boolean

%lex
%%

\s+

\"[^"]+\"  return 'WORD'
"or"       return 'OR'
"and"      return 'AND'
"not"      return 'NOT'
"("        return '('
")"        return ')'
<<EOF>>    return 'EOF'
.          return 'INVALID'

/lex

%left 'OR' 'AND'
%left 'NOT'

%start expressions

%%

expressions
    : e EOF
      {

        var query = $1;
        return query;
      }
    ;

e
    : e 'OR' e
        {$$ = {_or: [$1, $3]};}
    | e 'AND' e
        {$$ = {_and: [$1, $3]};}
    | 'NOT' e %prec NOT
        {$$ = {_not: $2};}
    | '(' e ')'
        {$$ = $2;}
    | WORD
        {
          $$ = "%" + yytext.substr(1, yytext.length-2) + "%";
          $$ = {text: {_like: $$}};
        }
    ;