Use rugged for diffing

diffy.gemspec

@@ -18,6 +18,10 @@ Gem::Specification.new do |spec|
   spec.test_files    = spec.files.grep(%r{^(test|spec|features)/})
   spec.require_paths = ["lib"]
 
+  spec.required_ruby_version = ">= 2.0.0"
+
+  spec.add_dependency "rugged", "~> 1.7"
+
   spec.add_development_dependency "rake"
   spec.add_development_dependency "rspec"
 end

lib/diffy.rb

@@ -1,11 +1,7 @@
-require 'tempfile'
 require 'erb'
 require 'rbconfig'
+require 'rugged'
 
-module Diffy
-  WINDOWS = (RbConfig::CONFIG['host_os'] =~ /mswin|mingw|cygwin/)
-end
-require 'open3' unless Diffy::WINDOWS
 require File.join(File.dirname(__FILE__), 'diffy', 'format')
 require File.join(File.dirname(__FILE__), 'diffy', 'html_formatter')
 require File.join(File.dirname(__FILE__), 'diffy', 'diff')

lib/diffy/diff.rb

@@ -1,12 +1,12 @@
 module Diffy
   class Diff
     ORIGINAL_DEFAULT_OPTIONS = {
-      :diff => '-U10000',
       :source => 'strings',
       :include_diff_info => false,
       :include_plus_and_minus_in_html => false,
-      :context => nil,
+      :context => 10_000,
       :allow_empty_diff => true,
+      :rugged => {},
     }
 
     class << self
@@ -37,43 +37,30 @@ def initialize(string1, string2, options = {})
       if ! ['strings', 'files'].include?(@options[:source])
         raise ArgumentError, "Invalid :source option #{@options[:source].inspect}. Supported options are 'strings' and 'files'."
       end
+      @options[:rugged][:context_lines] = @options[:context] if @options[:rugged][:context_lines].nil?
       @string1, @string2 = string1, string2
+      @diff_empty = false
     end
 
     def diff
       @diff ||= begin
-        @paths = case options[:source]
+        case options[:source]
           when 'strings'
-            [tempfile(string1), tempfile(string2)]
+            diff = Rugged::Patch.from_strings(string1, string2, **options[:rugged]).to_s
           when 'files'
-            [string1, string2]
+            diff = Rugged::Patch.from_strings(File.read(string1), File.read(string2), **options[:rugged]).to_s
           end
 
-        diff, _stderr, _process_status = Open3.capture3(diff_bin, *(diff_options + @paths))
         diff.force_encoding('ASCII-8BIT') if diff.respond_to?(:valid_encoding?) && !diff.valid_encoding?
         if diff =~ /\A\s*\Z/ && !options[:allow_empty_diff]
+          @diff_empty = true
           diff = case options[:source]
           when 'strings' then string1
           when 'files' then File.read(string1)
           end.gsub(/^/, " ")
         end
         diff
       end
-    ensure
-      # unlink the tempfiles explicitly now that the diff is generated
-      if defined? @tempfiles # to avoid Ruby warnings about undefined ins var.
-        Array(@tempfiles).each do |t|
-          begin
-            # check that the path is not nil and file still exists.
-            # REE seems to be very agressive with when it magically removes
-            # tempfiles
-            t.unlink if t.path && File.exist?(t.path)
-          rescue => e
-            warn "#{e.class}: #{e}"
-            warn e.backtrace.join("\n")
-          end
-        end
-      end
     end
 
     def each
@@ -82,11 +69,12 @@ def each
         # this "primes" the diff and sets up the paths we'll reference below.
         diff
 
-        # caching this regexp improves the performance of the loop by a
-        # considerable amount.
-        regexp = /^(--- "?#{@paths[0]}"?|\+\+\+ "?#{@paths[1]}"?|@@|\\\\)/
-
-        diff.split("\n").reject{|x| x =~ regexp }.map {|line| line + "\n" }
+        # diff --git a/file b/file
+        # index 71779d2..d5f7fc3 100644 
+        # --- test/file
+        # +++ b/file
+        # @@ -1 +1 @@
+        diff.split("\n").drop(@diff_empty ? 0 : 5).map {|line| line + "\n" }
 
       when true
         diff.split("\n").map {|line| line + "\n" }
@@ -119,18 +107,6 @@ def each_chunk
       end
     end
 
-    def tempfile(string)
-      t = Tempfile.new('diffy')
-      # ensure tempfiles aren't unlinked when GC runs by maintaining a
-      # reference to them.
-      @tempfiles ||=[]
-      @tempfiles.push(t)
-      t.print(string)
-      t.flush
-      t.close
-      t.path
-    end
-
     def to_s(format = nil)
       format ||= self.class.default_format
       formats = Format.instance_methods(false).map{|x| x.to_s}
@@ -143,33 +119,5 @@ def to_s(format = nil)
           "Format #{format.inspect} not found in #{formats.inspect}"
       end
     end
-    private
-
-    @@bin = nil
-    def diff_bin
-      return @@bin if @@bin
-
-      if @@bin = ENV['DIFFY_DIFF']
-        # system() trick from Minitest
-        raise "Can't execute diff program '#@@bin'" unless system(@@bin, __FILE__, __FILE__)
-        return @@bin
-      end
-
-      diffs = ['diff', 'ldiff']
-      diffs.first << '.exe' if WINDOWS  # ldiff does not have exe extension
-      @@bin = diffs.find { |name| system(name, __FILE__, __FILE__) }
-
-      if @@bin.nil?
-        raise "Can't find a diff executable in PATH #{ENV['PATH']}"
-      end
-
-      @@bin
-    end
-
-    # options pass to diff program
-    def diff_options
-      Array(options[:context] ? "-U#{options[:context]}" : options[:diff])
-    end
-
   end
 end

spec/diffy_spec.rb

@@ -1,4 +1,5 @@
 require 'rspec'
+require 'tempfile'
 require File.expand_path(File.join(File.dirname(__FILE__), '..', 'lib', 'diffy'))
 
 describe Diffy::Diff do
@@ -38,11 +39,8 @@ def tempfile(string, fn = 'diffy-spec')
       DIFF
     end
 
-    it "should accept file paths with spaces as arguments on windows" do
+    it "should accept file paths with spaces as arguments" do
       begin
-
-        orig_verbose, $VERBOSE = $VERBOSE, nil #silence redefine constant warnings
-        orig_windows, Diffy::WINDOWS = Diffy::WINDOWS, true
         string1 = "foo\nbar\nbang\n"
         string2 = "foo\nbang\n"
         path1, path2 = tempfile(string1, 'path with spaces'), tempfile(string2, 'path with spaces')
@@ -51,10 +49,7 @@ def tempfile(string, fn = 'diffy-spec')
 -bar
  bang
         DIFF
-      ensure
-        Diffy::WINDOWS, $VERBOSE = orig_windows, orig_verbose
       end
-
     end
 
     describe "with no line different" do
@@ -113,13 +108,6 @@ def tempfile(string, fn = 'diffy-spec')
   end
 
   describe "handling temp files" do
-    it "should unlink tempfiles after generating the diff" do
-      before_tmpfiles = Dir.entries(Dir.tmpdir)
-      ::Diffy::Diff.new("a", "b").to_s
-      after_tmpfiles = Dir.entries(Dir.tmpdir)
-      expect(before_tmpfiles).to match_array(after_tmpfiles)
-    end
-
     it "should still be able to generate multiple diffs" do
       d = ::Diffy::Diff.new("a", "b")
       expect(d.to_s).to be_a String
@@ -220,22 +208,13 @@ def tempfile(string, fn = 'diffy-spec')
   end
 
   describe "options[:diff]" do
-    it "should accept an option to diff" do
+    it "should accept options for rugged" do
       @diff = Diffy::Diff.new(" foo\nbar\n", "foo\nbar\n", :diff => "-w", :allow_empty_diff => false)
       expect(@diff.to_s).to eq <<-DIFF
   foo
  bar
       DIFF
     end
-
-    it "should accept multiple arguments to diff" do
-      @diff = Diffy::Diff.new(" foo\nbar\n", "foo\nbaz\n", :diff => ["-w", "-U 3"])
-      expect(@diff.to_s).to eq <<-DIFF
-  foo
--bar
-+baz
-      DIFF
-    end
   end
 
   describe "#to_s" do
@@ -285,6 +264,7 @@ def tempfile(string, fn = 'diffy-spec')
         Diffy::Diff.default_options = old_options.merge(:include_diff_info => true)
         expect(Diffy::Diff.new(@string1, @string2).to_s).
           to include('@@ -1,3 +1,2 @@')
+      ensure
         Diffy::Diff.default_options = old_options
       end
 
@@ -365,20 +345,6 @@ def tempfile(string, fn = 'diffy-spec')
 </div>
         HTML
       end
-
-      it "should accept overrides to diff's options" do
-        @diff = Diffy::Diff.new(@string1, @string2, :diff => "--rcs")
-        expect(@diff.to_s).to eq <<-DIFF
-d1 1
-a1 3
-one
-two
-three
-d4 1
-a4 1
-baz
-          DIFF
-      end
     end
 
     describe "html" do
@@ -548,7 +514,7 @@ def tempfile(string, fn = 'diffy-spec')
       it "should correctly do inline hightlighting when default diff options are changed" do
         original_options = ::Diffy::Diff.default_options
         begin
-              ::Diffy::Diff.default_options.merge!(:diff => '-U0')
+              ::Diffy::Diff.default_options.merge!(:context => 0)
 
               s1 = "foo\nbar\nbang"
               s2 = "foo\nbar\nbangleize"
@@ -621,7 +587,7 @@ def tempfile(string, fn = 'diffy-spec')
 
 describe Diffy::SplitDiff do
   before do
-    ::Diffy::Diff.default_options.merge!(:diff => '-U10000')
+    ::Diffy::Diff.default_options.merge!(:context => 10_000)
   end
 
   it "should fail with invalid format" do
@@ -691,4 +657,3 @@ def tempfile(string, fn = 'diffy-spec')
     expect(Diffy::CSS).to include 'diff{overflow:auto;}'
   end
 end
-