3.4. Итератор

3.4.1. Предназначение

За да направите обекта итеративен и да го направите да изглежда като колекция от обекти.

3.4.2. Примери

  • за обработка на файл ред по ред, като просто прекарате всички редове (които имат представяне на обект) за файл (което, разбира се, също е обект)

3.4.3. Забележка

Стандартната PHP библиотека (SPL) определя интерфейсен итератор, който е най-подходящ за това! Често бихте искали да внедрите и Countable интерфейса, за да позволите``count ($ object)`` на вашия итеративен обект

3.4.4. UML Диаграма

Alt Iterator UML Diagram

3.4.5. Код

Можете също да намерите този код в GitHub

Book.php

 1<?php
 2
 3declare(strict_types=1);
 4
 5namespace DesignPatterns\Behavioral\Iterator;
 6
 7class Book
 8{
 9    public function __construct(private string $title, private string $author)
10    {
11    }
12
13    public function getAuthor(): string
14    {
15        return $this->author;
16    }
17
18    public function getTitle(): string
19    {
20        return $this->title;
21    }
22
23    public function getAuthorAndTitle(): string
24    {
25        return $this->getTitle() . ' by ' . $this->getAuthor();
26    }
27}

BookList.php

 1<?php
 2
 3declare(strict_types=1);
 4
 5namespace DesignPatterns\Behavioral\Iterator;
 6
 7use Countable;
 8use Iterator;
 9
10class BookList implements Countable, Iterator
11{
12    /**
13     * @var Book[]
14     */
15    private array $books = [];
16    private int $currentIndex = 0;
17
18    public function addBook(Book $book)
19    {
20        $this->books[] = $book;
21    }
22
23    public function removeBook(Book $bookToRemove)
24    {
25        foreach ($this->books as $key => $book) {
26            if ($book->getAuthorAndTitle() === $bookToRemove->getAuthorAndTitle()) {
27                unset($this->books[$key]);
28            }
29        }
30
31        $this->books = array_values($this->books);
32    }
33
34    public function count(): int
35    {
36        return count($this->books);
37    }
38
39    public function current(): Book
40    {
41        return $this->books[$this->currentIndex];
42    }
43
44    public function key(): int
45    {
46        return $this->currentIndex;
47    }
48
49    public function next(): void
50    {
51        $this->currentIndex++;
52    }
53
54    public function rewind(): void
55    {
56        $this->currentIndex = 0;
57    }
58
59    public function valid(): bool
60    {
61        return isset($this->books[$this->currentIndex]);
62    }
63}

3.4.6. Тест

Tests/IteratorTest.php

 1<?php
 2
 3declare(strict_types=1);
 4
 5namespace DesignPatterns\Behavioral\Iterator\Tests;
 6
 7use DesignPatterns\Behavioral\Iterator\Book;
 8use DesignPatterns\Behavioral\Iterator\BookList;
 9use PHPUnit\Framework\TestCase;
10
11class IteratorTest extends TestCase
12{
13    public function testCanIterateOverBookList()
14    {
15        $bookList = new BookList();
16        $bookList->addBook(new Book('Learning PHP Design Patterns', 'William Sanders'));
17        $bookList->addBook(new Book('Professional Php Design Patterns', 'Aaron Saray'));
18        $bookList->addBook(new Book('Clean Code', 'Robert C. Martin'));
19
20        $books = [];
21
22        foreach ($bookList as $book) {
23            $books[] = $book->getAuthorAndTitle();
24        }
25
26        $this->assertSame(
27            [
28                'Learning PHP Design Patterns by William Sanders',
29                'Professional Php Design Patterns by Aaron Saray',
30                'Clean Code by Robert C. Martin',
31            ],
32            $books
33        );
34    }
35
36    public function testCanIterateOverBookListAfterRemovingBook()
37    {
38        $book = new Book('Clean Code', 'Robert C. Martin');
39        $book2 = new Book('Professional Php Design Patterns', 'Aaron Saray');
40
41        $bookList = new BookList();
42        $bookList->addBook($book);
43        $bookList->addBook($book2);
44        $bookList->removeBook($book);
45
46        $books = [];
47        foreach ($bookList as $book) {
48            $books[] = $book->getAuthorAndTitle();
49        }
50
51        $this->assertSame(
52            ['Professional Php Design Patterns by Aaron Saray'],
53            $books
54        );
55    }
56
57    public function testCanAddBookToList()
58    {
59        $book = new Book('Clean Code', 'Robert C. Martin');
60
61        $bookList = new BookList();
62        $bookList->addBook($book);
63
64        $this->assertCount(1, $bookList);
65    }
66
67    public function testCanRemoveBookFromList()
68    {
69        $book = new Book('Clean Code', 'Robert C. Martin');
70
71        $bookList = new BookList();
72        $bookList->addBook($book);
73        $bookList->removeBook($book);
74
75        $this->assertCount(0, $bookList);
76    }
77}