Add latest changes from gitlab-org/gitlab@13-9-stable-eev13.9.0-rc42

1 files changed, 74 insertions, 0 deletions

diff --git a/lib/gitlab/diff/char_diff.rb b/lib/gitlab/diff/char_diff.rb
new file mode 100644
index 00000000000..c8bb39e9f5d
--- /dev/null
+++ b/lib/gitlab/diff/char_diff.rb
@@ -0,0 +1,74 @@
+# frozen_string_literal: true
+
+module Gitlab
+  module Diff
+    class CharDiff
+      include Gitlab::Utils::StrongMemoize
+
+      def initialize(old_string, new_string)
+        @old_string = old_string.to_s
+        @new_string = new_string.to_s
+        @changes = []
+      end
+
+      def generate_diff
+        @changes = diff_match_patch.diff_main(@old_string, @new_string)
+        diff_match_patch.diff_cleanupSemantic(@changes)
+
+        @changes
+      end
+
+      def changed_ranges(offset: 0)
+        old_diffs = []
+        new_diffs = []
+        new_pointer = old_pointer = offset
+
+        generate_diff.each do |(action, content)|
+          content_size = content.size
+
+          if action == :equal
+            new_pointer += content_size
+            old_pointer += content_size
+          end
+
+          if action == :delete
+            old_diffs << (old_pointer..(old_pointer + content_size - 1))
+            old_pointer += content_size
+          end
+
+          if action == :insert
+            new_diffs << (new_pointer..(new_pointer + content_size - 1))
+            new_pointer += content_size
+          end
+        end
+
+        [old_diffs, new_diffs]
+      end
+
+      def to_html
+        @changes.map do |op, text|
+          %{<span class="#{html_class_names(op)}">#{ERB::Util.html_escape(text)}</span>}
+        end.join.html_safe
+      end
+
+      private
+
+      def diff_match_patch
+        strong_memoize(:diff_match_patch) { DiffMatchPatch.new }
+      end
+
+      def html_class_names(operation)
+        class_names = ['idiff']
+
+        case operation
+        when :insert
+          class_names << 'addition'
+        when :delete
+          class_names << 'deletion'
+        end
+
+        class_names.join(' ')
+      end
+    end
+  end
+end