Namespaces

• ICanBoogie
  • Event

Classes

• Event
• EventHook
• Events

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<?php

/*
 * This file is part of the ICanBoogie package.
 *
 * (c) Olivier Laviale <olivier.laviale@gmail.com>
 *
 * For the full copyright and license information, please view the LICENSE
 * file that was distributed with this source code.
 */

namespace ICanBoogie;

/**
 * Events collected from the "hooks" config or attached by the user.
 */
class Events implements \IteratorAggregate
{
    static private $jumptable = [

        'get' => [ __CLASS__, 'get' ]

    ];

    /**
     * Calls the callback of a patchable function.
     *
     * @param string $name Name of the function.
     * @param array $arguments Arguments.
     *
     * @return mixed
     */
    static public function __callstatic($name, array $arguments)
    {
        return call_user_func_array(self::$jumptable[$name], $arguments);
    }

    /**
     * Patches a patchable function.
     *
     * @param string $name Name of the function.
     * @param callable $callback Callback.
     *
     * @return callable Previous callable.
     *
     * @throws \RuntimeException is attempt to patch an undefined function.
     */
    static public function patch($name, $callback)
    {
        if (empty(self::$jumptable[$name]))
        {
            throw new \RuntimeException("Undefined patchable: $name.");
        }

        $previous = self::$jumptable[$name];
        self::$jumptable[$name] = $callback;

        return $previous;
    }

    /**
     * Returns the singleton instance of the class.
     *
     * @return Events
     */
    static private function get()
    {
        static $events;

        if (!$events)
        {
            $events = new static;
        }

        return $events;
    }

    /**
     * @param mixed $hook
     *
     * @throws \InvalidArgumentException if `$hook` is not a callable
     */
    static private function assert_callable($hook)
    {
        if (!is_callable($hook))
        {
            throw new \InvalidArgumentException(format
            (
                'The event hook must be a callable, %type given: :hook', [

                    'type' => gettype($hook),
                    'hook' => $hook

                ]
            ));
        }
    }

    /**
     * Event collection.
     *
     * @var array[string]array
     */
    protected $hooks = [];

    /**
     * Event hooks consolidated by class and type.
     *
     * @var array[string]array
     */
    protected $consolidated_hooks = [];

    /**
     * Lists of skippable events.
     *
     * @var array[string]bool
     */
    protected $skippable = [];

    private $once_collection = [];

    public function __construct(array $hooks = [])
    {
        $this->hooks = $hooks;
    }

    /**
     * Returns an iterator for event hooks.
     */
    public function getIterator()
    {
        return new \ArrayIterator($this->hooks);
    }

    /**
     * Adds events from a configuration.
     *
     * @param array $config
     */
    public function configure(array $config)
    {
        $hooks = $this->hooks;

        foreach ($config as $type => $type_hooks)
        {
            if (empty($hooks[$type]))
            {
                $hooks[$type] = $type_hooks;

                continue;
            }

            $hooks[$type] = array_merge($hooks[$type], $type_hooks);
        }

        $this->hooks = array_map('array_unique', $hooks);
        $this->revoke_traces();
    }

    protected function revoke_traces()
    {
        $this->consolidated_hooks = [];
        $this->once_collection = [];
        $this->skippable = [];
    }

    /**
     * Attaches an event hook.
     *
     * The name of the event is resolved from the parameters of the event hook. Consider the
     * following code:
     *
     * <pre>
     * <?php
     *
     * $events->attach(function(ICanBoogie\Operation\BeforeProcessEvent $event, ICanBoogie\SaveOperation $target) {
     *
     *     // …
     *
     * });
     * </pre>
     *
     * The hook will be attached to the `ICanBoogie\SaveOperation::process:before` event.
     *
     * @param string $name Event type or closure.
     * @param callable $hook The event hook, or nothing if $name is a closure.
     *
     * @return EventHook An event hook reference that can be used to easily detach the event
     * hook.
     *
     * @throws \InvalidArgumentException when `$hook` is not a callable.
     */
    public function attach($name, $hook = null)
    {
        if ($hook === null)
        {
            $hook = $name;
            $name = null;
        }

        self::assert_callable($hook);

        if ($name === null)
        {
            $name = self::resolve_event_type_from_hook($hook);
        }

        if (!isset($this->hooks[$name]))
        {
            $this->hooks[$name] = [];
        }

        array_unshift($this->hooks[$name], $hook);

        #
        # If the event is a targeted event, we reset the skippable and consolidated hooks arrays.
        #

        $this->skippable = [];

        if (strpos($name, '::') !== false)
        {
            $this->consolidated_hooks = [];
        }

        return new EventHook($this, $name, $hook);
    }

    /**
     * Attaches an event hook to a specific target.
     *
     * @param object $target
     * @param callable $hook
     *
     * @return EventHook
     */
    public function attach_to($target, $hook)
    {
        if (!is_object($target))
        {
            throw new \InvalidArgumentException("Target must be an object");
        }

        self::assert_callable($hook);

        $name = self::resolve_event_type_from_hook($hook);

        return $this->attach($name, function($e, $t) use ($target, $hook) {

            if ($t !== $target)
            {
                return;
            }

            $hook($e, $t);

        });
    }

    /**
     * Attach an event hook that is detached once used.
     *
     * @see attach()
     *
     * @param mixed $name
     * @param mixed $hook
     *
     * @return EventHook
     */
    public function once($name, $hook = null)
    {
        $event_hook = $this->attach($name, $hook);

        $this->once_collection[$event_hook->type][] = $event_hook;

        return $event_hook;
    }

    /**
     * Resolve an event type using the parameters of the specified hook.
     *
     * @param callable $hook
     *
     * @return string
     */
    static private function resolve_event_type_from_hook($hook)
    {
        if (is_array($hook))
        {
            $reflection = new \ReflectionMethod($hook[0], $hook[1]);
        }
        else if (is_string($hook) && strpos($hook, '::'))
        {
            list($class, $method) = explode('::', $hook);

            $reflection = new \ReflectionMethod($class, $method);
        }
        else
        {
            $reflection = new \ReflectionFunction($hook);
        }

        list($event, $target) = $reflection->getParameters();

        $event_class = self::get_parameter_class($event);
        $target_class = self::get_parameter_class($target);

        $event_class_base = basename('/' . strtr($event_class, '\\', '/'));
        $type = substr($event_class_base, 0, -5);

        if (strpos($event_class_base, 'Before') === 0)
        {
            $type = hyphenate(substr($type, 6)) . ':before';
        }
        else
        {
            $type = hyphenate($type);
        }

        $type = strtr($type, '-', '_');

        return $target_class . '::' . $type;
    }

    /**
     * Returns the class of a parameter reflection.
     *
     * Contrary of the {@link ReflectionParameter::getClass()} method, the class does not need to
     * be available to be successfully retrieved.
     *
     * @param \ReflectionParameter $param
     *
     * @return string|null
     */
    static private function get_parameter_class(\ReflectionParameter $param)
    {
        if (!preg_match('#\[\s*(<[^>]+>)?\s*([^\s]+)#', $param, $matches))
        {
            return null;
        }

        return $matches[2];
    }

    public function batch_attach(array $definitions)
    {
        $this->hooks = \array_merge_recursive($this->hooks, $definitions);
        $this->skippable = [];
        $this->consolidated_hooks = [];
    }

    /**
     * Detaches an event hook.
     *
     * @param string $name The name of the event.
     * @param callable $hook The event hook.
     *
     * @return void
     *
     * @throws \Exception when the event hook is not attached to the event name.
     */
    public function detach($name, $hook)
    {
        $hooks = &$this->hooks;

        if (isset($hooks[$name]))
        {
            foreach ($hooks[$name] as $key => $h)
            {
                if ($h != $hook)
                {
                    continue;
                }

                unset($hooks[$name][$key]);

                if (!count($hooks[$name]))
                {
                    unset($hooks[$name]);
                }

                if (strpos($name, '::') !== false)
                {
                    $this->consolidated_hooks = [];
                }

                #
                # Remove the event from the once collection.
                #

                $once = &$this->once_collection;

                if (isset($once[$name]))
                {
                    foreach ($once[$name] as $k => $event_hook)
                    {
                        if ($hook !== $event_hook->hook)
                        {
                            continue;
                        }

                        unset($once[$name][$k]);
                    }
                }

                return;
            }
        }

        throw new \Exception("The specified event hook is not attached to `{$name}`.");
    }

    /**
     * Marks an event as skippable.
     *
     * @param string $name The event name.
     */
    public function skip($name)
    {
        $this->skippable[$name] = true;
    }

    /**
     * Returns whether or not an event has been marked as skippable.
     *
     * @param string $name The event name.
     *
     * @return boolean `true` if the event can be skipped, `false` otherwise.
     */
    public function is_skippable($name)
    {
        return isset($this->skippable[$name]);
    }

    /**
     * Declare an event hook as _used_ by an event type, if the hook has been attached using {@link once()}
     * it is removed.
     *
     * @param $type
     * @param $hook
     */
    public function used($type, $hook)
    {
        if (empty($this->once_collection[$type]))
        {
            return;
        }

        /* @var $event_hook EventHook */

        foreach ($this->once_collection[$type] as $k => $event_hook)
        {
            if ($hook !== $event_hook->hook)
            {
                continue;
            }

            $event_hook->detach();

            break;
        }
    }

    /**
     * Returns the event hooks attached to the specified event name.
     *
     * If the class of the event's target is provided, event hooks are filtered according to
     * the class and its hierarchy.
     *
     * @param string $name The event name.
     *
     * @return array
     */
    public function get_hooks($name)
    {
        if (!strpos($name, '::'))
        {
            return isset($this->hooks[$name]) ? $this->hooks[$name] : [];
        }

        if (isset($this->consolidated_hooks[$name]))
        {
            return $this->consolidated_hooks[$name];
        }

        list($class, $type) = explode('::', $name);

        $hooks = [];
        $c = $class;

        while ($c)
        {
            if (isset($this->hooks[$c . '::' . $type]))
            {
                $hooks = array_merge($hooks, $this->hooks[$c . '::' . $type]);
            }

            $c = get_parent_class($c);
        }

        $this->consolidated_hooks[$name] = $hooks;

        return $hooks;
    }
}

/**
 * An event hook.
 *
 * An {@link EventHook} instance is created when an event hook is attached. The purpose of this
 * instance is to ease its detaching:
 *
 * <pre>
 * <?php
 *
 * use ICanBoogie\HTTP\Dispatcher;
 *
 * $eh = $events->attach(function(Dispatcher\CollectEvent $event, Dispatcher $target) {
 *
 *     // …
 *
 * });
 *
 * $eh->detach();
 * </pre>
 *
 * @property-read Events $events Events collection.
 * @property-read string $type Event type
 * @property-read callable $hook Event hook.
 */
class EventHook
{
    private $type;
    private $hook;
    private $events;

    public function __construct(Events $events, $type, $hook)
    {
        $this->events = $events;
        $this->type = $type;
        $this->hook = $hook;
    }

    public function __get($property)
    {
        static $readers = [ 'events', 'type', 'hook' ];

        if (in_array($property, $readers))
        {
            return $this->$property;
        }

        throw new PropertyNotDefined([ $property, $this ]);
    }

    /**
     * Detaches the event hook from the events.
     */
    public function detach()
    {
        $this->events->detach($this->type, $this->hook);
    }
}