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|
package bsoncore
import (
"errors"
"io"
"go.mongodb.org/mongo-driver/bson/bsontype"
)
// DocumentSequenceStyle is used to represent how a document sequence is laid out in a slice of
// bytes.
type DocumentSequenceStyle uint32
// These constants are the valid styles for a DocumentSequence.
const (
_ DocumentSequenceStyle = iota
SequenceStyle
ArrayStyle
)
// DocumentSequence represents a sequence of documents. The Style field indicates how the documents
// are laid out inside of the Data field.
type DocumentSequence struct {
Style DocumentSequenceStyle
Data []byte
Pos int
}
// ErrCorruptedDocument is returned when a full document couldn't be read from the sequence.
var ErrCorruptedDocument = errors.New("invalid DocumentSequence: corrupted document")
// ErrNonDocument is returned when a DocumentSequence contains a non-document BSON value.
var ErrNonDocument = errors.New("invalid DocumentSequence: a non-document value was found in sequence")
// ErrInvalidDocumentSequenceStyle is returned when an unknown DocumentSequenceStyle is set on a
// DocumentSequence.
var ErrInvalidDocumentSequenceStyle = errors.New("invalid DocumentSequenceStyle")
// DocumentCount returns the number of documents in the sequence.
func (ds *DocumentSequence) DocumentCount() int {
if ds == nil {
return 0
}
switch ds.Style {
case SequenceStyle:
var count int
var ok bool
rem := ds.Data
for len(rem) > 0 {
_, rem, ok = ReadDocument(rem)
if !ok {
return 0
}
count++
}
return count
case ArrayStyle:
_, rem, ok := ReadLength(ds.Data)
if !ok {
return 0
}
var count int
for len(rem) > 1 {
_, rem, ok = ReadElement(rem)
if !ok {
return 0
}
count++
}
return count
default:
return 0
}
}
// Empty returns true if the sequence is empty. It always returns true for unknown sequence styles.
func (ds *DocumentSequence) Empty() bool {
if ds == nil {
return true
}
switch ds.Style {
case SequenceStyle:
return len(ds.Data) == 0
case ArrayStyle:
return len(ds.Data) <= 5
default:
return true
}
}
//ResetIterator resets the iteration point for the Next method to the beginning of the document
//sequence.
func (ds *DocumentSequence) ResetIterator() {
if ds == nil {
return
}
ds.Pos = 0
}
// Documents returns a slice of the documents. If nil either the Data field is also nil or could not
// be properly read.
func (ds *DocumentSequence) Documents() ([]Document, error) {
if ds == nil {
return nil, nil
}
switch ds.Style {
case SequenceStyle:
rem := ds.Data
var docs []Document
var doc Document
var ok bool
for {
doc, rem, ok = ReadDocument(rem)
if !ok {
if len(rem) == 0 {
break
}
return nil, ErrCorruptedDocument
}
docs = append(docs, doc)
}
return docs, nil
case ArrayStyle:
if len(ds.Data) == 0 {
return nil, nil
}
vals, err := Document(ds.Data).Values()
if err != nil {
return nil, ErrCorruptedDocument
}
docs := make([]Document, 0, len(vals))
for _, v := range vals {
if v.Type != bsontype.EmbeddedDocument {
return nil, ErrNonDocument
}
docs = append(docs, v.Data)
}
return docs, nil
default:
return nil, ErrInvalidDocumentSequenceStyle
}
}
// Next retrieves the next document from this sequence and returns it. This method will return
// io.EOF when it has reached the end of the sequence.
func (ds *DocumentSequence) Next() (Document, error) {
if ds == nil || ds.Pos >= len(ds.Data) {
return nil, io.EOF
}
switch ds.Style {
case SequenceStyle:
doc, _, ok := ReadDocument(ds.Data[ds.Pos:])
if !ok {
return nil, ErrCorruptedDocument
}
ds.Pos += len(doc)
return doc, nil
case ArrayStyle:
if ds.Pos < 4 {
if len(ds.Data) < 4 {
return nil, ErrCorruptedDocument
}
ds.Pos = 4 // Skip the length of the document
}
if len(ds.Data[ds.Pos:]) == 1 && ds.Data[ds.Pos] == 0x00 {
return nil, io.EOF // At the end of the document
}
elem, _, ok := ReadElement(ds.Data[ds.Pos:])
if !ok {
return nil, ErrCorruptedDocument
}
ds.Pos += len(elem)
val := elem.Value()
if val.Type != bsontype.EmbeddedDocument {
return nil, ErrNonDocument
}
return val.Data, nil
default:
return nil, ErrInvalidDocumentSequenceStyle
}
}
|
