From a64a6f82eeec8650f5a536c108b682b7e6a81be2 Mon Sep 17 00:00:00 2001
From: Justin Hileman <justin@justinhileman.info>
Date: Fri, 27 Jul 2012 10:56:56 -0700
Subject: [PATCH] Handle broken pipes

---
 src/Mustache/Compiler.php                     |  6 +++--
 .../Test/FiveThree/Functional/FiltersTest.php | 22 +++++++++++++++++++
 2 files changed, 26 insertions(+), 2 deletions(-)

diff --git a/src/Mustache/Compiler.php b/src/Mustache/Compiler.php
index 7bc10b1..48d06ee 100644
--- a/src/Mustache/Compiler.php
+++ b/src/Mustache/Compiler.php
@@ -298,8 +298,10 @@ class Mustache_Compiler
     }
 
     const FILTER = '
-        $filter = $context->%s(%s);
-        $value = (is_string($filter) || !is_callable($filter)) ? "" : call_user_func($filter, $value);
+        if (!empty($value)) {
+            $filter = $context->%s(%s);
+            $value = (is_string($filter) || !is_callable($filter)) ? "" : call_user_func($filter, $value);
+        }
     ';
 
     /**
diff --git a/test/Mustache/Test/FiveThree/Functional/FiltersTest.php b/test/Mustache/Test/FiveThree/Functional/FiltersTest.php
index bc5b4de..ff2c7dd 100644
--- a/test/Mustache/Test/FiveThree/Functional/FiltersTest.php
+++ b/test/Mustache/Test/FiveThree/Functional/FiltersTest.php
@@ -50,4 +50,26 @@ class Mustache_Test_FiveThree_Functional_FiltersTest extends PHPUnit_Framework_T
 
         $this->assertEquals('[[2000-01-01 12:01:00]]', $tpl->render($foo));
     }
+
+    public function testBrokenPipe() {
+        $tpl = $this->mustache->loadTemplate('{{% FILTERS }}{{ foo | bar | baz }}');
+        $this->assertEquals('', $tpl->render(array(
+            'foo' => 'FOO',
+        )));
+
+        $this->assertEquals('', $tpl->render(array(
+            'foo' => 'FOO',
+            'bar' => function($value) { return 'BAR'; },
+        )));
+
+        $this->assertEquals('', $tpl->render(array(
+            'foo' => 'FOO',
+            'baz' => function($value) { return 'BAZ'; },
+        )));
+
+        $this->assertEquals('', $tpl->render(array(
+            'bar' => function($value) { return 'BAR'; },
+            'baz' => function($value) { return 'BAZ'; },
+        )));
+    }
 }