gtags

gtags is a dependency decompiler plugin for Gradle projects. The plugin traverses the dependency graph for a particular project configuration and decompiles all class files for all libraries in that configuration. Output from the plugin can be used as a developer reference while working on Java-based projects, or can be ingested with external tools like universal-ctags to generate tag files for enabling rudimentary completion and navigation within Vim.

This project was primarily built for supporting tag file generation of Java project dependencies, hence the name (gtags, or "Gradle tags").

gtags supports single- and multi-module Gradle projects. When collecting dependencies for decompilation, the plugin will recurse into subprojects. Projects that do not have the java (or java-library) plugin enabled are ignored.

Usage

To use the plugin, you can update your project build script:

plugins {
    id 'java'
    id 'ca.brandonrichardson.gtags' version '0.0.1'
}

gtags {
    /**
     * A list of dependency module patterns that should be included for decompilation.
     * If defined, `excludedModules` is ignored.
     * Optional. Default: []
     */
    includedModules = ['com.google.guava:guava', 'org.springframework:.*']

    /**
     * A list of dependency module patterns that should be excluded for decompilation.
     * Only respected if `includedModules` is unset.
     * Optional. Default: []
     */
    excludeModules = ['com.google.guava:guava', 'org.springframework:.*']

    /**
     * A list of project names that should be excluded for decompilation.
     * Optional. Default: []
     */
    excludedProjects = ['my-project-1', 'my-project-2']

    /**
     * A list of project configurations from which dependencies are collected.
     * Optional. Default: ['compileClasspath']
     */
    configs = ['runtimeClasspath', 'compileClasspath']

    /**
     * The number of threads to use for decompilation. Can improve performance when
     * the dependency graph large.
     * Optional. Default: 1
     */
    concurrency = 4

    /**
     * Output directory path. Directory structure is created if it does not exist.
     * Optional. Default: "${project.buildDir}/gtags"
     */
    outputDir = "${System.properties['user.home']}/gtags"
}

The plugin exposes a task 'decompileDependencies':

$ ./gradlew decompileDependencies

Alternativtely, you can use the init script:

$ export GTAGS_INCLUDED_MODULES='com.google.guava:guava,org.springframework:.*'
$ export GTAGS_EXCLUDED_MODULES='com.google.guava:guava,org.springframework:.*'
$ export GTAGS_EXCLUDED_PROJECTS='my-project-1,my-project-2'
$ export GTAGS_CONFIGS='runtimeClasspath,compileClasspath'
$ export GTAGS_CONCURRENCY=4
$ export GTAGS_OUTDIR=$HOME/gtags
$ ./gradlew --init-script gtags-init.gradle decompileDependencies

Generate tag files with universal-ctags

This plugin was built to make Java development a bit easier in Vim. Decompiled dependencies can be run through universal-ctags and used for insert-mode completion and navigation in Vim.

With universal-ctags installed, run:

$ ./gradlew decompileDependencies
$ ctags -R build/gtags

Be sure to configure Vim to use tag files as a completion source.

set complete+=t

Building

$ ./gradlew assemble

Special Thanks

Special thanks to fesh0r for hosting a fork of the upstream Fernflower project. The intelliJ-community project, which encompasses the fernflower project, is very large and including the whole project would be a tremendous pain to work with. Additionally, the library is not published anywhere useful, so I'm not able to add it as a dependency of this project.

This project uses Fernflower for bytecode decompilation. The fernflower project is maintained under the umbrella of the JetBrains IntelliJ Community Edition IDE. The project is licensed under the Apache License 2.0.

License