Add _is_first and _is_last to partial rendered by collection

actionpack/lib/action_view/renderer/partial_renderer.rb

@@ -340,7 +340,7 @@ def setup(context, options, block)
       end
 
       if @path
-        @variable, @variable_counter = retrieve_variable(@path)
+        @variable, @variable_counter, @variable_is_first, @variable_is_last = retrieve_variable(@path)
       else
         paths.map! { |path| retrieve_variable(path).unshift(path) }
       end
@@ -371,7 +371,11 @@ def find_partial
       if path = @path
         locals = @locals.keys
         locals << @variable
-        locals << @variable_counter if @collection
+        if @collection
+          locals << @variable_counter
+          locals << @variable_is_first
+          locals << @variable_is_last
+        end
         find_template(path, locals)
       end
     end
@@ -383,12 +387,14 @@ def find_template(path=@path, locals=@locals.keys)
 
     def collection_with_template
       segments, locals, template = [], @locals, @template
-      as, counter = @variable, @variable_counter
+      as, counter, is_first, is_last = @variable, @variable_counter, @variable_is_first, @variable_is_last
 
       locals[counter] = -1
 
       @collection.each do |object|
         locals[counter] += 1
+        locals[is_first] = locals[counter] == 0
+        locals[is_last] = locals[counter] == @collection.size-1
         locals[as] = object
         segments << template.render(@view, locals)
       end
@@ -445,8 +451,12 @@ def merge_prefix_into_object_path(prefix, object_path)
 
     def retrieve_variable(path)
       variable = @options[:as].try(:to_sym) || path[%r'_?(\w+)(\.\w+)*$', 1].to_sym
-      variable_counter = :"#{variable}_counter" if @collection
-      [variable, variable_counter]
+      if @collection
+        variable_counter = :"#{variable}_counter"
+        variable_is_first = :"#{variable}_is_first"
+        variable_is_last = :"#{variable}_is_last"
+      end
+      [variable, variable_counter, variable_is_first, variable_is_last]
     end
   end
 end

actionpack/test/controller/render_test.rb

@@ -612,6 +612,10 @@ def partial_collection_with_as_and_counter
     render :partial => "customer_counter_with_as", :collection => [ Customer.new("david"), Customer.new("mary") ], :as => :client
   end
 
+  def partial_collection_with_first_and_last
+    render :partial => "customer_first_last", :collection => [ Customer.new("david"), Customer.new("mary"), Customer.new("joseph") ]
+  end
+
   def partial_collection_with_locals
     render :partial => "customer_greeting", :collection => [ Customer.new("david"), Customer.new("mary") ], :locals => { :greeting => "Bonjour" }
   end

actionpack/test/fixtures/test/_customer_first_last.erb

@@ -0,0 +1 @@
+<%= customer_first_last.name %><%= customer_first_last_is_first %><%= customer_first_last_is_last %>

actionpack/test/template/render_test.rb

@@ -223,10 +223,15 @@ def test_render_partial_collection_as_by_symbol
   end
 
   def test_render_partial_collection_without_as
-    assert_equal "local_inspector,local_inspector_counter",
+    assert_equal "local_inspector,local_inspector_counter,local_inspector_is_first,local_inspector_is_last",
       @view.render(:partial => "test/local_inspector", :collection => [ Customer.new("mary") ])
   end
 
+  def test_render_partial_collection_with_first_and_last
+    assert_equal "davidtruefalsemaryfalsefalsejosephfalsetrue",
+      @view.render(:partial => "test/customer_first_last", :collection => [ Customer.new("david"), Customer.new("mary"), Customer.new("joseph") ])
+  end
+
   def test_render_partial_with_empty_collection_should_return_nil
     assert_nil @view.render(:partial => "test/customer", :collection => [])
   end