pretty: add "%aL" etc. to show local-part of email addresses

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.

Existing 'e/E' (as in "%ae" and "%aE") placeholders would show the
author's address as "prarit@redhat.com", which would waste columns to show
the same domain-part for all contributors when used in a project internal
to redhat.  Introduce 'l/L' placeholders that strip '@' and domain part from
the e-mail address.

Signed-off-by: Prarit Bhargava <prarit@redhat.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

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])
+'%al':: author email local-part (the part before the '@' sign)
+'%aL':: author local-part (see '%al') 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
@@ -175,6 +178,9 @@ The placeholders are:
 '%ce':: committer email
 '%cE':: committer email (respecting .mailmap, see
 	linkgit:git-shortlog[1] or linkgit:git-blame[1])
+'%cl':: author email local-part (the part before the '@' sign)
+'%cL':: author local-part (see '%cl') respecting .mailmap, see
+	linkgit:git-shortlog[1] or linkgit:git-blame[1])
 '%cd':: committer date (format respects --date= option)
 '%cD':: committer date, RFC2822 style
 '%cr':: committer date, relative

pretty.c

@@ -696,7 +696,7 @@ static size_t format_person_part(struct strbuf *sb, char part,
 	mail = s.mail_begin;
 	maillen = s.mail_end - s.mail_begin;
 
-	if (part == 'N' || part == 'E') /* mailmap lookup */
+	if (part == 'N' || part == 'E' || part == 'L') /* mailmap lookup */
 		mailmap_name(&mail, &maillen, &name, &namelen);
 	if (part == 'n' || part == 'N') {	/* name */
 		strbuf_add(sb, name, namelen);
@@ -706,6 +706,13 @@ static size_t format_person_part(struct strbuf *sb, char part,
 		strbuf_add(sb, mail, maillen);
 		return placeholder_len;
 	}
+	if (part == 'l' || part == 'L') {	/* local-part */
+		const char *at = memchr(mail, '@', maillen);
+		if (at)
+			maillen = at - mail;
+		strbuf_add(sb, mail, maillen);
+		return placeholder_len;
+	}
 
 	if (!s.date_begin)
 		goto skip;

t/t4203-mailmap.sh

@@ -412,6 +412,34 @@ test_expect_success 'Log output (complex mapping)' '
 	test_cmp expect actual
 '
 
+cat >expect << EOF
+Author email cto@coompany.xx has local-part cto
+Committer email $GIT_COMMITTER_EMAIL has local-part $TEST_COMMITTER_LOCALNAME
+
+Author email me@company.xx has local-part me
+Committer email $GIT_COMMITTER_EMAIL has local-part $TEST_COMMITTER_LOCALNAME
+
+Author email me@company.xx has local-part me
+Committer email $GIT_COMMITTER_EMAIL has local-part $TEST_COMMITTER_LOCALNAME
+
+Author email nick2@company.xx has local-part nick2
+Committer email $GIT_COMMITTER_EMAIL has local-part $TEST_COMMITTER_LOCALNAME
+
+Author email bugs@company.xx has local-part bugs
+Committer email $GIT_COMMITTER_EMAIL has local-part $TEST_COMMITTER_LOCALNAME
+
+Author email bugs@company.xx has local-part bugs
+Committer email $GIT_COMMITTER_EMAIL has local-part $TEST_COMMITTER_LOCALNAME
+
+Author email author@example.com has local-part author
+Committer email $GIT_COMMITTER_EMAIL has local-part $TEST_COMMITTER_LOCALNAME
+EOF
+
+test_expect_success 'Log output (local-part email address)' '
+	git log --pretty=format:"Author email %ae has local-part %al%nCommitter email %ce has local-part %cl%n" >actual &&
+	test_cmp expect actual
+'
+
 cat >expect << EOF
 Author: CTO <cto@company.xx>
 Author: Santa Claus <santa.claus@northpole.xx>

t/t6006-rev-list-format.sh

@@ -109,31 +109,35 @@ commit $head1
 EOF
 
 # we don't test relative here
-test_format author %an%n%ae%n%ad%n%aD%n%at <<EOF
+test_format author %an%n%ae%n%al%n%ad%n%aD%n%at <<EOF
 commit $head2
 $GIT_AUTHOR_NAME
 $GIT_AUTHOR_EMAIL
+$TEST_AUTHOR_LOCALNAME
 Thu Apr 7 15:13:13 2005 -0700
 Thu, 7 Apr 2005 15:13:13 -0700
 1112911993
 commit $head1
 $GIT_AUTHOR_NAME
 $GIT_AUTHOR_EMAIL
+$TEST_AUTHOR_LOCALNAME
 Thu Apr 7 15:13:13 2005 -0700
 Thu, 7 Apr 2005 15:13:13 -0700
 1112911993
 EOF
 
-test_format committer %cn%n%ce%n%cd%n%cD%n%ct <<EOF
+test_format committer %cn%n%ce%n%cl%n%cd%n%cD%n%ct <<EOF
 commit $head2
 $GIT_COMMITTER_NAME
 $GIT_COMMITTER_EMAIL
+$TEST_COMMITTER_LOCALNAME
 Thu Apr 7 15:13:13 2005 -0700
 Thu, 7 Apr 2005 15:13:13 -0700
 1112911993
 commit $head1
 $GIT_COMMITTER_NAME
 $GIT_COMMITTER_EMAIL
+$TEST_COMMITTER_LOCALNAME
 Thu Apr 7 15:13:13 2005 -0700
 Thu, 7 Apr 2005 15:13:13 -0700
 1112911993

t/test-lib.sh

@@ -404,9 +404,13 @@ unset VISUAL EMAIL LANGUAGE COLUMNS $("$PERL_PATH" -e '
 unset XDG_CACHE_HOME
 unset XDG_CONFIG_HOME
 unset GITPERLLIB
-GIT_AUTHOR_EMAIL=author@example.com
+TEST_AUTHOR_LOCALNAME=author
+TEST_AUTHOR_DOMAIN=example.com
+GIT_AUTHOR_EMAIL=${TEST_AUTHOR_LOCALNAME}@${TEST_AUTHOR_DOMAIN}
 GIT_AUTHOR_NAME='A U Thor'
-GIT_COMMITTER_EMAIL=committer@example.com
+TEST_COMMITTER_LOCALNAME=committer
+TEST_COMMITTER_DOMAIN=example.com
+GIT_COMMITTER_EMAIL=${TEST_COMMITTER_LOCALNAME}@${TEST_COMMITTER_DOMAIN}
 GIT_COMMITTER_NAME='C O Mitter'
 GIT_MERGE_VERBOSITY=5
 GIT_MERGE_AUTOEDIT=no