# hl7_conv

use strict;
use warnings;

my $input = q(AB\T\F\S\CD\E\E\E\R\R\R);
my $gen_out = '';
my $exp_out = q(AB&F^CD\\E\\R~R);

my %convs = (
    E   => '\\',
    F   => '|',
    R   => '~',
    S   => '^',
    T   => '&',
);

$gen_out = hl7_replace($input);

print "INPUT:   $input\n";
print "GEN_OUT: $gen_out\n";
print "EXP_OUT: $exp_out\n";

print $0, ': ', $gen_out eq $exp_out ? 'SUCCESS!' : '  Z z . c8o,  ', "\n";

exit 0;

sub hl7_replace
{
    my $in = shift;

    my @input = split //, $in;
    my @output = ();

    for (my $i = 0; $i <= $#input; ++$i)
    {
        if ($input[$i] eq "\\" && ($i + 2) <= $#input 
            && $convs{$input[$i + 1]} && $input[$i + 2] eq "\\")
        {
            push @output, $convs{$input[$i + 1]};
            $i += 2;
        }
        else
        {
            push @output, $input[$i];
        }
    }

    return join '', @output;
}

##</code><code>##

[ ~/tmp ] $ perl hl7_conv 
INPUT:   AB\T\F\S\CD\E\E\E\R\R\R
GEN_OUT: AB&F^CD\E\E~R\R
EXP_OUT: AB&F^CD\E\R~R
hl7_conv:   Z z . c8o,  
[ ~/tmp ] $ perl hl7_conv 
INPUT:   AB\T\F\S\CD\E\E\E\R\R\R
GEN_OUT: AB&F^CD\E\R~R
EXP_OUT: AB&F^CD\E\R~R
hl7_conv: SUCCESS!

##</code><code>##

# hl7_conv

use strict;
use warnings;

my $input = q(AB\T\F\S\CD\E\E\E\R\R\R);
my $gen_out = '';
my $exp_out = q(AB&F^CD\\E\\R~R);

my $rx_hl7_ctrl_chars = qr/\\([EFRST])\\/;
my %convs = (
    E   => '\\',
    F   => '|',
    R   => '~',
    S   => '^',
    T   => '&',
);

$gen_out = hl7_replace($input);

print "INPUT:   $input\n";
print "GEN_OUT: $gen_out\n";
print "EXP_OUT: $exp_out\n";

print $0, ': ', $gen_out eq $exp_out ? 'SUCCESS!' : '  Z z . c8o,  ', "\n";

exit 0;

sub hl7_replace
{
    my $in = shift;

    $in =~ s/$rx_hl7_ctrl_chars/$convs{$1}/g;

    return $in;
}

##</code><code>##

# hl7_conv

use strict;
use warnings;

my $input = q(AB\T\F\S\CD);
my $gen_out = '';
my $exp_out = q(AB&F^CD);

my %convs = (
    '|'     => qr/\\F\\/,
    '^'     => qr/\\S\\/,
    '&'     => qr/\\T\\/,
    '~'     => qr/\\R\\/,
    '\\'    => qr/\\E\\/,
);

$gen_out = hl7_replace($input);

print "INPUT:   $input\n";
print "GEN_OUT: $gen_out\n";
print "EXP_OUT: $exp_out\n";

print $0, ': ', $gen_out eq $exp_out ? 'SUCCESS!' : '  Z z . c8o,  ', "\n";

exit 0;

sub hl7_replace
{
    my $in = shift;

    foreach my $key (keys %convs)
    {
        $in =~ s/$convs{$key}/$key/g;
    }

    return $in;
}

##</code><code>##

[ ~/tmp ] $ perl hl7_conv 
INPUT:   AB\T\F\S\CD
GEN_OUT: AB&F^CD
EXP_OUT: AB&F^CD
hl7_conv: SUCCESS!
[ ~/tmp ] $