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package command
import (
"errors"
"log"
"os"
)
var (
ErrEmptyTree = errors.New("subcommand tree has no nodes")
ErrNoMatch = errors.New("did not match any subcommand")
)
func (n *node) Parse(arguments []string) error {
if n.usage == "" { // root node has zero length usage
if n.next != nil {
panic("invalid toplevel state")
}
goto match
}
if len(arguments) == 0 {
// unreachable: zero length args cause upper level to return with a help message
panic("attempted to parse with zero length args")
}
if arguments[0] != n.name {
if n.next == nil {
n.printf("%q is not a valid command", arguments[0])
return ErrNoMatch
}
n.next.prefix = n.prefix
return n.next.Parse(arguments)
}
arguments = arguments[1:]
match:
if n.child != nil {
// propagate help prefix early: flag set usage dereferences help
n.child.prefix = append(n.prefix, n.name)
}
if n.set.Parsed() {
panic("invalid set state")
}
if err := n.set.Parse(arguments); err != nil {
return FlagError{err}
}
args := n.set.Args()
if n.child != nil {
if n.f != nil {
if n.usage != "" { // root node early special case
panic("invalid subcommand tree state")
}
// special case: root node calls HandlerFunc for initialisation
if err := n.f(nil); err != nil {
return err
}
}
if len(args) == 0 {
return n.writeHelp()
}
return n.child.Parse(args)
}
if n.f == nil {
n.printf("%q has no subcommands", n.name)
return ErrEmptyTree
}
return n.f(args)
}
func (n *node) printf(format string, a ...any) {
if n.logf == nil {
log.Printf(format, a...)
} else {
n.logf(format, a...)
}
}
func (n *node) MustParse(arguments []string, handleError func(error)) {
switch err := n.Parse(arguments); err {
case nil:
return
case ErrHelp:
os.Exit(0)
case ErrNoMatch:
os.Exit(1)
case ErrEmptyTree:
os.Exit(1)
default:
flagError, ok := errors.AsType[FlagError](err)
if !ok { // returned by HandlerFunc
handleError(err)
os.Exit(1)
}
if flagError.Success() {
os.Exit(0)
}
os.Exit(1)
}
}
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