Golang Value.MapKeys方法代码示例

func (e *encodeState) writeMap(v reflect.Value, topLevel bool) {
	if v.IsNil() {
		return
	}
	if v.Type().Key().Kind() != reflect.String {
		abort(&EncodeTypeError{v.Type()})
	}
	offset := e.beginDoc()
	skipId := false
	if topLevel {
		idValue := v.MapIndex(idKey)
		if idValue.IsValid() {
			skipId = true
			e.encodeValue("_id", defaultFieldInfo, idValue)
		}
	}
	for _, k := range v.MapKeys() {
		sk := k.String()
		if !skipId || sk != "_id" {
			e.encodeValue(sk, defaultFieldInfo, v.MapIndex(k))
		}
	}
	e.WriteByte(0)
	e.endDoc(offset)
}

func (e *Encoder) encodeMap(av *dynamodb.AttributeValue, v reflect.Value, fieldTag tag) error {
	av.M = map[string]*dynamodb.AttributeValue{}
	for _, key := range v.MapKeys() {
		keyName := fmt.Sprint(key.Interface())
		if keyName == "" {
			return &InvalidMarshalError{msg: "map key cannot be empty"}
		}

		elemVal := v.MapIndex(key)
		elem := &dynamodb.AttributeValue{}
		err := e.encode(elem, elemVal, tag{})
		skip, err := keepOrOmitEmpty(fieldTag.OmitEmptyElem, elem, err)
		if err != nil {
			return err
		} else if skip {
			continue
		}

		av.M[keyName] = elem
	}
	if len(av.M) == 0 {
		encodeNull(av)
	}

	return nil
}

func convertMapToCFDictionaryHelper(m reflect.Value, helper func(reflect.Value) (cfTypeRef, error)) (C.CFDictionaryRef, error) {
	// assume m is a map, because our caller already checked
	if m.Type().Key().Kind() != reflect.String {
		// the map keys aren't strings
		return nil, &UnsupportedTypeError{m.Type()}
	}
	mapKeys := m.MapKeys()
	keys := make([]cfTypeRef, len(mapKeys))
	values := make([]cfTypeRef, len(mapKeys))
	// defer the release
	defer func() {
		for _, cfKey := range keys {
			cfRelease(cfTypeRef(cfKey))
		}
		for _, cfVal := range values {
			cfRelease(cfTypeRef(cfVal))
		}
	}()
	// create the keys and values slices
	for i, keyVal := range mapKeys {
		// keyVal is a Value representing a string
		cfStr := convertStringToCFString(keyVal.String())
		if cfStr == nil {
			return nil, errors.New("plist: could not convert string to CFStringRef")
		}
		keys[i] = cfTypeRef(cfStr)
		cfObj, err := helper(m.MapIndex(keyVal))
		if err != nil {
			return nil, err
		}
		values[i] = cfObj
	}
	return createCFDictionary(keys, values), nil
}

func (me *mapEncoder) encode(e *encodeState, v reflect.Value, opts encOpts) {
	if v.IsNil() {
		e.WriteString("null")
		return
	}
	e.WriteByte('{')

	// Extract and sort the keys.
	keys := v.MapKeys()
	sv := make([]reflectWithString, len(keys))
	for i, v := range keys {
		sv[i].v = v
		if err := sv[i].resolve(); err != nil {
			e.error(&MarshalerError{v.Type(), err})
		}
	}
	sort.Sort(byString(sv))

	for i, kv := range sv {
		if i > 0 {
			e.WriteByte(',')
		}
		e.string(kv.s, opts.escapeHTML)
		e.WriteByte(':')
		me.elemEnc(e, v.MapIndex(kv.v), opts)
	}
	e.WriteByte('}')
}

// decodeObjectInterface decodes the source value into map[string]interface{}
func decodeObjectInterface(s *decodeState, sv reflect.Value) map[string]interface{} {
	m := map[string]interface{}{}
	for _, key := range sv.MapKeys() {
		m[key.Interface().(string)] = decodeInterface(s, sv.MapIndex(key))
	}
	return m
}

func writeMap(w io.Writer, val reflect.Value) (err error) {
	key := val.Type().Key()
	if key.Kind() != reflect.String {
		return &MarshalError{val.Type()}
	}
	_, err = fmt.Fprint(w, "d")
	if err != nil {
		return
	}

	keys := val.MapKeys()

	// Sort keys

	svList := make(stringValueArray, len(keys))
	for i, key := range keys {
		svList[i].key = key.String()
		svList[i].value = val.MapIndex(key)
	}

	err = writeSVList(w, svList)
	if err != nil {
		return
	}

	_, err = fmt.Fprint(w, "e")
	if err != nil {
		return
	}
	return
}

// Validate checks whether the given value is writeable to this schema.
func (*NullSchema) Validate(v reflect.Value) bool {
	// Check if the value is something that can be null
	switch v.Kind() {
	case reflect.Interface:
		return v.IsNil()
	case reflect.Array:
		return v.Cap() == 0
	case reflect.Slice:
		return v.IsNil() || v.Cap() == 0
	case reflect.Map:
		return len(v.MapKeys()) == 0
	case reflect.String:
		return len(v.String()) == 0
	case reflect.Float32:
		// Should NaN floats be treated as null?
		return math.IsNaN(v.Float())
	case reflect.Float64:
		// Should NaN floats be treated as null?
		return math.IsNaN(v.Float())
	case reflect.Ptr:
		return v.IsNil()
	case reflect.Invalid:
		return true
	}

	// Nothing else in particular, so this should not validate?
	return false
}

func printMap(w io.Writer, tv reflect.Value, depth string) {
	fmt.Fprintf(w, "{\n")
	ss := make(sort.StringSlice, tv.Len())
	i := 0
	for _, kval := range tv.MapKeys() {
		if kval.Kind() == reflect.Interface {
			kval = kval.Elem()
		}

		if kval.Kind() != reflect.String {
			continue
		}

		ss[i] = kval.String()
		i++
	}
	sort.Sort(ss)
	for _, k := range ss {
		val := tv.MapIndex(reflect.ValueOf(k))
		v := val.Interface()
		nd := depth + "  "
		for i := 0; i < len(k)+2; i++ {
			nd += " "
		}
		fmt.Fprintf(w, "  %s%s: ", depth, k)
		printValue(w, v, nd)
	}
	fmt.Fprintf(w, "%s}\n", depth)
}

func reflectMap(v reflect.Value) map[interface{}]interface{} {
	switch v.Kind() {
	case reflect.Struct:
		m := map[interface{}]interface{}{}
		for i := 0; i < v.NumField(); i++ {
			sf := v.Type().Field(i)
			if sf.PkgPath != "" && !sf.Anonymous {
				continue // unexported
			}

			k := sf.Name
			v := v.Field(i).Interface()

			m[k] = v
		}
		return m
	case reflect.Map:
		m := map[interface{}]interface{}{}
		for _, mk := range v.MapKeys() {
			k := ""
			if mk.Interface() != nil {
				k = fmt.Sprintf("%v", mk.Interface())
			}
			v := v.MapIndex(mk).Interface()

			m[k] = v
		}
		return m
	default:
		return nil
	}
}

func deepCopyMap(src, dst reflect.Value, t reflect.Type) {
	for _, key := range src.MapKeys() {
		var nkey, nval reflect.Value
		if key.IsValid() && key.CanSet() {
			if key.Kind() == reflect.Ptr {
				nkey = reflect.New(key.Elem().Type())
			} else {
				nkey = reflect.New(key.Type())
				nkey = reflect.Indirect(nkey)
			}
			s := reflect.Indirect(key)
			d := reflect.Indirect(nkey)
			tt := s.Type()
			deepCopy(s, d, tt)
		} else {
			nkey = key
		}
		if val := src.MapIndex(key); val.IsValid() && val.CanSet() {
			if val.Kind() == reflect.Ptr {
				nval = reflect.New(val.Elem().Type())
			} else {
				nval = reflect.New(val.Type())
				nval = reflect.Indirect(nval)
			}
			s := reflect.Indirect(val)
			d := reflect.Indirect(nval)
			tt := s.Type()
			deepCopy(s, d, tt)
		} else {
			nval = val
		}
		dst.SetMapIndex(nkey, nval)
	}
}

func (m Master) retrieveValues(db *sql.DB, rv reflect.Value, cfgs ...interface{}) (idField reflect.Value, fields []string, holders []string, values []interface{}, table string, err error) {
	table = strings.ToLower(rv.Type().Name()) + "s"
	// var insertNull bool
	for _, c := range cfgs {
		switch c.(type) {
		// case InsertNull:
		// 	insertNull = true
		case TableName:
			table = string(c.(TableName))
		}
	}

	// _ = insertNull
	switch rv.Kind() {
	case reflect.Struct:
		idField, fields, holders, values, err = m.walkStruct(rv)
	case reflect.Map:
		if rv.Type().Key().Kind() != reflect.String {
			err = fmt.Errorf("sqlkungfu: Insert(map key is %s, want string)", rv.Type().Key().Kind())
			return
		}
		for _, k := range rv.MapKeys() {
			fields = append(fields, m.quoteColumn(k.String()))
			holders = append(holders, "?")
			values = append(values, rv.MapIndex(k).Interface())
		}
	}
	return
}

//AnySettableValue find if exist one value that you can set.
func AnySettableValue(val reflect.Value) bool {
	switch val.Kind() {
	case reflect.Array:
		for i := 0; i < val.Type().Len(); i++ {
			if AnySettableValue(val.Index(i)) {
				return true
			}
		}
	case reflect.Interface:
		return AnySettableValue(val.Elem())
	case reflect.Map:
		for _, key := range val.MapKeys() {
			if AnySettableValue(val.MapIndex(key)) {
				return true
			}
		}
	case reflect.Ptr:
		return AnySettableValue(val.Elem())
	case reflect.Slice:
		for i := 0; i < val.Len(); i++ {
			if AnySettableValue(val.Index(i)) {
				return true
			}
		}
	case reflect.Struct:
		for i := 0; i < val.Type().NumField(); i++ {
			if AnySettableValue(val.Field(i)) {
				return true
			}
		}
	default:
		return val.CanSet()
	}
	return false
}

func valEq(t *testing.T, name string, actual, expected reflect.Value) {
	switch expected.Kind() {
	case reflect.Slice:
		// Check the type/length/element type
		if !eq(t, name+" (type)", actual.Kind(), expected.Kind()) ||
			!eq(t, name+" (len)", actual.Len(), expected.Len()) ||
			!eq(t, name+" (elem)", actual.Type().Elem(), expected.Type().Elem()) {
			return
		}

		// Check value equality for each element.
		for i := 0; i < actual.Len(); i++ {
			valEq(t, fmt.Sprintf("%s[%d]", name, i), actual.Index(i), expected.Index(i))
		}

	case reflect.Ptr:
		// Check equality on the element type.
		valEq(t, name, actual.Elem(), expected.Elem())
	case reflect.Map:
		if !eq(t, name+" (len)", actual.Len(), expected.Len()) {
			return
		}
		for _, key := range expected.MapKeys() {
			expectedValue := expected.MapIndex(key)
			actualValue := actual.MapIndex(key)
			if actualValue.IsValid() {
				valEq(t, fmt.Sprintf("%s[%s]", name, key), actualValue, expectedValue)
			} else {
				t.Errorf("Expected key %s not found", key)
			}
		}
	default:
		eq(t, name, actual.Interface(), expected.Interface())
	}
}

func (e *Encoder) encodeMap(by []byte, m reflect.Value, strTable map[string]int, ptrTable map[uintptr]int) []byte {

	keys := m.MapKeys()

	l := len(keys)

	by = append(by, typeHASH)
	by = varint(by, uint(l))

	if e.PerlCompat {
		for _, k := range keys {
			by = e.encodeString(by, k.String(), true, strTable)
			v := m.MapIndex(k)
			by = e.encodeScalar(by, v, false, strTable, ptrTable)
		}
	} else {
		for _, k := range keys {
			by, _ = e.encode(by, k, true, strTable, ptrTable)
			v := m.MapIndex(k)
			by, _ = e.encode(by, v, false, strTable, ptrTable)
		}
	}

	return by
}

func approxDataSize(rv reflect.Value) (sum int) {
	switch rk := rv.Kind(); rk {
	case reflect.Invalid:
	case reflect.Ptr, reflect.Interface:
		sum += int(rv.Type().Size())
		sum += approxDataSize(rv.Elem())
	case reflect.Slice:
		sum += int(rv.Type().Size())
		for j := 0; j < rv.Len(); j++ {
			sum += approxDataSize(rv.Index(j))
		}
	case reflect.String:
		sum += int(rv.Type().Size())
		sum += rv.Len()
	case reflect.Map:
		sum += int(rv.Type().Size())
		for _, mk := range rv.MapKeys() {
			sum += approxDataSize(mk)
			sum += approxDataSize(rv.MapIndex(mk))
		}
	case reflect.Struct:
		//struct size already includes the full data size.
		//sum += int(rv.Type().Size())
		for j := 0; j < rv.NumField(); j++ {
			sum += approxDataSize(rv.Field(j))
		}
	default:
		//pure value types
		sum += int(rv.Type().Size())
	}
	return
}