1 files changed, 57 insertions, 0 deletions
diff --git a/lib/gitlab/word_diff/parser.rb b/lib/gitlab/word_diff/parser.rb
new file mode 100644
index 00000000000..3b6d4d4d384
--- /dev/null
+++ b/lib/gitlab/word_diff/parser.rb
@@ -0,0 +1,57 @@
+# frozen_string_literal: true
+
+# Converts git diff --word-diff=porcelain output to Gitlab::Diff::Line objects
+# see: https://git-scm.com/docs/git-diff#Documentation/git-diff.txt-porcelain
+module Gitlab
+  module WordDiff
+    class Parser
+      include Enumerable
+
+      def parse(lines, diff_file: nil)
+        return [] if lines.blank?
+
+        # By returning an Enumerator we make it possible to search for a single line (with #find)
+        # without having to instantiate all the others that come after it.
+        Enumerator.new do |yielder|
+          @chunks = ChunkCollection.new
+          @counter = PositionsCounter.new
+
+          lines.each do |line|
+            segment = LineProcessor.new(line).extract
+
+            case segment
+            when Segments::DiffHunk
+              next if segment.first_line?
+
+              counter.set_pos_num(old: segment.pos_old, new: segment.pos_new)
+
+              yielder << build_line(segment.to_s, 'match', parent_file: diff_file)
+
+            when Segments::Chunk
+              @chunks.add(segment)
+
+            when Segments::Newline
+              yielder << build_line(@chunks.content, nil, parent_file: diff_file)
+
+              @chunks.reset
+              counter.increase_pos_num
+            end
+          end
+        end
+      end
+
+      private
+
+      attr_reader :counter
+
+      def build_line(content, type, options = {})
+        Gitlab::Diff::Line.new(
+          content, type,
+          counter.line_obj_index, counter.pos_old, counter.pos_new,
+          **options).tap do
+          counter.increase_obj_index
+        end
+      end
+    end
+  end
+end