[Rubygems-developers] "gem install" bash readline completion

[Daniel Harple]

This adds completions to the "gem install" command. It grabs a list  
of available gems from rubyforge. It is very, very slow. I think it  
would be better if there was a "gem shell" command, that way  
completions would work across every platform (not everyone has bash).  
Also, if there was a yaml file of _just_ the available gems, or even  
a query page (/find_gems?q=blah resulting in a yaml file) this could  
be much faster. demo video [http://generalconsumption.org/externals/ 
temp/gems.mp4]

Create a file named gem in bash_completion.d/ with --

#+++
have gem &&
{
   # List gems from rubyforge
   _rubyforge_gems()
   {
     COMPREPLY=( $( compgen -P "$prefix" -W "$( ruby -e '
     require "rexml/parsers/sax2parser"
     require "rexml/sax2listener"
     require "open-uri"

     class RubyForgeGems
       include REXML::SAX2Listener
       attr_reader :gems
       def initialize
         @gems = []
       end

       def start_element(uri, localname, qname, attributes)
         @gems << attributes["href"][0..-5] if localname == "a" and  
attributes["href"] != "../"
       end
     end

     text = open("http://rubyforge.lauschmusik.de/gems/") { |f| f.read }
     parser = REXML::Parsers::SAX2Parser.new(text)
     listen = RubyForgeGems.new
     parser.listen(listen)
     parser.parse
     print listen.gems.join(" ")
   '
     ) " -- $cur ) )

   }

   _gem_commands()
   {
     COMPREPLY=( $( compgen -W "build cert check cleanup contents  
dependency environment help install list query rdoc search  
specification uninstall unpack update" -- $cur ) )
   }

   _gem()
   {
       local cur prev prefix temp

       COMPREPLY=()
       cur=${COMP_WORDS[COMP_CWORD]}
       prev=${COMP_WORDS[COMP_CWORD-1]}
       prefix=""

       # completing an option (may or may not be separated by a space)
       if [[ "$cur" == -?* ]]; then
   	    temp=$cur
   	    prev=${temp:0:2}
   	    cur=${temp:2}
   	    prefix=$prev
       fi

       case "$prev" in
   	    "install")
           _rubyforge_gems
   	      return 0
   	    ;;
       esac

       # handle case where first parameter is not a dash option
       #if [ $COMP_CWORD -eq 1 ] && [[ "$cur" != -* ]]; then
   	  #  _filedir
   	  #  return 0
       #fi

       return 0
   }
   complete -F _gem $default gem
}
#+++

-- Daniel