Iterator パターン | Java言語で学ぶ デザインパターン入門
2022年10年2日
Java言語で学ぶ デザインパターン入門
Iterator
PHP
Java言語で学ぶデザインパターン入門（第3版）第1章 Iterator パターンを、PHPで書き直してみようという試みです。
Book.php
namespace Iterator;
class Book {
private string $name;
public function __construct(string $name) {
$this->name = $name;
}
public function getName() {
return $this->name;
}
}
Aggregate.php
namespace Iterator;
interface Aggregate {
public function iterator();
}
BookShelf.php
namespace Iterator;
class BookShelf implements Aggregate {
public array $books = [];
public int $last = 0;
public function getBookAt(int $index) : Book {
return $this->books[$index];
}
public function appendBook(Book $book) : void {
$this->books[$this->last] = $book;
$this->last++;
}
public function getLength() : int {
return $this->last;
}
public function iterator() {
return new BookShelfIterator($this);
}
}
Iterator.php
namespace Iterator;
interface Iterator {
public function hasNext() : bool;
public function next() : Book;
}
BookShelfIterator.php
namespace Iterator;
class BookShelfIterator implements Iterator {
public BookShelf $bookShelf;
public int $index;
public function __construct(BookShelf $bookShelf) {
$this->bookShelf = $bookShelf;
$this->index = 0;
}
public function hasNext() : bool {
if ($this->index < $this->bookShelf->getLength()) {
return true;
} else {
return false;
}
}
public function next () : Book {
$book = $this->bookShelf->getBookAt($this->index++);
return $book;
}
}
index.php
use Iterator\Aggregate;
use Iterator\BookShelf;
use Iterator\Book;
use Iterator\Iterator;
use Iterator\BookShelfIterator;
$bookShelf = new BookShelf();
$bookShelf->appendBook(new Book('Around the World in 80 Days'));
$bookShelf->appendBook(new Book('Bible'));
$bookShelf->appendBook(new Book('Cinderella'));
$bookShelf->appendBook(new Book('Dassy-Long-Legs'));
$it = new BookShelfIterator($bookShelf);
while ($it->hasNext()) {
$book = $it->next();
echo $book->getName() . "\n";
}
出力結果
Around the World in 80 Days Bible Cinderella Dassy-Long-Legs
