# Strange Markup Language processor                         16mar14waw

# Strange Markup Language (anyway, strange to me) processor.
# refer to perlmonks node 1078356.

package SML;

use warnings FATAL => 'all';
use strict;


my $nobrackets = qr{ [^{}]+ }xms;  # maybe use * quantifier??

use constant XLT => (  # basic translation mapping
    # captured tagged substrings represented by $ below
    # tag                 translates as
    '\textsuperscript' => ' startsuperscript $ endsuperscript ',
    '\textsubscript'   => ' startsubscript $ endsubscript'     ,
    '\textit'          => ' startitalic $ enditalic'           ,
    '\textcolor'       => ''                                   ,
    ''                 => '($)'                                ,
    );


my %xlate1 = XLT;

# tag will be in separate scalar.
# tagged string will be returned by anon. subroutine.

# convert strings (and placeholders) of %xlate1 to anon. subs.
for (values %xlate1) {  # convert:
    # placeholder to function parameter;
    s{ \$ }'$_[0]'xms;
    # value to anon. sub returning string w/interpolated param
    $_ = eval qq{ sub { qq{$_} } };
    }


sub process_iter_1 {  # works -- iterative, 1 capture, uses /e

    my ($passes,  # number of processing passes to make
        $string,  # string to be processed
        @tags,    # tags to process in order of processing
        ) = @_;

    while ($passes-- >= 1) {  # count the passes
        for ($string) {  # aliases $string to $_ for s///
            for my $tag (@tags) {  # processes tags in order
                exists $xlate1{$tag} or die qq{unknown tag '$tag'};
                s{ \Q$tag\E \{ ($nobrackets) \} }
                 {   $xlate1{$tag}->($1)        }xmsge;
                }
            }
        }

    return $string;

    }


my %xlate2 = XLT;

# tag will be in separate scalar.
# tagged string will be returned by anon. subroutine.

# convert strings (and placeholders) of %xlate2 to anon. subs.
for (values %xlate2) {  # convert:
    # placeholder to function parameter;
    s{ \$ }'$_[0]'xms;
    # value to anon. sub returning ref. to string w/interpolated param
    $_ = eval qq{ sub { \\ qq{$_} } };
    }


sub process_iter_2 {  # works -- iterative, 1 capture, no /e

    my ($passes,  # number of processing passes to make
        $string,  # string to be processed
        @tags,    # tags to process in order of processing
        ) = @_;

    while ($passes-- >= 1) {  # count the passes
        for ($string) {  # aliases $string to $_ for s///
            for my $tag (@tags) {  # processes tags in order
                exists $xlate2{$tag} or die qq{unknown tag '$tag'};
                s{ \Q$tag\E \{ ($nobrackets) \} }
                 {${ $xlate2{$tag}->($1)       }}xmsg;
                }
            }
        }

    return $string;

    }


1;