Merge pull request #56 from oozou/for-else

For-else !!!

lib/liquid/tags/for.rb

@@ -13,6 +13,8 @@ module Liquid
   #      <div {% if forloop.first %}class="first"{% endif %}>
   #        Item {{ forloop.index }}: {{ item.name }}
   #      </div>
+  #    {% else %}
+  #      There is nothing in the collection.
   #    {% endfor %}
   #
   # You can also define a limit and offset much like SQL.  Remember
@@ -58,16 +60,22 @@ module Liquid
         raise SyntaxError.new("Syntax Error in 'for loop' - Valid syntax: for [item] in [collection]")
       end
 
+      @nodelist = @for_block = []
       super
     end
 
+    def unknown_tag(tag, markup, tokens)
+      return super unless tag == 'else'
+      @nodelist = @else_block = []
+    end
+  
     def render(context)        
       context.registers[:for] ||= Hash.new(0)
     
       collection = context[@collection_name]
       collection = collection.to_a if collection.is_a?(Range)
     
-      return '' unless collection.respond_to?(:each) 
+      return render_else(context) unless collection.respond_to?(:each) 
                                                  
       from = if @attributes['offset'] == 'continue'
         context.registers[:for][@name].to_i
@@ -81,7 +89,7 @@ module Liquid
                        
       segment = slice_collection_using_each(collection, from, to)      
       
-      return '' if segment.empty?
+      return render_else(context) if segment.empty?
       
       segment.reverse! if @reversed
 
@@ -105,7 +113,7 @@ module Liquid
             'first'   => (index == 0),
             'last'    => (index == length - 1) }
 
-          result << render_all(@nodelist, context)
+          result << render_all(@for_block, context)
         end
       end
       result     
@@ -130,6 +138,13 @@ module Liquid
 
       segments
     end
+
+    private
+
+      def render_else(context)
+        return @else_block ? [render_all(@else_block, context)] : ''
+      end
+
   end
 
   Template.register_tag('for', For)

test/lib/liquid/tags/standard_tag_test.rb

@@ -102,6 +102,12 @@ HERE
                            assigns)
   end
 
+  def test_for_else
+    assert_template_result('+++', '{%for item in array%}+{%else%}-{%endfor%}', 'array'=>[1,2,3])
+    assert_template_result('-',   '{%for item in array%}+{%else%}-{%endfor%}', 'array'=>[])
+    assert_template_result('-',   '{%for item in array%}+{%else%}-{%endfor%}', 'array'=>nil)
+  end
+
   def test_limiting
     assigns = {'array' => [1,2,3,4,5,6,7,8,9,0]}
     assert_template_result('12', '{%for i in array limit:2 %}{{ i }}{%endfor%}', assigns)