ANTLR and content assist in Eclipse

I have a project in Eclipse where I have an editor for a custom language. I am using ANTLR to generate the compiler for it. What I need is to add content assist to the editor.

The input is a source code in the custom language, and the position of the character where the user requested content assist. The source code is most of time incomplete as the user can ask for content assist any time. What I need is to calculate the list of possible tokens that are valid for the given position.

It is possible to write a custom code to do the calculation, but that code would have to be manually kept in sync with the grammar. I figured the parser is doing something similar. It has to be able to determine at a given context what开发者_如何学Python are the acceptable tokens. Is it possible to "reuse" that? What is the best practice in creating content assist anyway?

Thanks, Balint

Have a look at Xtext. Xtext uses Antlr3 under the hood and provides content assist for the Antlr based languages. Have a look especially into package org.eclipse.xtext.ui.editor.contentassist.

You may consider to redefine your grammar with Xtext, which would provide the content assist out-of-the-box. It is not possible to reuse the Antlr grammar of a custom language.