Preparatory changes for fix in next commit. Does not change Scintilla behaviour.

Add tests for contiguous deletions in forward and backward directions.
Use symbolic edition values.
Rename InsertionSpan to ChangeSpan and insertions to changes as holds both
insertions and deletions.
Add ChangeStack::Check.
Add comments.

1 files changed, 5 insertions, 3 deletions

diff --git a/src/ChangeHistory.h b/src/ChangeHistory.h
index 8a6e745dc..0475a3a6e 100644
--- a/src/ChangeHistory.h
+++ b/src/ChangeHistory.h
@@ -22,27 +22,29 @@ constexpr unsigned int bitSaved = 2;
 constexpr unsigned int bitModified = 4;
 constexpr unsigned int bitRevertedToModified = 8;
 
-struct InsertionSpan {
+struct ChangeSpan {
 	Sci::Position start;
 	Sci::Position length;
 	int edition;
 	enum class Direction { insertion, deletion } direction;
 };
 
+// EditionSet is ordered from oldest to newest, its not really a set
 using EditionSet = std::vector<int>;
 using EditionSetOwned = std::unique_ptr<EditionSet>;
 
 class ChangeStack {
 	std::vector<size_t> steps;
-	std::vector<InsertionSpan> insertions;
+	std::vector<ChangeSpan> changes;
 public:
 	void Clear() noexcept;
 	void AddStep();
 	void PushDeletion(Sci::Position positionDeletion, int edition);
 	void PushInsertion(Sci::Position positionInsertion, Sci::Position length, int edition);
 	[[nodiscard]] size_t PopStep() noexcept;
-	[[nodiscard]] InsertionSpan PopSpan() noexcept;
+	[[nodiscard]] ChangeSpan PopSpan() noexcept;
 	void SetSavePoint() noexcept;
+	void Check() const noexcept;
 };
 
 struct ChangeLog {