silverstripe-framework/Core/Extension.php

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<?php
namespace SilverStripe\Core;
use BadMethodCallException;
use SilverStripe\ORM\DataObject;
use SilverStripe\Core\Object;
/**
* Add extension that can be added to an object with {@link Object::add_extension()}.
* For {@link DataObject} extensions, use {@link DataExtension}.
* Each extension instance has an "owner" instance, accessible through
* {@link getOwner()}.
* Every object instance gets its own set of extension instances,
* meaning you can set parameters specific to the "owner instance"
* in new Extension instances.
*/
abstract class Extension {
/**
* This is used by extensions designed to be applied to controllers.
* It works the same way as {@link Controller::$allowed_actions}.
*/
private static $allowed_actions = null;
/**
* The object this extension is applied to.
*
* @var Object
*/
protected $owner;
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/**
* The base class that this extension was applied to; $this->owner must be one of these
*
* @var DataObject
*/
protected $ownerBaseClass;
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/**
* Ownership stack for recursive methods.
* Last item is current owner.
*
* @var array
*/
private $ownerStack = [];
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public $class;
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public function __construct() {
$this->class = get_class($this);
}
/**
* Called when this extension is added to a particular class
*
* @param string $class
* @param string $extensionClass
* @param mixed $args
*/
public static function add_to_class($class, $extensionClass, $args = null) {
// NOP
}
/**
* Set the owner of this extension.
*
* @param Object $owner The owner object,
* @param string $ownerBaseClass The base class that the extension is applied to; this may be
* the class of owner, or it may be a parent. For example, if Versioned was applied to SiteTree,
* and then a Page object was instantiated, $owner would be a Page object, but $ownerBaseClass
* would be 'SiteTree'.
*/
public function setOwner($owner, $ownerBaseClass = null) {
if($owner) {
$this->ownerStack[] = $owner;
}
$this->owner = $owner;
// Set ownerBaseClass
if($ownerBaseClass) {
$this->ownerBaseClass = $ownerBaseClass;
} elseif(!$this->ownerBaseClass && $owner) {
$this->ownerBaseClass = get_class($owner);
}
}
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/**
* Clear the current owner, and restore extension to the state prior to the last setOwner()
*/
public function clearOwner() {
if(empty($this->ownerStack)) {
throw new BadMethodCallException("clearOwner() called more than setOwner()");
}
array_pop($this->ownerStack);
if($this->ownerStack) {
$this->owner = end($this->ownerStack);
} else {
$this->owner = null;
}
}
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/**
* Returns the owner of this extension.
*
* @return Object
*/
public function getOwner() {
return $this->owner;
}
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/**
* Helper method to strip eval'ed arguments from a string
* that's passed to {@link DataObject::$extensions} or
* {@link Object::add_extension()}.
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*
* @param string $extensionStr E.g. "Versioned('Stage','Live')"
* @return string Extension classname, e.g. "Versioned"
*/
public static function get_classname_without_arguments($extensionStr) {
$parts = explode('(', $extensionStr);
return $parts[0];
}
}