gotosocial/vendor/go.mongodb.org/mongo-driver/bson/bsoncodec/pointer_codec.go

109 lines
3.2 KiB
Go

// 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 (
"reflect"
"go.mongodb.org/mongo-driver/bson/bsonrw"
"go.mongodb.org/mongo-driver/bson/bsontype"
)
var _ ValueEncoder = &PointerCodec{}
var _ ValueDecoder = &PointerCodec{}
// PointerCodec is the Codec used for pointers.
//
// Deprecated: PointerCodec will not be directly accessible in Go Driver 2.0. To
// override the default pointer encode and decode behavior, create a new registry
// with [go.mongodb.org/mongo-driver/bson.NewRegistry] and register a new
// encoder and decoder for pointers.
//
// For example,
//
// reg := bson.NewRegistry()
// reg.RegisterKindEncoder(reflect.Ptr, myPointerEncoder)
// reg.RegisterKindDecoder(reflect.Ptr, myPointerDecoder)
type PointerCodec struct {
ecache typeEncoderCache
dcache typeDecoderCache
}
// NewPointerCodec returns a PointerCodec that has been initialized.
//
// Deprecated: NewPointerCodec will not be available in Go Driver 2.0. See
// [PointerCodec] for more details.
func NewPointerCodec() *PointerCodec {
return &PointerCodec{}
}
// EncodeValue handles encoding a pointer by either encoding it to BSON Null if the pointer is nil
// or looking up an encoder for the type of value the pointer points to.
func (pc *PointerCodec) EncodeValue(ec EncodeContext, vw bsonrw.ValueWriter, val reflect.Value) error {
if val.Kind() != reflect.Ptr {
if !val.IsValid() {
return vw.WriteNull()
}
return ValueEncoderError{Name: "PointerCodec.EncodeValue", Kinds: []reflect.Kind{reflect.Ptr}, Received: val}
}
if val.IsNil() {
return vw.WriteNull()
}
typ := val.Type()
if v, ok := pc.ecache.Load(typ); ok {
if v == nil {
return ErrNoEncoder{Type: typ}
}
return v.EncodeValue(ec, vw, val.Elem())
}
// TODO(charlie): handle concurrent requests for the same type
enc, err := ec.LookupEncoder(typ.Elem())
enc = pc.ecache.LoadOrStore(typ, enc)
if err != nil {
return err
}
return enc.EncodeValue(ec, vw, val.Elem())
}
// DecodeValue handles decoding a pointer by looking up a decoder for the type it points to and
// using that to decode. If the BSON value is Null, this method will set the pointer to nil.
func (pc *PointerCodec) DecodeValue(dc DecodeContext, vr bsonrw.ValueReader, val reflect.Value) error {
if !val.CanSet() || val.Kind() != reflect.Ptr {
return ValueDecoderError{Name: "PointerCodec.DecodeValue", Kinds: []reflect.Kind{reflect.Ptr}, Received: val}
}
typ := val.Type()
if vr.Type() == bsontype.Null {
val.Set(reflect.Zero(typ))
return vr.ReadNull()
}
if vr.Type() == bsontype.Undefined {
val.Set(reflect.Zero(typ))
return vr.ReadUndefined()
}
if val.IsNil() {
val.Set(reflect.New(typ.Elem()))
}
if v, ok := pc.dcache.Load(typ); ok {
if v == nil {
return ErrNoDecoder{Type: typ}
}
return v.DecodeValue(dc, vr, val.Elem())
}
// TODO(charlie): handle concurrent requests for the same type
dec, err := dc.LookupDecoder(typ.Elem())
dec = pc.dcache.LoadOrStore(typ, dec)
if err != nil {
return err
}
return dec.DecodeValue(dc, vr, val.Elem())
}