my $template_text = read_file('test.tmpl');
    # get all expr attributes
    my @orig_exprs = ($template_text =~ /expr="[^"]*"/g);
    my @exprs = @orig_exprs;

    @exprs = map({s/\s+//g; s/^expr="//; s/"$//; s/not\((.*?)\)/!$1/g; $_} @exprs);

    @orig_exprs = map({s/[|&()]/\\$&/g; $_} @orig_exprs);

    # construct new tmpl_var/tmpl_if names in place of the expressions
    my @expr_names = @exprs;
    @expr_names = map({s/==/_is_/g; s/</_lt_/g; s/\|\|/_or_/g; s/\&\&/_and_/g;
                       s/!/not_/g; $_} @expr_names);

    # replace the expression names in the actual template
    $template_text =~ s/$orig_exprs[$_]/$expr_names[$_]/g for ( 0..$#exprs );

    @exprs = map({s/\w{2,}/\$row->\{$&\}/g; $_} @exprs);

    # generate new template file
    my $tmpl_filename = '/tmp/test.tmpl');
    write_file($tmpl_filename, $template_text);

##</code><code>##

sub _fill_expr_params {
    my ($row, $expr_names, $exprs) = @_;
    $row->{$expr_names->[$_]} = eval($exprs->[$_]) for ( 0.. $#$exprs );
}