++i)
 				data_.push_back(i1.cell(indices[i]));
 		}
@@ -83,7 +83,7 @@ struct Selection
 			i1.cell().erase(i1.pos_, i2.pos_);
 		else {
 			std::vector<MathInset::idx_type> indices =
-				i1.par_->idxBetween(i1.idx_, i2.idx_);
+				i1.par_->nucleus()->idxBetween(i1.idx_, i2.idx_);
 			for (unsigned i = 0; i < indices.size(); ++i)
 				i1.cell(indices[i]).erase();
 		}
@@ -130,7 +130,11 @@ MathCursor::MathCursor(InsetFormulaBase * formula, bool left)
 
 void MathCursor::push(MathAtom & t)
 {
-	Cursor_.push_back(MathCursorPos(t.nucleus()));
+	MathCursorPos p;
+	p.par_ = &t;
+	p.idx_ = 0;
+	p.pos_ = 0;
+	Cursor_.push_back(p);
 }
 
 
@@ -207,7 +211,7 @@ UpdatableInset * MathCursor::asHyperActiveInset() const
 bool MathCursor::isInside(MathInset const * p) const
 {
 	for (unsigned i = 0; i < Cursor_.size(); ++i) 
-		if (Cursor_[i].par_ == p) 
+		if (Cursor_[i].par_->nucleus() == p) 
 			return true;
 	return false;
 }
@@ -228,7 +232,7 @@ bool MathCursor::openable(MathAtom const & t, bool sel) const
 		// we can't move into anything new during selection
 		if (Cursor_.size() == Anchor_.size())
 			return false;
-		if (t.nucleus() != Anchor_[Cursor_.size()].par_)
+		if (&t != Anchor_[Cursor_.size()].par_)
 			return false;
 	}
 	return true;
@@ -323,16 +327,17 @@ void MathCursor::setPos(int x, int y)
 	cursor_type best_cursor;
 	double best_dist = 1e10;
 
-	MathIterator it(formula()->par().nucleus());
-	MathIterator et;
+	MathIterator it = ibegin(formula()->par());
+	MathIterator et = iend(formula()->par());
 	for ( ; it != et; ++it) {
+		//lyxerr << "*it: " << *it << "  *et: " << *et << "\n";
 		if (selection_) {
 			// avoid deeper nested insets when selecting
 			if (it.cursor().size() > Anchor_.size())
 				continue;
 			// anchor might be deeper!
 			if (it.cursor().size() == Anchor_.size())
-				if (it.par() != Anchor_.back().par_)
+				if (it.par().nucleus() != Anchor_.back().par_->nucleus())
 					continue;
 			//if (it.par() != Anchor_[it.cursor().size()].par_)
 			//	continue;
@@ -349,6 +354,7 @@ void MathCursor::setPos(int x, int y)
 	if (best_dist < 1e10)
 		Cursor_ = best_cursor;
 	//lyxerr << "x: " << x << " y: " << y << " dist: " << best_dist << "\n";
+	lyx::Assert(Cursor_.size());
 	dump("setPos 2");
 }
 
@@ -723,7 +729,6 @@ void MathCursor::drawSelection(Painter & pain) const
 	MathCursorPos i1;
 	MathCursorPos i2;
 	getSelection(i1, i2);
-	//lyxerr << "selection from: " << i1 << " to " << i2 << "\n";
 
 	if (i1.idx_ == i2.idx_) {
 		MathXArray & c = i1.xcell();
@@ -734,7 +739,7 @@ void MathCursor::drawSelection(Painter & pain) const
 		pain.fillRectangle(x1, y1, x2 - x1, y2 - y1, LColor::selection);
 	} else {
 		std::vector<MathInset::idx_type> indices
-			= i1.par_->idxBetween(i1.idx_, i2.idx_);
+			= (*i1.par_)->idxBetween(i1.idx_, i2.idx_);
 		for (unsigned i = 0; i < indices.size(); ++i) {
 			MathXArray & c = i1.xcell(indices[i]);
 			int x1 = c.xo();
@@ -798,20 +803,18 @@ void MathCursor::getPos(int & x, int & y)
 #ifdef WITH_WARNINGS
 #warning This should probably take cellXOffset and cellYOffset into account
 #endif
-	dump("getPos 1");
 	x = xarray().xo() + xarray().pos2x(pos());
 	y = xarray().yo();
-	dump("getPos 2");
 }
 
 
-MathInset * MathCursor::par() const
+MathAtom & MathCursor::par() const
 {
-	return cursor().par_;
+	return *cursor().par_;
 }
 
 
-InsetFormulaBase const * MathCursor::formula()
+InsetFormulaBase * MathCursor::formula()
 {
 	return formula_;
 }
@@ -856,7 +859,7 @@ bool MathCursor::selection() const
 MathGridInset * MathCursor::enclosingGrid(MathCursor::idx_type & idx) const
 {
 	for (int i = Cursor_.size() - 1; i >= 0; --i) {
-		MathGridInset * p = Cursor_[i].par_->asGridInset();
+		MathGridInset * p = (*Cursor_[i].par_)->asGridInset();
 		if (p) {
 			idx = Cursor_[i].idx_;
 			return p;
@@ -987,12 +990,24 @@ MathArray & MathCursor::array() const
 		return dummy;
 	}
 
+	if (Cursor_.size() == 0) {
+		lyxerr << "############  Cursor_.size() == 0 not valid\n";
+		return dummy;
+	}
+
 	return cursor().cell();
 }
 
 
 MathXArray & MathCursor::xarray() const
 {
+	static MathXArray dummy;
+
+	if (Cursor_.size() == 0) {
+		lyxerr << "############  Cursor_.size() == 0 not valid\n";
+		return dummy;
+	}
+
 	return cursor().xcell();
 }
 
@@ -1036,19 +1051,18 @@ void MathCursor::breakLine()
 		p->mutate(LM_OT_EQNARRAY);
 		idx() = 0;
 		pos() = size();
-		return;
-	}
-	
-	p->addRow(row());
+	} else {
+		p->addRow(row());
 
-	// split line
-	const row_type r = row();
-	for (col_type c = col() + 1; c < p->ncols(); ++c)
-		p->cell(p->index(r, c)).swap(p->cell(p->index(r + 1, c)));
+		// split line
+		const row_type r = row();
+		for (col_type c = col() + 1; c < p->ncols(); ++c)
+			p->cell(p->index(r, c)).swap(p->cell(p->index(r + 1, c)));
 
-	// split cell
-	splitCell();
-	p->cell(idx()).swap(p->cell(idx() + p->ncols() - 1));
+		// split cell
+		splitCell();
+		p->cell(idx()).swap(p->cell(idx() + p->ncols() - 1));
+	}
 }
 
 
@@ -1091,12 +1105,14 @@ void MathCursor::getSelection(MathCursorPos & i1, MathCursorPos & i2) const
 
 MathCursorPos & MathCursor::cursor()
 {
+	lyx::Assert(Cursor_.size());
 	return Cursor_.back();
 }
 
 
 MathCursorPos const & MathCursor::cursor() const
 {
+	lyx::Assert(Cursor_.size());
 	return Cursor_.back();
 }
 
@@ -1160,8 +1176,8 @@ bool MathCursor::bruteFind(int xlow, int xhigh, int ylow, int yhigh)
 	cursor_type best_cursor;
 	double best_dist = 1e10;
 
-	MathIterator it(formula()->par().nucleus());
-	MathIterator et;
+	MathIterator it = ibegin(formula()->par());
+	MathIterator et = iend(formula()->par());
 	for ( ; it != et; ++it) {
 		int xo = it.position().xpos();
 		int yo = it.position().ypos();
@@ -1395,6 +1411,7 @@ bool MathCursor::interpret(char c)
 
 MathCursorPos MathCursor::normalAnchor() const
 {
+	lyx::Assert(Anchor_.size() >= Cursor_.size());
 	// use Anchor on the same level as Cursor
 	MathCursorPos normal = Anchor_[Cursor_.size() - 1];
 	if (Cursor_.size() < Anchor_.size() && !(normal < cursor())) {
@@ -1420,82 +1437,3 @@ void MathCursor::stripFromLastEqualSign()
 }
 
 
-////////////////////////////////////////////////////////////////////////
-
-
-MathCursorPos::MathCursorPos()
-	: par_(0), idx_(0), pos_(0)
-{}
-
-
-MathCursorPos::MathCursorPos(MathInset * p)
-	: par_(p), idx_(0), pos_(0)
-{}
-
-
-MathArray & MathCursorPos::cell(MathCursor::idx_type idx) const
-{
-	return par_->cell(idx);
-}
-
-
-MathArray & MathCursorPos::cell() const
-{
-	return par_->cell(idx_);
-}
-
-
-MathXArray & MathCursorPos::xcell(MathCursor::idx_type idx) const
-{
-	return par_->xcell(idx);
-}
-
-
-MathXArray & MathCursorPos::xcell() const
-{
-	return par_->xcell(idx_);
-}
-
-
-int MathCursorPos::xpos() const
-{
-	return xcell().xo() + xcell().pos2x(pos_);
-}
-
-
-int MathCursorPos::ypos() const
-{
-	return xcell().yo();
-}
-
-std::ostream & operator<<(std::ostream & os, MathCursorPos const & p)
-{
-	os << "(par: " << p.par_ << " idx: " << p.idx_ << " pos: " << p.pos_ << ")";
-	return os;
-}
-
-
-bool operator==(MathCursorPos const & ti, MathCursorPos const & it)
-{
-	return ti.par_ == it.par_ && ti.idx_ == it.idx_ && ti.pos_ == it.pos_;
-}
-
-
-bool operator!=(MathCursorPos const & ti, MathCursorPos const & it)
-{
-	return ti.par_ != it.par_ || ti.idx_ != it.idx_ || ti.pos_ != it.pos_;
-}
-
-
-bool operator<(MathCursorPos const & ti, MathCursorPos const & it)
-{
-	if (ti.par_ != it.par_) {
-		lyxerr << "can't compare cursor and anchor in different insets\n";
-		return true;
-	}
-	if (ti.idx_ != it.idx_)
-		return ti.idx_ < it.idx_;
-	return ti.pos_ < it.pos_;
-}
-
-
diff --git a/src/mathed/math_cursor.h b/src/mathed/math_cursor.h
index f0fd8efd12..93f5d05bcf 100644
--- a/src/mathed/math_cursor.h
+++ b/src/mathed/math_cursor.h
@@ -23,6 +23,7 @@
 
 #include "math_defs.h"
 #include "math_inset.h"
+#include "math_pos.h"
 #include "LString.h"
 
 class InsetFormulaBase;
@@ -41,47 +42,6 @@ this formula's mathHullInset to the current position.
 */
 
 
-/// Description of a position 
-class MathCursorPos {
-public:
-	/// 
-	MathCursorPos();
-	/// 
-	explicit MathCursorPos(MathInset * p);
-
-	/// returns cell corresponding to this position
-	MathArray & cell() const;
-	/// returns cell corresponding to this position
-	MathArray & cell(MathInset::idx_type idx) const;
-	/// returns xcell corresponding to this position
-	MathXArray & xcell() const;
-	/// returns xcell corresponding to this position
-	MathXArray & xcell(MathInset::idx_type idx) const;
-	///
-	int xpos() const;
-	///
-	int ypos() const;
-
-public:
-	/// pointer to an inset
-	MathInset * par_;
-	/// cell index of a position in this inset
-	MathInset::idx_type idx_;
-	/// position in this cell
-	MathInset::pos_type pos_;
-};
-
-/// test for equality
-bool operator==(MathCursorPos const &, MathCursorPos const &);
-/// test for inequality
-bool operator!=(MathCursorPos const &, MathCursorPos const &);
-/// test for order
-bool operator<(MathCursorPos const &, MathCursorPos const &);
-/// output
-std::ostream & operator<<(std::ostream &, MathCursorPos const &);
-
-
-/// see above
 class MathCursor {
 public:
 	/// short of anything else reasonable
@@ -143,11 +103,11 @@ public:
 	/// in pixels from top of screen
 	void getPos(int & x, int & y);
 	/// 
-	MathInset * par() const;
+	MathAtom & par() const;
 	/// return the next enclosing grid inset and the cursor's index in it
 	MathGridInset * enclosingGrid(idx_type &) const;
 	///
-	InsetFormulaBase const * formula();
+	InsetFormulaBase * formula();
 	/// current offset in the current cell
 	pos_type pos() const;
 	/// current cell
@@ -305,7 +265,7 @@ private:
 	idx_type & idx();
 
 	///
-	InsetFormulaBase * const formula_;
+	InsetFormulaBase * formula_;
 	///
 	MathTextCodes lastcode_;
 	// Selection stuff
diff --git a/src/mathed/math_data.h b/src/mathed/math_data.h
index d603337526..b537e51d70 100644
--- a/src/mathed/math_data.h
+++ b/src/mathed/math_data.h
@@ -13,8 +13,8 @@
  *   the GNU General Public Licence version 2 or later.
  */
 
-#ifndef MATHEDARRAY_H
-#define MATHEDARRAY_H
+#ifndef MATH_DATA_H
+#define MATH_DATA_H
 
 #include <vector>
 
@@ -49,6 +49,10 @@ public:
 	typedef buffer_type::iterator        iterator;
 	///
 	typedef buffer_type::size_type       size_type;
+	///
+	typedef buffer_type::size_type       idx_type;
+	///
+	typedef buffer_type::size_type       pos_type;
 
 public:
 	///
diff --git a/src/mathed/math_iterator.C b/src/mathed/math_iterator.C
index 0ea88d5098..c0841de2bd 100644
--- a/src/mathed/math_iterator.C
+++ b/src/mathed/math_iterator.C
@@ -1,17 +1,18 @@
 
 #include <config.h>
 
-#include "debug.h"
 #include "math_iterator.h"
+#include "debug.h"
+#include "support/LAssert.h"
 
 
-MathIterator::MathIterator()
-{}
+//MathIterator::MathIterator()
+//{}
 
 
-MathIterator::MathIterator(MathInset * p)
+MathIterator::MathIterator(MathAtom & t)
 {
-	push(p);
+	push(t);
 }
 
 
@@ -22,12 +23,14 @@ MathIterator::MathIterator(MathCursor::cursor_type const & c)
 
 MathCursorPos const & MathIterator::position() const
 {
+	lyx::Assert(cursor_.size());
 	return cursor_.back();
 }
 
 
 MathCursorPos & MathIterator::position()
 {
+	lyx::Assert(cursor_.size());
 	return cursor_.back();
 }
 
@@ -38,38 +41,43 @@ MathCursor::cursor_type const & MathIterator::cursor() const
 }
 
 
-MathInset * MathIterator::par() const
+MathAtom const & MathIterator::par() const
+{
+	return *(position().par_);
+}
+
+
+MathAtom & MathIterator::par()
 {
-	return cursor_.size() ? cursor_.back().par_ : 0;
+	return *(position().par_);
 }
 
 
 MathXArray const & MathIterator::xcell() const
 {
-	if (!par())
-		lyxerr << "MathIterator::xcell: no cell\n";
 	return par()->xcell(position().idx_);
 }
 
 
-MathInset * MathIterator::nextInset() const
+MathAtom * MathIterator::nextInset() const
 {
 	if (position().pos_ == xcell().data_.size())
 		return 0;
-	return (xcell().begin() + position().pos_)->nucleus();
+	return const_cast<MathAtom *>(xcell().begin() + position().pos_);
 }
 
 
-void MathIterator::push(MathInset * p)
+void MathIterator::push(MathAtom & t)
 {
 	//lyxerr << "push: " << p << endl;
-	cursor_.push_back(MathCursorPos(p));
+	cursor_.push_back(MathCursorPos(t));
 }
 
 
 void MathIterator::pop()
 {
 	//lyxerr << "pop: " << endl;
+	lyx::Assert(cursor_.size());
 	cursor_.pop_back();
 }
 
@@ -86,12 +94,19 @@ MathCursorPos const & MathIterator::operator->() const
 }
 
 
+void MathIterator::goEnd()
+{
+	position().idx_ = par()->nargs() - 1;
+	position().pos_ = xcell().data_.size();
+}
+
+
 void MathIterator::operator++()
 {
 	// move into the current inset if possible
 	// it is impossible for pos() == size()!
-	if (nextInset() && nextInset()->isActive()) {
-		push(nextInset());
+	if (nextInset() && nextInset()->nucleus()->isActive()) {
+		push(*nextInset());
 		return;
 	}
 
@@ -110,7 +125,7 @@ void MathIterator::operator++()
 		return;
 	}
 
-	// otherwise leave array, move on one cell
+	// otherwise leave array, move on one position
 	// this might yield pos() == size(), but that's a ok.
 	pop();
 	++position().pos_;
@@ -135,3 +150,17 @@ bool operator!=(MathIterator const & it, MathIterator const & jt)
 	return it.cursor() != jt.cursor();	
 }
 
+
+
+MathIterator ibegin(MathAtom & t)
+{
+	return MathIterator(t);
+}
+
+
+MathIterator iend(MathAtom & t)
+{
+	MathIterator it(t);
+	it.goEnd();
+	return it;
+}
diff --git a/src/mathed/math_iterator.h b/src/mathed/math_iterator.h
index f56911c4d5..e351080906 100644
--- a/src/mathed/math_iterator.h
+++ b/src/mathed/math_iterator.h
@@ -8,9 +8,9 @@
 class MathIterator {
 public:
 	/// default constructor, used for end of range
-	MathIterator();
+	//MathIterator();
 	/// start with given formula
-	explicit MathIterator(MathInset * p);
+	explicit MathIterator(MathAtom & t);
 	/// start with given position
 	explicit MathIterator(MathCursor::cursor_type const & cursor);
 	///
@@ -26,15 +26,19 @@ public:
 	/// read access to full path
 	MathCursor::cursor_type const & cursor() const;
 	/// read access to top most inset
-	MathInset * par() const;
+	MathAtom const & par() const;
+	/// read access to top most inset
+	MathAtom & par();
+	/// helper for iend
+	void goEnd();
 	
 private:
 	/// write access to top most item
 	MathXArray const & xcell() const;
 	/// write access to top most item
-	MathInset * nextInset() const;
+	MathAtom * nextInset() const;
 	/// own level down
-	void push(MathInset *);
+	void push(MathAtom &);
 	/// own level up
 	void pop();
 
@@ -47,5 +51,9 @@ bool operator==(MathIterator const &, MathIterator const &);
 ///
 bool operator!=(MathIterator const &, MathIterator const &);
 
+///
+MathIterator ibegin(MathAtom & p);
+///
+MathIterator iend(MathAtom & p);
 
 #endif
diff --git a/src/mathed/math_pos.C b/src/mathed/math_pos.C
new file mode 100644
index 0000000000..889f13782a
--- /dev/null
+++ b/src/mathed/math_pos.C
@@ -0,0 +1,98 @@
+#include "config.h"
+
+#include <iostream>
+
+#include "math_pos.h"
+#include "math_inset.h"
+#include "debug.h"
+#include "support/LAssert.h"
+
+
+MathCursorPos::MathCursorPos()
+	: par_(0), idx_(0), pos_(0)
+{}
+
+
+MathCursorPos::MathCursorPos(MathAtom & t)
+	: par_(&t), idx_(0), pos_(0)
+{
+	lyx::Assert(par_);
+	lyx::Assert(par_->nucleus());
+}
+
+
+MathArray & MathCursorPos::cell(MathArray::idx_type idx) const
+{
+	lyx::Assert(par_);
+	lyx::Assert(par_->nucleus());
+	return par_->nucleus()->cell(idx);
+}
+
+
+MathArray & MathCursorPos::cell() const
+{
+	lyx::Assert(par_);
+	lyx::Assert(par_->nucleus());
+	return par_->nucleus()->cell(idx_);
+}
+
+
+MathXArray & MathCursorPos::xcell(MathArray::idx_type idx) const
+{
+	lyx::Assert(par_);
+	lyx::Assert(par_->nucleus());
+	return par_->nucleus()->xcell(idx);
+}
+
+
+MathXArray & MathCursorPos::xcell() const
+{
+	lyx::Assert(par_);
+	lyx::Assert(par_->nucleus());
+	return par_->nucleus()->xcell(idx_);
+}
+
+
+int MathCursorPos::xpos() const
+{
+	return xcell().xo() + xcell().pos2x(pos_);
+}
+
+
+int MathCursorPos::ypos() const
+{
+	return xcell().yo();
+}
+
+
+std::ostream & operator<<(std::ostream & os, MathCursorPos const & p)
+{
+	os << "(par: " << p.par_ << " idx: " << p.idx_ << " pos: " << p.pos_ << ")";
+	return os;
+}
+
+
+bool operator==(MathCursorPos const & p, MathCursorPos const & q)
+{
+	return p.par_ == q.par_ && p.idx_ == q.idx_ && p.pos_ == q.pos_;
+}
+
+
+bool operator!=(MathCursorPos const & p, MathCursorPos const & q)
+{
+	return p.par_ != q.par_ || p.idx_ != q.idx_ || p.pos_ != q.pos_;
+}
+
+
+bool operator<(MathCursorPos const & p, MathCursorPos const & q)
+{
+	if (p.par_ != q.par_) {
+		lyxerr << "can't compare cursor and anchor in different insets\n";
+		return true;
+	}
+	if (p.idx_ != q.idx_)
+		return p.idx_ < q.idx_;
+	return p.pos_ < q.pos_;
+}
+
+
diff --git a/src/mathed/math_pos.h b/src/mathed/math_pos.h
new file mode 100644
index 0000000000..8d8e9e951a
--- /dev/null
+++ b/src/mathed/math_pos.h
@@ -0,0 +1,47 @@
+#ifndef MATH_POS_H
+#define MATH_POS_H
+
+#include <iosfwd>
+#include "math_xdata.h"
+
+
+/// Description of a position 
+class MathCursorPos {
+public:
+	/// 
+	MathCursorPos();
+	/// 
+	explicit MathCursorPos(MathAtom &);
+
+	/// returns cell corresponding to this position
+	MathArray & cell() const;
+	/// returns cell corresponding to this position
+	MathArray & cell(MathArray::idx_type idx) const;
+	/// returns xcell corresponding to this position
+	MathXArray & xcell() const;
+	/// returns xcell corresponding to this position
+	MathXArray & xcell(MathArray::idx_type idx) const;
+	///
+	int xpos() const;
+	///
+	int ypos() const;
+
+public:
+	/// pointer to an inset
+	MathAtom * par_;
+	/// cell index of a position in this inset
+	MathArray::idx_type idx_;
+	/// position in this cell
+	MathArray::pos_type pos_;
+};
+
+/// test for equality
+bool operator==(MathCursorPos const &, MathCursorPos const &);
+/// test for inequality
+bool operator!=(MathCursorPos const &, MathCursorPos const &);
+/// test for order
+bool operator<(MathCursorPos const &, MathCursorPos const &);
+/// output
+std::ostream & operator<<(std::ostream &, MathCursorPos const &);
+
+#endif
-- 
2.39.2