Files
kte/UndoSystem.h
Kyle Isom 8ec0d6ac41 Add benchmarks, migration tests, and dev guide
Add benchmarks for core operations, migration edge case tests, improved
buffer I/O tests, and developer guide

- Introduced `test_benchmarks.cc` for performance benchmarking of key
  operations in `PieceTable` and `Buffer`, including syntax highlighting
  and iteration patterns.
- Added `test_migration_coverage.cc` to provide comprehensive tests for
  migration of `Buffer::Rows()` to `PieceTable` APIs, with edge cases,
  boundary handling, and consistency checks.
- Enhanced `test_buffer_io.cc` with additional cases for save/load
  workflows, file handling, and better integration with the core API.
- Documented architectural details and core concepts in a new
  `DEVELOPER_GUIDE.md`. Highlighted design principles, code
  organization, and contribution workflows.
2026-02-17 16:08:23 -08:00

121 lines
3.3 KiB
C++

/*
* UndoSystem.h - undo/redo system with tree-based branching
*
* UndoSystem manages the undo/redo history for a Buffer. It provides:
*
* - Tree-based undo: Multiple redo branches at each node (not just linear history)
* - Atomic grouping: Multiple operations can be undone/redone as a single step
* - Dirty tracking: Marks when buffer matches last saved state
* - Efficient storage: Nodes stored in UndoTree, operations applied to Buffer
*
* Key concepts:
*
* 1. Undo tree structure:
* - Each edit creates a node in the tree
* - Undo moves up the tree (toward root)
* - Redo moves down the tree (toward leaves)
* - Multiple redo branches preserved (not lost on new edits after undo)
*
* 2. Operation lifecycle:
* - Begin(type): Start recording an operation (insert/delete)
* - Append(text): Add content to the pending operation
* - commit(): Finalize and add to undo tree
* - discard_pending(): Cancel without recording
*
* 3. Atomic grouping:
* - BeginGroup()/EndGroup(): Bracket multiple operations
* - All operations in a group share the same group_id
* - Undo/redo treats the entire group as one step
*
* 4. Integration with Buffer:
* - UndoSystem holds a reference to its owning Buffer
* - apply() executes undo/redo by calling Buffer's editing methods
* - Buffer's dirty flag updated automatically
*
* Usage pattern:
* undo_system.Begin(UndoType::Insert);
* undo_system.Append("text");
* undo_system.commit(); // Now undoable
*
* See also: UndoTree.h (storage), UndoNode.h (node structure)
*/
#pragma once
#include <string_view>
#include <cstddef>
#include <cstdint>
#include "UndoTree.h"
class Buffer;
class UndoSystem {
public:
explicit UndoSystem(Buffer &owner, UndoTree &tree);
// Begin an atomic group: subsequent committed nodes with the same group_id will be
// undone/redone as a single step. Returns the active group id.
std::uint64_t BeginGroup();
void EndGroup();
void Begin(UndoType type);
void Append(char ch);
void Append(std::string_view text);
void commit();
void undo();
// Redo the current node's active child branch.
// If `branch_index` > 0, selects that redo sibling (0-based) and makes it active.
// When current is null (pre-first-edit), branches are selected among `tree_.root` siblings.
void redo(int branch_index = 0);
void mark_saved();
void discard_pending();
void clear();
void UpdateBufferReference(Buffer &new_buf);
#if defined(KTE_TESTS)
// Test-only introspection hook.
const UndoTree &TreeForTests() const
{
return tree_;
}
#endif
private:
enum class PendingAppendMode : std::uint8_t {
Append,
Prepend,
};
void apply(const UndoNode *node, int direction); // +1 redo, -1 undo
void free_node(UndoNode *node);
void free_branch(UndoNode *node); // frees redo siblings only
UndoNode *find_parent(UndoNode *from, UndoNode *target);
// Debug helpers (compiled only when KTE_UNDO_DEBUG is defined)
void debug_log(const char *op) const;
static const char *type_str(UndoType t);
static bool is_descendant(UndoNode *root, const UndoNode *target);
void update_dirty_flag();
PendingAppendMode pending_mode_ = PendingAppendMode::Append;
std::uint64_t active_group_id_ = 0;
std::uint64_t next_group_id_ = 1;
Buffer *buf_;
UndoTree &tree_;
};