ANTLR V4 lexer lookahead question

[TR]

Hi,

I'm trying to write a grammar for an XML-like language, where we use << instead of < characters.

This is a partial snap of the lexer, where TEXT represents the text between (outside) tags:

OPEN  : '<<' ;

CLOSE : '>>' ;

TEXT  : ~[^<]+ ;

The definition for TEXT above is clearly wrong, because it will stop at the first occurrence of < even when one is not followed by another <.

I am looking for a way to define "capture everything until you encounter a <<" but don't include the << in the match. So something like this won't work either:

TEXT  : .*? '<<' ;

Is there a way to accomplish that in ANTLR4?

-- TR

[Terence Parr]

On May 3, 2015, at 5:40 AM, TR <tzv...@gmail.com> wrote:

Hi,

I'm trying to write a grammar for an XML-like language, where we use << instead of < characters.

This is a partial snap of the lexer, where TEXT represents the text between (outside) tags:

OPEN  : '<<' ;

CLOSE : '>>' ;

TEXT  : ~[^<]+ ;

The definition for TEXT above is clearly wrong, because it will stop at the first occurrence of < even when one is not followed by another <.

hi. it should stop at << not <

Ter

I am looking for a way to define "capture everything until you encounter a <<" but don't include the << in the match. So something like this won't work either:

TEXT  : .*? '<<' ;

Is there a way to accomplish that in ANTLR4?

-- TR

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