duskmoon_code_engine

A Flutter code editor with an immutable document/state model and official Tree-sitter incremental parsing, provided by duskmoon_highlight.

Features

• Rope-based document model and immutable transactions, selections and facets.
• Per-editor Tree-sitter sessions with immutable UTF-16 syntax snapshots.
• Bundled grammars, including distinct JavaScript/JSX, TypeScript/TSX and C/C++ support.
• Owned Tag, HighlightStyle and TagStyle syntax colors.
• Undo/redo, bracket matching, comments, folding, search, selection and clipboard commands.
• Virtual scrolling, gutters, selection painting and an interactive Flutter widget.

Getting started

import 'package:duskmoon_code_engine/duskmoon_code_engine.dart';

CodeEditorWidget(
  initialDoc: 'void main() => print("Hello!");',
  language: dartLanguageSupport(),
  theme: EditorTheme.dark(),
);

Widgets and EditorViewController automatically initialize web grammar assets. Await controller.ready when programmatic work requires syntax to be available. Edits made during loading are retained and parsed when initialization completes.

Use a named factory such as typescriptLanguageSupport(), tsxLanguageSupport() or cppLanguageSupport(), or treeSitterLanguageSupport('bash') for any grammar in the shared inventory.

Raw EditorState users on web should await support.ensureInitialized() before creating the state, or retain the new state returned by await ensureSyntaxTree(state). Read its immutable snapshot with syntaxTree(state) and release resources with disposeSyntax(state). Controllers and widgets dispose their sessions automatically.

Migration

Requires Dart 3.10 / Flutter 3.38 and a native C/C++ build toolchain. Browser builds use bundled same-origin WebAssembly assets, with no CDN/index.html setup. The Lezer/regex parser APIs (GrammarData, LRParser, Tree, TreeCursor, NodeType, NodeProp, StreamLanguage, TokenRule) and generator are removed. Language now takes a bundled Tree-sitter name and optional editor metadata. SyntaxSnapshot.rootNode exposes copied nodes with type, from, to and children; offsets are UTF-16. Custom style tags remain supported.

The code engine guide describes the editor APIs. See the runtime guide for query/injection limits and source maintenance.

License

MIT. Tree-sitter and grammar license notices ship with duskmoon_highlight.