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// 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"
"sync"
"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.
type PointerCodec struct {
ecache map[reflect.Type]ValueEncoder
dcache map[reflect.Type]ValueDecoder
l sync.RWMutex
}
// NewPointerCodec returns a PointerCodec that has been initialized.
func NewPointerCodec() *PointerCodec {
return &PointerCodec{
ecache: make(map[reflect.Type]ValueEncoder),
dcache: make(map[reflect.Type]ValueDecoder),
}
}
// 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()
}
pc.l.RLock()
enc, ok := pc.ecache[val.Type()]
pc.l.RUnlock()
if ok {
if enc == nil {
return ErrNoEncoder{Type: val.Type()}
}
return enc.EncodeValue(ec, vw, val.Elem())
}
enc, err := ec.LookupEncoder(val.Type().Elem())
pc.l.Lock()
pc.ecache[val.Type()] = enc
pc.l.Unlock()
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}
}
if vr.Type() == bsontype.Null {
val.Set(reflect.Zero(val.Type()))
return vr.ReadNull()
}
if vr.Type() == bsontype.Undefined {
val.Set(reflect.Zero(val.Type()))
return vr.ReadUndefined()
}
if val.IsNil() {
val.Set(reflect.New(val.Type().Elem()))
}
pc.l.RLock()
dec, ok := pc.dcache[val.Type()]
pc.l.RUnlock()
if ok {
if dec == nil {
return ErrNoDecoder{Type: val.Type()}
}
return dec.DecodeValue(dc, vr, val.Elem())
}
dec, err := dc.LookupDecoder(val.Type().Elem())
pc.l.Lock()
pc.dcache[val.Type()] = dec
pc.l.Unlock()
if err != nil {
return err
}
return dec.DecodeValue(dc, vr, val.Elem())
}
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