PHP 实现享元模式

相关角色:
1、抽象享元角色：
2、具体享元角色：
3、非享元角色：
4、享元工厂角色：

<?php
interface Flyweight
{
    public function show();
}

class ConcreteFlyweight implements Flyweight
{
    private $state;
    function __construct($state)
    {
        $this->state = $state;
    }

    function show()
    {
        return $this->state;
    }
}

class UnsharedConcreteFlyweight implements Flyweight
{
    private $state;
    function __construct($state)
    {
        $this->state = $state;
    }

    public function show()
    {
        return $this->state;
    }
}

class FlyweightFactory
{
    private $flyweights = [];
    function getFlyweight($state)
    {
        if(!isset($this->flyweights[$state])) {
            echo "create ". $state.PHP_EOL;
            $this->flyweights[$state] = new ConcreteFlyweight($state);
            $flyweight = $this->flyweights[$state];
        } else {
            $flyweight = $this->flyweights[$state];
            echo "get ".$state." from pool".PHP_EOL;
        }

        return $flyweight;
    }
}

$flyweightFactory = new FlyweightFactory();
$flyweightOne = $flyweightFactory->getFlyweight("state A");
echo $flyweightOne->show();
$flyweightOne = $flyweightFactory->getFlyweight("state A");
echo $flyweightOne->show();
$flyweightTwo = new UnsharedConcreteFlyweight("state B");
echo $flyweightTwo->show();
?>

五子棋游戏,棋子只有黑白两色，可共享，但是具体的落子位置不一样，不共享。

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