From 26dbc09bd88ba6c33c18995c2b028726c370012f Mon Sep 17 00:00:00 2001
From: Joey Hess <joey@gnu.kitenet.net>
Date: Sat, 3 Oct 2009 15:46:53 -0400
Subject: [PATCH] implement support for DEPEND_EXISTS

Preliminary support, anyway.

If a dependency only includes DEPEND_EXISTS, then only changes that
involved adding or deleting a page can trigger it.

This is complicated by internal pages, since the code did not previously
differentiate between add, delete, and change of internal pages.
Now it tracks change separately from add+delete, so DEPEND_EXISTS pagespecs
that actually match internal pages (which will probably be quite rare in
practice) should work.
---
 IkiWiki/Render.pm | 38 +++++++++++++++++++++++++++++++-------
 1 file changed, 31 insertions(+), 7 deletions(-)

diff --git a/IkiWiki/Render.pm b/IkiWiki/Render.pm
index 246c2260d..9e00428c2 100644
--- a/IkiWiki/Render.pm
+++ b/IkiWiki/Render.pm
@@ -342,7 +342,7 @@ sub refresh () {
 	run_hooks(refresh => sub { shift->() });
 	my ($files, $exists)=find_src_files();
 
-	my (%rendered, @add, @del, @internal);
+	my (%rendered, @add, @del, @internal, @internal_change);
 	# check for added or removed pages
 	foreach my $file (@$files) {
 		my $page=pagename($file);
@@ -407,7 +407,7 @@ sub refresh () {
 	    	    $forcerebuild{$page}) {
 			$pagemtime{$page}=$stat[9];
 			if (isinternal($page)) {
-				push @internal, $file;
+				push @internal_change, $file;
 				# Preprocess internal page in scan-only mode.
 				preprocess($page, $page, readfile($srcfile), 1);
 			}
@@ -429,7 +429,7 @@ sub refresh () {
 		render($file);
 		$rendered{$file}=1;
 	}
-	foreach my $file (@internal) {
+	foreach my $file (@internal, @internal_change) {
 		# internal pages are not rendered
 		my $page=pagename($file);
 		delete $depends{$page};
@@ -454,10 +454,12 @@ sub refresh () {
 		}
 	}
 
-	if (%rendered || @del || @internal) {
+	if (%rendered || @del || @internal || @internal_change) {
 		my @changed=(keys %rendered, @del);
+		my @exists_changed=(@add, @del);
 
- 		my %lcchanged = map { lc(pagename($_)) => 1 } @changed;
+		my %lc_changed = map { lc(pagename($_)) => 1 } @changed;
+		my %lc_exists_changed = map { lc(pagename($_)) => 1 } @exists_changed;
  
 		# rebuild dependant pages
 		foreach my $f (@$files) {
@@ -467,7 +469,13 @@ sub refresh () {
 
 			if (exists $depends_simple{$p}) {
 				foreach my $d (keys %{$depends_simple{$p}}) {
-					if (exists $lcchanged{$d}) {
+					if ($depends_simple{$p}{$d} == $IkiWiki::DEPEND_EXISTS) {
+						if (exists $lc_exists_changed{$d}) {
+							$reason = $d;
+							last;
+						}
+					}
+					elsif (exists $lc_changed{$d}) {
 						$reason = $d;
 						last;
 					}
@@ -479,10 +487,26 @@ sub refresh () {
 					my $sub=pagespec_translate($d);
 					next if $@ || ! defined $sub;
 
+					my @candidates;
+					if ($depends{$p}{$d} == $IkiWiki::DEPEND_EXISTS) {
+						@candidates=@exists_changed;
+					}
+					else {
+						@candidates=@changed;
+					}
 					# only consider internal files
 					# if the page explicitly depends
 					# on such files
-					foreach my $file (@changed, $d =~ /internal\(/ ? @internal : ()) {
+					if ($d =~ /internal\(/) {
+						if ($depends{$p}{$d} == $IkiWiki::DEPEND_EXISTS) {
+							push @candidates, @internal;
+						}
+						else {
+							push @candidates, @internal, @internal_change;
+						}
+					}
+
+					foreach my $file (@candidates) {
 						next if $file eq $f;
 						my $page=pagename($file);
 						if ($sub->($page, location => $p)) {
-- 
2.26.2