[PATCH] pretty: Add "%aU"|"%au" option to output author's username

[Prarit Bhargava <prarit@redhat.com>]

In many projects the number of contributors is low enough that users know
each other and the full email address doesn't need to be displayed.
Displaying only the author's username saves a lot of columns on the screen.
For example displaying "prarit" instead of "prarit@redhat.com" saves 11
columns.

Add a "%aU"|"%au" option that outputs the author's email username.

Also add tests for "%ae" and "%an".

Signed-off-by: Prarit Bhargava <prarit@redhat.com>
---
 Documentation/pretty-formats.txt |  3 +++
 pretty.c                         |  5 +++++
 t/t4202-log.sh                   | 16 ++++++++++++++++
 3 files changed, 24 insertions(+)

diff --git a/Documentation/pretty-formats.txt b/Documentation/pretty-formats.txt
index b87e2e83e6d0..479a15a8ab12 100644
--- a/Documentation/pretty-formats.txt
+++ b/Documentation/pretty-formats.txt
@@ -163,6 +163,9 @@ The placeholders are:
 '%ae':: author email
 '%aE':: author email (respecting .mailmap, see linkgit:git-shortlog[1]
 	or linkgit:git-blame[1])
+'%au':: author username
+'%aU':: author username (respecting .mailmap, see linkgit:git-shortlog[1]
+	or linkgit:git-blame[1])
 '%ad':: author date (format respects --date= option)
 '%aD':: author date, RFC2822 style
 '%ar':: author date, relative
diff --git a/pretty.c b/pretty.c
index b32f0369531c..2a5b93022050 100644
--- a/pretty.c
+++ b/pretty.c
@@ -706,6 +706,11 @@ static size_t format_person_part(struct strbuf *sb, char part,
 		strbuf_add(sb, mail, maillen);
 		return placeholder_len;
 	}
+	if (part == 'u' || part == 'U') {	/* username */
+		maillen = strstr(s.mail_begin, "@") - s.mail_begin;
+		strbuf_add(sb, mail, maillen);
+		return placeholder_len;
+	}
 
 	if (!s.date_begin)
 		goto skip;
diff --git a/t/t4202-log.sh b/t/t4202-log.sh
index e803ba402e9e..2fee0c067197 100755
--- a/t/t4202-log.sh
+++ b/t/t4202-log.sh
@@ -1729,4 +1729,20 @@ test_expect_success 'log --end-of-options' '
        test_cmp expect actual
 '
 
+test_expect_success 'log pretty %an %ae %au' '
+	git checkout -b anaeau &&
+	test_commit anaeau_test anaeau_test_file &&
+	git log --pretty="%an" > actual &&
+	git log --pretty="%ae" >> actual &&
+	git log --pretty="%au" >> actual &&
+	git log > full &&
+	name=$(cat full | grep "^Author: " | awk -F "Author: " " { print \$2 } " | awk -F " <" " { print \$1 } ") &&
+	email=$(cat full | grep "^Author: " | awk -F "<" " { print \$2 } " | awk -F ">" " { print \$1 } ") &&
+	username=$(cat full | grep "^Author: " | awk -F "<" " { print \$2 } " | awk -F ">" " { print \$1 } " | awk -F "@" " { print \$1 } " ) &&
+	echo "${name}" > expect &&
+	echo "${email}" >> expect &&
+	echo "${username}" >> expect &&
+	test_cmp expect actual
+'
+
 test_done
-- 
2.21.0