[antlr-interest] How to recognize 'grammar' in parser ?

[Ilia Kantor]

I wrote simple grammar that should recognize 'grammar <name>;' in parser.
But somehow it fails on 'grammar <gr...>;' example.

Looks like I need to change to lookahead or another method ?


---------------- Test grammar ---------------
grammar Gram;

options {
    output=AST;
    ASTLabelType=CommonTree;
}

DIGIT
    :    '0'..'9'
    ;

LETTER_ENG
    : 'a'..'z'
    | 'A'..'Z'
    ;
    
WS  :
       (' '|'\r'|'\t'|'\u000C'|'\n' )+ {$channel=HIDDEN;}
    ;
    

id : namechar+;



alpha_num
	:	DIGIT | LETTER_ENG;

namechar
    : alpha_num | '_'
    ;

document : grammar_definition;

s_grammar
	:	'grammar';
	
grammar_definition: s_grammar id ';' -> ^(s_grammar id);

--------------------------- Test input

grammar gr;

------------------------- Output

[mTokens, mT8]: line 2:10 mismatched char: ';' on line 2; expecting char 'a'
[document, grammar_definition, id]: line 0:-1 required (...)+ loop 
(decision=1) did not match anything; token=[@-1,0:0='<no text>',<-1>,0:-1]