pretty: colorize pattern matches in commit messages

The "git log" command limits its output to the commits that contain strings
matched by a pattern when the "--grep=<pattern>" option is used, but unlike
output from "git grep -e <pattern>", the matches are not highlighted,
making them harder to spot.

Teach the pretty-printer code to highlight matches from the
"--grep=<pattern>", "--author=<pattern>" and "--committer=<pattern>"
options (to view the last one, you may have to ask for --pretty=fuller).

Also, it must be noted that we are effectively greping the content twice
(because it would be a hassle to rework the existing matching code to do
a /g match and then pass it all down to the coloring code), however it only
slows down "git log --author=^H" on this repository by around 1-2%
(compared to v2.33.0), so it should be a small enough slow down to justify
the addition of the feature.

Signed-off-by: Hamza Mahfooz <someguy@effective-light.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 5 insertions, 2 deletions

diff --git a/Documentation/config/color.txt b/Documentation/config/color.txt
index e05d520..91d9a9d 100644
--- a/Documentation/config/color.txt
+++ b/Documentation/config/color.txt
@@ -104,9 +104,12 @@ color.grep.<slot>::
 `matchContext`;;
 	matching text in context lines
 `matchSelected`;;
-	matching text in selected lines
+	matching text in selected lines. Also, used to customize the following
+	linkgit:git-log[1] subcommands: `--grep`, `--author` and `--committer`.
 `selected`;;
-	non-matching text in selected lines
+	non-matching text in selected lines. Also, used to customize the
+	following linkgit:git-log[1] subcommands: `--grep`, `--author` and
+	`--committer`.
 `separator`;;
 	separators between fields on a line (`:`, `-`, and `=`)
 	and between hunks (`--`)