gitea/vendor/go.mongodb.org/mongo-driver/bson/bsoncodec/map_codec.go
2020-09-01 10:01:23 -04:00

207 lines
5.3 KiB
Go
Vendored

// Copyright (C) MongoDB, Inc. 2017-present.
//
// Licensed under the Apache License, Version 2.0 (the "License"); you may
// not use this file except in compliance with the License. You may obtain
// a copy of the License at http://www.apache.org/licenses/LICENSE-2.0
package bsoncodec
import (
"fmt"
"reflect"
"strconv"
"go.mongodb.org/mongo-driver/bson/bsonoptions"
"go.mongodb.org/mongo-driver/bson/bsonrw"
"go.mongodb.org/mongo-driver/bson/bsontype"
)
var defaultMapCodec = NewMapCodec()
// MapCodec is the Codec used for map values.
type MapCodec struct {
DecodeZerosMap bool
EncodeNilAsEmpty bool
}
var _ ValueCodec = &MapCodec{}
// NewMapCodec returns a MapCodec with options opts.
func NewMapCodec(opts ...*bsonoptions.MapCodecOptions) *MapCodec {
mapOpt := bsonoptions.MergeMapCodecOptions(opts...)
codec := MapCodec{}
if mapOpt.DecodeZerosMap != nil {
codec.DecodeZerosMap = *mapOpt.DecodeZerosMap
}
if mapOpt.EncodeNilAsEmpty != nil {
codec.EncodeNilAsEmpty = *mapOpt.EncodeNilAsEmpty
}
return &codec
}
// EncodeValue is the ValueEncoder for map[*]* types.
func (mc *MapCodec) EncodeValue(ec EncodeContext, vw bsonrw.ValueWriter, val reflect.Value) error {
if !val.IsValid() || val.Kind() != reflect.Map {
return ValueEncoderError{Name: "MapEncodeValue", Kinds: []reflect.Kind{reflect.Map}, Received: val}
}
if val.IsNil() && !mc.EncodeNilAsEmpty {
// If we have a nil map but we can't WriteNull, that means we're probably trying to encode
// to a TopLevel document. We can't currently tell if this is what actually happened, but if
// there's a deeper underlying problem, the error will also be returned from WriteDocument,
// so just continue. The operations on a map reflection value are valid, so we can call
// MapKeys within mapEncodeValue without a problem.
err := vw.WriteNull()
if err == nil {
return nil
}
}
dw, err := vw.WriteDocument()
if err != nil {
return err
}
return mc.mapEncodeValue(ec, dw, val, nil)
}
// mapEncodeValue handles encoding of the values of a map. The collisionFn returns
// true if the provided key exists, this is mainly used for inline maps in the
// struct codec.
func (mc *MapCodec) mapEncodeValue(ec EncodeContext, dw bsonrw.DocumentWriter, val reflect.Value, collisionFn func(string) bool) error {
elemType := val.Type().Elem()
encoder, err := ec.LookupEncoder(elemType)
if err != nil && elemType.Kind() != reflect.Interface {
return err
}
keys := val.MapKeys()
for _, key := range keys {
keyStr := fmt.Sprint(key)
if collisionFn != nil && collisionFn(keyStr) {
return fmt.Errorf("Key %s of inlined map conflicts with a struct field name", key)
}
currEncoder, currVal, lookupErr := defaultValueEncoders.lookupElementEncoder(ec, encoder, val.MapIndex(key))
if lookupErr != nil && lookupErr != errInvalidValue {
return lookupErr
}
vw, err := dw.WriteDocumentElement(keyStr)
if err != nil {
return err
}
if lookupErr == errInvalidValue {
err = vw.WriteNull()
if err != nil {
return err
}
continue
}
if enc, ok := currEncoder.(ValueEncoder); ok {
err = enc.EncodeValue(ec, vw, currVal)
if err != nil {
return err
}
continue
}
err = encoder.EncodeValue(ec, vw, currVal)
if err != nil {
return err
}
}
return dw.WriteDocumentEnd()
}
// DecodeValue is the ValueDecoder for map[string/decimal]* types.
func (mc *MapCodec) DecodeValue(dc DecodeContext, vr bsonrw.ValueReader, val reflect.Value) error {
if val.Kind() != reflect.Map || (!val.CanSet() && val.IsNil()) {
return ValueDecoderError{Name: "MapDecodeValue", Kinds: []reflect.Kind{reflect.Map}, Received: val}
}
switch vrType := vr.Type(); vrType {
case bsontype.Type(0), bsontype.EmbeddedDocument:
case bsontype.Null:
val.Set(reflect.Zero(val.Type()))
return vr.ReadNull()
default:
return fmt.Errorf("cannot decode %v into a %s", vrType, val.Type())
}
dr, err := vr.ReadDocument()
if err != nil {
return err
}
if val.IsNil() {
val.Set(reflect.MakeMap(val.Type()))
}
if val.Len() > 0 && mc.DecodeZerosMap {
clearMap(val)
}
eType := val.Type().Elem()
decoder, err := dc.LookupDecoder(eType)
if err != nil {
return err
}
if eType == tEmpty {
dc.Ancestor = val.Type()
}
keyType := val.Type().Key()
keyKind := keyType.Kind()
for {
key, vr, err := dr.ReadElement()
if err == bsonrw.ErrEOD {
break
}
if err != nil {
return err
}
k := reflect.ValueOf(key)
if keyType != tString {
switch keyKind {
case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64,
reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64,
reflect.Float32, reflect.Float64:
parsed, err := strconv.ParseFloat(k.String(), 64)
if err != nil {
return fmt.Errorf("Map key is defined to be a decimal type (%v) but got error %v", keyKind, err)
}
k = reflect.ValueOf(parsed)
case reflect.String: // if keyType wraps string
default:
return fmt.Errorf("BSON map must have string or decimal keys. Got:%v", val.Type())
}
k = k.Convert(keyType)
}
elem := reflect.New(eType).Elem()
err = decoder.DecodeValue(dc, vr, elem)
if err != nil {
return err
}
val.SetMapIndex(k, elem)
}
return nil
}
func clearMap(m reflect.Value) {
var none reflect.Value
for _, k := range m.MapKeys() {
m.SetMapIndex(k, none)
}
}