Implement detach point access with SCI_SETUNDODETACH and SCI_GETUNDODETACH.

Write more documentation for undo history.

7 files changed, 59 insertions, 16 deletions

diff --git a/src/CellBuffer.cxx b/src/CellBuffer.cxx
index 691a811dd..6dde7eb84 100644
--- a/src/CellBuffer.cxx
+++ b/src/CellBuffer.cxx
@@ -1160,12 +1160,12 @@ int CellBuffer::UndoSavePoint() const noexcept {
 	return uh->SavePoint();
 }
 
-void CellBuffer::SetUndoCurrent(int action) {
-	uh->SetCurrent(action, Length());
+void CellBuffer::SetUndoDetach(int action) noexcept {
+	uh->SetDetachPoint(action);
 }
 
-int CellBuffer::UndoCurrent() const noexcept {
-	return uh->Current();
+int CellBuffer::UndoDetach() const noexcept {
+	return uh->DetachPoint();
 }
 
 void CellBuffer::SetUndoTentative(int action) noexcept {
@@ -1176,6 +1176,14 @@ int CellBuffer::UndoTentative() const noexcept {
 	return uh->TentativePoint();
 }
 
+void CellBuffer::SetUndoCurrent(int action) {
+	uh->SetCurrent(action, Length());
+}
+
+int CellBuffer::UndoCurrent() const noexcept {
+	return uh->Current();
+}
+
 int CellBuffer::UndoActionType(int action) const noexcept {
 	return uh->Type(action);
 }
diff --git a/src/CellBuffer.h b/src/CellBuffer.h
index 916937845..1c598480f 100644
--- a/src/CellBuffer.h
+++ b/src/CellBuffer.h
@@ -183,10 +183,12 @@ public:
 	int UndoActions() const noexcept;
 	void SetUndoSavePoint(int action) noexcept;
 	int UndoSavePoint() const noexcept;
-	void SetUndoCurrent(int action);
-	int UndoCurrent() const noexcept;
+	void SetUndoDetach(int action) noexcept;
+	int UndoDetach() const noexcept;
 	void SetUndoTentative(int action) noexcept;
 	int UndoTentative() const noexcept;
+	void SetUndoCurrent(int action);
+	int UndoCurrent() const noexcept;
 	int UndoActionType(int action) const noexcept;
 	Sci::Position UndoActionPosition(int action) const noexcept;
 	std::string_view UndoActionText(int action) const noexcept;
diff --git a/src/Document.cxx b/src/Document.cxx
index 8ab837daa..5f77ec2de 100644
--- a/src/Document.cxx
+++ b/src/Document.cxx
@@ -363,12 +363,12 @@ int Document::UndoSavePoint() const noexcept {
 	return cb.UndoSavePoint();
 }
 
-void Document::SetUndoCurrent(int action) {
-	cb.SetUndoCurrent(action);
+void Document::SetUndoDetach(int action) noexcept {
+	cb.SetUndoDetach(action);
 }
 
-int Document::UndoCurrent() const noexcept {
-	return cb.UndoCurrent();
+int Document::UndoDetach() const noexcept {
+	return cb.UndoDetach();
 }
 
 void Document::SetUndoTentative(int action) noexcept {
@@ -379,6 +379,14 @@ int Document::UndoTentative() const noexcept {
 	return cb.UndoTentative();
 }
 
+void Document::SetUndoCurrent(int action) {
+	cb.SetUndoCurrent(action);
+}
+
+int Document::UndoCurrent() const noexcept {
+	return cb.UndoCurrent();
+}
+
 int Document::UndoActionType(int action) const noexcept {
 	return cb.UndoActionType(action);
 }
diff --git a/src/Document.h b/src/Document.h
index 66f954724..912c719b5 100644
--- a/src/Document.h
+++ b/src/Document.h
@@ -409,10 +409,12 @@ public:
 	int UndoActions() const noexcept;
 	void SetUndoSavePoint(int action) noexcept;
 	int UndoSavePoint() const noexcept;
-	void SetUndoCurrent(int action);
-	int UndoCurrent() const noexcept;
+	void SetUndoDetach(int action) noexcept;
+	int UndoDetach() const noexcept;
 	void SetUndoTentative(int action) noexcept;
 	int UndoTentative() const noexcept;
+	void SetUndoCurrent(int action);
+	int UndoCurrent() const noexcept;
 	int UndoActionType(int action) const noexcept;
 	Sci::Position UndoActionPosition(int action) const noexcept;
 	std::string_view UndoActionText(int action) const noexcept;
diff --git a/src/Editor.cxx b/src/Editor.cxx
index e6aec550a..343529510 100644
--- a/src/Editor.cxx
+++ b/src/Editor.cxx
@@ -6605,12 +6605,12 @@ sptr_t Editor::WndProc(Message iMessage, uptr_t wParam, sptr_t lParam) {
 	case Message::GetUndoSavePoint:
 		return pdoc->UndoSavePoint();
 
-	case Message::SetUndoCurrent:
-		pdoc->SetUndoCurrent(static_cast<int>(wParam));
+	case Message::SetUndoDetach:
+		pdoc->SetUndoDetach(static_cast<int>(wParam));
 		break;
 
-	case Message::GetUndoCurrent:
-		return pdoc->UndoCurrent();
+	case Message::GetUndoDetach:
+		return pdoc->UndoDetach();
 
 	case Message::SetUndoTentative:
 		pdoc->SetUndoTentative(static_cast<int>(wParam));
@@ -6619,6 +6619,13 @@ sptr_t Editor::WndProc(Message iMessage, uptr_t wParam, sptr_t lParam) {
 	case Message::GetUndoTentative:
 		return pdoc->UndoTentative();
 
+	case Message::SetUndoCurrent:
+		pdoc->SetUndoCurrent(static_cast<int>(wParam));
+		break;
+
+	case Message::GetUndoCurrent:
+		return pdoc->UndoCurrent();
+
 	case Message::GetUndoActionType:
 		return pdoc->UndoActionType(static_cast<int>(wParam));
 
diff --git a/src/UndoHistory.cxx b/src/UndoHistory.cxx
index 62f871a60..810cd9a14 100644
--- a/src/UndoHistory.cxx
+++ b/src/UndoHistory.cxx
@@ -395,6 +395,18 @@ bool UndoHistory::AfterSavePoint() const noexcept {
 	return (savePoint >= 0) && (savePoint <= currentAction);
 }
 
+void UndoHistory::SetDetachPoint(int action) noexcept {
+	if (action == -1) {
+		detach = {};
+	} else {
+		detach = action;
+	}
+}
+
+int UndoHistory::DetachPoint() const noexcept {
+	return detach.value_or(-1);
+}
+
 bool UndoHistory::AfterDetachPoint() const noexcept {
 	return detach && (*detach < currentAction);
 }
diff --git a/src/UndoHistory.h b/src/UndoHistory.h
index 13aaca98c..10660a195 100644
--- a/src/UndoHistory.h
+++ b/src/UndoHistory.h
@@ -110,6 +110,10 @@ public:
 	bool BeforeOrAtSavePoint() const noexcept;
 	bool BeforeReachableSavePoint() const noexcept;
 	bool AfterSavePoint() const noexcept;
+
+	/// The detach point is the last action that was before an inaccessible missing save point.
+	void SetDetachPoint(int action) noexcept;
+	[[nodiscard]] int DetachPoint() const noexcept;
 	bool AfterDetachPoint() const noexcept;
 	bool AfterOrAtDetachPoint() const noexcept;