How to generate AST(abstract syntax tree) for Python source code using antlr

Question

Grammar for python is given on antlr site but on using it to generate AST its giving error. I am using same procedure as for java grammar which generated AST .

Errors:

> C:\testpython>java -cp antlr-3.2.jar org.antlr.Tool Python.g

error(10): internal error: : java.lang.Error: Error parsing Python.g: 'class' not expected 'grammar' org.antlr.tool.GrammarSpelunker.match(GrammarSpelunker.java:74) org.antlr.tool.GrammarSpelunker.grammarHeader(GrammarSpelunker.java:112) org.antlr.tool.GrammarSpelunker.parse(GrammarSpelunker.java:84) org.antlr.Tool.sortGrammarFiles(Tool.java:552) org.antlr.Tool.process(Tool.java:408) org.antlr.Tool.main(Tool.java:91) error(100): Python.g:56:1: syntax error: antlr: Python.g:56:1: unexpected token: class error(8): file Python.g contains grammar PythonParser; names must be identical error(100): Python.g:56:20: syntax error: antlr: Python.g:56:20: expecting SEMI, found 'extends' error(100): syntax error: invalid char literal: '014円' error(150): grammar file Python.g has no rules error(100): Python.g:0:0: syntax error: assign.types: :0:0: unexpected end of subtree error(100): Python.g:0:0: syntax error: define: :0:0: unexpected end of subtree

Any help?

Answer 1

You're trying to generate a parser with ANTLR v3 using a grammar that is written for ANTLR v2. Either find a grammar for v3, or keep the grammar and use ANTLR v2: http://www.antlr2.org/download.html

A grammar that starts like this is targeted for v2:

class FooParser extends Parser;

and this for v3:

grammar FooParser;