1 files changed, 169 insertions, 0 deletions
diff --git a/IkiWiki/Plugin/external.pm b/IkiWiki/Plugin/external.pm
new file mode 100644
index 000000000..e3504a30d
--- /dev/null
+++ b/IkiWiki/Plugin/external.pm
@@ -0,0 +1,169 @@
+#!/usr/bin/perl
+# Support for external plugins written in other languages.
+# Communication via XML RPC a pipe.
+# See externaldemo for an example of a plugin that uses this.
+package IkiWiki::Plugin::external;
+
+use warnings;
+use strict;
+use IkiWiki 2.00;
+use RPC::XML;
+use RPC::XML::Parser;
+use IPC::Open2;
+use IO::Handle;
+
+my %plugins;
+
+sub import { #{{{
+	my $self=shift;
+	my $plugin=shift;
+	return unless defined $plugin;
+
+	my ($plugin_read, $plugin_write);
+	my $pid = open2($plugin_read, $plugin_write, $plugin);
+
+	# open2 doesn't respect "use open ':utf8'"
+	binmode($plugin_read, ':utf8');
+	binmode($plugin_write, ':utf8');
+
+	$plugins{$plugin}={in => $plugin_read, out => $plugin_write, pid => $pid,
+		accum => ""};
+
+	rpc_call($plugins{$plugin}, "import");
+} #}}}
+
+sub rpc_write ($$) { #{{{
+	my $fh=shift;
+	my $string=shift;
+
+	$fh->print($string."\n");
+	$fh->flush;
+} #}}}
+
+sub rpc_call ($$;@) { #{{{
+	my $plugin=shift;
+	my $command=shift;
+
+	# send the command
+	my $req=RPC::XML::request->new($command, @_);
+	rpc_write($plugin->{out}, $req->as_string);
+
+	# process incoming rpc until a result is available
+	while ($_ = $plugin->{in}->getline) {
+		$plugin->{accum}.=$_;
+		while ($plugin->{accum} =~ /^\s*(<\?xml\s.*?<\/(?:methodCall|methodResponse)>)\n(.*)/s) {
+			$plugin->{accum}=$2;
+			my $r = RPC::XML::Parser->new->parse($1);
+			error("XML RPC parser failure: $r") unless ref $r;
+			if ($r->isa('RPC::XML::response')) {
+				my $value=$r->value;
+				if ($value->isa('RPC::XML::array')) {
+					return @{$value->value};
+				}
+				elsif ($value->isa('RPC::XML::struct')) {
+					return %{$value->value};
+				}
+				elsif ($value->isa('RPC::XML::fault')) {
+					die $value->string;
+				}
+				else {
+					return $value->value;
+				}
+			}
+
+			my $name=$r->name;
+			my @args=map { $_->value } @{$r->args};
+
+			# When dispatching a function, first look in 
+			# IkiWiki::RPC::XML. This allows overriding
+			# IkiWiki functions with RPC friendly versions.
+			my $ret;
+			if (exists $IkiWiki::RPC::XML::{$name}) {
+				$ret=$IkiWiki::RPC::XML::{$name}($plugin, @args);
+			}
+			elsif (exists $IkiWiki::{$name}) {
+				$ret=$IkiWiki::{$name}(@args);
+			}
+			else {
+				error("XML RPC call error, unknown function: $name");
+			}
+
+			my $string=eval { RPC::XML::response->new($ret)->as_string };
+			if ($@ && ref $ret) {
+				# One common reason for serialisation to
+				# fail is a complex return type that cannot
+				# be represented as an XML RPC response.
+				# Handle this case by just returning 1.
+				$string=eval { RPC::XML::response->new(1)->as_string };
+			}
+			if ($@) {
+				error("XML response serialisation failed: $@");
+			}
+			rpc_write($plugin->{out}, $string);
+		}
+	}
+
+	return undef;
+} #}}}
+
+package IkiWiki::RPC::XML;
+
+sub getvar ($$$) { #{{{
+	my $plugin=shift;
+	my $varname="IkiWiki::".shift;
+	my $key=shift;
+
+	no strict 'refs';
+	my $ret=$varname->{$key};
+	use strict 'refs';
+	return $ret;
+} #}}}
+
+sub setvar ($$$;@) { #{{{
+	my $plugin=shift;
+	my $varname="IkiWiki::".shift;
+	my $key=shift;
+
+	no strict 'refs';
+	my $ret=$varname->{$key}=@_;
+	use strict 'refs';
+	return $ret;
+} #}}}
+
+sub inject ($@) { #{{{
+	# Bind a given perl function name to a particular RPC request.
+	my $plugin=shift;
+	my %params=@_;
+
+	if (! exists $params{name} || ! exists $params{call}) {
+		die "inject needs name and call parameters";
+	}
+	my $sub = sub {
+		IkiWiki::Plugin::external::rpc_call($plugin, $params{call}, @_)
+	};
+	eval qq{*$params{name}=\$sub};
+	return 1;
+} #}}}
+
+sub hook ($@) { #{{{
+	# the call parameter is a function name to call, since XML RPC
+	# cannot pass a function reference
+	my $plugin=shift;
+	my %params=@_;
+
+	my $callback=$params{call};
+	delete $params{call};
+
+	IkiWiki::hook(%params, call => sub {
+		IkiWiki::Plugin::external::rpc_call($plugin, $callback, @_)
+	});
+} #}}}
+
+sub pagespec_match ($@) { #{{{
+	# convert pagespec_match's return object into a XML RPC boolean
+	my $plugin=shift;
+
+	return RPC::XML::boolean->new(0 + IkiWiki::pagespec_march(@_));
+} #}}}
+
+1