89 lines
2.4 KiB
Go
89 lines
2.4 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 bson
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import (
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"reflect"
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)
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var (
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_ ValueEncoder = &pointerCodec{}
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_ ValueDecoder = &pointerCodec{}
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)
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// pointerCodec is the Codec used for pointers.
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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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// 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 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 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() == TypeNull {
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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() == TypeUndefined {
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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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