From 0a04fa7bd38c8f491b429dc7d8578735ca7ca3f4 Mon Sep 17 00:00:00 2001
From: Eric Wong <e@80x24.org>
Date: Mon, 21 Jan 2019 03:19:20 +0000
Subject: highlight: initial wrapper and PSGI service

I'll probably expose the PSGI service for cgit;
but it could be useful to others as well.
---
 lib/PublicInbox/HlMod.pm | 126 +++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 126 insertions(+)
 create mode 100644 lib/PublicInbox/HlMod.pm

(limited to 'lib/PublicInbox/HlMod.pm')

diff --git a/lib/PublicInbox/HlMod.pm b/lib/PublicInbox/HlMod.pm
new file mode 100644
index 00000000..5cbfb298
--- /dev/null
+++ b/lib/PublicInbox/HlMod.pm
@@ -0,0 +1,126 @@
+# Copyright (C) 2019 all contributors <meta@public-inbox.org>
+# License: AGPL-3.0+ <https://www.gnu.org/licenses/agpl-3.0.txt>
+
+# I have no idea how stable or safe this is for handling untrusted
+# input, but it seems to have been around for a while, and the
+# highlight(1) executable is supported by gitweb and cgit.
+#
+# I'm also unsure about API stability, but highlight 3.x seems to
+# have been around a few years and ikiwiki (apparently the only
+# user of the SWIG/Perl bindings, at least in Debian) hasn't needed
+# major changes to support it in recent years.
+#
+# Some code stolen from ikiwiki (GPL-2.0+)
+# wrapper for SWIG-generated highlight.pm bindings
+package PublicInbox::HlMod;
+use strict;
+use warnings;
+use highlight; # SWIG-generated stuff
+
+sub _parse_filetypes ($) {
+	my $ft_conf = $_[0]->searchFile('filetypes.conf') or
+				die 'filetypes.conf not found by highlight';
+	open my $fh, '<', $ft_conf or die "failed to open($ft_conf): $!";
+	local $/;
+	my $cfg = <$fh>;
+	my %ext2lang;
+	my @shebang; # order matters
+
+	# Hrm... why isn't this exposed by the highlight API?
+	# highlight >= 3.2 format (bind-style) (from ikiwiki)
+	while ($cfg =~ /\bLang\s*=\s*\"([^"]+)\"[,\s]+
+			 Extensions\s*=\s*{([^}]+)}/sgx) {
+		my $lang = $1;
+		foreach my $bit (split(/,/, $2)) {
+			$bit =~ s/.*"(.*)".*/$1/s;
+			$ext2lang{$bit} = $lang;
+		}
+	}
+	# AFAIK, all the regexps used by in filetypes.conf distributed
+	# by highlight work as Perl REs
+	while ($cfg =~ /\bLang\s*=\s*\"([^"]+)\"[,\s]+
+			Shebang\s*=\s*\[\s*\[([^}]+)\s*\]\s*\]\s*}\s*,/sgx) {
+		my ($lang, $re) = ($1, $2);
+		eval {
+			my $perl_re = qr/$re/;
+			push @shebang, [ $lang, $perl_re ];
+		};
+		if ($@) {
+			warn "$lang shebang=[[$re]] did not work in Perl: $@";
+		}
+	}
+	(\%ext2lang, \@shebang);
+}
+
+sub new {
+	my ($class) = @_;
+	my $dir = highlight::DataDir->new;
+	$dir->initSearchDirectories('');
+	my ($ext2lang, $shebang) = _parse_filetypes($dir);
+	bless {
+		-dir => $dir,
+		-ext2lang => $ext2lang,
+		-shebang => $shebang,
+	}, $class;
+}
+
+sub _shebang2lang ($$) {
+	my ($self, $str) = @_;
+	my $shebang = $self->{-shebang};
+	foreach my $s (@$shebang) {
+		return $s->[0] if $$str =~ $s->[1];
+	}
+	undef;
+}
+
+sub _path2lang ($$) {
+	my ($self, $path) = @_;
+	my ($ext) = ($path =~ m!([^\\/\.]+)\z!);
+	$ext = lc($ext);
+	$self->{-ext2lang}->{$ext} || $ext;
+}
+
+sub do_hl {
+	my ($self, $str, $path) = @_;
+	my $lang = _path2lang($self, $path) if defined $path;
+	my $dir = $self->{-dir};
+	my $langpath;
+	if (defined $lang) {
+		$langpath = $dir->getLangPath("$lang.lang") or return;
+		$langpath = undef unless -f $langpath;
+	}
+	unless (defined $langpath) {
+		$lang = _shebang2lang($self, $str) or return;
+		$langpath = $dir->getLangPath("$lang.lang") or return;
+		$langpath = undef unless -f $langpath;
+	}
+	return unless defined $langpath;
+
+	my $gen = $self->{$langpath} ||= do {
+		my $g = highlight::CodeGenerator::getInstance($highlight::HTML);
+		$g->setFragmentCode(1); # generate html fragment
+		$g->setHTMLEnclosePreTag(1); # include <pre>
+
+		# whatever theme works
+		my $themepath = $dir->getThemePath('print.theme');
+		$g->initTheme($themepath);
+		$g->loadLanguage($langpath);
+		$g->setEncoding('utf-8');
+		$g;
+	};
+	\($gen->generateString($$str))
+}
+
+# SWIG instances aren't reference-counted, but $self is;
+# so we need to delete all the CodeGenerator instances manually
+# at our own destruction
+sub DESTROY {
+	my ($self) = @_;
+	foreach my $gen (values %$self) {
+		if (ref($gen) eq 'highlight::CodeGenerator') {
+			highlight::CodeGenerator::deleteInstance($gen);
+		}
+	}
+}
+
+1;
-- 
cgit v1.2.3-24-ge0c7