- Undo texts of 4 KiB or more (Insert/Paste from the buffer, Delete from
the spans the piece table remembers for its last large deletion) are
held as TextSpan references into the piece table's append-only
storage, after checking they hold exactly the recorded bytes. Undo and
redo insert them with Buffer::insert_spans, which adds pieces over the
stored bytes instead of copying them into storage again (the journal
still gets the bytes, as one record). A replace-all session on a 26 MB
file peaks at 181 MB instead of 332 MB; undo/redo cycles of a 6.6 MB
kill no longer grow memory by 6.6 MB each.
- UndoSystem keeps a byte budget (default max(64 MiB, twice the buffer
size); SetByteBudget). Over it, history is pruned to 75% of the budget:
branches off the current path, then the oldest edits (an undo group
goes whole, and never the current state's group), then the redo line.
When the saved state is dropped the buffer stays modified until saved.
- replace_all_bytes clears undo history, which was recorded against (and
may reference the storage of) the previous content.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_015rcVQiiWyTzoNrsvLSaAfB
Consolidation rewrites pieces without changing content or offsets but
invalidated the line index, so once a buffer passed the piece limit
every edit paid a full rescan again. A moved-from table kept the index
of the text it gave away, and Insert now updates that index in place,
producing ranges past the end of its buffer.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_015rcVQiiWyTzoNrsvLSaAfB
- PieceTable::Insert/Delete adjust a valid line index directly (shift
later line starts, add or drop starts for inserted or deleted
newlines) instead of invalidating it, which forced a byte-by-byte
rescan of the whole buffer on the next line query. On a 38 MB,
1M-line buffer, insert + line query drops from 14.7 ms to 0.28 ms.
- The terminal and ImGui renderers fetch only the rows they draw
(Nrows + GetLineString) instead of Buffer::Rows(), which rebuilt a
string for every line of the file on the first frame after each edit.
Qt's line-count uses switch to Nrows().
ImGuiRenderer.cc was syntax-checked with g++ and clang++ against the
vendored ImGui headers; the GUI targets could not be built here (no
SDL2 or Qt6).
Audit findings P1, P2.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_015rcVQiiWyTzoNrsvLSaAfB
Copy/move assignment kept the destination's line index, so closing a
buffer (vector erase move-assigns later buffers down) left the shifted
buffer with its predecessor's line offsets and out-of-bounds line views.
Appends that merged into an existing piece also skipped invalidation.
Audit findings M1, B12.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_015rcVQiiWyTzoNrsvLSaAfB
- Introduced comprehensive tests:
- `test_buffer_open_nonexistent_save.cc`: Save after opening a non-existent file.
- `test_buffer_save.cc`: Save buffer contents to disk.
- `test_buffer_save_existing.cc`: Save after opening existing files.
- Implemented `PieceTable::WriteToStream()` to directly stream content without full materialization.
- Updated `Buffer::Save` and `Buffer::SaveAs` to use efficient streaming via `PieceTable`.
- Enhanced editing commands (`Insert`, `Delete`, `Replace`, etc.) to use PieceTable APIs, ensuring proper undo and save functionality.
- Created `piece-table-migration.md` outlining the steps to transition from GapBuffer to a unified PieceTable architecture.
- Included phased approach: extending PieceTable, Buffer adapter layer, command updates, and renderer changes.
- Detailed API changes, file updates, testing strategy, risk assessment, and timeline for each migration phase.
- Document serves as a reference for architecture goals and implementation details.
- Added `PieceTable` class for efficient text manipulation and implemented core editing APIs (`Insert`, `Delete`, `Find`, etc.).
- Integrated `PieceTable` into `Buffer` class with an adapter for rows caching.
- Enabled seamless switching between legacy row-based and new PieceTable-backed editing via `KTE_USE_BUFFER_PIECE_TABLE`.
- Updated file I/O, line-based queries, and cursor operations to support PieceTable-based storage.
- Lazy rebuilding of line index and improved management of edit state for performance.
Claude
kyle