Usage

Note: each of these code samples can be seen in the example directory of the repo.

Here’s an example of basic usage of the mw library

<?php

use Krak\Mw;

function rot13() {
    return function($s) {
        return str_rot13($s);
    };
}

function wrapInner($v) {
    return function($s, $next) use ($v) {
        return $next($v . $s . $v);
    };
}
function wrapOuter($v) {
    return function($s, $next) use ($v) {
        return $v . $next($s) . $v;
    };
}

$handler = mw\compose([
    rot13(),
    wrapInner('o'),
    wrapOuter('a'),
]);

echo $handler('p') . PHP_EOL;
// abcba

The first value in the array is executed last; the last value is executed first.

Each middleware shares the same format:

function($arg1, $arg2, ..., $next);

A list of arguments, with a final argument $next which is the next middleware function to execute in the stack of middleware.

You can have 0 to n number of arguments. Every middleware needs to share the same signature. Composing a stack of middleware will return a handler which has the same signature as the middleware, but without the $next function.

IMPORTANT: At least one middleware MUST resolve a response else the handler will throw an error. So make sure that the last middleware executed (the first in the set) will return a response.

Before/After Middleware

Middleware can either be a before or after or both middleware. A before middleware runs before delegating to the $next middleware. An after middleware will runs after delegating to the $next middleware.

Before Style

<?php

function($param, $next) {
    // code goes here
    // you can also modify the $param and pass the modified version to the next middleware
    return $next($param);
}

After Style

<?php

function($param, $next) {
    $result = $next($param);

    // code goes here
    // you can also modify the $result and return the modified version to the previous handler

    return $result;
}

Stack

The library also comes with a MwStack that allows you to easily build a set of middleware.

<?php

use Krak\Mw;

$stack = mw\stack('Stack Name');
$stack->push(function($a, $next) {
    return $next($a . 'b');
})
->push(function($a, $next) {
    return $next($a) . 'z';
}, 0, 'c')
// replace the c middleware
->on('c', function($a, $next) {
    return $next($a) . 'c';
})
->before('c', function($a, $next) {
    return $next($a) . 'x';
})
->after('c', function($a, $next) {
    return $next($a) . 'y';
})
// this goes on first
->unshift(function($a, $next) {
    return $a;
});

$handler = $stack->compose();
$res = $handler('a');
assert($res == 'abxcy');