109 lines
3.2 KiB
Go
109 lines
3.2 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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"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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//
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// Deprecated: PointerCodec will not be directly accessible in Go Driver 2.0. To
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// override the default pointer encode and decode behavior, create a new registry
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// with [go.mongodb.org/mongo-driver/bson.NewRegistry] and register a new
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// encoder and decoder for pointers.
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//
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// For example,
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//
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// reg := bson.NewRegistry()
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// reg.RegisterKindEncoder(reflect.Ptr, myPointerEncoder)
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// reg.RegisterKindDecoder(reflect.Ptr, myPointerDecoder)
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type PointerCodec struct {
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ecache typeEncoderCache
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dcache typeDecoderCache
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}
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// NewPointerCodec returns a PointerCodec that has been initialized.
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//
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// Deprecated: NewPointerCodec will not be available in Go Driver 2.0. See
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// [PointerCodec] for more details.
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func NewPointerCodec() *PointerCodec {
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return &PointerCodec{}
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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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typ := val.Type()
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if v, ok := pc.ecache.Load(typ); ok {
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if v == nil {
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return ErrNoEncoder{Type: typ}
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}
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return v.EncodeValue(ec, vw, val.Elem())
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}
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// TODO(charlie): handle concurrent requests for the same type
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enc, err := ec.LookupEncoder(typ.Elem())
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enc = pc.ecache.LoadOrStore(typ, enc)
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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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typ := val.Type()
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if vr.Type() == bsontype.Null {
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val.Set(reflect.Zero(typ))
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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(typ))
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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(typ.Elem()))
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}
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if v, ok := pc.dcache.Load(typ); ok {
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if v == nil {
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return ErrNoDecoder{Type: typ}
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}
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return v.DecodeValue(dc, vr, val.Elem())
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}
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// TODO(charlie): handle concurrent requests for the same type
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dec, err := dc.LookupDecoder(typ.Elem())
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dec = pc.dcache.LoadOrStore(typ, dec)
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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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