BASH/ZSH auto-complete plugin for Composer

This is an experimental hack to add Symfony BASH auto complete to Composer via a plugin. It's a pretty slimy hack, but it works without editing Composer's code.

Installation

1. Run composer g require stecman/composer-bash-completion-plugin dev-master
2. Add a completion hook to your shell's user config file:

• If you're using BASH, put the following in your ~/.bash_profile file:

  # Modified version of what `composer _completion -g -p composer` generates
  # Composer will only load plugins when a valid composer.json is in its working directory,
  # so  for this hack to work, we are always running the completion command in ~/.composer
  function _composercomplete {
      export COMP_LINE COMP_POINT COMP_WORDBREAKS;
  
      RESULT=`cd $HOME/.composer && composer _completion`;
      STATUS=$?;
  
      if [ $STATUS -ne 0 ]; then
          echo $RESULT;
          return $?;
      fi;
  
      local cur;
      _get_comp_words_by_ref -n : cur;
  
      COMPREPLY=(`compgen -W "$RESULT" -- $cur`);
  
      __ltrim_colon_completions "$cur";
  };
  complete -F _composercomplete composer;

• If you're using ZSH, put the following in your ~/.zshrc file:

  function _composer {
      # Emulate BASH's command line contents variable
      local -x COMP_LINE="$words"
  
      # Emulate BASH's cursor position variable, setting it to the end of the current word.
      local -x COMP_POINT
      (( COMP_POINT = ${#${(j. .)words[1,CURRENT]}} ))
  
      RESULT=("${(@f)$( cd $HOME/.composer && composer _completion )}")
      STATUS=$?;
  
      # Bail out if PHP didn't exit cleanly
      if [ $STATUS -ne 0 ]; then
          echo $RESULT;
          return $?;
      fi;
  
      compadd -- $RESULT
  };
  
  compdef _composer composer;

3. Reload your bash profile (or open a new shell), and enjoy tab completion on Composer

Explanation

This hacky plugin injects an additional command into the Composer application at runtime. It relies on the fact that when handling an uncaught exception, Composer\Console\Application::renderException is called, which in turn calls getComposer and causes Composer plugins to be loaded. When the plugin in this package is activated and the first command line argument is _completion, the plugin effectively reboots the application with the completion command added.