[antlr-interest] Re: TokenStreamRewriteEngine class and samples of its usage

[Terence Parr]

On May 27, 2004, at 2:59 PM, kumarsriram wrote:

>>> Hi. You need to set the token object to be TokenWithIndex as
> well :)
>
> Thanks a lot for the quick response. But I'm not sure I understand.
> How do I SET the token object? In my code, I'm GETTING the token
> object from the TokenStreamRewriteEngine instance.
>
> I tried the following code as well:
>
> Mylexer = new MyLexer(new StringReader(inputStr));


Add

MyLexer.setTokenObjectClass("antlr.TokenWithIndex");

and it should work.  I use a special token with the rewrite engine.  
The lexer must create the special objects.  Doesn't the example usage 
show this?  I'll have to fix it.

Terence

> System.out.println("Input string is " + inputStr);
> TokenStreamRewriteEngine writer = new TokenStreamRewriteEngine
> (lexer);
> CommonToken dollarInput = new CommonToken(12, "$input"); //12 is the
> index of the toke "$input" in the lexer
> writer.replace(dollarInput, "get");
>
> When I execute, I get the following exception:
>
> java.lang.ClassCastException
> 	at antlr.TokenStreamRewriteEngine.replace
> (TokenStreamRewriteEngine.java:269)
> 	at antlr.TokenStreamRewriteEngine.replace
> (TokenStreamRewriteEngine.java:257)
> 	at NomisParserTest.main(NomisParserTest.java:32)
> exception: java.lang.ClassCastException
>
>
> Help appreciated. Thanks.
>
> Sriram
>
>
>
>
> --- In antlr-interest at yahoogroups.com, Terence Parr <parrt at c...>
> wrote:
>>
>> On May 26, 2004, at 7:04 PM, kumarsriram wrote:
>>
>>> Hi,
>>>
>>> I'm a novice to ANTLR. I'm trying to write an expression parser
>>> (extension to the one that is provided in the ANTLR examples). I
>>> have a case where I need to replace some input characters
>>> ("$input.xyz" should be replaced with "getXYZ()"). I figured out
>>> that I could use TokenStreamRewriteEngine to do that. But when I
> use
>>> it in my program, I end up with ClassCastExceptions whenever I
>>> invoke nextToken() method on the engine instance. Has anyone used
>>> TokenStreamRewriteEngine before? BTW, am I taking the correct
>>> approach?
>>>
>>> I have tested my Lexer and Parser and they seem to be work fine.
>>>
>>> Have enclosed my test code.
>>>
>>> MyLexer lexer = new MyLexer(new StringBufferInputStream
> (inputStr));
>>> System.out.println("Input string is " + inputStr);
>>> TokenStreamRewriteEngine writer = new TokenStreamRewriteEngine
>>> (lexer);
>>> Token t = writer.nextToken; //here's the problematic code
>>
>> Hi. You need to set the token object to be TokenWithIndex as
> well :)
>>
>> Terence
>
>
>
>
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