Hyphen #

Hyphen is a cross-platform Flutter package that provides high-quality word hyphenation, implemented in pure Dart. The same code runs on every platform Flutter supports — there is no native library to build and nothing to link.

The engine is a Dart port of hunspell/hyphen, the TeX-pattern hyphenation library originally cut from libHnj for OpenOffice.org. It reads the same hyph_*.dic dictionaries and was verified against the original C implementation over 9.26 million cases across 18 dictionaries, so output is identical rather than merely similar.

With Hyphen, you can split words into their hyphenation parts according to language-specific rules. The API returns a List<String> where each element is a chunk of the word between possible hyphenation points.

❗️ Breaking change in v0.4.0 #

• The dart:ffi bindings, the Emscripten JS/WASM runtime, the native build trees, and the Hyphen.fromDictionaryPathWithBindingsAndAllocator constructor are all gone. See the Changelog for details.

✨ Features #

• Works on all Flutter platforms: Android, iOS, macOS, Windows, Linux, Web — one pure-Dart implementation, no platform-specific builds
• Uses battle-tested hyphen dictionaries
• Combines hunspell/hyphen's two hyphenation APIs hnj_hyphen_hyphenate2 and hnj_hyphen_hyphenate3 into a single hyphenate function
• Unified API for all platforms – always use the same Hyphen class, no matter the platform

📦 Installing #

Add to your pubspec.yaml:

dependencies:
  hyphen: ^0.4.0

Then run:

flutter pub get

📚 Dictionaries #

Hyphen requires a .dic file for the language you want to hyphenate.
These are not bundled due to licensing reasons.

👉 You need to generate or obtain these .dic files yourself.

Where to get dictionary files #

Hyphenation dictionaries are created from TeX hyphenation pattern files (commonly available on CTAN and other TeX distribution sources).

🔨 Step-by-step Example: English (US) #

1. Download the pattern file hyph-en-us.tex

2. Run the substrings.pl script (from hunspell/hyphen):

   perl substrings.pl hyph-en-us.tex hyph_en_US.dic UTF-8
   

   This generates a file called hyph_en_US.dic.

3. Add the file to your Flutter project:

   assets/hyph_en_US.dic
   

4. Declare it in pubspec.yaml:

   flutter:
     assets:
       - assets/hyph_en_US.dic
   

🚀 Usage #

import 'package:hyphen/hyphen.dart';

Future<void> main() async {
  // Load a dictionary from assets
  final hyphen = await Hyphen.fromDictionaryPath('assets/hyph_en_US.dic');

  // Hyphenate a word
  final result = hyphen.hyphenate('hyphenation');
  print(result); // ["hy", "phen", "ation"]

  // Using the additional parameters to define a minimum distance from the start/end of the word
  // to the first break
  final result2 = hyphen.hyphenate(
    'hyphenation',
    lhmin: 3,
    rhmin: 3,
  );
  print(result2); // ["hyphen", "ation"]
}

Loading a dictionary #

From a Flutter asset:

final hyphen = await Hyphen.fromDictionaryPath('assets/hyph_en_US.dic');

From bytes, with no asset bundle — usable in plain Dart, tests and CLI tools:

import 'dart:io';

final hyphen = Hyphen.fromDictionaryBytes(File('hyph_en_US.dic').readAsBytesSync());

🖥 Platform Notes #

Hyphen is a pure-Dart package. It runs identically on Android, iOS, macOS, Windows, Linux and Web — there is no native library to build, no platform-specific plugin implementation, and nothing to link. On every platform, you must still provide your own .dic file; see Dictionaries above.

⚠️ License #

This package is dual-licensed:

• Package code (the public API, dictionary loading and hyphenation engine): licensed under MIT.
• A small number of files are a Dart port of Hunspell/Hyphen C sources and remain covered by that project's license. See THIRD_PARTY_LICENSES.md for exactly which files and terms.

Hyphenation dictionaries come with their own licenses – check the hunspell/hyphen repo before redistributing.

🤝 Contributing #

Issues and pull requests are welcome!