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Contextual code completion for Erlang using Erlang itself. This library includes a module that generates completion suggestion structures and a front-end module that converts these into TextMate snippets. It would be relatively easy for someone familiar with distel to write a front-end module for Emacs. The TextMate integration also includes a TCP server process written in Erlang and a Python client that sends completion requests.

The complete:string/2 function is designed to take the local module and the text before the caret and provide a set of completions relevant to the context. It uses erl_scan:string/1 to get a set of syntax tokens for the context. By reversing the list of syntax tokens it can look back from the caret and determine what kind of completions to generate.

If for example the input was “lists:f” the reversed set of tokens would be [{atom,1,f},{':',1},{atom,1,lists}||_]. The set of completions in this case would be all the functions exported by module lists. A sample of the return value is {1,[{call,{flatten,1},{call,{flatten,2}},{call,{foldl,3}},{call,{foldr,3}}|_]}. After getting a set of completions it generates a set of menu options with tm_complete:menu/1. It prompts the TextMate user by passing this list to tm_menu:selection/1 and then matching the menu option selected with the underlying completion chosen. In the case that the user selects “flatten/2” the underlying completion option is identified as {call,{flatten,2}}. Passing the prefix length (1 because letter f is already typed) and this completion to tm_complete:snippet/2 function generates the TextMate snippet "latten(${1:Arg1}, ${2:Arg2})".

The entire code base and development history is available at the Erlang Code Completion project on GitHub.

I will gladly assist anyone who is eager to integrate Erlang code completion into their favorite editor or IDE. The ins and out of developing extensions/plug-ins for your editor or IDE are your domain and I will unfortunately not be able to help there.

NOTE: As of this writing this is not yet part of the standard Erlang.tmbundle available in the TextMate bundle repository. A patch has been forwarded a patch for it to textmate-dev@lists.macromates.com. This patch has also individually been sent to Mietek Bąk (the Erlang.tmbundle maintainer) to be reviewed and commited if he deems it fit.