ref/refname: Add refname validation

1 files changed, 75 insertions, 0 deletions

diff --git a/ref/refname/worktree.go b/ref/refname/worktree.go
new file mode 100644
index 00000000..48ca215d
--- /dev/null
+++ b/ref/refname/worktree.go
@@ -0,0 +1,75 @@
+package refname
+
+import "strings"
+
+// WorktreeType classifies one worktree-qualified refname prefix.
+type WorktreeType uint8
+
+const (
+	// WorktreeShared is one ordinary shared refname.
+	WorktreeShared WorktreeType = iota
+
+	// WorktreeCurrent is one current-worktree-only refname like HEAD or refs/worktree/...
+	WorktreeCurrent
+
+	// WorktreeMain is one main-worktree-qualified refname like main-worktree/HEAD.
+	WorktreeMain
+
+	// WorktreeOther is one other-worktree-qualified refname like worktrees/wt1/HEAD.
+	WorktreeOther
+)
+
+// IsPerWorktree reports whether name is one per-worktree ref namespace.
+func IsPerWorktree(name string) bool {
+	return strings.HasPrefix(name, "refs/worktree/") ||
+		strings.HasPrefix(name, "refs/bisect/") ||
+		strings.HasPrefix(name, "refs/rewritten/")
+}
+
+// ParsedWorktreeRef is the result of parsing one worktree-qualified refname.
+type ParsedWorktreeRef struct {
+	Type         WorktreeType
+	WorktreeName string
+	BareRefName  string
+}
+
+// ParseWorktree parses Git's worktree ref prefixes.
+func ParseWorktree(name string) ParsedWorktreeRef {
+	if bare, ok := strings.CutPrefix(name, "worktrees/"); ok {
+		worktreeName, rest, found := strings.Cut(bare, "/")
+		if !found {
+			return ParsedWorktreeRef{
+				Type:         WorktreeOther,
+				WorktreeName: worktreeName,
+				BareRefName:  "",
+			}
+		}
+
+		if isCurrentWorktreeRef(rest) {
+			return ParsedWorktreeRef{
+				Type:         WorktreeOther,
+				WorktreeName: worktreeName,
+				BareRefName:  rest,
+			}
+		}
+	}
+
+	if bare, ok := strings.CutPrefix(name, "main-worktree/"); ok && isCurrentWorktreeRef(bare) {
+		return ParsedWorktreeRef{
+			Type:        WorktreeMain,
+			BareRefName: bare,
+		}
+	}
+
+	if isCurrentWorktreeRef(name) {
+		return ParsedWorktreeRef{
+			Type:        WorktreeCurrent,
+			BareRefName: name,
+		}
+	}
+
+	return ParsedWorktreeRef{
+		Type:        WorktreeShared,
+		BareRefName: name,
+	}
+}