[antlr-interest] Using the python output with ANTLR3

[Sam Harwell]

You'll need to convert all actions and semantic predicates to valid python code. These are present in [at least] the following rules:

assignmentOperator
relationalOp
shiftOp
ENUM
ASSERT

Sam

-----Original Message-----
From: antlr-interest-bounces at antlr.org [mailto:antlr-interest-bounces at antlr.org] On Behalf Of Dahlhoff Achim (CM-AI/PJ-VW37)
Sent: Thursday, February 19, 2009 9:10 AM
To: 'antlr-interest at antlr.org'
Subject: [antlr-interest] Using the python output with ANTLR3

Hi all.

I just signed up on this list after contacting Mr. Niemann about the antlr Python binding. He suggested checking here for a little help.

To transform a large bunch of java interface files to classes and stubs for a (broad) Java-to-C interface, I would like to generate all of the wrapper code and tables needed for JNI using a code-generator written in Python (I have more experience in python and think it es better suited for creating text outputs).

When I launch ANTLR 3.1.1 with the Python output option on the Java 1.5 grammar file (from the antlr website), I am experiencing some problems.

First of all, antlr outputs an internal error and some warnings. Then, the generated python files contain a few lines of code, which are more java than python and won't compile without some manual fixing. And when I'm done with that, the generated parser won't work... :-(

Am I missing something here?



The output of antlr when taking the Java 1.5 grammer and just adding the 'language=Python' option:


C:\MIB\ANTLR>java -classpath ./antlrworks-1.2.1.jar org.antlr.Tool grammar\Java.g

ANTLR Parser Generator  Version 3.1.1
error(10):  internal error: eval tree parse error : <AST>:0:0: unexpected AST node:

org.antlr.stringtemplate.language.ActionEvaluator.expr(Unknown Source)
org.antlr.stringtemplate.language.ActionEvaluator.action(Unknown Source)
org.antlr.stringtemplate.language.ASTExpr.evaluateExpression(Unknown Source)
org.antlr.stringtemplate.language.ASTExpr.handleExprOptions(Unknown Source)
org.antlr.stringtemplate.language.ASTExpr.write(Unknown Source)
org.antlr.stringtemplate.StringTemplate.write(Unknown Source)
org.antlr.stringtemplate.language.ConditionalExpr.writeSubTemplate(Unknown Sourc
e)
org.antlr.stringtemplate.language.ConditionalExpr.write(Unknown Source)
org.antlr.stringtemplate.StringTemplate.write(Unknown Source)
org.antlr.stringtemplate.language.ASTExpr.write(Unknown Source)
org.antlr.stringtemplate.language.ASTExpr.writeAttribute(Unknown Source)
org.antlr.stringtemplate.language.ActionEvaluator.action(Unknown Source)
org.antlr.stringtemplate.language.ASTExpr.write(Unknown Source)
org.antlr.stringtemplate.StringTemplate.write(Unknown Source)
org.antlr.stringtemplate.language.ASTExpr.write(Unknown Source)
org.antlr.stringtemplate.language.ASTExpr.writeAttribute(Unknown Source)
org.antlr.stringtemplate.language.ActionEvaluator.action(Unknown Source)
org.antlr.stringtemplate.language.ASTExpr.write(Unknown Source)
org.antlr.stringtemplate.StringTemplate.write(Unknown Source)
org.antlr.codegen.CodeGenerator.write(CodeGenerator.java:1275)
org.antlr.codegen.Target.genRecognizerFile(Target.java:94)
org.antlr.codegen.CodeGenerator.genRecognizer(CodeGenerator.java:460)
org.antlr.Tool.generateRecognizer(Tool.java:420)
org.antlr.Tool.process(Tool.java:287)
org.antlr.Tool.main(Tool.java:72)



Then, the python interpreter stumbles over this:

   if not ((t1.getLine() == t2.getLine() && .....

(python requires 'and', not '&&'.)

or this:

   protected boolean enumIsKeyword = true;

that looks like java. Python wood need something like    enumIsKeyword=True
Finally this:

   if (!enumIsKeyword) _type=Identifier;

Here, the ! operator instead of 'not' is used, and the colon is missing.
It should be:     if not enumIsKeyword: _type=Identifier


When I fix these little bugs manually in the antlr output and try to feed it with a sample java file, the parser fails:

 Traceback (most recent call last):
   File "testprog.py", line 59, in ?
     main(sys.argv[1:])
   File "testprog.py", line 35, in main
     parser.compilationUnit()
   File "grammar\JavaParser.py", line 361, in compilationUnit
     alt8 = self.dfa8.predict(self.input)
   File "C:\Dahlhoff\MIB\ANTLRtest\antlr3\dfa.py", line 92, in predict
     c = input.LA(1)
   File "C:\Dahlhoff\MIB\ANTLRtest\antlr3\streams.py", line 859, in LA
     return self.LT(i).type
   File "C:\Dahlhoff\MIB\ANTLRtest\antlr3\streams.py", line 801, in LT
     self.fillBuffer()
   File "C:\Dahlhoff\MIB\ANTLRtest\antlr3\streams.py", line 669, in fillBuffer
     t = self.tokenSource.nextToken()
   File "C:\Dahlhoff\MIB\ANTLRtest\antlr3\recognizers.py", line 1133, in nextToken
     self._state.tokenStartCharIndex = self.input.index()
 TypeError: find/rfind/index/rindex() takes at least 1 argument (0 given)



Thanks for any help with this.

Achim.
____________________________________

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