This is freaking me out, I just can't find a solution to it. I have a grammar for search queries and would like to match any searchterm in a query composed out of printable letters except for special characters "(", ")". Strings enclosed in quotes are handled separately and work.
Here is a somewhat working grammar:
/* ANTLR Grammar for Minidb Query Language */
grammar Mdb;
start
: searchclause EOF
;
searchclause
: table expr
;
expr
: fieldsearch
| searchop fieldsearch
| unop expr
| expr relop expr
| lparen expr relop expr rparen
;
lparen
: '('
;
rparen
: ')'
;
unop
: NOT
;
relop
: AND
| OR
;
searchop
: NO
| EVERY
;
fieldsearch
: field EQ searchterm
;
field
: ID
;
table
: ID
;
searchterm
:
| STRING
| ID+
| DIGIT+
| DIGIT+ ID+
;
STRING
: '"' ~('
'|'"')* ('"' )
;
AND
: 'and'
;
OR
: 'or'
;
NOT
: 'not'
;
NO
: 'no'
;
EVERY
: 'every'
;
EQ
: '='
;
fragment VALID_ID_START
: ('a' .. 'z') | ('A' .. 'Z') | '_'
;
fragment VALID_ID_CHAR
: VALID_ID_START | ('0' .. '9')
;
ID
: VALID_ID_START VALID_ID_CHAR*
;
DIGIT
: ('0' .. '9')
;
/*
NOT_SPECIAL
: ~(' ' | '\t' | '
' | '' | '\'' | '"' | ';' | '.' | '=' | '(' | ')' )
; */
WS
: [
\t] + -> skip
;
The problem is that searchterm is too restricted. It should match any character that is in the commented out NOT_SPECIAL, i.e., valid queries would be:
Person Name=%
Person Address=^%Street%%%$^&*@^
But whenever I try to put NOT_SPECIAL in any way into the definition of searchterm it doesn't work. I have tried putting it literally into the rule, too (commenting out NOT_SPECIAL) and many others things, but it just doesn't work. In most of my attempts the grammar just complained about extraneous input after "=" and said it was expecting EOF. But I also cannot put EOF into NOT_SPECIAL.
Is there any way I can simply parse every text after "=" in rule fieldsearch until there is a whitespace or ")", "("?
N.B. The STRING rule works fine, but the user ought not be required to use quotes every time, because this is a command line tool and they'd need to be escaped.
Target language is Go.