for-each-ref: let upstream/push optionally report the remote name

There are times when e.g. scripts want to know not only the name of the
upstream branch on the remote repository, but also the name of the
remote.

This patch offers the new suffix :remotename for the upstream and for
the push atoms, allowing to show exactly that. Example:

	$ cat .git/config
	...
	[remote "origin"]
		url = https://where.do.we.come/from
		fetch = refs/heads/*:refs/remote/origin/*
	[remote "hello-world"]
		url = https://hello.world/git
		fetch = refs/heads/*:refs/remote/origin/*
		pushURL = hello.world:git
		push = refs/heads/*:refs/heads/*
	[branch "master"]
		remote = origin
		pushRemote = hello-world
	...

	$ git for-each-ref \
	  --format='%(upstream) %(upstream:remotename) %(push:remotename)' \
	  refs/heads/master
	refs/remotes/origin/master origin hello-world

The implementation chooses *not* to DWIM the push remote if no explicit
push remote was configured; The reason is that it is possible to DWIM this
by using

	%(if)%(push:remotename)%(then)
		%(push:remotename)
	%(else)
		%(upstream:remotename)
	%(end)

while it would be impossible to "un-DWIM" the information in case the
caller is really only interested in explicit push remotes.

While `:remote` would be shorter, it would also be a bit more ambiguous,
and it would also shut the door e.g. for `:remoteref` (which would
obviously refer to the corresponding ref in the remote repository).

Note: the dashless, non-CamelCased form `:remotename` follows the
example of the `:trackshort` example.

Signed-off-by: Johannes Schindelin <[email protected]>
Signed-off-by: Junio C Hamano <[email protected]>

Author: dscho

Documentation/git-for-each-ref.txt

@@ -140,17 +140,20 @@ upstream::
 	(behind), "<>" (ahead and behind), or "=" (in sync). `:track`
 	also prints "[gone]" whenever unknown upstream ref is
 	encountered. Append `:track,nobracket` to show tracking
-	information without brackets (i.e "ahead N, behind M").  Has
-	no effect if the ref does not have tracking information
-	associated with it.  All the options apart from `nobracket`
-	are mutually exclusive, but if used together the last option
-	is selected.
+	information without brackets (i.e "ahead N, behind M").
++
+Also respects `:remotename` to state the name of the *remote* instead of
+the ref.
++
+Has no effect if the ref does not have tracking information associated
+with it.  All the options apart from `nobracket` are mutually exclusive,
+but if used together the last option is selected.
 
 push::
 	The name of a local ref which represents the `@{push}`
 	location for the displayed ref. Respects `:short`, `:lstrip`,
-	`:rstrip`, `:track`, and `:trackshort` options as `upstream`
-	does. Produces an empty string if no `@{push}` ref is
+	`:rstrip`, `:track`, `:trackshort` and `:remotename` options as
+	`upstream` does. Produces an empty string if no `@{push}` ref is
 	configured.
 
 HEAD::

ref-filter.c

@@ -76,9 +76,11 @@ static struct used_atom {
 		char color[COLOR_MAXLEN];
 		struct align align;
 		struct {
-			enum { RR_REF, RR_TRACK, RR_TRACKSHORT } option;
+			enum {
+				RR_REF, RR_TRACK, RR_TRACKSHORT, RR_REMOTE_NAME
+			} option;
 			struct refname_atom refname;
-			unsigned int nobracket : 1;
+			unsigned int nobracket : 1, push : 1, push_remote : 1;
 		} remote_ref;
 		struct {
 			enum { C_BARE, C_BODY, C_BODY_DEP, C_LINES, C_SIG, C_SUB, C_TRAILERS } option;
@@ -137,6 +139,9 @@ static void remote_ref_atom_parser(const struct ref_format *format, struct used_
 	struct string_list params = STRING_LIST_INIT_DUP;
 	int i;
 
+	if (!strcmp(atom->name, "push") || starts_with(atom->name, "push:"))
+		atom->u.remote_ref.push = 1;
+
 	if (!arg) {
 		atom->u.remote_ref.option = RR_REF;
 		refname_atom_parser_internal(&atom->u.remote_ref.refname,
@@ -156,7 +161,10 @@ static void remote_ref_atom_parser(const struct ref_format *format, struct used_
 			atom->u.remote_ref.option = RR_TRACKSHORT;
 		else if (!strcmp(s, "nobracket"))
 			atom->u.remote_ref.nobracket = 1;
-		else {
+		else if (!strcmp(s, "remotename")) {
+			atom->u.remote_ref.option = RR_REMOTE_NAME;
+			atom->u.remote_ref.push_remote = 1;
+		} else {
 			atom->u.remote_ref.option = RR_REF;
 			refname_atom_parser_internal(&atom->u.remote_ref.refname,
 						     arg, atom->name);
@@ -1245,6 +1253,15 @@ static void fill_remote_ref_details(struct used_atom *atom, const char *refname,
 			*s = ">";
 		else
 			*s = "<>";
+	} else if (atom->u.remote_ref.option == RR_REMOTE_NAME) {
+		int explicit;
+		const char *remote = atom->u.remote_ref.push ?
+			pushremote_for_branch(branch, &explicit) :
+			remote_for_branch(branch, &explicit);
+		if (explicit)
+			*s = xstrdup(remote);
+		else
+			*s = "";
 	} else
 		die("BUG: unhandled RR_* enum");
 }
@@ -1354,16 +1371,20 @@ static void populate_value(struct ref_array_item *ref)
 			if (refname)
 				fill_remote_ref_details(atom, refname, branch, &v->s);
 			continue;
-		} else if (starts_with(name, "push")) {
+		} else if (atom->u.remote_ref.push) {
 			const char *branch_name;
 			if (!skip_prefix(ref->refname, "refs/heads/",
 					 &branch_name))
 				continue;
 			branch = branch_get(branch_name);
 
-			refname = branch_get_push(branch, NULL);
-			if (!refname)
-				continue;
+			if (atom->u.remote_ref.push_remote)
+				refname = NULL;
+			else {
+				refname = branch_get_push(branch, NULL);
+				if (!refname)
+					continue;
+			}
 			fill_remote_ref_details(atom, refname, branch, &v->s);
 			continue;
 		} else if (starts_with(name, "color:")) {