Folding related fixes. Initiated by bug #3323805.

Make fold highlighting follow closely the actual folding implementation.

Introduce a concept of fold headers with a tail to accommodate certain
fold highlighting situations.

Optimize PaintSelMargin(), so it doesn't waste time with fold markers,
unless really necessary.

Make EnsureLineVisible() find right parent, when called on whitespace line.

Fix wrong fold tail marker when needWhiteClosure is true.

1 files changed, 60 insertions, 91 deletions

diff --git a/src/Document.cxx b/src/Document.cxx
index 85bb98135..da07b6b73 100644
--- a/src/Document.cxx
+++ b/src/Document.cxx
@@ -316,15 +316,18 @@ static bool IsSubordinate(int levelStart, int levelTry) {
 		return (levelStart & SC_FOLDLEVELNUMBERMASK) < (levelTry & SC_FOLDLEVELNUMBERMASK);
 }
 
-int Document::GetLastChild(int lineParent, int level) {
+int Document::GetLastChild(int lineParent, int level, int lastLine) {
 	if (level == -1)
 		level = GetLevel(lineParent) & SC_FOLDLEVELNUMBERMASK;
 	int maxLine = LinesTotal();
+	int lookLastLine = (lastLine != -1) ? Platform::Minimum(LinesTotal() - 1, lastLine) : -1;
 	int lineMaxSubord = lineParent;
 	while (lineMaxSubord < maxLine - 1) {
 		EnsureStyledTo(LineStart(lineMaxSubord + 2));
 		if (!IsSubordinate(level, GetLevel(lineMaxSubord + 1)))
 			break;
+		if ((lookLastLine != -1) && (lineMaxSubord >= lookLastLine) && !(GetLevel(lineMaxSubord) & SC_FOLDLEVELWHITEFLAG))
+			break;
 		lineMaxSubord++;
 	}
 	if (lineMaxSubord > lineParent) {
@@ -355,108 +358,74 @@ int Document::GetFoldParent(int line) {
 	}
 }
 
-void Document::GetHighlightDelimiters(HighlightDelimiter &highlightDelimiter, int line, int topLine, int bottomLine) {
-	int noNeedToParseBefore = Platform::Minimum(line, topLine) - 1;
-	int noNeedToParseAfter = Platform::Maximum(line, bottomLine) + 1;
-	int endLine = LineFromPosition(Length());
-	int beginFoldBlock = noNeedToParseBefore;
-	int endFoldBlock = -1;
-	int beginMarginCorrectlyDrawnZone = noNeedToParseBefore;
-	int endMarginCorrectlyDrawnZone = noNeedToParseAfter;
-	int endOfTailOfWhiteFlag = -1; //endOfTailOfWhiteFlag points the last SC_FOLDLEVELWHITEFLAG if follow a fold block. Otherwise endOfTailOfWhiteFlag points end of fold block.
+void Document::GetHighlightDelimiters(HighlightDelimiter &highlightDelimiter, int line, int lastLine) {
 	int level = GetLevel(line);
-	int levelNumber = -1;
-	int lineLookLevel = 0;
-	int lineLookLevelNumber = -1;
-	int lineLook = line;
-	bool beginFoldBlockFound = false;
-	bool endFoldBlockFound = false;
-	bool beginMarginCorrectlyDrawnZoneFound = false;
-	bool endMarginCorrectlyDrawnZoneFound = false;
-
-	/*******************************************************************************/
-	/*      search backward (beginFoldBlock & beginMarginCorrectlyDrawnZone)       */
-	/*******************************************************************************/
-	for (endOfTailOfWhiteFlag = line; (lineLook > noNeedToParseBefore || (lineLookLevel & SC_FOLDLEVELWHITEFLAG)) && (!beginFoldBlockFound || !beginMarginCorrectlyDrawnZoneFound); --lineLook) {
-		lineLookLevel = GetLevel(lineLook);
-		if (levelNumber != -1) {
-			lineLookLevelNumber = lineLookLevel & SC_FOLDLEVELNUMBERMASK;
-			if (!beginMarginCorrectlyDrawnZoneFound && (lineLookLevelNumber > levelNumber)) {
-				beginMarginCorrectlyDrawnZoneFound = true;
-				beginMarginCorrectlyDrawnZone = endOfTailOfWhiteFlag;
-			}
-			//find the last space line (SC_FOLDLEVELWHITEFLAG).
-			if (!beginMarginCorrectlyDrawnZoneFound && !(lineLookLevel & SC_FOLDLEVELWHITEFLAG)) {
-				endOfTailOfWhiteFlag = lineLook - 1;
-			}
-			if (!beginFoldBlockFound && (lineLookLevelNumber < levelNumber)) {
-				beginFoldBlockFound = true;
-				beginFoldBlock = lineLook;
-				if (!beginMarginCorrectlyDrawnZoneFound) {
-					beginMarginCorrectlyDrawnZoneFound = true;
-					beginMarginCorrectlyDrawnZone = lineLook - 1;
+	int lookLastLine = Platform::Maximum(line, lastLine) + 1;
+
+	int lookLine = line;
+	int lookLineLevel = level;
+	int lookLineLevelNum = lookLineLevel & SC_FOLDLEVELNUMBERMASK;
+	while ((lookLine > 0) && ((lookLineLevel & SC_FOLDLEVELWHITEFLAG) || 
+		((lookLineLevel & SC_FOLDLEVELHEADERFLAG) && (lookLineLevelNum >= (GetLevel(lookLine + 1) & SC_FOLDLEVELNUMBERMASK))))) {
+		lookLineLevel = GetLevel(--lookLine);
+		lookLineLevelNum = lookLineLevel & SC_FOLDLEVELNUMBERMASK;
+	}
+
+	int beginFoldBlock = (lookLineLevel & SC_FOLDLEVELHEADERFLAG) ? lookLine : GetFoldParent(lookLine);
+	if (beginFoldBlock == -1) {
+		highlightDelimiter.Clear();
+		return;
+	}
+
+	int endFoldBlock = GetLastChild(beginFoldBlock, -1, lookLastLine);
+	int firstChangeableLineBefore = -1;
+	if (endFoldBlock < line) {
+		lookLine = beginFoldBlock - 1;
+		lookLineLevel = GetLevel(lookLine);
+		lookLineLevelNum = lookLineLevel & SC_FOLDLEVELNUMBERMASK;
+		while ((lookLine >= 0) && (lookLineLevelNum >= SC_FOLDLEVELBASE)) {
+			if (lookLineLevel & SC_FOLDLEVELHEADERFLAG) {
+				if (GetLastChild(lookLine, -1, lookLastLine) == line) {
+					beginFoldBlock = lookLine;
+					endFoldBlock = line;
+					firstChangeableLineBefore = line - 1;
 				}
-			} else 	if (!beginFoldBlockFound && lineLookLevelNumber == SC_FOLDLEVELBASE) {
-				beginFoldBlockFound = true;
-				beginFoldBlock = -1;
-			}
-		} else if (!(lineLookLevel & SC_FOLDLEVELWHITEFLAG)) {
-			endOfTailOfWhiteFlag = lineLook - 1;
-			levelNumber = lineLookLevel & SC_FOLDLEVELNUMBERMASK;
-			if (lineLookLevel & SC_FOLDLEVELHEADERFLAG &&
-			        //Managed the folding block when a fold header does not have any subordinate lines to fold away.
-			        (levelNumber < (GetLevel(lineLook + 1) & SC_FOLDLEVELNUMBERMASK))) {
-				beginFoldBlockFound = true;
-				beginFoldBlock = lineLook;
-				beginMarginCorrectlyDrawnZoneFound = true;
-				beginMarginCorrectlyDrawnZone = endOfTailOfWhiteFlag;
-				levelNumber = GetLevel(lineLook + 1) & SC_FOLDLEVELNUMBERMASK;;
 			}
+			if ((lookLine > 0) && (lookLineLevelNum == SC_FOLDLEVELBASE) && ((GetLevel(lookLine - 1) & SC_FOLDLEVELNUMBERMASK) > lookLineLevelNum))
+				break;
+			lookLineLevel = GetLevel(--lookLine);
+			lookLineLevelNum = lookLineLevel & SC_FOLDLEVELNUMBERMASK;
 		}
 	}
-
-	/****************************************************************************/
-	/*       search forward (endStartBlock & endMarginCorrectlyDrawnZone)       */
-	/****************************************************************************/
-	if (level & SC_FOLDLEVELHEADERFLAG) {
-		//ignore this line because this line is on first one of block.
-		lineLook = line + 1;
-	} else {
-		lineLook = line;
-	}
-	for (; lineLook < noNeedToParseAfter && (!endFoldBlockFound || !endMarginCorrectlyDrawnZoneFound); ++lineLook) {
-		lineLookLevel = GetLevel(lineLook);
-		lineLookLevelNumber = lineLookLevel & SC_FOLDLEVELNUMBERMASK;
-		if (!endFoldBlockFound && !(lineLookLevel & SC_FOLDLEVELWHITEFLAG) && lineLookLevelNumber < levelNumber) {
-			endFoldBlockFound = true;
-			endFoldBlock = lineLook - 1;
-			if (!endMarginCorrectlyDrawnZoneFound) {
-				endMarginCorrectlyDrawnZoneFound = true;
-				endMarginCorrectlyDrawnZone = lineLook;
+	if (firstChangeableLineBefore == -1) {
+		for (lookLine = line - 1, lookLineLevel = GetLevel(lookLine), lookLineLevelNum = lookLineLevel & SC_FOLDLEVELNUMBERMASK; 
+			lookLine >= beginFoldBlock; 
+			lookLineLevel = GetLevel(--lookLine), lookLineLevelNum = lookLineLevel & SC_FOLDLEVELNUMBERMASK) {
+			if ((lookLineLevel & SC_FOLDLEVELWHITEFLAG) || (lookLineLevelNum > (level & SC_FOLDLEVELNUMBERMASK))) {
+				firstChangeableLineBefore = lookLine;
+				break;
 			}
-		} else if (!endFoldBlockFound && lineLookLevel == SC_FOLDLEVELBASE) {
-			endFoldBlockFound = true;
-			endFoldBlock = -1;
-		}
-		if (!endMarginCorrectlyDrawnZoneFound && (lineLookLevel & SC_FOLDLEVELHEADERFLAG) &&
-		        //Managed the folding block when a fold header does not have any subordinate lines to fold away.
-		        (levelNumber < (GetLevel(lineLook + 1) & SC_FOLDLEVELNUMBERMASK))) {
-			endMarginCorrectlyDrawnZoneFound = true;
-			endMarginCorrectlyDrawnZone = lineLook;
 		}
 	}
-	if (!endFoldBlockFound && ((lineLook > endLine && lineLookLevelNumber < levelNumber) ||
-	        (levelNumber > SC_FOLDLEVELBASE))) {
-		//manage when endfold is incorrect or on last line.
-		endFoldBlock = lineLook - 1;
-		//useless to set endMarginCorrectlyDrawnZone.
-		//if endMarginCorrectlyDrawnZoneFound equals false then endMarginCorrectlyDrawnZone already equals to endLine + 1.
+	if (firstChangeableLineBefore == -1)
+		firstChangeableLineBefore = beginFoldBlock - 1;
+
+	int firstChangeableLineAfter = -1;
+	for (lookLine = line + 1, lookLineLevel = GetLevel(lookLine), lookLineLevelNum = lookLineLevel & SC_FOLDLEVELNUMBERMASK; 
+		lookLine <= endFoldBlock; 
+		lookLineLevel = GetLevel(++lookLine), lookLineLevelNum = lookLineLevel & SC_FOLDLEVELNUMBERMASK) {
+		if ((lookLineLevel & SC_FOLDLEVELHEADERFLAG) && (lookLineLevelNum < (GetLevel(lookLine + 1) & SC_FOLDLEVELNUMBERMASK))) {
+			firstChangeableLineAfter = lookLine;
+			break;
+		}
 	}
+	if (firstChangeableLineAfter == -1)
+		firstChangeableLineAfter = endFoldBlock + 1;
 
 	highlightDelimiter.beginFoldBlock = beginFoldBlock;
 	highlightDelimiter.endFoldBlock = endFoldBlock;
-	highlightDelimiter.beginMarginCorrectlyDrawnZone = beginMarginCorrectlyDrawnZone;
-	highlightDelimiter.endMarginCorrectlyDrawnZone = endMarginCorrectlyDrawnZone;
+	highlightDelimiter.firstChangeableLineBefore = firstChangeableLineBefore;
+	highlightDelimiter.firstChangeableLineAfter = firstChangeableLineAfter;
 }
 
 int Document::ClampPositionIntoDocument(int pos) {