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From: Eric Wong <e@80x24.org>
To: spew@80x24.org
Subject: [PATCH] thread: avoid recursion
Date: Fri,  5 Aug 2016 00:24:18 +0000
Message-Id: <20160805002418.7274-1-e@80x24.org>
List-Id: <spew@80x24.org>

(bug reported to CPAN RT, awaiting bug #)
---
 lib/PublicInbox/Thread.pm | 25 +++++++++++++++++++++++++
 1 file changed, 25 insertions(+)

diff --git a/lib/PublicInbox/Thread.pm b/lib/PublicInbox/Thread.pm
index 44a565a..95627de 100644
--- a/lib/PublicInbox/Thread.pm
+++ b/lib/PublicInbox/Thread.pm
@@ -42,6 +42,31 @@ sub topmost {
 	$_[0]->SUPER::topmost || PublicInbox::Thread::CPANRTBug106498->new;
 }
 
+sub recurse_down {
+	my ($self, $callback) = @_;
+	my %seen;
+	my @q = ($self);
+	while (my $cont = shift @q) {
+		$seen{$cont}++;
+		$callback->($cont);
+
+		if (my $next = $cont->next) {
+			if ($seen{$next}) {
+				$cont->next(undef);
+			} else {
+				push @q, $next;
+			}
+		}
+		if (my $child = $cont->child) {
+			if ($seen{$child}) {
+				$cont->child(undef);
+			} else {
+				push @q, $child;
+			}
+		}
+	}
+}
+
 # ref:
 # - http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=795913
 # - https://rt.cpan.org/Ticket/Display.html?id=106498
-- 
EW