add Parser.Subcommand and Parser.SubcommandNames

1 files changed, 37 insertions, 0 deletions

diff --git a/subcommand.go b/subcommand.go
new file mode 100644
index 0000000..b73e933
--- /dev/null
+++ b/subcommand.go
@@ -0,0 +1,37 @@
+package arg
+
+// Subcommand returns the user struct for the subcommand selected by
+// the command line arguments most recently processed by the parser.
+// The return value is always a pointer to a struct. If no subcommand
+// was specified then it returns the top-level arguments struct. If
+// no command line arguments have been processed by this parser then it
+// returns nil.
+func (p *Parser) Subcommand() interface{} {
+	if p.lastCmd == nil || p.lastCmd.parent == nil {
+		return nil
+	}
+	return p.readable(p.lastCmd.dest).Interface()
+}
+
+// SubcommandNames returns the sequence of subcommands specified by the
+// user. If no subcommands were given then it returns an empty slice.
+func (p *Parser) SubcommandNames() []string {
+	if p.lastCmd == nil {
+		return nil
+	}
+
+	// make a list of ancestor commands
+	var ancestors []string
+	cur := p.lastCmd
+	for cur.parent != nil { // we want to exclude the root
+		ancestors = append(ancestors, cur.name)
+		cur = cur.parent
+	}
+
+	// reverse the list
+	out := make([]string, len(ancestors))
+	for i := 0; i < len(ancestors); i++ {
+		out[i] = ancestors[len(ancestors)-i-1]
+	}
+	return out
+}