[antlr-interest] Selective ignoring of whitespace

[Ratul Bhadury]

Thanks for the tips guys.

I've made some progress but seeing one peculiarity which I would be grateful
if someone could explain.

Single line input like 'sec=      sec,    dfd    dfdf' is accepted as I
intend, i.e sec & dfd    dfdf are regarded as search_terms. However if I put
a space before the '=', the line cannot be parsed. I tried putted a WS*
element in the definition of keyword_field, and also tried putting it in
keyword_clause, but they made no difference.

Can someone explain to me why this is the case?  Grammar is below.

Many thanks!

Ratul

-------------------------------------------
------------ THE GRAMAR --------
-------------------------------------------

grammar MopedSearch;

options
{
    language=CSharp2;
}


/*------------------------------------------------------------------
 * PARSER RULES
 *------------------------------------------------------------------*/

clause        returns [ SearchExpression searchExpr ]
    :    keyword_clause EOF
    ;

keyword_clause
    : keyword_field EQ search_term_list
    ;

id_clause
    : id_field EQ id_list
    ;

search_term_list    :    search_term (',' search_term)*
                    ;

id_list                :    NUMBER (',' NUMBER)*;

keyword_field    : 'sec'
                | 'cp'
                | 'our'
                ;

id_field        : 't'
                | 'p'
                | 'c'
                ;

search_term        : keyword_field
                | KEYWORD
                ;

NUMBER        : DIGIT+;
EQ            : '=';
KEYWORD        : CHAR(CHAR|' ')*;

fragment CHAR   :
ALPHA_UC|ALPHA_LC|DIGIT|'$'|'£'|'&'|'^'|'%'|'('|')'|'['|']'|':'|';'|'*'|'<'|'>'|'/'|'\\'|'@'|'#'|'?'|'!'|'.';

fragment ALPHA_UC   : 'A'..'Z';
fragment ALPHA_LC   : 'a'..'z';
fragment DIGIT        : '0'..'9';
WS        :    (' ' | '\t') {$channel=HIDDEN;}
        ;
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