shiki_flutter_engine_interface

The regex-engine seam shared by shiki_flutter and its engine backends. It is a tiny, dependency-free package holding only the contract the TextMate tokenizer runs on:

• ShikiHighlighterEngine: the factory that builds scanners and strings.
• OnigScanner: finds the earliest match among a set of patterns on a line.
• OnigString, OnigMatch, OnigCaptureIndex, kUnmatchedOffset: the value types passed across that seam.

It mirrors vscode-textmate's IOnigLib / onigLib.ts and Shiki's JavaScript scanner.ts.

Installation

dependencies:
  shiki_flutter_engine_interface: ^1.0.0

Most apps never add this directly: it comes in transitively through shiki_flutter and whichever engine package you depend on (shiki_flutter_dart_engine, shiki_flutter_native_engine). Depend on it directly only if you're implementing your own ShikiHighlighterEngine.

Why it exists

shiki_flutter's regex engine is pluggable. Extracting the contract into its own package means every implementation depends on the same types and can be swapped in interchangeably:

Because this package pulls in nothing (not even Flutter), a backend can implement the seam without depending on all of shiki_flutter.

Usage

Implementing an engine

import 'package:shiki_flutter_engine_interface/shiki_flutter_engine_interface.dart';

class MyEngine implements ShikiHighlighterEngine {
  const MyEngine();

  // A stable literal (not derived from runtimeType, which minifies on web).
  @override
  String get id => 'my-engine';

  @override
  OnigScanner createScanner(List<String> sources) => MyScanner(sources);

  @override
  OnigString createString(String str) => OnigString(str);
}

Then point the highlighter at it, e.g. on IO: ShikiHighlighter.config = ShikiHighlighter.config.copyWith(ioEngine: const MyEngine());.