editbox: replace lines edited with recreated line text

program model now emits a signal when a program line is changed (though
its contents may not have actually changed) or inserted; this signal is
connected to the program changed slot in edit box, which retrieves the
recreated text for the line and replaces the line with this text (unless
the line text is null indicating the line has an error and therefore the
text of the line is not replaced)

the program model line text function was modified to return a null
string if the line has an error; this required a slight change to the
recreator where the output string is initialized to an empty string
instead of being cleared (which sets the string to a null string)

added a 'recreating line' flag to prevent a circular loop when the text
of the line is replaced, which generates a document changed and cursor
moved signals; this flag prevents these signals from being processed
during the text replacement

there are two issues with these changes the need to be resolved: when a
program is initially loaded, the lines are not recreated because the
text cursor is not valid yet (preventing the replacement of text) and
the replacing of text interferes with the undo/redo stack by adding
extra commands in the undo stack for each line replaced

editbox.cpp

@@ -41,7 +41,8 @@ EditBox::EditBox(ProgramModel *programUnit, QWidget *parent) :
 	m_modifiedLine(-1),
 	m_modifiedLineIsNew(false),
 	m_lineCount(0),
-	m_cursorValid(false)
+	m_cursorValid(false),
+	m_recreatingLine(false)
 {
 	// set the edit box to a fixed width font
 	QFont font = this->font();
@@ -65,6 +66,10 @@ EditBox::EditBox(ProgramModel *programUnit, QWidget *parent) :
 	//  FROM PROGRAM CONNECTIONS
 	//============================
 
+	// connect to catch program line changes
+	connect(m_programUnit, SIGNAL(programChange(int)),
+		this, SLOT(programChanged(int)));
+
 	// connect to catch when an error has been inserted
 	connect(m_programUnit, SIGNAL(errorInserted(int, ErrorItem)),
 		this, SLOT(errorInserted(int, ErrorItem)));
@@ -308,6 +313,11 @@ void EditBox::resetModified(void)
 
 void EditBox::documentChanged(int position, int charsRemoved, int charsAdded)
 {
+	if (m_recreatingLine)
+	{
+		return;  // change due to recreated line, ignore
+	}
+
 	int linesInserted = 0;
 	int linesDeleted = 0;
 	QStringList lines;
@@ -456,6 +466,10 @@ void EditBox::documentChanged(int position, int charsRemoved, int charsAdded)
 
 void EditBox::cursorMoved(void)
 {
+	if (m_recreatingLine)
+	{
+		return;  // ignore cursor movements when recreating line
+	}
 	if (!m_cursorValid)  // waiting for cursor to be valid?
 	{
 		m_cursorValid = true;  // cursor is now valid
@@ -480,6 +494,32 @@ void EditBox::setPlainText(const QString &text)
 }
 
 
+// function to received program model line changes
+void EditBox::programChanged(int lineNumber)
+{
+	QString lineText = m_programUnit->lineText(lineNumber);
+	if (lineText.isNull())  // line has error?
+	{
+		return;  // don't do anything
+	}
+	if (!m_cursorValid)
+	{
+		return;  // FIXME can't replace lines until cursor is valid
+	}
+
+	QTextCursor cursor = textCursor();
+	cursor.setPosition(document()->findBlockByLineNumber(lineNumber)
+		.position());
+	cursor.movePosition(QTextCursor::EndOfBlock, QTextCursor::KeepAnchor);
+
+	// prevent document changed and cursor moved signals
+	// from being processed before replacing line text
+	m_recreatingLine = true;
+	cursor.insertText(lineText);
+	m_recreatingLine = false;
+}
+
+
 // function to check if current line was modified and to process it
 
 void EditBox::captureModifiedLine(int offset)

editbox.h

@@ -77,6 +77,7 @@ public slots:
 	void documentChanged(int position, int charsRemoved, int charsAdded);
 	void cursorMoved(void);
 	void setPlainText(const QString &text);
+	void programChanged(int lineNumber);
 
 private slots:
 	void errorListChanged(void);
@@ -102,6 +103,7 @@ private slots:
 		m_extraSelections;			// error highlight extra selections list
 	bool m_cursorValid;				// flag for when text cursor is valid
 	QList<ErrorItem> m_errors;		// list of errors during startup
+	bool m_recreatingLine;			// change due to recreated text flag
 };
 
 

programmodel.cpp

@@ -178,11 +178,16 @@ QString ProgramModel::dictionariesDebugText(void)
 // function to return text for a given program line
 QString ProgramModel::lineText(int lineIndex)
 {
+	QString string;
+
 	LineInfo &lineInfo = m_lineInfo[lineIndex];
-	RpnList *rpnList = decode(lineInfo);
-	QString string = m_recreator->recreate(rpnList);
-	delete rpnList;
-	return string;
+	if (lineInfo.errIndex == -1)
+	{
+		RpnList *rpnList = decode(lineInfo);
+		string = m_recreator->recreate(rpnList);
+		delete rpnList;
+	}
+	return string;  // return null string if line has error
 }
 
 
@@ -292,30 +297,30 @@ bool ProgramModel::updateLine(Operation operation, int lineNumber,
 	{
 		LineInfo &lineInfo = m_lineInfo[lineNumber];
 		RpnList *currentRpnList = decode(lineInfo);
-		bool same = *rpnList == *currentRpnList;
+		bool changed = *rpnList != *currentRpnList;
 		delete currentRpnList;
-		if (same)
+		if (changed)
 		{
-			delete rpnList;  // not needed
-			return false;  // line not changed; nothing more to do here
-		}
+			// derefence old line
+			// (line gets deleted if new line has an error)
+			dereference(lineInfo);
 
-		// derefence old line
-		// (line gets deleted if new line has an error)
-		dereference(lineInfo);
+			// line is different, encode it if there was no translation error
+			if (errorItem.isEmpty())
+			{
+				lineCode = encode(rpnList);
+			}
 
-		// line is different, encode it if there was no translation error
-		if (errorItem.isEmpty())
-		{
-			lineCode = encode(rpnList);
-		}
-		delete rpnList;  // no longer needed
+			updateError(lineNumber, lineInfo, errorItem, false);
 
-		updateError(lineNumber, lineInfo, errorItem, false);
+			// replace with new line
+			m_code.replaceLine(lineInfo.offset, lineInfo.size, lineCode);
+			m_lineInfo.replace(lineNumber, lineCode.size());
+		}
 
-		// replace with new line
-		m_code.replaceLine(lineInfo.offset, lineInfo.size, lineCode);
-		m_lineInfo.replace(lineNumber, lineCode.size());
+		emit programChange(lineNumber);
+		delete rpnList;  // no longer needed
+		return changed;
 	}
 	else if (operation == Insert_Operation)
 	{
@@ -346,6 +351,7 @@ bool ProgramModel::updateLine(Operation operation, int lineNumber,
 		m_code.insertLine(lineInfo.offset, lineCode);
 
 		m_lineInfo.insert(lineNumber, lineInfo);
+		emit programChange(lineNumber);
 	}
 	else if (operation == Remove_Operation)
 	{

programmodel.h

@@ -231,6 +231,7 @@ class ProgramModel : public QAbstractListModel
 
 signals:
 	void lineCountChanged(int newLineCount);
+	void programChange(int lineNumber);
 	void errorInserted(int errIndex, const ErrorItem &errorItem);
 	void errorChanged(int errIndex, const ErrorItem &errorItem);
 	void errorRemoved(int errIndex);

recreator.cpp

@@ -38,7 +38,7 @@ Recreator::Recreator(void) :
 // function to recreate original program text from an rpn list
 QString Recreator::recreate(RpnList *rpnList, bool exprMode)
 {
-	m_output.clear();
+	m_output = "";
 	for (int i = 0; i < rpnList->count(); i++)
 	{
 		RpnItem *rpnItem = rpnList->at(i);