3.3. Iterator¶

 1<?php
 2
 3class User
 4{
 5    public function __construct(
 6        private readonly string $name,
 7        private readonly int    $age
 8    ) {
 9    }
10
11    public function getName(): string
12    {
13        return $this->name;
14    }
15
16    public function getAge(): int
17    {
18        return $this->age;
19    }
20
21    public function getUserInfo(): string
22    {
23        return $this->getName() . ' (' . $this->getAge() . ')';
24    }
25}

 1<?php
 2
 3class UserList implements Countable, Iterator
 4{
 5    /**
 6     * @var User[]
 7     */
 8    private array $users = [];
 9    private int $currentIndex = 0;
10
11    public function addUser(User $user)
12    {
13        $this->users[] = $user;
14    }
15
16    public function removeUser(User $userToRemove)
17    {
18        foreach ($this->users as $key => $user) {
19            if ($user->getUserInfo() === $userToRemove->getUserInfo()) {
20                unset($this->users[$key]);
21            }
22        }
23
24        $this->users = array_values($this->users);
25    }
26
27    public function count(): int
28    {
29        return count($this->users);
30    }
31
32    public function current(): User
33    {
34        return $this->users[$this->currentIndex];
35    }
36
37    public function key(): int
38    {
39        return $this->currentIndex;
40    }
41
42    public function next()
43    {
44        $this->currentIndex++;
45    }
46
47    public function rewind()
48    {
49        $this->currentIndex = 0;
50    }
51
52    public function valid(): bool
53    {
54        return isset($this->users[$this->currentIndex]);
55    }
56}

 1<?php
 2
 3// create some users
 4$user1 = new User('Saleh', 31);
 5$user2 = new User('Ahmad', 28);
 6$user3 = new User('Mina', 31);
 7
 8// create a user list and add the users to it
 9$userList = new UserList();
10$userList->addUser($user1);
11$userList->addUser($user2);
12$userList->addUser($user3);
13
14// iterate over the user list and output each user's name
15foreach ($userList as $user) {
16    echo $user->getName() . PHP_EOL;
17}
18
19// remove a user from the list
20$userList->removeUser($user2);
21
22// iterate over the user list again, this time only outputting the age
23foreach ($userList as $user) {
24    echo $user->getAge() . PHP_EOL;
25}
26
27// output the total number of users in the list
28echo 'Total number of users: ' . count($userList) . PHP_EOL;