Function rebindChild

pointer.go:320–362

rebindChild writes newChild back into node at decodedToken. For cases where the child was already mutated in place (pointer aliasing, addressable slice elements) the rebind is a safe no-op. For cases where the child was returned by value (map entries holding a slice, slices reached through a non-a

(node any, decodedToken string, newChild any, nameProvider NameProvider)

// Parents implementing [JSONPointable] are left alone: they took ownership of the child via
// JSONLookup and did not opt into a JSONSet-based rebind on intermediate tokens.
func rebindChild(node any, decodedToken string, newChild any, nameProvider NameProvider) (any, error) {
	if _, ok := node.(JSONPointable); ok {
		return node, nil
	}

	rValue := reflect.Indirect(reflect.ValueOf(node))

	switch rValue.Kind() {
	case reflect.Struct:
		nm, ok := nameProvider.GetGoNameForType(rValue.Type(), decodedToken)
		if !ok {
			return node, fmt.Errorf("object has no field %q: %w", decodedToken, ErrPointer)
		}
		fld := rValue.FieldByName(nm)
		if !fld.CanSet() {
			return node, nil
		}
		assignReflectValue(fld, newChild)
		return node, nil

	case reflect.Map:
		rValue.SetMapIndex(reflect.ValueOf(decodedToken), reflect.ValueOf(newChild))
		return node, nil

	case reflect.Slice:
		if decodedToken == dashToken {
			return node, errDashIntermediate()
		}
		idx, err := strconv.Atoi(decodedToken)
		if err != nil {
			return node, errors.Join(err, ErrPointer)
		}
		elem := rValue.Index(idx)
		if !elem.CanSet() {
			return node, nil
		}
		assignReflectValue(elem, newChild)
		return node, nil

	default:
		return node, errInvalidReference(decodedToken)
	}
}

// assignReflectValue assigns src into dst, unwrapping a pointer when dst expects the pointee type.
//