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| <?php
interface Middleware
{
public static function handle(Closure $next);
}
class Middleware1 implements Middleware
{
public static function handle(Closure $next)
{
echo "Middleware1 before\n";
$next();
echo "Middleware1 after\n";
}
}
class Middleware2 implements Middleware
{
public static function handle(Closure $next)
{
echo "Middleware2 before\n";
$next();
echo "Middleware2 after\n";
}
}
class Middleware3 implements Middleware
{
public static function handle(Closure $next)
{
echo "Middleware3 before\n";
$next();
echo "Middleware3 after\n";
}
}
function getSlice() // 返回一个函数，与上文的f一致
{
return function ($stack, $pipe) {
return function () use ($stack, $pipe) {
return $pipe::handle($stack);
};
};
}
function then()
{
$pipes = [
"Middleware1",
"Middleware2",
"Middleware3",
];
$firstSlice = function () { // 上文的目标函数 target
echo "请求向路由器传递，返回响应.\n";
};
//嵌套闭包的解包方式是先从外到内，然后从内回归到外面,所以要根据注册顺序进行逆序
$pipes = array_reverse($pipes);
$closure = array_reduce($pipes, getSlice(), $firstSlice);
var_dump($closure);//打印下该闭包
// 因为最终返回了一个函数，所以需要call_user_func
call_user_func(array_reduce($pipes, getSlice(), $firstSlice));
}
then();
echo "\n";
//array_reduce($pipes, getSlice(), $firstSlice)，执行完成后相当于生成了f嵌套闭包
//function f()
//{
// return Middleware1::handle(
// function () {
// return Middleware2::handle(
// function () {
// return Middleware3::handle(function () {
// echo "请求向路由器传递，返回响应.\n";
// });
// }
// );
// }
// );
//}
//call_user_func('f');
|
