# search.yp
#
# Copyright (C) 2013 Tim Retout <tim@retout.co.uk>
#
# Copying and distribution of this file, with or without modification,
# are permitted in any medium without royalty.  This file is offered as-is,
# without any warranty.


%left OR
%left AND
%left NOT

%%

search:  LPAREN search RPAREN    { "( $_[2] )" }
    |    search OR search        { "( $_[1] OR $_[3] )" }
    |    search AND search       { "( $_[1] AND $_[3] )" }
    |    search search %prec AND { "( $_[1] AND $_[2] )" }
    |    NOT search              { "(!$_[2])" }
    |    TERM                    { "$_[1]" }
    ;    

%%

sub _error {
    exists $_[0]->YYData->{ERRMSG}
    and do {
        print $_[0]->YYData->{ERRMSG};
        delete $_[0]->YYData->{ERRMSG};
        return;
    };
    print "Syntax error.\n";
}

sub _lexer {
    my $parser = shift;

    $parser->YYData->{INPUT} =~ s/^\s*//;

    for ($parser->YYData->{INPUT}) {
        s/^(or)\b//i     and return ('OR', $1);
        s/^(and)\b//i    and return ('AND', $1);
        s/^(not|-)\b//i  and return ('NOT', $1);
        s/^\(//          and return ('LPAREN', '(');
        s/^\)//          and return ('RPAREN', ')');
        s/^("[^"]*")//   and return ('TERM', $1);
        s/^([^()\s]+)//  and return ('TERM', $1);
    }

    return ('', undef);
}

sub run {
    my $class = shift;

    while (<>) {
        chomp;
        my $self = $class->new;
        $self->YYData->{INPUT} = $_;
    	my $result = $self->YYParse( yylex => \&_lexer, yyerror => \&_error);
        print $result . "\n";
    }
}