Use string form for selection undo history as it saves significant space.

On average takes around 20% of SelectionSimple.

4 files changed, 21 insertions, 47 deletions

diff --git a/src/EditModel.cxx b/src/EditModel.cxx
index 1f9c2d064..033d79bd2 100644
--- a/src/EditModel.cxx
+++ b/src/EditModel.cxx
@@ -58,21 +58,9 @@ using namespace Scintilla::Internal;
 Caret::Caret() noexcept :
 	active(false), on(false), period(500) {}
 
-SelectionSimple::SelectionSimple(const Selection &sel) {
-	selType = sel.selType;
-	if (sel.IsRectangular()) {
-		// rectangular or thin
-		// Could be large so don't remember each range, just the rectangular bounds then reconstitute when undone
-		rangeRectangular = sel.RectangularCopy();
-	} else {
-		ranges = sel.RangesCopy();
-	}
-	mainRange = sel.Main();
-}
-
 void ModelState::RememberSelectionForUndo(int index, const Selection &sel) {
 	historyForUndo.indexCurrent = index;
-	historyForUndo.ssCurrent = SelectionSimple(sel);
+	historyForUndo.ssCurrent = sel.ToString();
 }
 
 void ModelState::ForgetSelectionForUndo() noexcept {
@@ -87,22 +75,22 @@ void ModelState::RememberSelectionOntoStack(int index) {
 }
 
 void ModelState::RememberSelectionForRedoOntoStack(int index, const Selection &sel) {
-	historyForRedo.stack[index] = SelectionSimple(sel);
+	historyForRedo.stack[index] = sel.ToString();
 }
 
-const SelectionSimple *ModelState::SelectionFromStack(int index, UndoRedo history) const {
+std::string_view ModelState::SelectionFromStack(int index, UndoRedo history) const {
 	const SelectionHistory &sh = history == UndoRedo::undo ? historyForUndo : historyForRedo;
-	std::map<int, SelectionSimple>::const_iterator it = sh.stack.find(index);
+	const SelectionStack::const_iterator it = sh.stack.find(index);
 	if (it != sh.stack.end()) {
-		return &it->second;
+		return it->second;
 	}
 	return {};
 }
 
 void ModelState::TruncateUndo(int index) {
-	std::map<int, SelectionSimple>::iterator itUndo = historyForUndo.stack.find(index);
+	const SelectionStack::const_iterator itUndo = historyForUndo.stack.find(index);
 	historyForUndo.stack.erase(itUndo, historyForUndo.stack.end());
-	std::map<int, SelectionSimple>::iterator itRedo = historyForRedo.stack.find(index);
+	const SelectionStack::const_iterator itRedo = historyForRedo.stack.find(index);
 	historyForRedo.stack.erase(itRedo, historyForRedo.stack.end());
 }
 
diff --git a/src/EditModel.h b/src/EditModel.h
index f75cece44..b9c331573 100644
--- a/src/EditModel.h
+++ b/src/EditModel.h
@@ -21,26 +21,15 @@ public:
 	Caret() noexcept;
 };
 
-// Simplified version of selection which won't contain rectangular selection realized
-// into ranges as too much data.
-// Just a type and single range for now.
-
-struct SelectionSimple {
-	std::vector<SelectionRange> ranges;
-	SelectionRange rangeRectangular;
-	size_t mainRange = 0;
-	Selection::SelTypes selType = Selection::SelTypes::stream;
-
-	SelectionSimple() = default;
-	explicit SelectionSimple(const Selection &sel);
-};
-
 enum class UndoRedo { undo, redo };
 
+// Selection stack is sparse so use a map
+using SelectionStack = std::map<int, std::string>;
+
 struct SelectionHistory {
 	int indexCurrent = 0;
-	SelectionSimple ssCurrent;
-	std::map<int, SelectionSimple> stack;
+	std::string ssCurrent;
+	SelectionStack stack;
 };
 
 struct ModelState : ViewState {
@@ -50,7 +39,7 @@ struct ModelState : ViewState {
 	void ForgetSelectionForUndo() noexcept;
 	void RememberSelectionOntoStack(int index);
 	void RememberSelectionForRedoOntoStack(int index, const Selection &sel);
-	const SelectionSimple *SelectionFromStack(int index, UndoRedo history) const;
+	std::string_view SelectionFromStack(int index, UndoRedo history) const;
 	virtual void TruncateUndo(int index) final;
 };
 
diff --git a/src/Editor.cxx b/src/Editor.cxx
index 0d1a221cd..10c694990 100644
--- a/src/Editor.cxx
+++ b/src/Editor.cxx
@@ -2403,19 +2403,18 @@ void Editor::RestoreSelection(Sci::Position newPos, UndoRedo history) {
 	if ((undoSelectionHistoryOption == UndoSelectionHistoryOption::Enabled) && modelState) {
 		// Undo wants the element after the current as it just undid it
 		const int index = pdoc->UndoCurrent() + (history == UndoRedo::undo ? 1 : 0);
-		const SelectionSimple *pss = modelState->SelectionFromStack(index, history);
-		if (pss) {
-			sel.selType = pss->selType;
+		const std::string_view ss = modelState->SelectionFromStack(index, history);
+		if (!ss.empty()) {
+			sel = Selection(ss);
 			if (sel.IsRectangular()) {
-				sel.Rectangular() = pss->rangeRectangular;
+				const size_t mainForRectangular = sel.Main();
 				// Reconstitute ranges from rectangular range
 				SetRectangularRange();
-			} else {
-				sel.SetRanges(pss->ranges);
+				// Restore main if possible.
+				if (mainForRectangular < sel.Count()) {
+					sel.SetMain(mainForRectangular);
+				}
 			}
-			// Unsure if this is safe with SetMain potentially failing if document doesn't appear the same.
-			// Maybe this can occur if the user changes font or wrap mode?
-			sel.SetMain(pss->mainRange);
 			newPos = -1; // Used selection from stack so don't use position returned from undo/redo.
 		}
 	}
diff --git a/src/Editor.h b/src/Editor.h
index 655184a31..a6a484ede 100644
--- a/src/Editor.h
+++ b/src/Editor.h
@@ -178,8 +178,6 @@ constexpr XYScrollOptions operator|(XYScrollOptions a, XYScrollOptions b) noexce
 	return static_cast<XYScrollOptions>(static_cast<int>(a) | static_cast<int>(b));
 }
 
-struct SelectionStack;
-
 /**
  */
 class Editor : public EditModel, public DocWatcher {