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200 lines
6.2 KiB
Go
200 lines
6.2 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 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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errorOnInlineDuplicates bool
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intMinSize bool
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stringifyMapKeysWithFmt bool
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nilMapAsEmpty bool
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nilSliceAsEmpty bool
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nilByteSliceAsEmpty bool
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omitZeroStruct bool
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useJSONStructTags bool
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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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// TODO:(GODRIVER-2719): Remove error return value.
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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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//
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// Deprecated: Use [NewEncoder] and use the Encoder configuration methods to set the desired marshal
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// behavior instead.
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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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// See [Marshal] for details about BSON marshaling behavior.
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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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// Copy the configurations applied to the Encoder over to the EncodeContext, which actually
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// communicates those configurations to the default ValueEncoders.
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if e.errorOnInlineDuplicates {
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e.ec.ErrorOnInlineDuplicates()
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}
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if e.intMinSize {
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e.ec.MinSize = true
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}
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if e.stringifyMapKeysWithFmt {
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e.ec.StringifyMapKeysWithFmt()
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}
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if e.nilMapAsEmpty {
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e.ec.NilMapAsEmpty()
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}
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if e.nilSliceAsEmpty {
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e.ec.NilSliceAsEmpty()
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}
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if e.nilByteSliceAsEmpty {
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e.ec.NilByteSliceAsEmpty()
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}
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if e.omitZeroStruct {
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e.ec.OmitZeroStruct()
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}
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if e.useJSONStructTags {
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e.ec.UseJSONStructTags()
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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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// TODO:(GODRIVER-2719): Remove error return value.
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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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// TODO:(GODRIVER-2719): Remove error return value.
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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 ec.
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//
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// Deprecated: Use the Encoder configuration methods set the desired marshal behavior instead.
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func (e *Encoder) SetContext(ec bsoncodec.EncodeContext) error {
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// TODO:(GODRIVER-2719): Remove error return value.
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e.ec = ec
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return nil
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}
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// ErrorOnInlineDuplicates causes the Encoder to return an error if there is a duplicate field in
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// the marshaled BSON when the "inline" struct tag option is set.
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func (e *Encoder) ErrorOnInlineDuplicates() {
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e.errorOnInlineDuplicates = true
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}
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// IntMinSize causes the Encoder to marshal Go integer values (int, int8, int16, int32, int64, uint,
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// uint8, uint16, uint32, or uint64) as the minimum BSON int size (either 32 or 64 bits) that can
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// represent the integer value.
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func (e *Encoder) IntMinSize() {
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e.intMinSize = true
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}
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// StringifyMapKeysWithFmt causes the Encoder to convert Go map keys to BSON document field name
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// strings using fmt.Sprint instead of the default string conversion logic.
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func (e *Encoder) StringifyMapKeysWithFmt() {
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e.stringifyMapKeysWithFmt = true
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}
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// NilMapAsEmpty causes the Encoder to marshal nil Go maps as empty BSON documents instead of BSON
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// null.
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func (e *Encoder) NilMapAsEmpty() {
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e.nilMapAsEmpty = true
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}
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// NilSliceAsEmpty causes the Encoder to marshal nil Go slices as empty BSON arrays instead of BSON
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// null.
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func (e *Encoder) NilSliceAsEmpty() {
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e.nilSliceAsEmpty = true
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}
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// NilByteSliceAsEmpty causes the Encoder to marshal nil Go byte slices as empty BSON binary values
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// instead of BSON null.
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func (e *Encoder) NilByteSliceAsEmpty() {
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e.nilByteSliceAsEmpty = true
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}
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// TODO(GODRIVER-2820): Update the description to remove the note about only examining exported
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// TODO struct fields once the logic is updated to also inspect private struct fields.
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// OmitZeroStruct causes the Encoder to consider the zero value for a struct (e.g. MyStruct{})
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// as empty and omit it from the marshaled BSON when the "omitempty" struct tag option is set.
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//
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// Note that the Encoder only examines exported struct fields when determining if a struct is the
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// zero value. It considers pointers to a zero struct value (e.g. &MyStruct{}) not empty.
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func (e *Encoder) OmitZeroStruct() {
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e.omitZeroStruct = true
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}
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// UseJSONStructTags causes the Encoder to fall back to using the "json" struct tag if a "bson"
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// struct tag is not specified.
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func (e *Encoder) UseJSONStructTags() {
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e.useJSONStructTags = true
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}
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