| // 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" |
| |
| "github.com/mongodb/mongo-go-driver/bson/bsonrw" |
| "github.com/mongodb/mongo-go-driver/bson/bsontype" |
| ) |
| |
| var defaultPointerCodec = &PointerCodec{ |
| ecache: make(map[reflect.Type]ValueEncoder), |
| dcache: make(map[reflect.Type]ValueDecoder), |
| } |
| |
| 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 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()) |
| } |