Is it feasible to use Antlr for source code completion?

Question

I don't know, if this question is valid since i'm not very familiar with source code parsing. My goal is to write a source code completion function for one existing programming language (Language "X") for learning purposes. Is Antlr(v4) suitable for such a task or should the necessary AST/Parse Tree creation and parsing be done by hand, assuming no existing solutions exists?

I haven't found much information about that specific topic, except a list of compiler books, except a compiler is not what i'm after for.

Answer 1

The code completion in GoWorks is completely implemented using ANTLR 4. The following video shows the level of completion of this code completion engine. The code completion example runs from 5 minutes through the end of the video.

Intro to Tunnel Vision Labs' GoWorks IDE (Preview Release)

I have been working on code completion algorithms for many years, and strongly believe that there is no better solution (automated or manual) for producing a code completion solution for a new language that meets the requirements for what I would call highly-responsive code completion. If you are not interested in that level of performance or accuracy, other solutions may be easier for you to get involved with (I don't work with those personally, because I am too easily disappointed in the results).

Answer 2

Xtext uses ANTLR3 and has good autocomplete facilities. The problem is, it generates a seperate parser (again using antlr3) for autocomplete processing which is derived from AbstractInternalContentAssistParser. This multi-thousand line code part shows that the error recovery of ANTLR3 alone found to be insufficient by the xtext team.

Meanwhile ANTLR4 has a function parser.getExpectedTokensWithinCurrentRule() which lists possible token types for given position. It works when used in a ParseTreeListener. Remaining is semantics, scoping etc which is out of ANTLRs scope.