Bo Peng's patch.

git-svn-id: svn://svn.lyx.org/lyx/lyx-devel/trunk@6139 a592a061-630c-0410-9148-cb99ea01b6c8

src/mathed/ChangeLog

@@ -1,3 +1,12 @@
+
+2003-02-13  Bo Peng <bpeng@rice.edu>
+ 
+	* math_cursor.h:
+	* math_cursor.C (backspace, erase): return false for empty mathboxes.
+
+	* formulabase.C: When LFUN_DELETE, LFUN_BACKSPACE return false, delete 
+		the empty mathbox. Fix Bug 686.
+
 2003-01-12  Michael Schmitt <michael.schmitt@teststep.org>
 
 	* formula.C (draw, width): Fix spacing around previewed formula.

src/mathed/formulabase.C

@@ -417,6 +417,9 @@ Inset::RESULT InsetFormulaBase::localDispatch(FuncRequest const & cmd)
 	//	<< " y: '" << cmd.y
 	//	<< "' button: " << cmd.button() << endl;
 
+	// delete empty mathbox (LFUN_BACKSPACE and LFUN_DELETE)
+	bool remove_inset; 
+
 	switch (cmd.action) {
 		case LFUN_MOUSE_PRESS:
 			return lfunMousePress(cmd);
@@ -558,15 +561,25 @@ Inset::RESULT InsetFormulaBase::localDispatch(FuncRequest const & cmd)
 	case LFUN_DELETE_WORD_BACKWARD:
 	case LFUN_BACKSPACE:
 		bv->lockedInsetStoreUndo(Undo::EDIT);
-		mathcursor->backspace();
+		if (mathcursor->backspace()) {
+			result = DISPATCHED;
+		} else {
+			result = FINISHED;
+			remove_inset = true;
+		}
 		updateLocal(bv, true);
 		break;
 
 	case LFUN_DELETE_WORD_FORWARD:
 	case LFUN_DELETE:
 		bv->lockedInsetStoreUndo(Undo::EDIT);
-		mathcursor->erase();
-		bv->updateInset(this, true);
+		if (mathcursor->erase()) {
+			result = DISPATCHED;
+		} else {
+			result = FINISHED;
+			remove_inset = true;
+		}
+		updateLocal(bv, true);
 		break;
 
 	//    case LFUN_GETXY:
@@ -826,6 +839,8 @@ Inset::RESULT InsetFormulaBase::localDispatch(FuncRequest const & cmd)
 	} else {
 		releaseMathCursor(bv);
 		bv->unlockInset(this);
+		if (remove_inset)
+			bv->owner()->dispatch(FuncRequest(LFUN_DELETE));
 	}
 
 	return result;  // original version

src/mathed/math_cursor.C

@@ -410,56 +410,66 @@ void MathCursor::paste(string const & data)
 }
 
 
-void MathCursor::backspace()
+bool MathCursor::backspace()
 {
 	autocorrect_ = false;
 
 	if (selection_) {
 		selDel();
-		return;
+		return true;
 	}
 
 	if (pos() == 0) {
-		pullArg();
-		return;
+		if (par()->ncols() == 1 && par()->nrows() == 1 && depth() == 1 && size() == 0)
+			return false;
+		else{
+			pullArg();
+			return true;
+		}
 	}
 
 	if (inMacroMode()) {
 		MathUnknownInset * p = activeMacro();
 		if (p->name().size() > 1) {
 			p->setName(p->name().substr(0, p->name().size() - 1));
-			return;
+			return true;
 		}
 	}
 
 	--pos();
 	plainErase();
+        return true;
 }
 
 
-void MathCursor::erase()
+bool MathCursor::erase()
 {
 	autocorrect_ = false;
 	if (inMacroMode())
-		return;
+		return true;
 
 	if (selection_) {
 		selDel();
-		return;
+		return true;
 	}
 
 	// delete empty cells if possible
 	if (array().empty())
 		if (par()->idxDelete(idx()))
-			return;
+			return true;
 
 	// old behaviour when in last position of cell
 	if (pos() == size()) {
-		par()->idxGlue(idx());
-		return;
+		if (par()->ncols() == 1 && par()->nrows() == 1 && depth() == 1 && size() == 0)
+			return false;
+		else{
+			par()->idxGlue(idx());
+			return true;
+		}
 	}
 
 	plainErase();
+	return true;
 }
 
 

src/mathed/math_cursor.h

@@ -64,10 +64,10 @@ public:
 	void insert(MathArray const &);
 	///
 	void paste(string const & data);
-	///
-	void erase();
-	///
-	void backspace();
+	/// return false for empty math insets
+	bool erase();
+	/// return false for empty math insets
+	bool backspace();
 	/// called for LFUN_HOME etc
 	bool home(bool sel = false);
 	/// called for LFUN_END etc