From 205bd19d3fa6b2f2bef717ac71aaa09667b0975e Mon Sep 17 00:00:00 2001
From: Justin Li <jli.justinli@gmail.com>
Date: Wed, 4 Feb 2015 12:43:09 -0500
Subject: [PATCH] Add forloop.parentloop as a reference to the parent loop

---
 lib/liquid/tags/for.rb                | 20 ++++++++++++--------
 test/integration/tags/for_tag_test.rb | 16 ++++++++++++++++
 2 files changed, 28 insertions(+), 8 deletions(-)

diff --git a/lib/liquid/tags/for.rb b/lib/liquid/tags/for.rb
index 31da9d6..33f12af 100644
--- a/lib/liquid/tags/for.rb
+++ b/lib/liquid/tags/for.rb
@@ -42,6 +42,7 @@ module Liquid
   #                   where 0 is the last item.
   # forloop.first:: Returns true if the item is the first item.
   # forloop.last:: Returns true if the item is the last item.
+  # forloop.parentloop:: Provides access to the parent loop, if present.
   #
   class For < Block
     Syntax = /\A(#{VariableSegment}+)\s+in\s+(#{QuotedFragment}+)\s*(reversed)?/o
@@ -98,18 +99,21 @@ module Liquid
       # Store our progress through the collection for the continue flag
       context.registers[:for][@name] = from + segment.length
 
+      parent_loop = context['forloop'.freeze]
+
       context.stack do
         segment.each_with_index do |item, index|
           context[@variable_name] = item
           context['forloop'.freeze] = {
-            'name'.freeze    => @name,
-            'length'.freeze  => length,
-            'index'.freeze   => index + 1,
-            'index0'.freeze  => index,
-            'rindex'.freeze  => length - index,
-            'rindex0'.freeze => length - index - 1,
-            'first'.freeze   => (index == 0),
-            'last'.freeze    => (index == length - 1)
+            'name'.freeze       => @name,
+            'length'.freeze     => length,
+            'index'.freeze      => index + 1,
+            'index0'.freeze     => index,
+            'rindex'.freeze     => length - index,
+            'rindex0'.freeze    => length - index - 1,
+            'first'.freeze      => (index == 0),
+            'last'.freeze       => (index == length - 1),
+            'parentloop'.freeze => parent_loop
           }
 
           result << @for_block.render(context)
diff --git a/test/integration/tags/for_tag_test.rb b/test/integration/tags/for_tag_test.rb
index 8ccc056..23752bb 100644
--- a/test/integration/tags/for_tag_test.rb
+++ b/test/integration/tags/for_tag_test.rb
@@ -298,6 +298,22 @@ HERE
                 'string' => "test string")
   end
 
+  def test_for_parentloop_references_parent_loop
+    assert_template_result('1.1 1.2 1.3 2.1 2.2 2.3 ',
+                           '{% for inner in outer %}{% for k in inner %}' +
+                           '{{ forloop.parentloop.index }}.{{ forloop.index }} ' +
+                           '{% endfor %}{% endfor %}',
+                           'outer' => [[1, 1, 1], [1, 1, 1]])
+  end
+
+  def test_for_parentloop_nil_when_not_present
+    assert_template_result('.1 .2 ',
+                           '{% for inner in outer %}' +
+                           '{{ forloop.parentloop.index }}.{{ forloop.index }} ' +
+                           '{% endfor %}',
+                           'outer' => [[1, 1, 1], [1, 1, 1]])
+  end
+
   def test_blank_string_not_iterable
     assert_template_result('', "{% for char in characters %}I WILL NOT BE OUTPUT{% endfor %}", 'characters' => '')
   end