Finalizing encoding-aware diff fixes.

* Diff::LCS::Hunk could not properly generate a difference for
  comparison sets that are not US-ASCII-compatible because of the use of
  literal regular expressions and strings. Jon Rowe (JonRowe) found this
  in rspec/rspec-expectations#219 and provided a first pass
  implementation in diff-lcs#15. I've reworked it because of test
  failures in Rubinius when running in Ruby 1.9 mode. This coerces the
  added values to the encoding of the old dataset (as determined by the
  first piece of the old dataset).
  https://github.com/rspec/rspec-expectations/issues/219
  https://github.com/halostatue/diff-lcs/pull/15
* Adding Travis CI testing for Ruby 2.0.

1 files changed, 21 insertions, 29 deletions

diff --git a/lib/diff/lcs/hunk.rb b/lib/diff/lcs/hunk.rb
index bcd85d5..6c5ea6a 100644
--- a/lib/diff/lcs/hunk.rb
+++ b/lib/diff/lcs/hunk.rb
@@ -11,7 +11,9 @@ class Diff::LCS::Hunk
   def initialize(data_old, data_new, piece, flag_context, file_length_difference)
     # At first, a hunk will have just one Block in it
     @blocks = [ Diff::LCS::Block.new(piece) ]
-    @preferred_data_encoding = data_old[0].encoding if String.method_defined?(:encoding)
+    if String.method_defined?(:encoding)
+      @preferred_data_encoding = data_old[0].encoding
+    end
     @data_old = data_old
     @data_new = data_new
 
@@ -146,17 +148,17 @@ class Diff::LCS::Hunk
     # file -- don't take removed items into account.
     lo, hi, num_added, num_removed = @start_old, @end_old, 0, 0
 
-    outlist = @data_old[lo .. hi].collect { |e| match_encoding_gsub(e,'^', ' ') }
+    outlist = @data_old[lo .. hi].map { |e| e.insert(0, encode(' ')) }
 
     @blocks.each do |block|
       block.remove.each do |item|
-        op = item.action.to_s # -
+        op     = item.action.to_s # -
         offset = item.position - lo + num_added
-        match_encoding_gsub!(outlist[offset],'^ ', op.to_s)
+        outlist[offset][0, 1] = encode(op)
         num_removed += 1
       end
       block.insert.each do |item|
-        op = item.action.to_s # +
+        op     = item.action.to_s # +
         offset = item.position - @start_new + num_removed
         outlist[offset, 0] = encode(op) + @data_new[item.position]
         num_added += 1
@@ -177,10 +179,11 @@ class Diff::LCS::Hunk
     lo, hi = @start_old, @end_old
     removes = @blocks.select { |e| not e.remove.empty? }
     if removes
-      outlist = @data_old[lo .. hi].collect { |e| match_encoding_gsub(e,'^', ' ') }
+      outlist = @data_old[lo .. hi].map { |e| e.insert(0, encode(' ')) }
+
       removes.each do |block|
         block.remove.each do |item|
-          match_encoding_gsub!( outlist[item.position - lo], '^ ') { block.op } # - or !
+          outlist[item.position - lo][0, 1] = encode(block.op) # - or !
         end
       end
       s << outlist.join("\n")
@@ -190,10 +193,10 @@ class Diff::LCS::Hunk
     lo, hi = @start_new, @end_new
     inserts = @blocks.select { |e| not e.insert.empty? }
     if inserts
-      outlist = @data_new[lo .. hi].collect { |e| match_encoding_gsub(e,'^', '  ') }
+      outlist = @data_new[lo .. hi].collect { |e| e.insert(0, encode(' ')) }
       inserts.each do |block|
         block.insert.each do |item|
-          match_encoding_gsub!( outlist[item.position - lo], '^ ') { block.op } # + or !
+          outlist[item.position - lo][0, 1] = encode(block.op) # + or !
         end
       end
       s << outlist.join("\n")
@@ -209,7 +212,7 @@ class Diff::LCS::Hunk
     if format == :reverse_ed
       s = encode("#{op_act[@blocks[0].op]}#{context_range(:old)}\n")
     else
-      s = encode("#{match_encoding_gsub(context_range(:old), ',', ' ')}#{op_act[@blocks[0].op]}\n")
+      s = encode("#{context_range(:old, ' ')}#{op_act[@blocks[0].op]}\n")
     end
 
     unless @blocks[0].insert.empty?
@@ -222,7 +225,7 @@ class Diff::LCS::Hunk
 
   # Generate a range of item numbers to print. Only print 1 number if the
   # range has only one item in it. Otherwise, it's 'start,end'
-  def context_range(mode)
+  def context_range(mode, op = ',')
     case mode
     when :old
       s, e = (@start_old + 1), (@end_old + 1)
@@ -230,7 +233,7 @@ class Diff::LCS::Hunk
       s, e = (@start_new + 1), (@end_new + 1)
     end
 
-    (s < e) ? "#{s},#{e}" : "#{e}"
+    (s < e) ? "#{s}#{op}#{e}" : "#{e}"
   end
   private :context_range
 
@@ -252,33 +255,22 @@ class Diff::LCS::Hunk
   private :unified_range
 
   if String.method_defined?(:encoding)
-    def encode(literal)
-      literal.encode @preferred_data_encoding
+    def encode(literal, target_encoding = @preferred_data_encoding)
+      literal.encode target_encoding
     end
 
-    def encode_to(string, args)
+    def encode_as(string, *args)
       args.map { |arg| arg.encode(string.encoding) }
     end
   else
-    def encode(literal)
+    def encode(literal, target_encoding = nil)
       literal
     end
-    def encode_to(string, args)
+    def encode_as(string, *args)
       args
     end
   end
 
   private :encode
-  private :encode_to
-
-  def match_encoding_gsub(string, *args, &block)
-    string.gsub(*encode_to(string,args), &block)
-  end
-  private :match_encoding_gsub
-
-  def match_encoding_gsub!(string, *args, &block)
-    string.gsub!(*encode_to(string,args), &block)
-  end
-  private :match_encoding_gsub!
-
+  private :encode_as
 end