Kyle Isom
78b9345799
- Introduced `SwapManager` for buffering and writing incremental edits to sidecar `.kte.swp` files. - Implemented basic operations: insertion, deletion, split, join, and checkpointing. - Added recovery design doc (`docs/plans/swap-files.md`). - Updated editor initialization to integrate `SwapManager` instance for crash recovery across buffers.
122 lines
4.5 KiB
Markdown
122 lines
4.5 KiB
Markdown
Syntax highlighting in kte
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==========================
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Overview
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--------
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kte provides lightweight syntax highlighting with a pluggable
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highlighter interface. The initial implementation targets C/C++ and
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focuses on speed and responsiveness.
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Core types
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----------
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- `TokenKind` — token categories (keywords, types, strings, comments,
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numbers, preprocessor, operators, punctuation, identifiers,
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whitespace, etc.).
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- `HighlightSpan` — a half-open column range `[col_start, col_end)` with
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a `TokenKind`.
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- `LineHighlight` — a vector of `HighlightSpan` and the buffer `version`
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used to compute it.
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Engine and caching
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------------------
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- `HighlighterEngine` maintains a per-line cache of `LineHighlight`
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keyed by row and buffer version.
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- Cache invalidation occurs when the buffer version changes or when the
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buffer calls `InvalidateFrom(row)`, which clears cached lines and line
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states from `row` downward.
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- The engine supports both stateless and stateful highlighters. For
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stateful highlighters, it memoizes a simple per-line state and
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computes lines sequentially when necessary.
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Stateful highlighters
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---------------------
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- `LanguageHighlighter` is the base interface for stateless per-line
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tokenization.
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- `StatefulHighlighter` extends it with a `LineState` and the method
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`HighlightLineStateful(buf, row, prev_state, out)`.
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- The engine detects `StatefulHighlighter` via dynamic_cast and feeds
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each line the previous line’s state, caching the resulting state per
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line.
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C/C++ highlighter
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-----------------
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- `CppHighlighter` implements `StatefulHighlighter`.
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- Stateless constructs: line comments `//`, strings `"..."`, chars
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`'...'`, numbers, identifiers (keywords/types), preprocessor at
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beginning of line after leading whitespace, operators/punctuation, and
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whitespace.
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- Stateful constructs (v2):
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- Multi-line block comments `/* ... */` — the state records whether
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the next line continues a comment.
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- Raw strings `R"delim(... )delim"` — the state tracks whether we
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are inside a raw string and its delimiter `delim` until the
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closing sequence appears.
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Limitations and TODOs
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---------------------
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- Raw string detection is intentionally simple and does not handle all
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corner cases of the C++ standard.
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- Preprocessor handling is line-based; continuation lines with `\\` are
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not yet tracked.
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- No semantic analysis; identifiers are classified via small
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keyword/type sets.
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- Additional languages (JSON, Markdown, Shell, Python, Go, Rust,
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Lisp, …) are planned.
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- Terminal color mapping is conservative to support 8/16-color
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terminals. Rich color-pair themes can be added later.
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Renderer integration
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--------------------
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- Terminal and GUI renderers request line spans via
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`Highlighter()->GetLine(buf, row, buf.Version())`.
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- Search highlight and cursor overlays take precedence over syntax
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colors.
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Renderer-side robustness
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------------------------
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- Renderers defensively sanitize `HighlightSpan` data before use to
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ensure stability even if a highlighter misbehaves:
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- Clamp `col_start/col_end` to the line length and ensure
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`end >= start`.
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- Drop empty/invalid spans and sort by start.
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- Clip drawing to the horizontally visible region and the
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tab-expanded line length.
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- The highlighter engine returns `LineHighlight` by value to avoid
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cross-thread lifetime issues; renderers operate on a local copy for
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each frame.
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Extensibility (Phase 4)
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-----------------------
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- Public registration API: external code can register custom
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highlighters by filetype.
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- Use
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`HighlighterRegistry::Register("mylang", []{ return std::make_unique<MyHighlighter>(); });`
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- Registered factories are preferred over built-ins for the same
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filetype key.
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- Filetype keys are normalized via
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`HighlighterRegistry::Normalize()`.
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- Optional Tree-sitter adapter: disabled by default to keep dependencies
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minimal.
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- Enable with CMake option `-DKTE_ENABLE_TREESITTER=ON` and provide
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`-DTREESITTER_INCLUDE_DIR=...` and `-DTREESITTER_LIBRARY=...` if
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needed.
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- Register a Tree-sitter-backed highlighter for a language (example
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assumes you link a grammar):
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```c++
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extern "C" const TSLanguage* tree_sitter_c();
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kte::HighlighterRegistry::RegisterTreeSitter("c", &tree_sitter_c);
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```
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- Current adapter is a stub scaffold; it compiles and integrates
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cleanly when enabled, but
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intentionally emits no spans until Tree-sitter node-to-token
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mapping is implemented.
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