[antlr-interest] Rewrite bug?

[Bart Kiers]

Hi Surj,

I could not reproduce this. Here's what I did on my (Linux) pc:

wget http://surge.it/static/antlr/JavaBroken.g
wget http://www.antlr.org/download/antlr-3.3-complete.jar
java -cp antlr-3.3-complete.jar org.antlr.Tool JavaBroken.g
javac -cp antlr-3.3-complete.jar *.java

ANTLR does produce an error because you have an empty `tokens{ ... }`
block, but it does generate the .java source files of the lexer and parser.
And these .java source files get compiled just fine.

Regards,

Bart.


On Thu, Jul 19, 2012 at 7:13 PM, Surj Basan <s.basan at surge.it> wrote:

> Hi Bart,
>
> Thanks for your reply.
>
> I've posted a cut-down grammar which exhibits the errors, along with
> generated files here:
>
> http://surge.it/static/antlr/
>
> The grammar rule is in JavaBroken.g:180-183, the Java error is
> in JavaBrokenParser.java:8659.
>
> Any help greatly appreciated,
> Surj
>
>
> On 19 July 2012 17:01, Bart Kiers <bkiers at gmail.com> wrote:
>
>> Hi Surj,
>>
>> Can you:
>>
>>    - post a complete grammar that reproduces this (not just a small
>>    snippet), and
>>    - indicate what ANTLR version you're using
>>
>> Regards,
>>
>> Bart.
>>
>>
>> On Thu, Jul 19, 2012 at 5:56 PM, Surj Basan <s.basan at surge.it> wrote:
>>
>>> Hi,
>>>
>>> No replies yet, so I'm guessing I've either missed something or this is a
>>> genuine bug.
>>>
>>> If anyone knows, could you send a quick reply so I can move forward.
>>>
>>> To recap: ANTLR is producing code that does not have a variable
>>> declaration
>>> in the Parser.
>>>
>>> Thanks,
>>> Surj
>>>
>>> On 16 July 2012 07:24, Surj Basan <s.basan at surge.it> wrote:
>>>
>>> > Hi All,
>>> >
>>> > I have a Java grammar (taken from the openjdk, one linked off
>>> > the ANTLR site:
>>> > http://openjdk.java.net/projects/compiler-grammar/antlrworks/Java.g).
>>> >
>>> > One of the rewrite rules produces Java code which does not have a var
>>> > decl, and so does not compile.
>>> >
>>> > I took the rule straight out of Terrence Parr's page on rewrite rules
>>> and
>>> > added it to the grammar (
>>> > http://www.antlr.org/wiki/display/ANTLR3/Tree+construction, paragraph
>>> > beginning "Using a rewrite rule at a
>>> non-extreme-right-edge-of-production
>>> > location is ok..").
>>> >
>>> > Can someone explain if this is a bug in ANTLR? Code is below, for ref.
>>> >
>>> > Grammar rule:
>>> >
>>> > statement
>>> >     :   [more rules here]
>>> >     |   'if' parExpression s1=statement ('else' s2=statement -> ^('if'
>>> > parExpression $s1 $s2)
>>> >                                         |                      ->
>>> ^('if'
>>> > parExpression $s1)
>>> >                                         )
>>> >     [more rules here]
>>> >     ;
>>> >
>>> >
>>> > Generated parser code:
>>> >
>>> >     // $ANTLR start synpred139_AntlrJava
>>> >     public final void synpred139_AntlrJava_fragment() throws
>>> > RecognitionException {
>>> >         void  =null;
>>> >
>>> >
>>> >         // AntlrJava.g:926:42: ( 'else' s2= statement )
>>> >         // AntlrJava.g:926:42: 'else' s2= statement
>>> >         {
>>> >
>>> >
>>> match(input,KEYWORD_ELSE,FOLLOW_KEYWORD_ELSE_in_synpred139_AntlrJava4927);
>>> > if (state.failed) return ;
>>> >
>>> >         pushFollow(FOLLOW_statement_in_synpred139_AntlrJava4931);
>>> >         s2=statement();
>>> >
>>> >         state._fsp--;
>>> >         if (state.failed) return ;
>>> >
>>> >         }
>>> >
>>> >     }
>>> >
>>> > (For what it's worth, I find that various permutations of rewrite rules
>>> > exhibit the same behaviour: missing var decls in the generated parser.
>>> > Java.g is a pretty complex grammar. Would I have more luck if I split
>>> the
>>> > grammar into the lexer/parser and a separate tree building one,
>>> instead of
>>> > combining it all into a single file?)
>>> >
>>> > Any help greatly appreciated.
>>> >
>>> > Thanks,
>>> > Surj
>>> >
>>>
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>>
>>
>