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// Copyright (C) MongoDB, Inc. 2023-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 codecutil
import (
"bytes"
"errors"
"fmt"
"io"
"reflect"
"go.mongodb.org/mongo-driver/bson"
"go.mongodb.org/mongo-driver/x/bsonx/bsoncore"
)
var ErrNilValue = errors.New("value is nil")
// MarshalError is returned when attempting to transform a value into a document
// results in an error.
type MarshalError struct {
Value interface{}
Err error
}
// Error implements the error interface.
func (e MarshalError) Error() string {
return fmt.Sprintf("cannot transform type %s to a BSON Document: %v",
reflect.TypeOf(e.Value), e.Err)
}
// EncoderFn is used to functionally construct an encoder for marshaling values.
type EncoderFn func(io.Writer) (*bson.Encoder, error)
// MarshalValue will attempt to encode the value with the encoder returned by
// the encoder function.
func MarshalValue(val interface{}, encFn EncoderFn) (bsoncore.Value, error) {
// If the val is already a bsoncore.Value, then do nothing.
if bval, ok := val.(bsoncore.Value); ok {
return bval, nil
}
if val == nil {
return bsoncore.Value{}, ErrNilValue
}
buf := new(bytes.Buffer)
enc, err := encFn(buf)
if err != nil {
return bsoncore.Value{}, err
}
// Encode the value in a single-element document with an empty key. Use
// bsoncore to extract the first element and return the BSON value.
err = enc.Encode(bson.D{{Key: "", Value: val}})
if err != nil {
return bsoncore.Value{}, MarshalError{Value: val, Err: err}
}
return bsoncore.Document(buf.Bytes()).Index(0).Value(), nil
}
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