6 files changed, 38 insertions, 0 deletions

diff --git a/src/CellBuffer.cxx b/src/CellBuffer.cxx
index f02d5348a..d94ffaaea 100644
--- a/src/CellBuffer.cxx
+++ b/src/CellBuffer.cxx
@@ -71,6 +71,7 @@ public:
 	virtual void SetLineStart(Sci::Line line, Sci::Position position) noexcept = 0;
 	virtual void RemoveLine(Sci::Line line) = 0;
 	virtual Sci::Line Lines() const noexcept = 0;
+	virtual void AllocateLines(Sci::Line lines) = 0;
 	virtual Sci::Line LineFromPosition(Sci::Position pos) const noexcept = 0;
 	virtual Sci::Position LineStart(Sci::Line line) const noexcept = 0;
 	virtual void InsertCharacters(Sci::Line line, CountWidths delta) noexcept = 0;
@@ -132,6 +133,11 @@ public:
 		const Sci::Position widthCurrent = LineWidth(line);
 		starts.InsertText(static_cast<POS>(line), static_cast<POS>(width - widthCurrent));
 	}
+	void AllocateLines(Sci::Line lines) {
+		if (lines > starts.Partitions()) {
+			starts.ReAllocate(lines);
+		}
+	}
 	void InsertLines(Sci::Line line, Sci::Line lines) {
 		// Insert multiple lines with each temporarily 1 character wide.
 		// The line widths will be fixed up by later measuring code.
@@ -237,6 +243,17 @@ public:
 	Sci::Line Lines() const noexcept override {
 		return static_cast<Sci::Line>(starts.Partitions());
 	}
+	void AllocateLines(Sci::Line lines) override {
+		if (lines > Lines()) {
+			starts.ReAllocate(lines);
+			if (FlagSet(activeIndices, LineCharacterIndexType::Utf32)) {
+				startsUTF32.AllocateLines(lines);
+			}
+			if (FlagSet(activeIndices, LineCharacterIndexType::Utf16)) {
+				startsUTF16.AllocateLines(lines);
+			}
+		}
+	}
 	Sci::Line LineFromPosition(Sci::Position pos) const noexcept override {
 		return static_cast<Sci::Line>(starts.PartitionFromPosition(static_cast<POS>(pos)));
 	}
@@ -789,6 +806,10 @@ Sci::Line CellBuffer::Lines() const noexcept {
 	return plv->Lines();
 }
 
+void CellBuffer::AllocateLines(Sci::Line lines) {
+	plv->AllocateLines(lines);
+}
+
 Sci::Position CellBuffer::LineStart(Sci::Line line) const noexcept {
 	if (line < 0)
 		return 0;
@@ -903,7 +924,9 @@ bool CellBuffer::UTF8IsCharacterBoundary(Sci::Position position) const {
 
 void CellBuffer::ResetLineEnds() {
 	// Reinitialize line data -- too much work to preserve
+	const Sci::Line lines = plv->Lines();
 	plv->Init();
+	plv->AllocateLines(lines);
 
 	constexpr Sci::Position position = 0;
 	const Sci::Position length = Length();
diff --git a/src/CellBuffer.h b/src/CellBuffer.h
index 637d0a6b5..be7957e99 100644
--- a/src/CellBuffer.h
+++ b/src/CellBuffer.h
@@ -191,6 +191,7 @@ public:
 	void AllocateLineCharacterIndex(Scintilla::LineCharacterIndexType lineCharacterIndex);
 	void ReleaseLineCharacterIndex(Scintilla::LineCharacterIndexType lineCharacterIndex);
 	Sci::Line Lines() const noexcept;
+	void AllocateLines(Sci::Line lines);
 	Sci::Position LineStart(Sci::Line line) const noexcept;
 	Sci::Position IndexLineStart(Sci::Line line, Scintilla::LineCharacterIndexType lineCharacterIndex) const noexcept;
 	Sci::Line LineFromPosition(Sci::Position pos) const noexcept;
diff --git a/src/Document.cxx b/src/Document.cxx
index 6194f772e..96bee868e 100644
--- a/src/Document.cxx
+++ b/src/Document.cxx
@@ -2266,6 +2266,10 @@ Sci::Line Document::LinesTotal() const noexcept {
 	return cb.Lines();
 }
 
+void Document::AllocateLines(Sci::Line lines) {
+	cb.AllocateLines(lines);
+}
+
 void Document::SetDefaultCharClasses(bool includeWordClass) {
     charClass.SetDefaultCharClasses(includeWordClass);
 }
diff --git a/src/Document.h b/src/Document.h
index fe27f4936..7984ad018 100644
--- a/src/Document.h
+++ b/src/Document.h
@@ -445,6 +445,7 @@ public:
 	void AllocateLineCharacterIndex(Scintilla::LineCharacterIndexType lineCharacterIndex);
 	void ReleaseLineCharacterIndex(Scintilla::LineCharacterIndexType lineCharacterIndex);
 	Sci::Line LinesTotal() const noexcept;
+	void AllocateLines(Sci::Line lines);
 
 	void SetDefaultCharClasses(bool includeWordClass);
 	void SetCharClasses(const unsigned char *chars, CharacterClass newCharClass);
diff --git a/src/Editor.cxx b/src/Editor.cxx
index 5a0c153da..db7e2366e 100644
--- a/src/Editor.cxx
+++ b/src/Editor.cxx
@@ -5988,6 +5988,10 @@ sptr_t Editor::WndProc(Message iMessage, uptr_t wParam, sptr_t lParam) {
 		else
 			return pdoc->LinesTotal();
 
+	case Message::AllocateLines:
+		pdoc->AllocateLines(wParam);
+		break;
+
 	case Message::GetModify:
 		return !pdoc->IsSavePoint();
 
diff --git a/src/Partitioning.h b/src/Partitioning.h
index cf1bb6a7b..efa6bf95e 100644
--- a/src/Partitioning.h
+++ b/src/Partitioning.h
@@ -110,6 +110,11 @@ public:
 		return static_cast<T>(body->Length())-1;
 	}
 
+	void ReAllocate(ptrdiff_t newSize) {
+		// + 1 accounts for initial element that is always 0.
+		body->ReAllocate(newSize + 1);
+	}
+
 	T Length() const noexcept {
 		return PositionFromPartition(Partitions());
 	}