mecab_for_dart

MeCab (Japanese Morphological Analyzer) bindings for standalone dart. The Flutter version of this package can be found here

Try it out using flutter in the browser!.

Android	iOS	Windows	MacOS	Linux	Web	Web --wasm
✅	✅	✅	✅	✅	✅	❌

Installation

1. Add this plug in as a dependency in your pubspec.yaml file.

dependencies:   
   mecab_for_dart: <your_version> 

Getting the binaries

Pre-compiled binaries are provided for Linux (arm64), Macos (x86/arm64) and Windows (x86/arm64), you can download them here. Download the one you need and place them somwhere your dart application can access them, in this README that path will be called <LIB_MECAB_PATH>

Getting a dictionary

Any dictionary that is compatible with mecab will work, but for ease of getting started, a copy of ipadic and unidic is provided here. Download the one you need and place them somewhere your dart application can access them, in this README that path will be donated by <DICT_MECAB_PATH>

Example

Init Mecab:

var tagger = new Mecab();
await tagger.init("<LIB_MECAB_PATH>", "<DICT_MECAB_PATH>", true);

Set the boolean option in init function to true if you want to get the tokens including features, set it to false if you only want the token surfaces.

Use the tagger to parse text:

var tokens = tagger.parse('にわにわにわにわとりがいる。');
var text = '';

for(var token in tokens) {
  text += token.surface + "\t";
  for(var i = 0; i < token.features.length; i++) {
    text += token.features[i];
    if(i + 1 < token.features.length) {
       text += ",";
    }
  }
  text += "\n";
}

Notes for web usage

This library tries to load the mecab dictionary from the WASM filesystem. The easiest way to get the dictionary in it, is by bundling it when compiling mecab to wasm. However, it may be desirable to swap dictionaries. To do this, you need to load the dictionary into libmecab's wasm memory.

Building the binaries

Linux

cd linux/
# this builds for the architecture you are on
make libmecab

MacOS

cd macos/Classes/
make libmecab

# use rosetta on apple silicone to cross compile
arch -x86_64 make libmecab

Windows

Because mecab uses nmake on windows to compile, the mecab DLL needs to be created separately. For this open a Developer Command Prompt and change in the windows/src directory. In this directory execute nmake -f Makefile.x64.msvc (compile on x86) or nmake -f Makefile.arm64.msvc (compile on arm64). After the build process finished, there should be a libmecab.dll in windows/src.

Android / iOS

As dart is not really useed for running on iOS / Android there are no precompiled binaries or build scripts available. If you see a need for this please open an issue or PR!

Web

On web this plugin uses WASM.

To compile for WASM this project uses Emscripten. Therefore, to compile a wasm binary, first emscripten needs to be installed. Then, a WASM binary can be compiled by running compile_wasm_bare.sh (no dictionary included) or compile_wasm_embed.sh (ipadic embedded). This will generate libmecab.js and libmecab.wasm in the folder emcc_out/. Those files then need to be loaded by your application. For more details, see the example.