func marshalMap()

in marshal.go [1886:1947]
52 lines of code
16 McCabe index (conditional complexity)

func marshalMap(info TypeInfo, value interface{}) ([]byte, error) {
	mapInfo, ok := info.(CollectionType)
	if !ok {
		return nil, marshalErrorf("marshal: can not marshal none collection type into map")
	}

	if value == nil {
		return nil, nil
	} else if _, ok := value.(unsetColumn); ok {
		return nil, nil
	}

	rv := reflect.ValueOf(value)

	t := rv.Type()
	if t.Kind() != reflect.Map {
		return nil, marshalErrorf("can not marshal %T into %s", value, info)
	}

	if rv.IsNil() {
		return nil, nil
	}

	buf := &bytes.Buffer{}
	n := rv.Len()

	if err := writeCollectionSize(mapInfo, n, buf); err != nil {
		return nil, err
	}

	keys := rv.MapKeys()
	for _, key := range keys {
		item, err := Marshal(mapInfo.Key, key.Interface())
		if err != nil {
			return nil, err
		}
		itemLen := len(item)
		// Set the key to null for supported protocols
		if item == nil && mapInfo.proto > protoVersion2 {
			itemLen = -1
		}
		if err := writeCollectionSize(mapInfo, itemLen, buf); err != nil {
			return nil, err
		}
		buf.Write(item)

		item, err = Marshal(mapInfo.Elem, rv.MapIndex(key).Interface())
		if err != nil {
			return nil, err
		}
		itemLen = len(item)
		// Set the value to null for supported protocols
		if item == nil && mapInfo.proto > protoVersion2 {
			itemLen = -1
		}
		if err := writeCollectionSize(mapInfo, itemLen, buf); err != nil {
			return nil, err
		}
		buf.Write(item)
	}
	return buf.Bytes(), nil
}