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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 driver
import (
"context"
"errors"
"io"
"strings"
"go.mongodb.org/mongo-driver/x/bsonx/bsoncore"
)
// ListCollectionsBatchCursor is a special batch cursor returned from ListCollections that properly
// handles current and legacy ListCollections operations.
type ListCollectionsBatchCursor struct {
legacy bool // server version < 3.0
bc *BatchCursor
currentBatch *bsoncore.DocumentSequence
err error
}
// NewListCollectionsBatchCursor creates a new non-legacy ListCollectionsCursor.
func NewListCollectionsBatchCursor(bc *BatchCursor) (*ListCollectionsBatchCursor, error) {
if bc == nil {
return nil, errors.New("batch cursor must not be nil")
}
return &ListCollectionsBatchCursor{bc: bc, currentBatch: new(bsoncore.DocumentSequence)}, nil
}
// NewLegacyListCollectionsBatchCursor creates a new legacy ListCollectionsCursor.
func NewLegacyListCollectionsBatchCursor(bc *BatchCursor) (*ListCollectionsBatchCursor, error) {
if bc == nil {
return nil, errors.New("batch cursor must not be nil")
}
return &ListCollectionsBatchCursor{legacy: true, bc: bc, currentBatch: new(bsoncore.DocumentSequence)}, nil
}
// ID returns the cursor ID for this batch cursor.
func (lcbc *ListCollectionsBatchCursor) ID() int64 {
return lcbc.bc.ID()
}
// Next indicates if there is another batch available. Returning false does not necessarily indicate
// that the cursor is closed. This method will return false when an empty batch is returned.
//
// If Next returns true, there is a valid batch of documents available. If Next returns false, there
// is not a valid batch of documents available.
func (lcbc *ListCollectionsBatchCursor) Next(ctx context.Context) bool {
if !lcbc.bc.Next(ctx) {
return false
}
if !lcbc.legacy {
lcbc.currentBatch.Style = lcbc.bc.currentBatch.Style
lcbc.currentBatch.Data = lcbc.bc.currentBatch.Data
lcbc.currentBatch.ResetIterator()
return true
}
lcbc.currentBatch.Style = bsoncore.SequenceStyle
lcbc.currentBatch.Data = lcbc.currentBatch.Data[:0]
var doc bsoncore.Document
for {
doc, lcbc.err = lcbc.bc.currentBatch.Next()
if lcbc.err != nil {
if lcbc.err == io.EOF {
lcbc.err = nil
break
}
return false
}
doc, lcbc.err = lcbc.projectNameElement(doc)
if lcbc.err != nil {
return false
}
lcbc.currentBatch.Data = append(lcbc.currentBatch.Data, doc...)
}
return true
}
// Batch will return a DocumentSequence for the current batch of documents. The returned
// DocumentSequence is only valid until the next call to Next or Close.
func (lcbc *ListCollectionsBatchCursor) Batch() *bsoncore.DocumentSequence { return lcbc.currentBatch }
// Server returns a pointer to the cursor's server.
func (lcbc *ListCollectionsBatchCursor) Server() Server { return lcbc.bc.server }
// Err returns the latest error encountered.
func (lcbc *ListCollectionsBatchCursor) Err() error {
if lcbc.err != nil {
return lcbc.err
}
return lcbc.bc.Err()
}
// Close closes this batch cursor.
func (lcbc *ListCollectionsBatchCursor) Close(ctx context.Context) error { return lcbc.bc.Close(ctx) }
// project out the database name for a legacy server
func (*ListCollectionsBatchCursor) projectNameElement(rawDoc bsoncore.Document) (bsoncore.Document, error) {
elems, err := rawDoc.Elements()
if err != nil {
return nil, err
}
var filteredElems []byte
for _, elem := range elems {
key := elem.Key()
if key != "name" {
filteredElems = append(filteredElems, elem...)
continue
}
name := elem.Value().StringValue()
collName := name[strings.Index(name, ".")+1:]
filteredElems = bsoncore.AppendStringElement(filteredElems, "name", collName)
}
var filteredDoc []byte
filteredDoc = bsoncore.BuildDocument(filteredDoc, filteredElems)
return filteredDoc, nil
}
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