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Mastering DART

You're reading from   Mastering DART Master the art of programming high-performance applications with Dart

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Product type Paperback
Published in Nov 2014
Publisher Packt
ISBN-13 9781783989560
Length 346 pages
Edition 1st Edition
Languages
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Author (1):
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Sergey Akopkokhyants Sergey Akopkokhyants
Author Profile Icon Sergey Akopkokhyants
Sergey Akopkokhyants
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Table of Contents (14) Chapters Close

Preface 1. Beyond Dart's Basics 2. Advanced Techniques and Reflection FREE CHAPTER 3. Object Creation 4. Asynchronous Programming 5. The Stream Framework 6. The Collection Framework 7. Dart and JavaScript Interoperation 8. Internalization and Localization 9. Client-to-server Communication 10. Advanced Storage 11. Supporting Other HTML5 Features 12. Security Aspects Index

BidirectionalIterator


Sometimes, we need to iterate over a collection of elements in both directions. To help in such cases, Dart provides BidirectionalIterator. In the following code, BiListIterator is the implementation of BidirectionalIterator:

class BiListIterator<E> implements BidirectionalIterator<E> {
  final Iterable<E> _iterable;
  final int _length;
  int _index;
  E _current;

The constructor has an extra optional back parameter that defines the direction of the iteration:

  BiListIterator(Iterable<E> iterable, {bool back:false}) :
    _iterable = iterable, _length = iterable.length,
    _index = back ? iterable.length - 1 : 0;

  E get current => _current;

The following code shows the moveNext method of the Iterator to move forward. This and the next method compare the length of the Iterable and the actual length of the collection to check concurrent modifications. The code is as follows:

  bool moveNext() {
    int length = _iterable.length;
    if (_length...
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