<?php

// http://wiki.php.net/rfc/closures

$lprint = function ($text) { static $p = ''; echo "$p$text\n" . str_repeat('-', strlen($text)) . "\n\n"; $p = "\n\n"; };


$lprint("Lambda: anonymous functions");

$lambda = function () { echo "Hello World!\n"; };

$lambda();


$lprint("Closure support");

function replace_in_array ($search, $replacement, $array) {
 $map = function ($text) use ($search, $replacement) {
   if (strpos ($text, $search) > 50) {
     return str_replace ($search, $replacement, $text);
   } else {
     return $text;
   }
 };
 return array_map ($map, $array);
}

var_dump(replace_in_array('aaa', 'bbb', array('aaaccc', 'ccccccccccthistextshouldbereplacedbynewtextreplacedaaa')));


$lprint("Closure lifetime");

function getAdder($x) {
  return function ($y) use ($x) {
    // or: lexical $x;
    return $x + $y;
  };
}

$adder = getAdder(1);

var_dump($adder(2), $adder(3));


$lprint("References vs. Copies");

$x = 1;
$lambda1 = function () use ($x) {
  $x *= 2;
};
$lambda2 = function () use (&$x) {
  $x *= 3;
};
$lambda1 ();
var_dump ($x); // gives: 1
$lambda2 ();
var_dump ($x); // gives: 3


$lprint("Interaction with OOP");

class Example {
  private $search;
  public $x = 4;

  public function __construct ($search = '') {
    $this->search = $search;
  }

  public function setSearch ($search) {
    $this->search = $search;
  }

  public function getReplacer ($replacement) {
    return function ($text) use ($replacement) {
      return str_replace ($this->search, $replacement, $text);
    };
  }

  public static function staticClosure () {
    $x = 4;
    $closure = static function ($y) use ($x) {
      return $x + $y;
    };
    return $closure (6);
  }

  public function __invoke () {
    echo "Hello World!\n";
  }

  static function staticPrinter () { echo "Hello World!\n"; }

  function printer () { echo "Hello World: $this->x!\n"; }
}

$example = new Example ('hello');
$replacer = $example->getReplacer ('goodbye');
echo $replacer ('hello world'), "\n"; // goodbye world
$example->setSearch ('world');
echo $replacer ('hello world'), "\n"; // hello goodbye
var_dump(Example::staticClosure());


$lprint("Additional goody: __invoke");

$foo = new Example;
$foo ();


$lprint("Interaction with reflection: static");

$class = new ReflectionClass ('Example');
$method = $class->getMethod ('staticPrinter');
$closure = $method->getClosure ();
$closure ();


$lprint("Interaction with reflection: dynamic");

$class = new ReflectionClass ('Example');
$method = $class->getMethod ('printer');

$object = new Example;
$closure = $method->getClosure ($object);
$closure ();
$object->x = 5;
$closure ();