Function setSingleImpl

pointer.go:544–635

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

}

func setSingleImpl(node, data any, decodedToken string, nameProvider NameProvider) (any, error) {
	// check for nil to prevent panic when calling rValue.Type()
	if isNil(node) {
		return node, fmt.Errorf("cannot set field %q on nil value: %w", decodedToken, ErrPointer)
	}

	if ns, ok := node.(JSONSetable); ok {
		return node, ns.JSONSet(decodedToken, data)
	}

	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, fmt.Errorf("can't set struct field %s to %v: %w", nm, data, ErrPointer)
		}

		value := reflect.ValueOf(data)
		valueType := value.Type()
		assignedType := fld.Type()

		if !valueType.AssignableTo(assignedType) {
			return node, fmt.Errorf("can't set value with type %T to field %s with type %v: %w", data, nm, assignedType, ErrPointer)
		}

		fld.Set(value)

		return node, nil

	case reflect.Map:
		kv := reflect.ValueOf(decodedToken)
		rValue.SetMapIndex(kv, reflect.ValueOf(data))

		return node, nil

	case reflect.Slice:
		if decodedToken == dashToken {
			// RFC 6901 §4 / RFC 6902 append semantics: terminal "-" appends the value to the slice.
			//
			// We rebind in place when the slice is reachable via an addressable ancestor; otherwise we
			// return the new slice header for the parent (or the public Set) to rebind.
			value := reflect.ValueOf(data)
			elemType := rValue.Type().Elem()
			if !value.Type().AssignableTo(elemType) {
				return node, fmt.Errorf("can't append value of type %T to slice of %v: %w", data, elemType, ErrPointer)
			}
			newSlice := reflect.Append(rValue, value)
			if rValue.CanSet() {
				rValue.Set(newSlice)
				return node, nil
			}