diff --git a/docdiff/view.rb b/docdiff/view.rb
index e15282b..c7ae9c1 100644
--- a/docdiff/view.rb
+++ b/docdiff/view.rb
@@ -99,22 +99,21 @@ class View
     d1l = doc1_line_number = 1
     d2l = doc2_line_number = 1
     @difference.each_with_index{|entry, i|
+      source = format_block(entry[1])
+      target = format_block(entry[2])
       if block_given?
-        source = yield entry[1].to_s
-        target = yield entry[2].to_s
-      else
-        source = entry[1].to_s
-        target = entry[2].to_s
+        source = yield source
+        target = yield target
       end
       if  i == 0
         context_pre  = ""  # no pre context for the first entry
       else
-        context_pre  = @difference[i-1][1].to_s.scan(context_pre_pat).to_s
+        context_pre  = format_block(@difference[i-1][1]).scan(context_pre_pat).to_s
       end
       if (i + 1) == @difference.size
         context_post = ""  # no post context for the last entry
       else
-        context_post = @difference[i+1][1].to_s.scan(context_post_pat).to_s
+        context_post = format_block(@difference[i+1][1]).scan(context_post_pat).to_s
       end
       # elements for an entry
       e_header       = Proc.new {|pos_str|