110 lines
2.8 KiB
Go
110 lines
2.8 KiB
Go
// Copyright (C) MongoDB, Inc. 2017-present.
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//
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// Licensed under the Apache License, Version 2.0 (the "License"); you may
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// not use this file except in compliance with the License. You may obtain
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// a copy of the License at http://www.apache.org/licenses/LICENSE-2.0
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package bsoncodec
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import (
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"reflect"
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"sync"
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"go.mongodb.org/mongo-driver/bson/bsonrw"
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"go.mongodb.org/mongo-driver/bson/bsontype"
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)
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var _ ValueEncoder = &PointerCodec{}
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var _ ValueDecoder = &PointerCodec{}
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// PointerCodec is the Codec used for pointers.
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type PointerCodec struct {
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ecache map[reflect.Type]ValueEncoder
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dcache map[reflect.Type]ValueDecoder
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l sync.RWMutex
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}
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// NewPointerCodec returns a PointerCodec that has been initialized.
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func NewPointerCodec() *PointerCodec {
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return &PointerCodec{
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ecache: make(map[reflect.Type]ValueEncoder),
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dcache: make(map[reflect.Type]ValueDecoder),
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}
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}
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// EncodeValue handles encoding a pointer by either encoding it to BSON Null if the pointer is nil
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// or looking up an encoder for the type of value the pointer points to.
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func (pc *PointerCodec) EncodeValue(ec EncodeContext, vw bsonrw.ValueWriter, val reflect.Value) error {
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if val.Kind() != reflect.Ptr {
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if !val.IsValid() {
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return vw.WriteNull()
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}
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return ValueEncoderError{Name: "PointerCodec.EncodeValue", Kinds: []reflect.Kind{reflect.Ptr}, Received: val}
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}
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if val.IsNil() {
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return vw.WriteNull()
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}
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pc.l.RLock()
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enc, ok := pc.ecache[val.Type()]
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pc.l.RUnlock()
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if ok {
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if enc == nil {
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return ErrNoEncoder{Type: val.Type()}
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}
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return enc.EncodeValue(ec, vw, val.Elem())
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}
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enc, err := ec.LookupEncoder(val.Type().Elem())
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pc.l.Lock()
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pc.ecache[val.Type()] = enc
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pc.l.Unlock()
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if err != nil {
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return err
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}
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return enc.EncodeValue(ec, vw, val.Elem())
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}
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// DecodeValue handles decoding a pointer by looking up a decoder for the type it points to and
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// using that to decode. If the BSON value is Null, this method will set the pointer to nil.
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func (pc *PointerCodec) DecodeValue(dc DecodeContext, vr bsonrw.ValueReader, val reflect.Value) error {
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if !val.CanSet() || val.Kind() != reflect.Ptr {
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return ValueDecoderError{Name: "PointerCodec.DecodeValue", Kinds: []reflect.Kind{reflect.Ptr}, Received: val}
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}
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if vr.Type() == bsontype.Null {
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val.Set(reflect.Zero(val.Type()))
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return vr.ReadNull()
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}
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if vr.Type() == bsontype.Undefined {
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val.Set(reflect.Zero(val.Type()))
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return vr.ReadUndefined()
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}
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if val.IsNil() {
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val.Set(reflect.New(val.Type().Elem()))
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}
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pc.l.RLock()
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dec, ok := pc.dcache[val.Type()]
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pc.l.RUnlock()
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if ok {
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if dec == nil {
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return ErrNoDecoder{Type: val.Type()}
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}
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return dec.DecodeValue(dc, vr, val.Elem())
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}
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dec, err := dc.LookupDecoder(val.Type().Elem())
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pc.l.Lock()
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pc.dcache[val.Type()] = dec
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pc.l.Unlock()
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if err != nil {
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return err
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}
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return dec.DecodeValue(dc, vr, val.Elem())
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}
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