sudachi_dart 0.0.2

Flutter FFI plugin for Japanese morphological analysis using Sudachi. Tokenizes Japanese text into morphemes with POS tags, readings, and dictionary forms.

sudachi_dart

A Flutter FFI plugin for Japanese morphological analysis using Sudachi. Wraps the Rust sudachi.rs library via a C FFI layer.

Platform support

Platform	Supported
macOS	✓
Linux	✓
Windows	✓
iOS	✗
Android	✗

Requirements

• Rust toolchain — the native library is built from source at compile time.
• A Sudachi system dictionary (.dic file) — not bundled, see Dictionary below.

Installation

dependencies:
  sudachi_dart: ^0.0.1

Usage

import 'package:sudachi_dart/sudachi_dart.dart';

final dict = await SudachiDictionary.init(
  configPath: '/path/to/sudachi.json',
  dictionaryPath: '/path/to/system_full.dic',
);

final tokenizer = await SudachiTokenizer.init(dict);

final morphemes = await tokenizer.tokenize('東京都に住む', mode: Mode.c);

for (final m in morphemes) {
  print('${m.surface} [${m.readingForm}] ${m.partOfSpeech.take(2).join('-')}');
}

// Free native resources when done.
tokenizer.dispose();
dict.dispose();

Split modes

Mode	Granularity
Mode.a	Short / atomic units
Mode.b	Middle
Mode.c	Natural-language units (default)

Morpheme fields

Field	Description
surface	The original text span
dictionaryForm	Base (dictionary) form
normalizedForm	Normalized form
readingForm	Yomi (reading) in katakana
partOfSpeech	Up to 8 hierarchical POS tags

Dictionary

The system dictionary is not included in this package because of its size.

1. Download the full dictionary from the SudachiDict releases — get the SudachiDict_full archive.
2. Extract system_full.dic and place it somewhere accessible at runtime (e.g. copied to applicationSupportDirectory).
3. Pass the path to SudachiDictionary.init(dictionaryPath: ...).

A ready-to-use sudachi.json config is included in the example at example/assets/sudachi/sudachi.json. Copy it alongside your dictionary and pass its path to configPath. The dictionary path is supplied separately via dictionaryPath, so no edits to the config file are needed.

Running the example

1. Download the SudachiDict_full archive from SudachiDict releases.
2. Extract system_full.dic and place it at:

   example/assets/sudachi/system_full.dic
   

   The sudachi.json config is already in that folder.
3. Run:

   cd example
   flutter run
   

The example app copies both files to the app's support directory on first launch, then loads the dictionary from there.

Project structure

src/                   C header + Rust source (sudachi_rs_wrapper)
lib/                   Dart API
hook/build.dart        Builds the Rust library at compile time
ffigen.yaml            Generates Dart FFI bindings from the C header

To regenerate the Dart FFI bindings after changing the C header:

dart run ffigen --config ffigen.yaml

See also

• sudachi.rs API docs — original Rust library documentation.
• WorksApplications/sudachi.rs — Rust library source.
• WorksApplications/SudachiDict — dictionary releases.

Credits & License

This Dart package is licensed under the Apache-2.0 License.

This project wraps and relies on sudachi.rs, developed by Works Applications Co., Ltd., which is licensed under the Apache License 2.0.