C/Migemo library

C/Migemo is regexp pattern generator/expander.

C/Migemo is a C-language implementation of Migemo (Ruby/Migemo). Software utilizing the C/Migemo library gains the ability to perform incremental Japanese searches using Romaji input. Because it is implemented in C, it is easier to integrate with the vast amount of software written in C compared to the original Ruby/Migemo, and —presumably— it offers improved execution speed.

The original Migemo is a tool devised by Satoru Takabayashi that converts Romaji input into regular expressions for Japanese text searching. It was implemented using Ruby and Emacs Lisp to enable incremental Japanese searches in Emacs while typing in Romaji.

Getting Started

Build

$ cmake -B build
$ cmake --build build

Test

$ cmake --build build --target test

Profiling

$ cmake --build build --target profile

See build/profile.log for the profiling result.

Clean

$ cmake --build build --target clean

Or just rm -rf build.

Pre-requirements

• Building the program

  • CMake (3.21 or above)
  • C11 compiler and binutils equivalents (gcc, clang, msvc or so)

• Building the dictionary

  • CMake (3.21 or above)
  • curl
  • iconv
  • gzip
  • perl

  The dictionary is built from SKK-JISYO.L

• Profiling

  • gprof

Build

$ cmake -B build
$ cmake --build build

Build Options & Packaging

The following options and components are available for selective building and installation (e.g., for distribution packaging):

• BUILD_DICT (CMake Option, default: ON):

  Set to OFF (cmake -B build -DBUILD_DICT=OFF) to skip dictionary generation and its external build dependencies (perl, iconv, gzip, etc.).

• Target dictionaries:

  Builds all dictionary encodings at once:

  cmake --build build --target dictionaries
  

• Install Components:

  Allows installing core files or dictionary files separately:

  # Install core binary, library, and headers only
  cmake --install build --component core
  
  # Install generated dictionary files only
  cmake --install build --component dict
  

Static Dictionary (sdict)

C/Migemo supports a pre-compiled binary dictionary format called sdict (Static Dictionary).

Benefits

• Fast Startup: Drastically reduces initialization/load time (e.g., from ~50ms down to ~4ms).
• Memory Efficiency: Significantly reduces memory footprint (e.g., from ~18MB down to ~8MB).
• Improved Performance: Enhances query execution speed due to better CPU cache locality.

CLI Options

cmigemo provides the following options for sdict:

• --convert: Converts loaded dynamic dictionaries to sdict in-memory and continues execution. Useful for testing sdict performance quickly.
• --save <dict>: Saves the converted sdict to a specified file path (implies --convert).
• --sdict <dict>: Loads a pre-compiled sdict file directly (conflicts with -d/-s/-u and --convert/--save).

Trying sdict in Development

$ make

# Generate and save an sdict file (using -w '' to exit immediately after saving)
$ ./build/bin/cmigemo --save build/dict/utf-8/migemo-sdict -w ''

# Launch cmigemo using the saved sdict
$ ./build/bin/cmigemo --sdict build/dict/utf-8/migemo-sdict

Vim plugin

If you want to use C/Migemo only as a vim plugin, use https://github.com/haya14busa/vim-migemo

Licenses

C/Migemo is distributed under the MIT License.

The built dictionary is subject to the GPL, in accordance with the license of the source SKK-JISYO.L.