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// Copyright (C) MongoDB, Inc. 2017-present.
//
// Licensed under the Apache License, Version 2.0 (the "License"); you may
// not use this file except in compliance with the License. You may obtain
// a copy of the License at http://www.apache.org/licenses/LICENSE-2.0
package bson
import (
"errors"
"reflect"
"sync"
"go.mongodb.org/mongo-driver/bson/bsoncodec"
"go.mongodb.org/mongo-driver/bson/bsonrw"
)
// This pool is used to keep the allocations of Encoders down. This is only used for the Marshal*
// methods and is not consumable from outside of this package. The Encoders retrieved from this pool
// must have both Reset and SetRegistry called on them.
var encPool = sync.Pool{
New: func() interface{} {
return new(Encoder)
},
}
// An Encoder writes a serialization format to an output stream. It writes to a bsonrw.ValueWriter
// as the destination of BSON data.
type Encoder struct {
ec bsoncodec.EncodeContext
vw bsonrw.ValueWriter
}
// NewEncoder returns a new encoder that uses the DefaultRegistry to write to vw.
func NewEncoder(vw bsonrw.ValueWriter) (*Encoder, error) {
if vw == nil {
return nil, errors.New("cannot create a new Encoder with a nil ValueWriter")
}
return &Encoder{
ec: bsoncodec.EncodeContext{Registry: DefaultRegistry},
vw: vw,
}, nil
}
// NewEncoderWithContext returns a new encoder that uses EncodeContext ec to write to vw.
func NewEncoderWithContext(ec bsoncodec.EncodeContext, vw bsonrw.ValueWriter) (*Encoder, error) {
if ec.Registry == nil {
ec = bsoncodec.EncodeContext{Registry: DefaultRegistry}
}
if vw == nil {
return nil, errors.New("cannot create a new Encoder with a nil ValueWriter")
}
return &Encoder{
ec: ec,
vw: vw,
}, nil
}
// Encode writes the BSON encoding of val to the stream.
//
// The documentation for Marshal contains details about the conversion of Go
// values to BSON.
func (e *Encoder) Encode(val interface{}) error {
if marshaler, ok := val.(Marshaler); ok {
// TODO(skriptble): Should we have a MarshalAppender interface so that we can have []byte reuse?
buf, err := marshaler.MarshalBSON()
if err != nil {
return err
}
return bsonrw.Copier{}.CopyDocumentFromBytes(e.vw, buf)
}
encoder, err := e.ec.LookupEncoder(reflect.TypeOf(val))
if err != nil {
return err
}
return encoder.EncodeValue(e.ec, e.vw, reflect.ValueOf(val))
}
// Reset will reset the state of the encoder, using the same *EncodeContext used in
// the original construction but using vw.
func (e *Encoder) Reset(vw bsonrw.ValueWriter) error {
e.vw = vw
return nil
}
// SetRegistry replaces the current registry of the encoder with r.
func (e *Encoder) SetRegistry(r *bsoncodec.Registry) error {
e.ec.Registry = r
return nil
}
// SetContext replaces the current EncodeContext of the encoder with er.
func (e *Encoder) SetContext(ec bsoncodec.EncodeContext) error {
e.ec = ec
return nil
}
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