Function parsePositionalArguments

api/rpc/json.go:286–319

parsePositionalArguments tries to parse the given args to an array of values with the given types. It returns the parsed values or an error when the args could not be parsed. Missing optional arguments are returned as reflect.Zero values.

(rawArgs json.RawMessage, types []reflect.Type)

// given types. It returns the parsed values or an error when the args could not be
// parsed. Missing optional arguments are returned as reflect.Zero values.
func parsePositionalArguments(rawArgs json.RawMessage, types []reflect.Type) ([]reflect.Value, Error) {
	// Read beginning of the args array.
	dec := json.NewDecoder(bytes.NewReader(rawArgs))
	if tok, _ := dec.Token(); tok != json.Delim('[') {
		return nil, &invalidParamsError{"non-array args"}
	}
	// Read args.
	args := make([]reflect.Value, 0, len(types))
	for i := 0; dec.More(); i++ {
		if i >= len(types) {
			return nil, &invalidParamsError{fmt.Sprintf("too many arguments, want at most %d", len(types))}
		}
		argval := reflect.New(types[i])
		if err := dec.Decode(argval.Interface()); err != nil {
			return nil, &invalidParamsError{fmt.Sprintf("invalid argument %d: %v", i, err)}
		}
		if argval.IsNil() && types[i].Kind() != reflect.Ptr {
			return nil, &invalidParamsError{fmt.Sprintf("missing value for required argument %d", i)}
		}
		args = append(args, argval.Elem())
	}
	// Read end of args array.
	if _, err := dec.Token(); err != nil {
		return nil, &invalidParamsError{err.Error()}
	}
	// Set any missing args to nil.
	for i := len(args); i < len(types); i++ {
		if types[i].Kind() != reflect.Ptr {
			return nil, &invalidParamsError{fmt.Sprintf("missing value for required argument %d", i)}
		}
		args = append(args, reflect.Zero(types[i]))
	}
	return args, nil
}

// CreateResponse will create a JSON-RPC success response with the given id and reply as result.
func (c *jsonCodec) CreateResponse(id interface{}, reply interface{}) interface{} {