[PATCH v5 4/6] worktree: factor out dwim_branch function

[Thomas Gummerer <t.gummerer@gmail.com>]

Factor out a dwim_branch function, which takes care of the dwim'ery in
'git worktree add <path>'.  It's not too much code currently, but we're
adding a new kind of dwim in a subsequent patch, at which point it makes
more sense to have it as a separate function.

Factor it out now to reduce the patch noise in the next patch.

Signed-off-by: Thomas Gummerer <t.gummerer@gmail.com>
---
 builtin/worktree.c | 27 +++++++++++++++++----------
 1 file changed, 17 insertions(+), 10 deletions(-)

diff --git a/builtin/worktree.c b/builtin/worktree.c
index 1e4a919a00..c296c3eacb 100644
--- a/builtin/worktree.c
+++ b/builtin/worktree.c
@@ -366,6 +366,20 @@ static int add_worktree(const char *path, const char *refname,
 	return ret;
 }
 
+static const char *dwim_branch(const char *path, struct add_opts *opts)
+{
+	int n;
+	const char *s = worktree_basename(path, &n);
+	opts->new_branch = xstrndup(s, n);
+	if (guess_remote) {
+		struct object_id oid;
+		const char *remote =
+			unique_tracking_name(opts->new_branch, &oid);
+		return remote;
+	}
+	return NULL;
+}
+
 static int add(int ac, const char **av, const char *prefix)
 {
 	struct add_opts opts;
@@ -417,16 +431,9 @@ static int add(int ac, const char **av, const char *prefix)
 	}
 
 	if (ac < 2 && !opts.new_branch && !opts.detach) {
-		int n;
-		const char *s = worktree_basename(path, &n);
-		opts.new_branch = xstrndup(s, n);
-		if (guess_remote) {
-			struct object_id oid;
-			const char *remote =
-				unique_tracking_name(opts.new_branch, &oid);
-			if (remote)
-				branch = remote;
-		}
+		const char *dwim_branchname = dwim_branch(path, &opts);
+		if (dwim_branchname)
+			branch = dwim_branchname;
 	}
 
 	if (ac == 2 && !opts.new_branch && !opts.detach) {
-- 
2.16.1.77.g8685934aa2