Support selective highlighting of lines

Instead of highlighting all lines when not all of them
are needed, only highlight from the beginning up to
the specified limit.

The `BlobPresenter#highlight` method has been updated
to support `to` param. This param will be used to limit
the content to be highlighted.

1 files changed, 3 insertions, 5 deletions

diff --git a/app/presenters/blobs/unfold_presenter.rb b/app/presenters/blobs/unfold_presenter.rb
index a256dd05a4d..487c6fe0757 100644
--- a/app/presenters/blobs/unfold_presenter.rb
+++ b/app/presenters/blobs/unfold_presenter.rb
@@ -26,8 +26,6 @@ module Blobs
       # so we can accurately show the rest of the diff when unfolding.
       load_all_blob_data
 
-      @all_lines = blob.data.lines
-
       handle_full_or_end!
     end
 
@@ -46,7 +44,7 @@ module Blobs
 
     def lines
       strong_memoize(:lines) do
-        limit(highlight.lines).map(&:html_safe)
+        limit(highlight(to: to).lines).map(&:html_safe)
       end
     end
 
@@ -76,7 +74,7 @@ module Blobs
 
     def all_lines_size
       strong_memoize(:all_lines_size) do
-        @all_lines.size
+        all_lines.size
       end
     end
 
@@ -101,7 +99,7 @@ module Blobs
 
     def limited_blob_lines
       strong_memoize(:limited_blob_lines) do
-        limit(@all_lines)
+        limit(all_lines)
       end
     end