Fix some encoding issues within Diff::LCS::Hunk

lib/diff/lcs/hunk.rb

@@ -11,6 +11,7 @@ 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)
     @data_old = data_old
     @data_new = data_new
 
@@ -120,19 +121,19 @@ def old_diff
     # Calculate item number range. Old diff range is just like a context
     # diff range, except the ranges are on one line with the action between
     # them.
-    s = "#{context_range(:old)}#{op_act[block.op]}#{context_range(:new)}\n"
+    s = encode("#{context_range(:old)}#{op_act[block.op]}#{context_range(:new)}\n")
     # If removing anything, just print out all the remove lines in the hunk
     # which is just all the remove lines in the block.
-    @data_old[@start_old .. @end_old].each { |e| s << "< #{e}\n" } unless block.remove.empty?
-    s << "---\n" if block.op == "!"
-    @data_new[@start_new .. @end_new].each { |e| s << "> #{e}\n" } unless block.insert.empty?
+    @data_old[@start_old .. @end_old].each { |e| s << encode("< ") + e + encode("\n") } unless block.remove.empty?
+    s << encode("---\n") if block.op == "!"
+    @data_new[@start_new .. @end_new].each { |e| s << encode("> ") + e + encode("\n") } unless block.insert.empty?
     s
   end
   private :old_diff
 
   def unified_diff
     # Calculate item number range.
-    s = "@@ -#{unified_range(:old)} +#{unified_range(:new)} @@\n"
+    s = encode("@@ -#{unified_range(:old)} +#{unified_range(:new)} @@\n")
 
     # Outlist starts containing the hunk of the old file. Removing an item
     # just means putting a '-' in front of it. Inserting an item requires
@@ -145,54 +146,54 @@ def unified_diff
     # 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| e.gsub(/^/, ' ') }
+    outlist = @data_old[lo .. hi].collect { |e| match_encoding_gsub(e,'^', ' ') }
 
     @blocks.each do |block|
       block.remove.each do |item|
         op = item.action.to_s # -
         offset = item.position - lo + num_added
-        outlist[offset].gsub!(/^ /, op.to_s)
+        match_encoding_gsub!(outlist[offset],'^ ', op.to_s)
         num_removed += 1
       end
       block.insert.each do |item|
         op = item.action.to_s # +
         offset = item.position - @start_new + num_removed
-        outlist[offset, 0] = "#{op}#{@data_new[item.position]}"
+        outlist[offset, 0] = encode(op) + @data_new[item.position]
         num_added += 1
       end
     end
 
-    s << outlist.join("\n")
+    s << outlist.join(encode("\n"))
   end
   private :unified_diff
 
   def context_diff
-    s = "***************\n"
-    s << "*** #{context_range(:old)} ****\n"
+    s = encode("***************\n")
+    s << encode("*** #{context_range(:old)} ****\n")
     r = context_range(:new)
 
     # Print out file 1 part for each block in context diff format if there
     # are any blocks that remove items
     lo, hi = @start_old, @end_old
     removes = @blocks.select { |e| not e.remove.empty? }
     if removes
-      outlist = @data_old[lo .. hi].collect { |e| e.gsub(/^/, '  ') }
+      outlist = @data_old[lo .. hi].collect { |e| match_encoding_gsub(e,'^', ' ') }
       removes.each do |block|
         block.remove.each do |item|
-          outlist[item.position - lo].gsub!(/^ /) { block.op } # - or !
+          match_encoding_gsub!( outlist[item.position - lo], '^ ') { block.op } # - or !
         end
       end
       s << outlist.join("\n")
     end
 
-    s << "\n--- #{r} ----\n"
+    s << encode("\n--- #{r} ----\n")
     lo, hi = @start_new, @end_new
     inserts = @blocks.select { |e| not e.insert.empty? }
     if inserts
-      outlist = @data_new[lo .. hi].collect { |e| e.gsub(/^/, '  ') }
+      outlist = @data_new[lo .. hi].collect { |e| match_encoding_gsub(e,'^', '  ') }
       inserts.each do |block|
         block.insert.each do |item|
-          outlist[item.position - lo].gsub!(/^ /) { block.op } # + or !
+          match_encoding_gsub!( outlist[item.position - lo], '^ ') { block.op } # + or !
         end
       end
       s << outlist.join("\n")
@@ -206,14 +207,14 @@ def ed_diff(format)
     warn "Expecting only one block in an old diff hunk!" if @blocks.size > 1
 
     if format == :reverse_ed
-      s = "#{op_act[@blocks[0].op]}#{context_range(:old)}\n"
+      s = encode("#{op_act[@blocks[0].op]}#{context_range(:old)}\n")
     else
-      s = "#{context_range(:old).gsub(/,/, ' ')}#{op_act[@blocks[0].op]}\n"
+      s = encode("#{match_encoding_gsub(context_range(:old), ',', ' ')}#{op_act[@blocks[0].op]}\n")
     end
 
     unless @blocks[0].insert.empty?
-      @data_new[@start_new .. @end_new].each { |e| s << "#{e}\n" }
-      s << ".\n"
+      @data_new[@start_new .. @end_new].each { |e| s << e + encode("\n") }
+      s << encode(".\n")
     end
     s
   end
@@ -249,4 +250,35 @@ def unified_range(mode)
     (length == 1) ? "#{first}" : "#{first},#{length}"
   end
   private :unified_range
+
+  if String.method_defined?(:encoding)
+    def encode(literal)
+      literal.encode @preferred_data_encoding
+    end
+
+    def encode_to(string, args)
+      args.map { |arg| arg.encode(string.encoding) }
+    end
+  else
+    def encode(literal)
+      literal
+    end
+    def encode_to(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!
+
 end

spec/hunk_spec.rb

@@ -0,0 +1,59 @@
+# -*- ruby encoding: utf-8 -*-
+
+require 'spec_helper'
+
+describe "Diff::LCS::Hunk" do
+
+  if String.method_defined?(:encoding)
+
+    let(:old_data) { ["Tu avec carté {count} itém has".encode('UTF-16LE')] }
+    let(:new_data) { ["Tu avec carte {count} item has".encode('UTF-16LE')] }
+    let(:peices)   { Diff::LCS.diff old_data, new_data }
+    let(:hunk)     { Diff::LCS::Hunk.new(old_data, new_data, peices[0], 3, 0) }
+
+    it 'should be able to produce a unified diff from the two peices' do
+      expected =
+(<<-EOD.encode('UTF-16LE').chomp)
+@@ -1,2 +1,2 @@
+Tu avec carté {count} itém has
++Tu avec carte {count} item has
+EOD
+      expect(hunk.diff(:unified).to_s == expected).to eql true
+    end
+
+    it 'should be able to produce a context diff from the two peices' do
+      expected =
+(<<-EOD.encode('UTF-16LE').chomp)
+***************
+*** 1,2 ****
+Tu avec carté {count} itém has
+--- 1,2 ----
+Tu avec carte {count} item has
+EOD
+      expect(hunk.diff(:context).to_s == expected).to eql true
+    end
+
+    it 'should be able to produce an old diff from the two peices' do
+      expected =
+(<<-EOD.encode('UTF-16LE').chomp)
+1,2c1,2
+< Tu avec carté {count} itém has
+---
+> Tu avec carte {count} item has
+
+EOD
+      expect(hunk.diff(:old).to_s == expected).to eql true
+    end
+
+    it 'should be able to produce a reverse ed diff from the two peices' do
+      expected =
+(<<-EOD.encode('UTF-16LE').chomp)
+c1,2
+Tu avec carte {count} item has
+.
+
+EOD
+      expect(hunk.diff(:reverse_ed).to_s == expected).to eql true
+    end
+  end
+end