Kyle Isom
ceef6af3ae
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- Implemented runtime API for registering custom highlighters. - Added optional Tree-sitter integration for advanced syntax parsing (disabled by default). - Updated buffer initialization and copying to support dynamic highlighter configuration. - Introduced `NullHighlighter` as a fallback for unsupported filetypes. - Enhanced CMake configuration with `KTE_ENABLE_TREESITTER` option.
71 lines
3.8 KiB
Markdown
71 lines
3.8 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 highlighter interface. The initial implementation targets C/C++ and 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, numbers, preprocessor, operators, punctuation, identifiers, whitespace, etc.).
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- `HighlightSpan` — a half-open column range `[col_start, col_end)` with a `TokenKind`.
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- `LineHighlight` — a vector of `HighlightSpan` and the buffer `version` 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` keyed by row and buffer version.
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- Cache invalidation occurs when the buffer version changes or when the buffer calls `InvalidateFrom(row)`, which clears cached lines and line states from `row` downward.
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- The engine supports both stateless and stateful highlighters. For stateful highlighters, it memoizes a simple per-line state and 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 tokenization.
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- `StatefulHighlighter` extends it with a `LineState` and the method `HighlightLineStateful(buf, row, prev_state, out)`.
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- The engine detects `StatefulHighlighter` via dynamic_cast and feeds each line the previous line’s state, caching the resulting state per 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 `'...'`, numbers, identifiers (keywords/types), preprocessor at beginning of line after leading whitespace, operators/punctuation, and whitespace.
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- Stateful constructs (v2):
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- Multi-line block comments `/* ... */` — the state records whether the next line continues a comment.
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- Raw strings `R"delim(... )delim"` — the state tracks whether we are inside a raw string and its delimiter `delim` until the 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 corner cases of the C++ standard.
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- Preprocessor handling is line-based; continuation lines with `\\` are not yet tracked.
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- No semantic analysis; identifiers are classified via small keyword/type sets.
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- Additional languages (JSON, Markdown, Shell, Python, Go, Rust, Lisp, …) are planned.
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- Terminal color mapping is conservative to support 8/16-color 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 `Highlighter()->GetLine(buf, row, buf.Version())`.
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- Search highlight and cursor overlays take precedence over syntax colors.
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Extensibility (Phase 4)
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-----------------------
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- Public registration API: external code can register custom highlighters by filetype.
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- Use `HighlighterRegistry::Register("mylang", []{ return std::make_unique<MyHighlighter>(); });`
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- Registered factories are preferred over built-ins for the same filetype key.
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- Filetype keys are normalized via `HighlighterRegistry::Normalize()`.
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- Optional Tree-sitter adapter: disabled by default to keep dependencies 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 needed.
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- Register a Tree-sitter-backed highlighter for a language (example 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 cleanly when enabled, but
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intentionally emits no spans until Tree-sitter node-to-token mapping is implemented.
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