func UnmarshalComposite()

in internal/encoding/decode.go [237:284]
36 lines of code
12 McCabe index (conditional complexity)

func UnmarshalComposite(r *buffer.Buffer, type_ AMQPType, fields ...UnmarshalField) error {
	cType, numFields, err := readCompositeHeader(r)
	if err != nil {
		return err
	}

	// check type matches expectation
	if cType != type_ {
		return fmt.Errorf("invalid header %#0x for %#0x", cType, type_)
	}

	// Validate the field count is less than or equal to the number of fields
	// provided. Fields may be omitted by the sender if they are not set.
	if numFields > int64(len(fields)) {
		return fmt.Errorf("invalid field count %d for %#0x", numFields, type_)
	}

	for i, field := range fields[:numFields] {
		// If the field is null and handleNull is set, call it.
		if tryReadNull(r) {
			if field.HandleNull != nil {
				err = field.HandleNull()
				if err != nil {
					return err
				}
			}
			continue
		}

		// Unmarshal each of the received fields.
		err = Unmarshal(r, field.Field)
		if err != nil {
			return fmt.Errorf("unmarshaling field %d: %v", i, err)
		}
	}

	// check and call handleNull for the remaining fields
	for _, field := range fields[numFields:] {
		if field.HandleNull != nil {
			err = field.HandleNull()
			if err != nil {
				return err
			}
		}
	}

	return nil
}