diff.rb ignores insides of <pre> and <code> blocks - this is better than mangling them

lib/diff.rb

@@ -82,8 +82,13 @@ module Diff
         when :tag
           if end_of_tag? char
             cur += use_brackets ? ']' : '>'
+            case cur
+            when '<pre>' then mode = :pre
+            when '<code>' then mode = :code
+            else 
               out.push cur
               cur, mode  = '', :char
+            end
           else
             cur += char
           end
@@ -98,6 +103,22 @@ module Diff
           else
             cur += char
           end
+        when :pre
+          if end_of_tag?(char) and cur =~ %r!</pre$!
+            cur += '>'
+            out.push cur
+            cur, mode  = '', :char
+          else
+            cur += char
+          end
+        when :code
+          if end_of_tag?(char) and cur =~ %r!</code$!
+            cur += '>'
+            out.push cur
+            cur, mode  = '', :char
+          else
+            cur += char
+          end
         end
       end
       
@@ -437,13 +458,13 @@ module HTMLDiff
     include Diff::Utilities
 
     def diff(a, b)
-      a, b = html2list(explode(a)), html2list(explode(b))
+      a = html2list(explode(a))
+      b = html2list(explode(b))
       
       out = Builder.new(a, b)
+
       sequence_matcher = Diff::SequenceMatcher.new(a, b)
-
       sequence_matcher.get_opcodes.each {|opcode| out.do_op(opcode)}
-
       out.result
     end
   end