106 lines
2.9 KiB
PHP
106 lines
2.9 KiB
PHP
<?php
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/**
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* Add extension that can be added to an object with {@link Object::add_extension()}.
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* For {@link DataObject} extensions, use {@link DataExtension}.
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* Each extension instance has an "owner" instance, accessible through
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* {@link getOwner()}.
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* Every object instance gets its own set of extension instances,
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* meaning you can set parameters specific to the "owner instance"
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* in new Extension instances.
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*
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* @package framework
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* @subpackage core
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*/
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abstract class Extension {
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/**
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* This is used by extensions designed to be applied to controllers.
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* It works the same way as {@link Controller::$allowed_actions}.
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*/
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public static $allowed_actions = null;
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/**
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* The object this extension is applied to.
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*
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* @var Object
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*/
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protected $owner;
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/**
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* The base class that this extension was applied to; $this->owner must be one of these
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* @var DataObject
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*/
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protected $ownerBaseClass;
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/**
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* Reference counter to ensure that the owner isn't cleared until clearOwner() has
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* been called as many times as setOwner()
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*/
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private $ownerRefs = 0;
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public $class;
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function __construct() {
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$this->class = get_class($this);
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}
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/**
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* Called when this extension is added to a particular class
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*
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* TODO: This is likely to be replaced by event sytem before 3.0 final, so be aware
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* this API is fairly unstable.
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*
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* @static
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* @param $class
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*/
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static function add_to_class($class, $extensionClass, $args) {
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Config::add_static_source($class, $extensionClass);
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}
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/**
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* Set the owner of this extension.
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* @param Object $owner The owner object,
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* @param string $ownerBaseClass The base class that the extension is applied to; this may be
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* the class of owner, or it may be a parent. For example, if Versioned was applied to SiteTree,
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* and then a Page object was instantiated, $owner would be a Page object, but $ownerBaseClass
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* would be 'SiteTree'.
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*/
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function setOwner($owner, $ownerBaseClass = null) {
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if($owner) $this->ownerRefs++;
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$this->owner = $owner;
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if($ownerBaseClass) $this->ownerBaseClass = $ownerBaseClass;
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else if(!$this->ownerBaseClass && $owner) $this->ownerBaseClass = $owner->class;
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}
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function clearOwner() {
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if($this->ownerRefs <= 0) user_error("clearOwner() called more than setOwner()", E_USER_WARNING);
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$this->ownerRefs--;
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if($this->ownerRefs == 0) $this->owner = null;
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}
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/**
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* Returns the owner of this extension.
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*
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* @return Object
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*/
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public function getOwner() {
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return $this->owner;
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}
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/**
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* Helper method to strip eval'ed arguments from a string
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* thats passed to {@link DataObject::$extensions} or
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* {@link Object::add_extension()}.
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*
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* @param string $extensionStr E.g. "Versioned('Stage','Live')"
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* @return string Extension classname, e.g. "Versioned"
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*/
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public static function get_classname_without_arguments($extensionStr) {
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return (($p = strpos($extensionStr, '(')) !== false) ? substr($extensionStr, 0, $p) : $extensionStr;
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}
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}
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