Check whether blocks are called from erb using a special __in_erb_template variable visible in block binding.

6 files changed, 62 insertions, 39 deletions

diff --git a/actionpack/lib/action_view/helpers/capture_helper.rb b/actionpack/lib/action_view/helpers/capture_helper.rb
index 9cd9d3d06a..990c30b90d 100644
--- a/actionpack/lib/action_view/helpers/capture_helper.rb
+++ b/actionpack/lib/action_view/helpers/capture_helper.rb
@@ -31,10 +31,13 @@ module ActionView
       #   </body></html>
       #
       def capture(*args, &block)
-        if output_buffer
+        # Return captured buffer in erb.
+        if block_called_from_erb?(block)
           with_output_buffer { block.call(*args) }
+
+        # Return block result otherwise, but protect buffer also.
         else
-          block.call(*args)
+          with_output_buffer { return block.call(*args) }
         end
       end
 
@@ -117,6 +120,7 @@ module ActionView
         ivar = "@content_for_#{name}"
         content = capture(&block) if block_given?
         instance_variable_set(ivar, "#{instance_variable_get(ivar)}#{content}")
+        nil
       end
 
       private
diff --git a/actionpack/lib/action_view/helpers/form_tag_helper.rb b/actionpack/lib/action_view/helpers/form_tag_helper.rb
index 3a97f1390f..ccebec3692 100644
--- a/actionpack/lib/action_view/helpers/form_tag_helper.rb
+++ b/actionpack/lib/action_view/helpers/form_tag_helper.rb
@@ -6,7 +6,7 @@ module ActionView
     # Provides a number of methods for creating form tags that doesn't rely on an Active Record object assigned to the template like
     # FormHelper does. Instead, you provide the names and values manually.
     #
-    # NOTE: The HTML options <tt>disabled</tt>, <tt>readonly</tt>, and <tt>multiple</tt> can all be treated as booleans. So specifying 
+    # NOTE: The HTML options <tt>disabled</tt>, <tt>readonly</tt>, and <tt>multiple</tt> can all be treated as booleans. So specifying
     # <tt>:disabled => true</tt> will give <tt>disabled="disabled"</tt>.
     module FormTagHelper
       # Starts a form tag that points the action to an url configured with <tt>url_for_options</tt> just like
@@ -20,15 +20,15 @@ module ActionView
       # * A list of parameters to feed to the URL the form will be posted to.
       #
       # ==== Examples
-      #   form_tag('/posts')                      
+      #   form_tag('/posts')
       #   # => <form action="/posts" method="post">
       #
-      #   form_tag('/posts/1', :method => :put)   
+      #   form_tag('/posts/1', :method => :put)
       #   # => <form action="/posts/1" method="put">
       #
-      #   form_tag('/upload', :multipart => true) 
+      #   form_tag('/upload', :multipart => true)
       #   # => <form action="/upload" method="post" enctype="multipart/form-data">
-      # 
+      #
       #   <% form_tag '/posts' do -%>
       #     <div><%= submit_tag 'Save' %></div>
       #   <% end -%>
@@ -88,7 +88,7 @@ module ActionView
       # * <tt>:size</tt> - The number of visible characters that will fit in the input.
       # * <tt>:maxlength</tt> - The maximum number of characters that the browser will allow the user to enter.
       # * Any other key creates standard HTML attributes for the tag.
-      # 
+      #
       # ==== Examples
       #   text_field_tag 'name'
       #   # => <input id="name" name="name" type="text" />
@@ -146,13 +146,13 @@ module ActionView
       #   # => <input id="token" name="token" type="hidden" value="VUBJKB23UIVI1UU1VOBVI@" />
       #
       #   hidden_field_tag 'collected_input', '', :onchange => "alert('Input collected!')"
-      #   # => <input id="collected_input" name="collected_input" onchange="alert('Input collected!')" 
+      #   # => <input id="collected_input" name="collected_input" onchange="alert('Input collected!')"
       #   #    type="hidden" value="" />
       def hidden_field_tag(name, value = nil, options = {})
         text_field_tag(name, value, options.stringify_keys.update("type" => "hidden"))
       end
 
-      # Creates a file upload field.  If you are using file uploads then you will also need 
+      # Creates a file upload field.  If you are using file uploads then you will also need
       # to set the multipart option for the form tag:
       #
       #   <%= form_tag { :action => "post" }, { :multipart => true } %>
@@ -160,7 +160,7 @@ module ActionView
       #     <%= submit_tag %>
       #   <%= end_form_tag %>
       #
-      # The specified URL will then be passed a File object containing the selected file, or if the field 
+      # The specified URL will then be passed a File object containing the selected file, or if the field
       # was left blank, a StringIO object.
       #
       # ==== Options
@@ -181,7 +181,7 @@ module ActionView
       #   # => <input id="resume" name="resume" type="file" value="~/resume.doc" />
       #
       #   file_field_tag 'user_pic', :accept => 'image/png,image/gif,image/jpeg'
-      #   # => <input accept="image/png,image/gif,image/jpeg" id="user_pic" name="user_pic" type="file" /> 
+      #   # => <input accept="image/png,image/gif,image/jpeg" id="user_pic" name="user_pic" type="file" />
       #
       #   file_field_tag 'file', :accept => 'text/html', :class => 'upload', :value => 'index.html'
       #   # => <input accept="text/html" class="upload" id="file" name="file" type="file" value="index.html" />
@@ -286,7 +286,7 @@ module ActionView
         tag :input, html_options
       end
 
-      # Creates a radio button; use groups of radio buttons named the same to allow users to 
+      # Creates a radio button; use groups of radio buttons named the same to allow users to
       # select from a group of options.
       #
       # ==== Options
@@ -313,14 +313,14 @@ module ActionView
         tag :input, html_options
       end
 
-      # Creates a submit button with the text <tt>value</tt> as the caption. 
+      # Creates a submit button with the text <tt>value</tt> as the caption.
       #
       # ==== Options
       # * <tt>:confirm => 'question?'</tt> - This will add a JavaScript confirm
       #   prompt with the question specified. If the user accepts, the form is
       #   processed normally, otherwise no action is taken.
       # * <tt>:disabled</tt> - If true, the user will not be able to use this input.
-      # * <tt>:disable_with</tt> - Value of this parameter will be used as the value for a disabled version 
+      # * <tt>:disable_with</tt> - Value of this parameter will be used as the value for a disabled version
       #   of the submit button when the form is submitted.
       # * Any other key creates standard HTML options for the tag.
       #
@@ -335,7 +335,7 @@ module ActionView
       #   # => <input disabled="disabled" name="commit" type="submit" value="Save edits" />
       #
       #   submit_tag "Complete sale", :disable_with => "Please wait..."
-      #   # => <input name="commit" onclick="this.disabled=true;this.value='Please wait...';this.form.submit();" 
+      #   # => <input name="commit" onclick="this.disabled=true;this.value='Please wait...';this.form.submit();"
       #   #    type="submit" value="Complete sale" />
       #
       #   submit_tag nil, :class => "form_submit"
@@ -346,7 +346,7 @@ module ActionView
       #   #    name="commit" type="submit" value="Edit" />
       def submit_tag(value = "Save changes", options = {})
         options.stringify_keys!
-        
+
         if disable_with = options.delete("disable_with")
           options["onclick"] = [
             "this.setAttribute('originalValue', this.value)",
@@ -358,15 +358,15 @@ module ActionView
             "return result;",
           ].join(";")
         end
-        
+
         if confirm = options.delete("confirm")
           options["onclick"] ||= ''
           options["onclick"] += "return #{confirm_javascript_function(confirm)};"
         end
-        
+
         tag :input, { "type" => "submit", "name" => "commit", "value" => value }.update(options.stringify_keys)
       end
-      
+
       # Displays an image which when clicked will submit the form.
       #
       # <tt>source</tt> is passed to AssetTagHelper#image_path
@@ -412,7 +412,7 @@ module ActionView
         concat(content)
         concat("</fieldset>")
       end
-      
+
       private
         def html_options_for_form(url_for_options, options, *parameters_for_url)
           returning options.stringify_keys do |html_options|
@@ -420,7 +420,7 @@ module ActionView
             html_options["action"]  = url_for(url_for_options, *parameters_for_url)
           end
         end
-        
+
         def extra_tags_for_form(html_options)
           case method = html_options.delete("method").to_s
             when /^get$/i # must be case-insentive, but can't use downcase as might be nil
@@ -434,12 +434,12 @@ module ActionView
               content_tag(:div, tag(:input, :type => "hidden", :name => "_method", :value => method) + token_tag, :style => 'margin:0;padding:0')
           end
         end
-        
+
         def form_tag_html(html_options)
           extra_tags = extra_tags_for_form(html_options)
           tag(:form, html_options, true) + extra_tags
         end
-        
+
         def form_tag_in_block(html_options, &block)
           content = capture(&block)
           concat(form_tag_html(html_options))
diff --git a/actionpack/lib/action_view/helpers/tag_helper.rb b/actionpack/lib/action_view/helpers/tag_helper.rb
index e1abec1847..649ec87a24 100644
--- a/actionpack/lib/action_view/helpers/tag_helper.rb
+++ b/actionpack/lib/action_view/helpers/tag_helper.rb
@@ -12,14 +12,14 @@ module ActionView
       BOOLEAN_ATTRIBUTES = %w(disabled readonly multiple).to_set
       BOOLEAN_ATTRIBUTES.merge(BOOLEAN_ATTRIBUTES.map(&:to_sym))
 
-      # Returns an empty HTML tag of type +name+ which by default is XHTML 
-      # compliant. Set +open+ to true to create an open tag compatible 
-      # with HTML 4.0 and below. Add HTML attributes by passing an attributes 
+      # Returns an empty HTML tag of type +name+ which by default is XHTML
+      # compliant. Set +open+ to true to create an open tag compatible
+      # with HTML 4.0 and below. Add HTML attributes by passing an attributes
       # hash to +options+. Set +escape+ to false to disable attribute value
       # escaping.
       #
       # ==== Options
-      # The +options+ hash is used with attributes with no value like (<tt>disabled</tt> and 
+      # The +options+ hash is used with attributes with no value like (<tt>disabled</tt> and
       # <tt>readonly</tt>), which you can give a value of true in the +options+ hash. You can use
       # symbols or strings for the attribute names.
       #
@@ -30,7 +30,7 @@ module ActionView
       #   tag("br", nil, true)
       #   # => <br>
       #
-      #   tag("input", { :type => 'text', :disabled => true }) 
+      #   tag("input", { :type => 'text', :disabled => true })
       #   # => <input type="text" disabled="disabled" />
       #
       #   tag("img", { :src => "open & shut.png" })
@@ -43,13 +43,13 @@ module ActionView
       end
 
       # Returns an HTML block tag of type +name+ surrounding the +content+. Add
-      # HTML attributes by passing an attributes hash to +options+. 
+      # HTML attributes by passing an attributes hash to +options+.
       # Instead of passing the content as an argument, you can also use a block
       # in which case, you pass your +options+ as the second parameter.
       # Set escape to false to disable attribute value escaping.
       #
       # ==== Options
-      # The +options+ hash is used with attributes with no value like (<tt>disabled</tt> and 
+      # The +options+ hash is used with attributes with no value like (<tt>disabled</tt> and
       # <tt>readonly</tt>), which you can give a value of true in the +options+ hash. You can use
       # symbols or strings for the attribute names.
       #
@@ -68,7 +68,13 @@ module ActionView
       def content_tag(name, content_or_options_with_block = nil, options = nil, escape = true, &block)
         if block_given?
           options = content_or_options_with_block if content_or_options_with_block.is_a?(Hash)
-          concat(content_tag_string(name, capture(&block), options, escape))
+          content_tag = content_tag_string(name, capture(&block), options, escape)
+
+          if block_called_from_erb?(block)
+            concat(content_tag)
+          else
+            content_tag
+          end
         else
           content_tag_string(name, content_or_options_with_block, options, escape)
         end
@@ -102,6 +108,16 @@ module ActionView
       end
 
       private
+        BLOCK_CALLED_FROM_ERB = 'defined? __in_erb_template'
+
+        # Check whether we're called from an erb template.
+        # We'd return a string in any other case, but erb <%= ... %>
+        # can't take an <% end %> later on, so we have to use <% ... %>
+        # and implicitly concat.
+        def block_called_from_erb?(block)
+          eval(BLOCK_CALLED_FROM_ERB, block)
+        end
+
         def content_tag_string(name, content, options, escape = true)
           tag_options = tag_options(options, escape) if options
           "<#{name}#{tag_options}>#{content}</#{name}>"
diff --git a/actionpack/lib/action_view/helpers/text_helper.rb b/actionpack/lib/action_view/helpers/text_helper.rb
index a1a91f6b3d..d98c5bd0d5 100644
--- a/actionpack/lib/action_view/helpers/text_helper.rb
+++ b/actionpack/lib/action_view/helpers/text_helper.rb
@@ -30,11 +30,7 @@ module ActionView
           ActiveSupport::Deprecation.warn("The binding argument of #concat is no longer needed.  Please remove it from your views and helpers.")
         end
 
-        if output_buffer && string
-          output_buffer << string
-        else
-          string
-        end
+        output_buffer << string
       end
 
       if RUBY_VERSION < '1.9'
diff --git a/actionpack/lib/action_view/template_handlers/compilable.rb b/actionpack/lib/action_view/template_handlers/compilable.rb
index 1aef81ba1a..783456ab53 100644
--- a/actionpack/lib/action_view/template_handlers/compilable.rb
+++ b/actionpack/lib/action_view/template_handlers/compilable.rb
@@ -106,7 +106,13 @@ module ActionView
           locals_code << "#{key} = local_assigns[:#{key}]\n"
         end
 
-        "def #{render_symbol}(local_assigns)\nold_output_buffer = output_buffer;#{locals_code}#{body}\nensure\nself.output_buffer = old_output_buffer\nend"
+        <<-end_src
+          def #{render_symbol}(local_assigns)
+            old_output_buffer = output_buffer;#{locals_code}#{body}
+          ensure
+            self.output_buffer = old_output_buffer
+          end
+        end_src
       end
 
       # Return true if the given template was compiled for a superset of the keys in local_assigns
diff --git a/actionpack/lib/action_view/template_handlers/erb.rb b/actionpack/lib/action_view/template_handlers/erb.rb
index 0733b3e3c2..458416b6cb 100644
--- a/actionpack/lib/action_view/template_handlers/erb.rb
+++ b/actionpack/lib/action_view/template_handlers/erb.rb
@@ -48,7 +48,8 @@ module ActionView
       self.erb_trim_mode = '-'
 
       def compile(template)
-        ::ERB.new(template.source, nil, erb_trim_mode, '@output_buffer').src
+        src = ::ERB.new(template.source, nil, erb_trim_mode, '@output_buffer').src
+        "__in_erb_template=true;#{src}"
       end
 
       def cache_fragment(block, name = {}, options = nil) #:nodoc: