Merge pull request #9555 from tmm1/optimize-erb

Optimize generated ERB to reduce method calls

actionpack/lib/action_view/buffers.rb

@@ -8,9 +8,15 @@ def initialize(*)
     end
 
     def <<(value)
+      return self if value.nil?
       super(value.to_s)
     end
     alias :append= :<<
+
+    def safe_concat(value)
+      return self if value.nil?
+      super(value.to_s)
+    end
     alias :safe_append= :safe_concat
   end
 

actionpack/lib/action_view/template/handlers/erb.rb

@@ -6,12 +6,23 @@ class Template
     module Handlers
       class Erubis < ::Erubis::Eruby
         def add_preamble(src)
+          @newline_pending = 0
           src << "@output_buffer = output_buffer || ActionView::OutputBuffer.new;"
         end
 
         def add_text(src, text)
           return if text.empty?
-          src << "@output_buffer.safe_concat('" << escape_text(text) << "');"
+
+          if text == "\n"
+            @newline_pending += 1
+          else
+            src << "@output_buffer.safe_append='"
+            src << "\n" * @newline_pending if @newline_pending > 0
+            src << escape_text(text)
+            src << "';"
+
+            @newline_pending = 0
+          end
         end
 
         # Erubis toggles <%= and <%== behavior when escaping is enabled.
@@ -28,24 +39,39 @@ def add_expr(src, code, indicator)
         BLOCK_EXPR = /\s+(do|\{)(\s*\|[^|]*\|)?\s*\Z/
 
         def add_expr_literal(src, code)
+          flush_newline_if_pending(src)
           if code =~ BLOCK_EXPR
             src << '@output_buffer.append= ' << code
           else
-            src << '@output_buffer.append= (' << code << ');'
+            src << '@output_buffer.append=(' << code << ');'
           end
         end
 
         def add_expr_escaped(src, code)
+          flush_newline_if_pending(src)
           if code =~ BLOCK_EXPR
             src << "@output_buffer.safe_append= " << code
           else
-            src << "@output_buffer.safe_concat((" << code << ").to_s);"
+            src << "@output_buffer.safe_append=(" << code << ");"
           end
         end
 
+        def add_stmt(src, code)
+          flush_newline_if_pending(src)
+          super
+        end
+
         def add_postamble(src)
+          flush_newline_if_pending(src)
           src << '@output_buffer.to_s'
         end
+
+        def flush_newline_if_pending(src)
+          if @newline_pending > 0
+            src << "@output_buffer.safe_append='#{"\n" * @newline_pending}';"
+            @newline_pending = 0
+          end
+        end
       end
 
       class ERB