[Haml] [html2haml] Use Erubis and ruby_parser to figure out where ERB blocks start and end.

lib/haml/html.rb

@@ -122,8 +122,8 @@ module Haml
         Haml::Util.check_encoding(template) {|msg, line| raise Haml::Error.new(msg, line)}
 
         if @options[:erb]
-          match_to_html(template, /<%=(.*?)-?%>/m, 'loud')
-          match_to_html(template, /<%-?(.*?)-?%>/m,  'silent')
+          require 'haml/html/erb'
+          template = ERB.compile(template)
         end
 
         method = @options[:xhtml] ? Hpricot.method(:XML) : method(:Hpricot)
@@ -228,7 +228,15 @@ module Haml
 
         output = tabulate(tabs)
         if options[:erb] && name[0...5] == 'haml:'
-          return output + send("haml_tag_#{name[5..-1]}", CGI.unescapeHTML(self.inner_text))
+          case name[5..-1]
+          when "loud"
+            return output + "= #{CGI.unescapeHTML(inner_text).gsub(/\n\s*/, ' ').strip}\n"
+          when "silent"
+            return output + CGI.unescapeHTML(inner_text).split("\n").
+              map {|line| "- #{line.strip}\n"}.join
+          when "block"
+            return render_children("", tabs, options)
+          end
         end
 
         output << "%#{name}" unless name == 'div' &&
@@ -265,12 +273,16 @@ module Haml
           end
         end
 
-        (self.children || []).inject(output + "\n") do |output, child|
-          output + child.to_haml(tabs + 1, options)
-        end
+        render_children(output + "\n", tabs, options)
       end
 
       private
+
+      def render_children(so_far, tabs, options)
+        (self.children || []).inject(so_far) do |output, child|
+          output + child.to_haml(tabs + 1, options)
+        end
+      end
       
       def dynamic_attributes
         @dynamic_attributes ||= begin
@@ -305,14 +317,6 @@ module Haml
         "#{tabulate(tabs)}:javascript\n#{content}"
       end
 
-      def haml_tag_loud(text)
-        "= #{text.gsub(/\n\s*/, ' ').strip}\n"
-      end
-
-      def haml_tag_silent(text)
-        text.split("\n").map { |line| "- #{line.strip}\n" }.join
-      end
-
       def static_attribute?(name, options)
         attributes[name] and !dynamic_attribute?(name, options)
       end
@@ -340,13 +344,5 @@ module Haml
         "{#{attrs.join(', ')}}"
       end
     end
-
-    private
-
-    def match_to_html(string, regex, tag)
-      string.gsub!(regex) do
-        "<haml:#{tag}>#{CGI.escapeHTML($1)}</haml:#{tag}>"
-      end
-    end
   end
 end

lib/haml/html/erb.rb

@@ -0,0 +1,71 @@
+require 'cgi'
+require 'erubis'
+require 'ruby_parser'
+
+module Haml
+  class HTML
+    class ERB < Erubis::Basic::Engine
+      def self.compile(template)
+        new(template).src
+      end
+
+      def escaped_expr(code)
+        raise "html2haml doesn't support escaped expressions."
+      end
+
+      def add_preamble(src); end
+      def add_postamble(src); end
+
+      def add_text(src, text)
+        src << text
+      end
+
+      def add_stmt(src, code)
+        src << '</haml:block>' if block_closer?(code) || mid_block?(code)
+        src << '<haml:silent>' << h(code) << '</haml:silent>' unless code.strip == "end"
+        src << '<haml:block>' if block_opener?(code) || mid_block?(code)
+      end
+
+      def add_expr_literal(src, code)
+        src << '<haml:loud>' << h(code) << '</haml:loud>'
+        src << '<haml:block>' if block_opener?(code)
+      end
+
+      def add_expr_debug(src, code)
+        raise "html2haml doesn't support debugging expressions."
+      end
+
+      private
+
+      def h(code)
+        CGI.escapeHTML(code)
+      end
+
+      # Returns whether the code is valid Ruby code on its own
+      def valid_ruby?(code)
+        RubyParser.new.parse(code)
+      rescue Racc::ParseError => e
+        false
+      end
+
+      # Checks if the Ruby code opens a block
+      def block_opener?(code)
+        valid_ruby?(code + "\nend") ||
+          valid_ruby?(code + "\nwhen foo\nend")
+      end
+
+      # Checks if the Ruby code closes a block
+      def block_closer?(code)
+        valid_ruby?("begin\n" + code)
+      end
+
+      # Checks if the Ruby code comes in the middle of a block
+      def mid_block?(code)
+        return if valid_ruby?(code)
+        valid_ruby?("if foo\n#{code}\nend") || # else, elsif
+          valid_ruby?("begin\n#{code}\nend") || # rescue, ensure
+          valid_ruby?("case foo\n#{code}\nend") # when
+      end
+    end
+  end
+end