Add a (first) hook, to resolve otherwise unresolved link reference.

.aspelldict

@@ -1,4 +1,5 @@
-personal_ws-1.1 en 180 
+personal_ws-1.1 en 184 
+Babelmark
 BlockTree
 CDATA
 CommonMark
@@ -32,6 +33,7 @@ ProhibitLvalueSubstr
 ProhibitMultiplePackages
 ProhibitStringyEval
 ProhibitUnusedCapture
+README
 RequireArgUnpacking
 RequireConstantVersion
 TODO
@@ -61,6 +63,7 @@ codepoints
 colgroup
 commonmark
 cond
+cpanm
 del
 delim
 dest
@@ -89,6 +92,7 @@ gfm
 github
 gx
 gxc
+hashref
 hd
 helpfull
 helpoptions

Changes

@@ -1,5 +1,10 @@
 Revision history for pmarkdown and the Markdown::Perl module.
 
+1.06 - ??
+
+ - Add support for setting processing hooks.
+ - Add a hook to resolve unresolved link reference.
+
 1.05 - 2024-05-14
 
  [Improve the inline_delimiters option]

lib/Markdown/Perl.pm

@@ -9,17 +9,19 @@ use Carp;
 use English;
 use Exporter 'import';
 use Hash::Util 'lock_keys';
+use List::Util 'none';
 use List::MoreUtils 'pairwise';
 use Markdown::Perl::BlockParser;
 use Markdown::Perl::Inlines;
 use Markdown::Perl::HTML 'html_escape', 'decode_entities';
+use Readonly;
 use Scalar::Util 'blessed';
 
 use parent 'Markdown::Perl::Options';
 
 our $VERSION = '1.05';  # Remember to also set the App::pmarkdown version.
 
-our @EXPORT_OK = qw(convert set_options);
+our @EXPORT_OK = qw(convert set_options set_mode set_hooks);
 our %EXPORT_TAGS = (all => \@EXPORT_OK);
 
 sub new {
@@ -28,7 +30,8 @@ sub new {
   my $this = $class->SUPER::new(
     mode => undef,
     options => {},
-    local_options => {});
+    local_options => {},
+    hooks => {});
   $this->SUPER::set_options(options => @options);
   lock_keys(%{$this});
 
@@ -47,6 +50,24 @@ sub set_mode {
   return;
 }
 
+Readonly::Array my @VALID_HOOKS => qw(resolve_link_ref);
+
+sub set_hooks {
+  my ($this, %hooks) = &_get_this_and_args;  ## no critic (ProhibitAmpersandSigils)
+  while (my ($k, $v) = each %hooks) {
+    if (none { $_ eq $k } @VALID_HOOKS) {
+      croak "Invalid hook name: ${k}";
+    } elsif (!defined $v) {
+      delete $this->{hooks}{$k};
+    } elsif (ref $v ne 'CODE') {
+      carp 'Hook target must be a CODE reference';
+    } else {
+      $this->{hooks}{$k} = $v;
+    }
+  }
+  return;
+}
+
 # Returns @_, unless the first argument is not blessed as a Markdown::Perl
 # object, in which case it returns a default object.
 my $default_this = Markdown::Perl->new();
@@ -280,6 +301,29 @@ Converts the given $md string into HTML. The input string must be a decoded
 Unicode string (or an ASCII string) and the output is similarly a decoded
 Unicode string.
 
+=head2 set_hooks
+
+  $pmarkdown->set_hooks(hook_name => sub { ... }, ...);
+  Markdown::Perl::set_hooks(hook_name => sub { ... }, ...);
+
+Registers hooks to be called during the processing of a Markdown document. Each
+hook must point to a code reference. You can remove a hook by passing C<undef>
+as the value associated with a hook.
+
+There is currently a single hook:
+
+=over 4
+
+=item *
+
+C<resolve_link_ref>: this hook will receive a single string an argument,
+containing the label of a link reference in case where there was no matching
+link definition in the document and it must returns either C<undef> or a
+hash-reference containing a C<target> key, pointing to the link destination and
+optionally a C<title> key containing the title of the key.
+
+=back
+
 =head1 AUTHOR
 
 Mathias Kende <mathias@cpan.org>

lib/Markdown/Perl/Inlines.pm

@@ -460,7 +460,12 @@ sub parse_reference_link {
 # Returns a hashref with (title and dest) or undef.
 sub get_linkref {
   my ($that, $linkrefs, $ref) = @_;
-  return $linkrefs->{$ref};
+  if (exists $linkrefs->{$ref}) {
+    return $linkrefs->{$ref};
+  } elsif (exists $that->{hooks}{resolve_link_ref}) {
+    return $that->{hooks}{resolve_link_ref}->($ref);
+  }
+  return;
 }
 
 # This methods remove line break at the beginning and end of lines (inside text

t/500-hooks-resolve_link_ref.t

@@ -0,0 +1,38 @@
+use strict;
+use warnings;
+use utf8;
+
+use Markdown::Perl 'convert', 'set_hooks';
+use Test2::V0;
+
+sub hook {
+  my ($ref) = @_;
+  if ($ref eq 'foo') {
+    return { target => 'http://foo' };
+  } elsif ($ref eq 'bar') {
+    return { target => 'http://bar', title => 'BAR' };
+  }
+  return;
+}
+
+set_hooks(resolve_link_ref => \&hook);
+is(convert("[text][foo]"), "<p><a href=\"http://foo\">text</a></p>\n", 'resolved in full link reference');
+is(convert("[foo][]"), "<p><a href=\"http://foo\">foo</a></p>\n", 'resolved in collapsed link reference');
+is(convert("[foo]"), "<p><a href=\"http://foo\">foo</a></p>\n", 'resolved in shortcut link reference');
+
+is(convert("[bar]"), "<p><a href=\"http://bar\" title=\"BAR\">bar</a></p>\n", 'resolved with title');
+is(convert("[none]"), "<p>[none]</p>\n", 'not resolved');
+
+is(convert("[foo]\n\n[foo]: http://other"), "<p><a href=\"http://other\">foo</a></p>\n", 'source has precedence');
+
+{
+  my $p = Markdown::Perl->new();
+  is($p->convert("[foo]"), "<p>[foo]</p>\n", 'no default hook');
+  $p->set_hooks(resolve_link_ref => \&hook); 
+  is($p->convert("[foo]"), "<p><a href=\"http://foo\">foo</a></p>\n", 'set_hooks object-oriented');
+}
+
+set_hooks(resolve_link_ref => undef);
+is(convert("[foo]"), "<p>[foo]</p>\n", 'hook can be removed');
+
+done_testing;