sub slow_match 
{
    my ( $hash_ref_1, $hash_ref_2 ) = @_;
    # %texts, %patterns coming from global (was: %hash1, %hash2)

    my %matches;
    foreach my $pattern ( keys %$patterns_ref )
    {
        $matches{$pattern} = qr/\b$pattern\b/;
    }

    while ( my ( $text_id, $text ) = each %texts )
    {
        study $text;

        while ( my ( $pattern, $high_lvl_id ) = each %patterns )
        {
            if ( $text =~ $matches{$pattern} )
            {
                $$hash_ref_1{$text_id} .= ':'.$high_lvl_id;
                foreach my $part (split(/\s/,$pattern))
                {
                    $$hash_ref_2{$text_id} -> {$part} = 0;
                }
            }
        }
    }
}