[antlr-interest] C Runtime and Strings

[Stefan Klinger]

Jim Idle wrote:
> This is just:
> 
> I1=IDENTIFIER
> {
>   //here $I1.text returns the string for it as ANTLR3_STRING
>  //      $I1.text->chars is the actual pointer


But this seems to return a null terminated string, so it can't be of the 
input buffer directly.

My idea was that i refer to the input buffer directly so that i can 
simply get the range of match directly of the input buffer.

Because if i allocate a buffer for the combined tokens i have to free it 
in the calling rule, and this would be error prone and slower than 
directly referring to the input buffer.

Is there any way to to this?


To explain the idea a bit more verbose (not actually working code):

struct CombinedString {
	char *begin;
	char *end;
};

Append(CombinedString *buffer, char *ptr, size_t length) {
	if(!buffer->begin) {
		buffer->begin = ptr;
	}
	buffer->end = ptr + length;
}

scoped_identifier returns [CombinedString name]
	@init { name.begin = NULL; name.end = NULL; }
	: ((a=NAMESPACE_COLON {Append($name, $a, $a.length);} )?
	((b=IDENTIFIER c=NAMESPACE_COLON) {Append($name, $b, $b.length); 
Append($name, $c, $c.length);} )*
	d=IDENTIFIER {Append($name, $d, $d.length);} );

> 
>> -----Original Message-----
>> From: antlr-interest-bounces at antlr.org [mailto:antlr-interest-
>> bounces at antlr.org] On Behalf Of dev.null.nix at gmail.com
>> Sent: Friday, August 24, 2007 5:33 AM
>> To: antlr-interest at antlr.org
>> Subject: [antlr-interest] C Runtime and Strings
>>
>> Hi,
>>
>> I have a rule like this in a C target language grammar:
>>
>> scoped_identifier : NAMESPACE_COLON? (IDENTIFIER NAMESPACE_COLON)*
>> IDENTIFIER;
>>
>> I would like to return the string representing scoped_identifier.
>>
>> Is there any way to access the buffer location of a token in the input
>> buffer (like storing a pointer to the first and the last char).
>>
>> And if there is a way, is the input buffer read into one big buffer so
>> that it is valid for the whole parser?
>>
>> Thanks,
>> Stefan
>