[antlr-interest] Non-greedy lexer rule in ANTLR4

[Terence Parr]

oh. if no newline and such what Bart suggests might be best.  maybe '<<' (~[\r\n] | .)* '>>' which is nongreedy
T
On Oct 12, 2012, at 3:50 PM, Terence Parr wrote:

> would '<<' .* '>>' work?
> Ter
> On Oct 12, 2012, at 10:17 AM, Bart Kiers wrote:
> 
>>> Is it possible to write a non-greedy lexer rule that does not contain a
>>> dot in ANTLR4? For example:
>>> 
>>> ANCHOR
>>>  : '<<' ( ~( '>>' | '\r' | '\n' ) )* '>>'
>>>  ;
>>> 
>> 
>> Hi Michel,
>> 
>> You can't negate two (or more) characters: negation only works for
>> char-sets that match a single character.
>> 
>> 
>> 
>>> I'm using 4.0b2 and the above seems to be greedy.
>>> 
>>> Alternatively, would it be possible to rewrite this rule so it includes
>>> everything from '<<' to the first '>>' but not more?
>>> 
>> 
>> Try something like this:
>> 
>> ANCHOR
>>  : '<<' ( ~( '>' | '\r' | '\n' ) | '>' ~'>' )* '>>'
>>  ;
>> 
>> regards,
>> 
>> Bart.
>> 
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> 
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