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reader_iterator.go
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/
reader_iterator.go
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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
// ReaderIterator facilitates iterating over a bson.Reader.
type ReaderIterator struct {
r Reader
pos uint32
end uint32
elem *Element
err error
}
// NewReaderIterator constructors a new ReaderIterator over a given Reader.
func NewReaderIterator(r Reader) (*ReaderIterator, error) {
itr := new(ReaderIterator)
if len(r) < 5 {
return nil, NewErrTooSmall()
}
givenLength := readi32(r[0:4])
if len(r) < int(givenLength) {
return nil, ErrInvalidLength
}
itr.r = r
itr.pos = 4
itr.end = uint32(givenLength)
itr.elem = &Element{value: &Value{}}
return itr, nil
}
// Next fetches the next element of the Reader, returning whether or not the next element was able
// to be fetched. If true is returned, then call Element to get the element. If false is returned,
// call Err to check if an error occurred.
func (itr *ReaderIterator) Next() bool {
if itr.pos >= itr.end {
itr.err = ErrInvalidReadOnlyDocument
return false
}
if itr.r[itr.pos] == '\x00' {
return false
}
elemStart := itr.pos
itr.pos++
n, err := itr.r.validateKey(itr.pos, itr.end)
itr.pos += n
if err != nil {
itr.err = err
return false
}
itr.elem.value.start = elemStart
itr.elem.value.offset = itr.pos
itr.elem.value.data = itr.r
n, err = itr.elem.value.validate(false)
itr.pos += n
if err != nil {
itr.err = err
return false
}
return true
}
// Element returns the current element of the ReaderIterator. The pointer that it returns will
// _always_ be the same for a given ReaderIterator.
func (itr *ReaderIterator) Element() *Element {
return itr.elem
}
// Err returns the error that occurred when iterating, or nil if none occurred.
func (itr *ReaderIterator) Err() error {
return itr.err
}