[antlr-interest] Java grammar accepting junk

[Ron Hunter-Duvar]

Funny, I went looking for just such a method and didn't find one. Now I 
go back and see exactly the code you pointed to. Accomplishes the same 
thing with slightly less code.

About my other question, though, if errors have occurred, with 
backtracking and recovery going on, how can I know if it succeeded in 
recovering and got to the end of file or just gave up early?

Thanks,
Ron


Terence Parr wrote:
> BaseRecognizer:
>
>     /** Get number of recognition errors (lexer, parser, tree 
> parser).  Each
>      *  recognizer tracks its own number.  So parser and lexer each have
>      *  separate count.  Does not count the spurious errors found between
>      *  an error and next valid token match
>      *
>      *  See also reportError()
>      */
>     public int getNumberOfSyntaxErrors() {
>         return state.syntaxErrors;
>     }
>
> Ter
> On Aug 15, 2008, at 3:13 PM, Ron Hunter-Duvar wrote:
>
>> So that would be by creating a RecognizerSharedState object, passing 
>> it to the parser constructor, then checking state.syntaxErrors > 0 at 
>> the end, correct?
>>
>> Is there a way to know whether the parser succeeded in recovering and 
>> parsing to the end of the file or gave up part way through?
>>
>> Thanks,
>> Ron
>>
>>
>> Terence Parr wrote:
>>> Well, take "succeeded" not very seriously...it just prints
>>>
>>>                        System.out.println("finished parsing OK");
>>>
>>> if there was no exception... all of the recognition exceptions are 
>>> caught inside the parser.  You could check the parser for the number 
>>> of errors.
>>>
>>> Ter
>>> On Aug 15, 2008, at 2:04 PM, Ron Hunter-Duvar wrote:
>>>
>>>> Hi,
>>>>
>>>> I'm doing some Java parsing with Antlr 3.1 and the Java.g grammar 
>>>> from Antlr.org. When I pass it non-Java input (e.g. shell scripts), 
>>>> it complains a lot, but still acts as if the parsing succeeded. I 
>>>> noticed that the grammar didn't have an EOF token to force it to go 
>>>> to end of file, so I added a new top level rule:
>>>>
>>>> sourceFile
>>>> : compilationUnit EOF
>>>> ;
>>>>
>>>> and invoked it with that new target. Seemed simple enough. But it 
>>>> didn't help. The parser still happily accepts garbage:
>>>>
>>>> Parsing: test.sh
>>>> line 1:0 no viable alternative at character '#'
>>>> line 5:0 no viable alternative at character '#'
>>>> line 5:1 no viable alternative at character '#'
>>>> line 5:2 no viable alternative at character '#'
>>>> line 1:1 no viable alternative at input '!'
>>>>  Succeeded
>>>>
>>>> The first and last line of output are from my driver code. 
>>>> Basically I was expecting the parser to throw an exception, which 
>>>> would have counted as a failure. Since it didn't, it counts it as a 
>>>> success.
>>>>
>>>> Maybe I'm not understanding how error reporting works in Antlr 3.1. 
>>>> I've worked quite a bit with Antlr 2.7, but I'm new to Antlr 3. I 
>>>> don't have the book, and haven't found anything in the wiki that 
>>>> explains this. Perhaps someone can enlighten me?
>>>>
>>>> Thanks,
>>>> Ron
>>>>
>>>> -- 
>>>> Ron Hunter-Duvar | Software Developer V | 403-272-6580
>>>> Oracle Service Engineering
>>>> Gulf Canada Square 401 - 9th Avenue S.W., Calgary, AB, Canada T2P 3C5
>>>>
>>>> All opinions expressed here are mine, and do not necessarily represent
>>>> those of my employer.
>>>>
>>>
>>>
>>
>> -- 
>> Ron Hunter-Duvar | Software Developer V | 403-272-6580
>> Oracle Service Engineering
>> Gulf Canada Square 401 - 9th Avenue S.W., Calgary, AB, Canada T2P 3C5
>>
>> All opinions expressed here are mine, and do not necessarily represent
>> those of my employer.
>>
>
>

-- 
Ron Hunter-Duvar | Software Developer V | 403-272-6580
Oracle Service Engineering
Gulf Canada Square 401 - 9th Avenue S.W., Calgary, AB, Canada T2P 3C5

All opinions expressed here are mine, and do not necessarily represent
those of my employer.