#!/usr/bin/perl -w

$data = { key1 => 'value1',
	  key2 => 'value2', };

sub macro_replace {
    $_ = shift;

    my $helper = sub {
	$_ = shift;
	return $data->{$_} if $data->{$_};
	return undef;
    };

    chomp (my $pwd = `pwd`);
    s/\[\[(pwd)\]\]/$pwd/g;
    s/\[\[(\w+)\]\]/@{[$helper->($1)]}/g;
    return $_;
}

print macro_replace ("blah [[key1]] [[key2]] [[pwd]] blah blah\n");