[PATCH v2] pretty: add "%aL"|"%al|%cL|%cl" option to output local-part of email addresses

[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 "%aL"|"%al|%cL|%cl" option that output the local-part of an email
address.

Also add tests for "%ae","%an", "%ce", and "%cn".

Changes in v2:
- Changed option to 'L' based on https://www.ietf.org/rfc/rfc2822.txt
  definition of 'local-part' of email addresses.
- added additional information to documentation for %cL and %cl
- added mailmap output test
- modified code to use mailmap output for "L" option
- modified code to check if email address field has '@' symbol
- modified tests based on input from Peff

Signed-off-by: Prarit Bhargava <prarit@redhat.com>
Cc: Junio C Hamano <gitster@pobox.com>
Cc: brian m. carlson <sandals@crustytoothpaste.net>
Cc: Jeff King <peff@peff.net>
---
 Documentation/pretty-formats.txt | 10 ++++++++++
 pretty.c                         |  9 ++++++++-
 t/t4202-log.sh                   | 30 ++++++++++++++++++++++++++++++
 t/test-lib.sh                    | 10 ++++++++--
 4 files changed, 56 insertions(+), 3 deletions(-)

diff --git a/Documentation/pretty-formats.txt b/Documentation/pretty-formats.txt
index b87e2e83e6d0..9a1f900f114a 100644
--- a/Documentation/pretty-formats.txt
+++ b/Documentation/pretty-formats.txt
@@ -163,6 +163,11 @@ The placeholders are:
 '%ae':: author email
 '%aE':: author email (respecting .mailmap, see linkgit:git-shortlog[1]
 	or linkgit:git-blame[1])
+'%al':: author local-part (the portion of the email address preceding the '@'
+	symbol)
+'%aL':: author local-part (the portion of the email address preceding the '@'
+	symbol, 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 +180,11 @@ The placeholders are:
 '%ce':: committer email
 '%cE':: committer email (respecting .mailmap, see
 	linkgit:git-shortlog[1] or linkgit:git-blame[1])
+'%cl':: author local-part (the portion of the email address preceding the '@'
+	symbol)
+'%cL':: author local-part (the portion of the email address preceding the '@'
+	symbol, 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
diff --git a/pretty.c b/pretty.c
index b32f0369531c..93eb6e837071 100644
--- a/pretty.c
+++ b/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;
diff --git a/t/t4202-log.sh b/t/t4202-log.sh
index e803ba402e9e..fa6ecf3588b7 100755
--- a/t/t4202-log.sh
+++ b/t/t4202-log.sh
@@ -1729,4 +1729,34 @@ test_expect_success 'log --end-of-options' '
        test_cmp expect actual
 '
 
+test_expect_success 'log pretty %an %ae %al %aN %aE %aL' '
+	git checkout -b anaeal &&
+	test_commit anaeal_test anaeal_test_file &&
+	git log --pretty="%an%n%ae%n%al%n%aN%n%aE%n%aL" -1 > actual &&
+	{
+		echo "${GIT_AUTHOR_NAME}" &&
+		echo "${GIT_AUTHOR_EMAIL}" &&
+		echo "${TEST_AUTHOR_LOCALNAME}"
+		echo "${GIT_AUTHOR_NAME}" &&
+		echo "${GIT_AUTHOR_EMAIL}" &&
+		echo "${TEST_AUTHOR_LOCALNAME}"
+	} > expect &&
+	test_cmp expect actual
+'
+
+test_expect_success 'log pretty %cn %ce %cl %cN %cE %cL' '
+	git checkout -b cncecl &&
+	test_commit cncecl_test cncecl_test_file &&
+	git log --pretty="%cn%n%ce%n%cl%n%cN%n%cE%n%cL" -1 > actual &&
+	{
+		echo "${GIT_COMMITTER_NAME}" &&
+		echo "${GIT_COMMITTER_EMAIL}" &&
+		echo "${TEST_COMMITTER_LOCALNAME}"
+		echo "${GIT_COMMITTER_NAME}" &&
+		echo "${GIT_COMMITTER_EMAIL}" &&
+		echo "${TEST_COMMITTER_LOCALNAME}"
+	} > expect &&
+	test_cmp expect actual
+'
+
 test_done
diff --git a/t/test-lib.sh b/t/test-lib.sh
index e06fa02a0eec..5ef0ad8c1a2a 100644
--- a/t/test-lib.sh
+++ b/t/test-lib.sh
@@ -404,14 +404,20 @@ 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
 export GIT_MERGE_VERBOSITY GIT_MERGE_AUTOEDIT
+export TEST_AUTHOR_LOCALNAME TEST_AUTHOR_DOMAIN
 export GIT_AUTHOR_EMAIL GIT_AUTHOR_NAME
+export TEST_COMMITTER_LOCALNAME TEST_COMMITTER_DOMAIN
 export GIT_COMMITTER_EMAIL GIT_COMMITTER_NAME
 export EDITOR
 
-- 
2.21.0