Don Newton | 379ae25 | 2019-04-01 12:17:06 -0400 | [diff] [blame^] | 1 | // Copyright (C) MongoDB, Inc. 2017-present. |
| 2 | // |
| 3 | // Licensed under the Apache License, Version 2.0 (the "License"); you may |
| 4 | // not use this file except in compliance with the License. You may obtain |
| 5 | // a copy of the License at http://www.apache.org/licenses/LICENSE-2.0 |
| 6 | |
| 7 | package bsoncodec |
| 8 | |
| 9 | import ( |
| 10 | "reflect" |
| 11 | "sync" |
| 12 | |
| 13 | "github.com/mongodb/mongo-go-driver/bson/bsonrw" |
| 14 | "github.com/mongodb/mongo-go-driver/bson/bsontype" |
| 15 | ) |
| 16 | |
| 17 | var defaultPointerCodec = &PointerCodec{ |
| 18 | ecache: make(map[reflect.Type]ValueEncoder), |
| 19 | dcache: make(map[reflect.Type]ValueDecoder), |
| 20 | } |
| 21 | |
| 22 | var _ ValueEncoder = &PointerCodec{} |
| 23 | var _ ValueDecoder = &PointerCodec{} |
| 24 | |
| 25 | // PointerCodec is the Codec used for pointers. |
| 26 | type PointerCodec struct { |
| 27 | ecache map[reflect.Type]ValueEncoder |
| 28 | dcache map[reflect.Type]ValueDecoder |
| 29 | l sync.RWMutex |
| 30 | } |
| 31 | |
| 32 | // NewPointerCodec returns a PointerCodec that has been initialized. |
| 33 | func NewPointerCodec() *PointerCodec { |
| 34 | return &PointerCodec{ |
| 35 | ecache: make(map[reflect.Type]ValueEncoder), |
| 36 | dcache: make(map[reflect.Type]ValueDecoder), |
| 37 | } |
| 38 | } |
| 39 | |
| 40 | // EncodeValue handles encoding a pointer by either encoding it to BSON Null if the pointer is nil |
| 41 | // or looking up an encoder for the type of value the pointer points to. |
| 42 | func (pc *PointerCodec) EncodeValue(ec EncodeContext, vw bsonrw.ValueWriter, val reflect.Value) error { |
| 43 | if val.Kind() != reflect.Ptr { |
| 44 | if !val.IsValid() { |
| 45 | return vw.WriteNull() |
| 46 | } |
| 47 | return ValueEncoderError{Name: "PointerCodec.EncodeValue", Kinds: []reflect.Kind{reflect.Ptr}, Received: val} |
| 48 | } |
| 49 | |
| 50 | if val.IsNil() { |
| 51 | return vw.WriteNull() |
| 52 | } |
| 53 | |
| 54 | pc.l.RLock() |
| 55 | enc, ok := pc.ecache[val.Type()] |
| 56 | pc.l.RUnlock() |
| 57 | if ok { |
| 58 | if enc == nil { |
| 59 | return ErrNoEncoder{Type: val.Type()} |
| 60 | } |
| 61 | return enc.EncodeValue(ec, vw, val.Elem()) |
| 62 | } |
| 63 | |
| 64 | enc, err := ec.LookupEncoder(val.Type().Elem()) |
| 65 | pc.l.Lock() |
| 66 | pc.ecache[val.Type()] = enc |
| 67 | pc.l.Unlock() |
| 68 | if err != nil { |
| 69 | return err |
| 70 | } |
| 71 | |
| 72 | return enc.EncodeValue(ec, vw, val.Elem()) |
| 73 | } |
| 74 | |
| 75 | // DecodeValue handles decoding a pointer by looking up a decoder for the type it points to and |
| 76 | // using that to decode. If the BSON value is Null, this method will set the pointer to nil. |
| 77 | func (pc *PointerCodec) DecodeValue(dc DecodeContext, vr bsonrw.ValueReader, val reflect.Value) error { |
| 78 | if !val.CanSet() || val.Kind() != reflect.Ptr { |
| 79 | return ValueDecoderError{Name: "PointerCodec.DecodeValue", Kinds: []reflect.Kind{reflect.Ptr}, Received: val} |
| 80 | } |
| 81 | |
| 82 | if vr.Type() == bsontype.Null { |
| 83 | val.Set(reflect.Zero(val.Type())) |
| 84 | return vr.ReadNull() |
| 85 | } |
| 86 | |
| 87 | if val.IsNil() { |
| 88 | val.Set(reflect.New(val.Type().Elem())) |
| 89 | } |
| 90 | |
| 91 | pc.l.RLock() |
| 92 | dec, ok := pc.dcache[val.Type()] |
| 93 | pc.l.RUnlock() |
| 94 | if ok { |
| 95 | if dec == nil { |
| 96 | return ErrNoDecoder{Type: val.Type()} |
| 97 | } |
| 98 | return dec.DecodeValue(dc, vr, val.Elem()) |
| 99 | } |
| 100 | |
| 101 | dec, err := dc.LookupDecoder(val.Type().Elem()) |
| 102 | pc.l.Lock() |
| 103 | pc.dcache[val.Type()] = dec |
| 104 | pc.l.Unlock() |
| 105 | if err != nil { |
| 106 | return err |
| 107 | } |
| 108 | |
| 109 | return dec.DecodeValue(dc, vr, val.Elem()) |
| 110 | } |