branch: introduce --show-current display option

When called with --show-current, git branch will print the current
branch name and terminate. Only the actual name gets printed,
without refs/heads. In detached HEAD state, nothing is output.

Intended both for scripting and interactive/informative use.
Unlike git branch --list, no filtering is needed to just get the
branch name.

Signed-off-by: Daniels Umanovskis <daniels@umanovskis.se>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/Documentation/git-branch.txt b/Documentation/git-branch.txt
index bf5316ffa929a88aa98f5b3c7a892ee43638a098..0babb9b1be4db9727694e706835434a944e2754e 100644 (file)
--- a/Documentation/git-branch.txt
+++ b/Documentation/git-branch.txt
@@ -9,7 +9,7 @@ SYNOPSIS
 --------
 [verse]
 'git branch' [--color[=<when>] | --no-color] [-r | -a]
-       [--list] [-v [--abbrev=<length> | --no-abbrev]]
+       [--list] [--show-current] [-v [--abbrev=<length> | --no-abbrev]]
        [--column[=<options>] | --no-column] [--sort=<key>]
        [(--merged | --no-merged) [<commit>]]
        [--contains [<commit]] [--no-contains [<commit>]]
@@ -160,6 +160,10 @@ This option is only applicable in non-verbose mode.
        branch --list 'maint-*'`, list only the branches that match
        the pattern(s).
 
+--show-current::
+       Print the name of the current branch. In detached HEAD state,
+       nothing is printed.
+
 -v::
 -vv::
 --verbose::

diff --git a/builtin/branch.c b/builtin/branch.c
index c396c41533c38630378db370f1db30e99aad849b..46f91dc06dc64c2b24ae41ac1e57488f118e255e 100644 (file)
--- a/builtin/branch.c
+++ b/builtin/branch.c
@@ -443,6 +443,21 @@ static void print_ref_list(struct ref_filter *filter, struct ref_sorting *sortin
        free(to_free);
 }
 
+static void print_current_branch_name(void)
+{
+       int flags;
+       const char *refname = resolve_ref_unsafe("HEAD", 0, NULL, &flags);
+       const char *shortname;
+       if (!refname)
+               die(_("could not resolve HEAD"));
+       else if (!(flags & REF_ISSYMREF))
+               return;
+       else if (skip_prefix(refname, "refs/heads/", &shortname))
+               puts(shortname);
+       else
+               die(_("HEAD (%s) points outside of refs/heads/"), refname);
+}
+
 static void reject_rebase_or_bisect_branch(const char *target)
 {
        struct worktree **worktrees = get_worktrees(0);
@@ -581,6 +596,7 @@ static int edit_branch_description(const char *branch_name)
 int cmd_branch(int argc, const char **argv, const char *prefix)
 {
        int delete = 0, rename = 0, copy = 0, force = 0, list = 0;
+       int show_current = 0;
        int reflog = 0, edit_description = 0;
        int quiet = 0, unset_upstream = 0;
        const char *new_upstream = NULL;
@@ -620,6 +636,7 @@ int cmd_branch(int argc, const char **argv, const char *prefix)
                OPT_BIT('c', "copy", &copy, N_("copy a branch and its reflog"), 1),
                OPT_BIT('C', NULL, &copy, N_("copy a branch, even if target exists"), 2),
                OPT_BOOL('l', "list", &list, N_("list branch names")),
+               OPT_BOOL(0, "show-current", &show_current, N_("show current branch name")),
                OPT_BOOL(0, "create-reflog", &reflog, N_("create the branch's reflog")),
                OPT_BOOL(0, "edit-description", &edit_description,
                         N_("edit the description for the branch")),
@@ -662,14 +679,15 @@ int cmd_branch(int argc, const char **argv, const char *prefix)
        argc = parse_options(argc, argv, prefix, options, builtin_branch_usage,
                             0);
 
-       if (!delete && !rename && !copy && !edit_description && !new_upstream && !unset_upstream && argc == 0)
+       if (!delete && !rename && !copy && !edit_description && !new_upstream &&
+           !show_current && !unset_upstream && argc == 0)
                list = 1;
 
        if (filter.with_commit || filter.merge != REF_FILTER_MERGED_NONE || filter.points_at.nr ||
            filter.no_commit)
                list = 1;
 
-       if (!!delete + !!rename + !!copy + !!new_upstream +
+       if (!!delete + !!rename + !!copy + !!new_upstream + !!show_current +
            list + unset_upstream > 1)
                usage_with_options(builtin_branch_usage, options);
 
@@ -697,6 +715,9 @@ int cmd_branch(int argc, const char **argv, const char *prefix)
                if (!argc)
                        die(_("branch name required"));
                return delete_branches(argc, argv, delete > 1, filter.kind, quiet);
+       } else if (show_current) {
+               print_current_branch_name();
+               return 0;
        } else if (list) {
                /*  git branch --local also shows HEAD when it is detached */
                if ((filter.kind & FILTER_REFS_BRANCHES) && filter.detached)

diff --git a/t/t3203-branch-output.sh b/t/t3203-branch-output.sh
index ee6787614c80edb9b5b24065277dd413350a6fc6..be5514893030313bbe08b9041b9e3d85f7fbde2b 100755 (executable)
--- a/t/t3203-branch-output.sh
+++ b/t/t3203-branch-output.sh
@@ -100,6 +100,50 @@ test_expect_success 'git branch -v pattern does not show branch summaries' '
        test_must_fail git branch -v branch*
 '
 
+test_expect_success 'git branch `--show-current` shows current branch' '
+       cat >expect <<-\EOF &&
+       branch-two
+       EOF
+       git checkout branch-two &&
+       git branch --show-current >actual &&
+       test_cmp expect actual
+'
+
+test_expect_success 'git branch `--show-current` is silent when detached HEAD' '
+       git checkout HEAD^0 &&
+       git branch --show-current >actual &&
+       test_must_be_empty actual
+'
+
+test_expect_success 'git branch `--show-current` works properly when tag exists' '
+       cat >expect <<-\EOF &&
+       branch-and-tag-name
+       EOF
+       test_when_finished "
+               git checkout branch-one
+               git branch -D branch-and-tag-name
+       " &&
+       git checkout -b branch-and-tag-name &&
+       test_when_finished "git tag -d branch-and-tag-name" &&
+       git tag branch-and-tag-name &&
+       git branch --show-current >actual &&
+       test_cmp expect actual
+'
+
+test_expect_success 'git branch `--show-current` works properly with worktrees' '
+       cat >expect <<-\EOF &&
+       branch-one
+       branch-two
+       EOF
+       git checkout branch-one &&
+       git worktree add worktree branch-two &&
+       {
+               git branch --show-current &&
+               git -C worktree branch --show-current
+       } >actual &&
+       test_cmp expect actual
+'
+
 test_expect_success 'git branch shows detached HEAD properly' '
        cat >expect <<EOF &&
 * (HEAD detached at $(git rev-parse --short HEAD^0))