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100 lines
2.8 KiB
100 lines
2.8 KiB
// 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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"errors"
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"reflect"
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"sync"
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"go.mongodb.org/mongo-driver/bson/bsoncodec"
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"go.mongodb.org/mongo-driver/bson/bsonrw"
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)
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// This pool is used to keep the allocations of Encoders down. This is only used for the Marshal*
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// methods and is not consumable from outside of this package. The Encoders retrieved from this pool
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// must have both Reset and SetRegistry called on them.
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var encPool = sync.Pool{
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New: func() interface{} {
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return new(Encoder)
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},
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}
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// An Encoder writes a serialization format to an output stream. It writes to a bsonrw.ValueWriter
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// as the destination of BSON data.
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type Encoder struct {
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ec bsoncodec.EncodeContext
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vw bsonrw.ValueWriter
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}
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// NewEncoder returns a new encoder that uses the DefaultRegistry to write to vw.
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func NewEncoder(vw bsonrw.ValueWriter) (*Encoder, error) {
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if vw == nil {
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return nil, errors.New("cannot create a new Encoder with a nil ValueWriter")
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}
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return &Encoder{
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ec: bsoncodec.EncodeContext{Registry: DefaultRegistry},
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vw: vw,
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}, nil
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}
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// NewEncoderWithContext returns a new encoder that uses EncodeContext ec to write to vw.
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func NewEncoderWithContext(ec bsoncodec.EncodeContext, vw bsonrw.ValueWriter) (*Encoder, error) {
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if ec.Registry == nil {
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ec = bsoncodec.EncodeContext{Registry: DefaultRegistry}
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}
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if vw == nil {
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return nil, errors.New("cannot create a new Encoder with a nil ValueWriter")
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}
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return &Encoder{
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ec: ec,
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vw: vw,
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}, nil
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}
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// Encode writes the BSON encoding of val to the stream.
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//
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// The documentation for Marshal contains details about the conversion of Go
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// values to BSON.
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func (e *Encoder) Encode(val interface{}) error {
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if marshaler, ok := val.(Marshaler); ok {
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// TODO(skriptble): Should we have a MarshalAppender interface so that we can have []byte reuse?
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buf, err := marshaler.MarshalBSON()
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if err != nil {
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return err
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}
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return bsonrw.Copier{}.CopyDocumentFromBytes(e.vw, buf)
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}
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encoder, err := e.ec.LookupEncoder(reflect.TypeOf(val))
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if err != nil {
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return err
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}
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return encoder.EncodeValue(e.ec, e.vw, reflect.ValueOf(val))
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}
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// Reset will reset the state of the encoder, using the same *EncodeContext used in
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// the original construction but using vw.
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func (e *Encoder) Reset(vw bsonrw.ValueWriter) error {
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e.vw = vw
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return nil
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}
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// SetRegistry replaces the current registry of the encoder with r.
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func (e *Encoder) SetRegistry(r *bsoncodec.Registry) error {
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e.ec.Registry = r
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return nil
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}
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// SetContext replaces the current EncodeContext of the encoder with er.
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func (e *Encoder) SetContext(ec bsoncodec.EncodeContext) error {
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e.ec = ec
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return nil
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}
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