[antlr-interest] ast rewrite

[Gavin Lambert]

At 08:33 5/12/2006, Terence Parr wrote:
 >
 >Hi Alexander.  I think it's okay, because the Java API for 
String
 >says "The substring begins at the specified beginIndex and 
extends
 >to the character at index endIndex - 1."

Yeah, but if you pass getText().length() as endIndex then 
endIndex-1 is the trailing single quote.  So the OP is quite 
correct.

I prefer doing something that avoids copying the text though; more 
like this:

String : '\'' str=UnquotedString '\''  { emit($str); 
$setType(String); };
fragment UnquotedString: ~('\'')*;

The subrule outputs a token (which simply indexes into the input 
stream rather than copying the text), which the parent rule then 
uses as its own output.  Note that I'm not 100% sure of the syntax 
you have to use in that first rule, you might have to experiment a 
bit.