From ba6e3e3da62d0d5d654f163792554cf9da8c7e8e Mon Sep 17 00:00:00 2001
From: Tom Burns <tom.burns@jadedpixel.com>
Date: Mon, 28 Jul 2014 14:12:11 +0000
Subject: [PATCH 1/6] lazily create stacks

---
 lib/liquid.rb         |  1 +
 lib/liquid/context.rb | 17 +++++++++++++++--
 2 files changed, 16 insertions(+), 2 deletions(-)

diff --git a/lib/liquid.rb b/lib/liquid.rb
index bb81745..f196d3b 100644
--- a/lib/liquid.rb
+++ b/lib/liquid.rb
@@ -41,6 +41,7 @@ module Liquid
 
   singleton_class.send(:attr_accessor, :cache_classes)
   self.cache_classes = true
+
 end
 
 require "liquid/version"
diff --git a/lib/liquid/context.rb b/lib/liquid/context.rb
index faa3da2..b3bd776 100644
--- a/lib/liquid/context.rb
+++ b/lib/liquid/context.rb
@@ -27,6 +27,12 @@ module Liquid
       @parsed_variables = Hash.new{ |cache, markup| cache[markup] = variable_parse(markup) } 
       squash_instance_assigns_with_environments
 
+      @used_stacks = 0
+      @unused_stacks = 0
+      @max_stack_depth = 0
+      @this_stack_depth = 0
+      @this_stack_used = false
+
       if rethrow_errors
         self.exception_handler = ->(e) { true }
       end
@@ -134,10 +140,13 @@ module Liquid
     #
     #   context['var]  #=> nil
     def stack(new_scope={})
-      push(new_scope)
+      old_stack_used = @this_stack_used
+      @this_stack_used = (new_scope != {})
+      push(new_scope) if @this_stack_used
       yield
     ensure
-      pop
+      pop if @this_stack_used
+      @this_stack_used = old_stack_used
     end
 
     def clear_instance_assigns
@@ -146,6 +155,10 @@ module Liquid
 
     # Only allow String, Numeric, Hash, Array, Proc, Boolean or <tt>Liquid::Drop</tt>
     def []=(key, value)
+      if !@this_stack_used
+        @this_stack_used = true
+        push({})
+      end
       @scopes[0][key] = value
     end
 

From 6b56bdd74f08800116c34209bd354dc93e6618c8 Mon Sep 17 00:00:00 2001
From: Tom Burns <tom.burns@jadedpixel.com>
Date: Mon, 28 Jul 2014 14:23:16 +0000
Subject: [PATCH 2/6] remove variables used for counting empty stacks

---
 lib/liquid/context.rb | 4 ----
 1 file changed, 4 deletions(-)

diff --git a/lib/liquid/context.rb b/lib/liquid/context.rb
index b3bd776..94bd4f5 100644
--- a/lib/liquid/context.rb
+++ b/lib/liquid/context.rb
@@ -27,10 +27,6 @@ module Liquid
       @parsed_variables = Hash.new{ |cache, markup| cache[markup] = variable_parse(markup) } 
       squash_instance_assigns_with_environments
 
-      @used_stacks = 0
-      @unused_stacks = 0
-      @max_stack_depth = 0
-      @this_stack_depth = 0
       @this_stack_used = false
 
       if rethrow_errors

From f5e67a12f9a0a0d084fcf4943add4d27c2111a46 Mon Sep 17 00:00:00 2001
From: Tom Burns <tom.burns@jadedpixel.com>
Date: Mon, 28 Jul 2014 14:24:29 +0000
Subject: [PATCH 3/6] remove added newline in liquid.rb

---
 lib/liquid.rb | 1 -
 1 file changed, 1 deletion(-)

diff --git a/lib/liquid.rb b/lib/liquid.rb
index f196d3b..bb81745 100644
--- a/lib/liquid.rb
+++ b/lib/liquid.rb
@@ -41,7 +41,6 @@ module Liquid
 
   singleton_class.send(:attr_accessor, :cache_classes)
   self.cache_classes = true
-
 end
 
 require "liquid/version"

From e53d102a2c0c5659120b82ff813349cb4fac9263 Mon Sep 17 00:00:00 2001
From: Tom Burns <tom.burns@jadedpixel.com>
Date: Wed, 30 Jul 2014 14:59:56 +0000
Subject: [PATCH 4/6] use 'unless' instead of 'if !' for simple conditional

---
 lib/liquid/context.rb | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/lib/liquid/context.rb b/lib/liquid/context.rb
index 94bd4f5..6e8ceb8 100644
--- a/lib/liquid/context.rb
+++ b/lib/liquid/context.rb
@@ -151,7 +151,7 @@ module Liquid
 
     # Only allow String, Numeric, Hash, Array, Proc, Boolean or <tt>Liquid::Drop</tt>
     def []=(key, value)
-      if !@this_stack_used
+      unless @this_stack_used
         @this_stack_used = true
         push({})
       end

From 15f6cabf838cc4059837db6e450fb9c93d094d3b Mon Sep 17 00:00:00 2001
From: Tom Burns <tom.burns@jadedpixel.com>
Date: Wed, 30 Jul 2014 15:12:22 +0000
Subject: [PATCH 5/6] avoid a hash comparison

---
 lib/liquid/context.rb | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/lib/liquid/context.rb b/lib/liquid/context.rb
index 6e8ceb8..a075b26 100644
--- a/lib/liquid/context.rb
+++ b/lib/liquid/context.rb
@@ -135,9 +135,9 @@ module Liquid
     #   end
     #
     #   context['var]  #=> nil
-    def stack(new_scope={})
+    def stack(new_scope=nil)
       old_stack_used = @this_stack_used
-      @this_stack_used = (new_scope != {})
+      @this_stack_used = (new_scope != nil)
       push(new_scope) if @this_stack_used
       yield
     ensure

From 794ca9f604ec223c57b7f03b661dcf9930b02534 Mon Sep 17 00:00:00 2001
From: Tom Burns <tom.burns@jadedpixel.com>
Date: Wed, 30 Jul 2014 15:42:24 +0000
Subject: [PATCH 6/6] make the conditions around stack creation easier to read

---
 lib/liquid/context.rb | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/lib/liquid/context.rb b/lib/liquid/context.rb
index a075b26..efd74cb 100644
--- a/lib/liquid/context.rb
+++ b/lib/liquid/context.rb
@@ -137,8 +137,13 @@ module Liquid
     #   context['var]  #=> nil
     def stack(new_scope=nil)
       old_stack_used = @this_stack_used
-      @this_stack_used = (new_scope != nil)
-      push(new_scope) if @this_stack_used
+      if new_scope
+        push(new_scope)
+        @this_stack_used = true
+      else
+        @this_stack_used = false
+      end
+
       yield
     ensure
       pop if @this_stack_used