silverstripe-framework/Core/Object.php

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<?php
namespace SilverStripe\Core;
use SilverStripe\Core\Injector\Injectable;
use SilverStripe\Core\Config\Configurable;
use Exception;
use ReflectionClass;
/**
* A base class for all SilverStripe objects to inherit from.
*
* This class provides a number of pattern implementations, as well as methods and fixes to add extra psuedo-static
* and method functionality to PHP.
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*
* See {@link Extension} on how to implement a custom multiple
* inheritance for object instances based on PHP5 method call overloading.
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*
* @todo Create instance-specific removeExtension() which removes an extension from $extension_instances,
* but not from static $extensions, and clears everything added through defineMethods(), mainly $extra_methods.
*/
abstract class Object {
use Extensible;
use Injectable;
use Configurable;
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/**
* @var string the class name
*/
public $class;
private static $_cache_inst_args = array();
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/**
* Create an object from a string representation. It treats it as a PHP constructor without the
* 'new' keyword. It also manages to construct the object without the use of eval().
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*
* Construction itself is done with Object::create(), so that Object::useCustomClass() calls
* are respected.
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*
* `Object::create_from_string("Versioned('Stage','Live')")` will return the result of
* `Versioned::create('Stage', 'Live);`
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*
* It is designed for simple, cloneable objects. The first time this method is called for a given
* string it is cached, and clones of that object are returned.
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*
* If you pass the $firstArg argument, this will be prepended to the constructor arguments. It's
* impossible to pass null as the firstArg argument.
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*
* `Object::create_from_string("Varchar(50)", "MyField")` will return the result of
* `Varchar::create('MyField', '50');`
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*
* Arguments are always strings, although this is a quirk of the current implementation rather
* than something that can be relied upon.
*
* @param string $classSpec
* @param mixed $firstArg
* @return object
*/
public static function create_from_string($classSpec, $firstArg = null) {
if(!isset(self::$_cache_inst_args[$classSpec.$firstArg])) {
// an $extension value can contain parameters as a string,
// e.g. "Versioned('Stage','Live')"
if(strpos($classSpec,'(') === false) {
if($firstArg === null) {
self::$_cache_inst_args[$classSpec.$firstArg] = Object::create($classSpec);
} else {
self::$_cache_inst_args[$classSpec.$firstArg] = Object::create($classSpec, $firstArg);
}
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} else {
list($class, $args) = self::parse_class_spec($classSpec);
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if($firstArg !== null) {
array_unshift($args, $firstArg);
}
array_unshift($args, $class);
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self::$_cache_inst_args[$classSpec.$firstArg] = call_user_func_array(array('SilverStripe\\Core\\Object','create'), $args);
}
}
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return clone self::$_cache_inst_args[$classSpec.$firstArg];
}
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/**
* Parses a class-spec, such as "Versioned('Stage','Live')", as passed to create_from_string().
* Returns a 2-element array, with classname and arguments
*
* @param string $classSpec
* @return array
* @throws Exception
*/
public static function parse_class_spec($classSpec) {
$tokens = token_get_all("<?php $classSpec");
$class = null;
$args = array();
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// Keep track of the current bucket that we're putting data into
$bucket = &$args;
$bucketStack = array();
$hadNamespace = false;
$currentKey = null;
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foreach($tokens as $token) {
// $forceResult used to allow null result to be detected
$result = $forceResult = null;
$tokenName = is_array($token) ? $token[0] : $token;
// Get the class name
if($class === null && is_array($token) && $token[0] === T_STRING) {
$class = $token[1];
} elseif(is_array($token) && $token[0] === T_NS_SEPARATOR) {
$class .= $token[1];
$hadNamespace = true;
} elseif($hadNamespace && is_array($token) && $token[0] === T_STRING) {
$class .= $token[1];
$hadNamespace = false;
// Get arguments
} else if(is_array($token)) {
switch($token[0]) {
case T_CONSTANT_ENCAPSED_STRING:
$argString = $token[1];
switch($argString[0]) {
case '"':
$result = stripcslashes(substr($argString,1,-1));
break;
case "'":
$result = str_replace(array("\\\\", "\\'"),array("\\", "'"), substr($argString,1,-1));
break;
default:
throw new Exception("Bad T_CONSTANT_ENCAPSED_STRING arg $argString");
}
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break;
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case T_DNUMBER:
$result = (double)$token[1];
break;
case T_LNUMBER:
$result = (int)$token[1];
break;
case T_DOUBLE_ARROW:
// We've encountered an associative array (the array itself has already been
// added to the bucket), so the previous item added to the bucket is the key
end($bucket);
$currentKey = current($bucket);
array_pop($bucket);
break;
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case T_STRING:
switch($token[1]) {
case 'true': $result = true; break;
case 'false': $result = false; break;
case 'null': $result = null; $forceResult = true; break;
default: throw new Exception("Bad T_STRING arg '{$token[1]}'");
}
break;
case T_ARRAY:
$result = array();
break;
}
} else {
if($tokenName === '[') {
$result = array();
} elseif(($tokenName === ')' || $tokenName === ']') && ! empty($bucketStack)) {
// Store the bucket we're currently working on
$oldBucket = $bucket;
// Fetch the key for the bucket at the top of the stack
end($bucketStack);
$key = key($bucketStack);
reset($bucketStack);
// Re-instate the bucket from the top of the stack
$bucket = &$bucketStack[$key];
// Add our saved, "nested" bucket to the bucket we just popped off the stack
$bucket[$key] = $oldBucket;
// Remove the bucket we just popped off the stack
array_pop($bucketStack);
}
}
// If we've got something to add to the bucket, add it
if($result !== null || $forceResult) {
if($currentKey) {
$bucket[$currentKey] = $result;
$currentKey = null;
} else {
$bucket[] = $result;
}
// If we've just pushed an array, that becomes our new bucket
if($result === array()) {
// Fetch the key that the array was pushed to
end($bucket);
$key = key($bucket);
reset($bucket);
// Store reference to "old" bucket in the stack
$bucketStack[$key] = &$bucket;
// Set the active bucket to be our newly-pushed, empty array
$bucket = &$bucket[$key];
}
}
}
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return array($class, $args);
}
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/**
* Get the value of a static property of a class, even in that property is declared protected (but not private),
* without any inheritance, merging or parent lookup if it doesn't exist on the given class.
*
* @param string $class The class to get the static from
* @param string $name The property to get from the class
* @param mixed $default The value to return if property doesn't exist on class
* @return mixed The value of the static property $name on class $class,
* or $default if that property is not defined
*/
public static function static_lookup($class, $name, $default = null) {
if (is_subclass_of($class, 'SilverStripe\\Core\\Object')) {
if (isset($class::$$name)) {
$parent = get_parent_class($class);
if (!$parent || !isset($parent::$$name) || $parent::$$name !== $class::$$name) return $class::$$name;
}
return $default;
} else {
// TODO: This gets set once, then not updated, so any changes to statics after this is called the first
// time for any class won't be exposed
static $static_properties = array();
if (!isset($static_properties[$class])) {
$reflection = new ReflectionClass($class);
$static_properties[$class] = $reflection->getStaticProperties();
}
if (isset($static_properties[$class][$name])) {
$value = $static_properties[$class][$name];
$parent = get_parent_class($class);
if (!$parent) return $value;
if (!isset($static_properties[$parent])) {
$reflection = new ReflectionClass($parent);
$static_properties[$parent] = $reflection->getStaticProperties();
}
if (!isset($static_properties[$parent][$name]) || $static_properties[$parent][$name] !== $value) {
return $value;
}
}
}
return $default;
}
public function __construct() {
$this->class = get_class($this);
$this->constructExtensions();
}
// --------------------------------------------------------------------------------------------------------------
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/**
* Return true if this object "exists" i.e. has a sensible value
*
* This method should be overriden in subclasses to provide more context about the classes state. For example, a
* {@link DataObject} class could return false when it is deleted from the database
*
* @return bool
*/
public function exists() {
return true;
}
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/**
* @return string this classes parent class
*/
public function parentClass() {
return get_parent_class($this);
}
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/**
* Check if this class is an instance of a specific class, or has that class as one of its parents
*
* @param string $class
* @return bool
*/
public function is_a($class) {
return $this instanceof $class;
}
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/**
* @return string the class name
*/
public function __toString() {
return $this->class;
}
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}