silverstripe-framework/View/SSViewer_Scope.php

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<?php
namespace SilverStripe\View;
use ArrayIterator;
use Iterator;
/**
* This tracks the current scope for an SSViewer instance. It has three goals:
* - Handle entering & leaving sub-scopes in loops and withs
* - Track Up and Top
* - (As a side effect) Inject data that needs to be available globally (used to live in ViewableData)
*
* In order to handle up, rather than tracking it using a tree, which would involve constructing new objects
* for each step, we use indexes into the itemStack (which already has to exist).
*
* Each item has three indexes associated with it
*
* - Pop. Which item should become the scope once the current scope is popped out of
* - Up. Which item is up from this item
* - Current. Which item is the first time this object has appeared in the stack
*
* We also keep the index of the current starting point for lookups. A lookup is a sequence of obj calls -
* when in a loop or with tag the end result becomes the new scope, but for injections, we throw away the lookup
* and revert back to the original scope once we've got the value we're after
*/
class SSViewer_Scope
{
const ITEM = 0;
const ITEM_ITERATOR = 1;
const ITEM_ITERATOR_TOTAL = 2;
const POP_INDEX = 3;
const UP_INDEX = 4;
const CURRENT_INDEX = 5;
const ITEM_OVERLAY = 6;
// The stack of previous "global" items
// An indexed array of item, item iterator, item iterator total, pop index, up index, current index & parent overlay
private $itemStack = array();
/**
* The current "global" item (the one any lookup starts from)
*/
protected $item;
/**
* If we're looping over the current "global" item, here's the iterator that tracks with item we're up to
*
* @var Iterator
*/
protected $itemIterator;
//Total number of items in the iterator
protected $itemIteratorTotal;
// A pointer into the item stack for which item should be scope on the next pop call
private $popIndex;
// A pointer into the item stack for which item is "up" from this one
private $upIndex = null;
// A pointer into the item stack for which item is this one (or null if not in stack yet)
private $currentIndex = null;
private $localIndex;
public function __construct($item, $inheritedScope = null)
{
$this->item = $item;
$this->localIndex = 0;
$this->localStack = array();
if ($inheritedScope instanceof SSViewer_Scope) {
$this->itemIterator = $inheritedScope->itemIterator;
$this->itemIteratorTotal = $inheritedScope->itemIteratorTotal;
$this->itemStack[] = array($this->item, $this->itemIterator, $this->itemIteratorTotal, null, null, 0);
} else {
$this->itemStack[] = array($this->item, null, 0, null, null, 0);
}
}
public function getItem()
{
return $this->itemIterator ? $this->itemIterator->current() : $this->item;
}
/** Called at the start of every lookup chain by SSTemplateParser to indicate a new lookup from local scope */
public function locally()
{
list($this->item, $this->itemIterator, $this->itemIteratorTotal, $this->popIndex, $this->upIndex,
$this->currentIndex) = $this->itemStack[$this->localIndex];
// Remember any un-completed (resetLocalScope hasn't been called) lookup chain. Even if there isn't an
// un-completed chain we need to store an empty item, as resetLocalScope doesn't know the difference later
$this->localStack[] = array_splice($this->itemStack, $this->localIndex + 1);
return $this;
}
public function resetLocalScope()
{
$previousLocalState = $this->localStack ? array_pop($this->localStack) : null;
array_splice($this->itemStack, $this->localIndex + 1, count($this->itemStack), $previousLocalState);
list($this->item, $this->itemIterator, $this->itemIteratorTotal, $this->popIndex, $this->upIndex,
$this->currentIndex) = end($this->itemStack);
}
public function getObj($name, $arguments = [], $cache = false, $cacheName = null)
{
$on = $this->itemIterator ? $this->itemIterator->current() : $this->item;
return $on->obj($name, $arguments, $cache, $cacheName);
}
/**
* @param string $name
* @param array $arguments
* @param bool $cache
* @param string $cacheName
* @return $this
*/
public function obj($name, $arguments = [], $cache = false, $cacheName = null)
{
switch ($name) {
case 'Up':
if ($this->upIndex === null) {
user_error('Up called when we\'re already at the top of the scope', E_USER_ERROR);
}
list($this->item, $this->itemIterator, $this->itemIteratorTotal, $unused2, $this->upIndex,
$this->currentIndex) = $this->itemStack[$this->upIndex];
break;
case 'Top':
list($this->item, $this->itemIterator, $this->itemIteratorTotal, $unused2, $this->upIndex,
$this->currentIndex) = $this->itemStack[0];
break;
default:
$this->item = $this->getObj($name, $arguments, $cache, $cacheName);
$this->itemIterator = null;
$this->upIndex = $this->currentIndex ? $this->currentIndex : count($this->itemStack) - 1;
$this->currentIndex = count($this->itemStack);
break;
}
$this->itemStack[] = array(
$this->item,
$this->itemIterator,
$this->itemIteratorTotal,
null,
$this->upIndex,
$this->currentIndex
);
return $this;
}
/**
* Gets the current object and resets the scope.
*
* @return object
*/
public function self()
{
$result = $this->itemIterator ? $this->itemIterator->current() : $this->item;
$this->resetLocalScope();
return $result;
}
public function pushScope()
{
$newLocalIndex = count($this->itemStack) - 1;
$this->popIndex = $this->itemStack[$newLocalIndex][SSViewer_Scope::POP_INDEX] = $this->localIndex;
$this->localIndex = $newLocalIndex;
// We normally keep any previous itemIterator around, so local $Up calls reference the right element. But
// once we enter a new global scope, we need to make sure we use a new one
$this->itemIterator = $this->itemStack[$newLocalIndex][SSViewer_Scope::ITEM_ITERATOR] = null;
return $this;
}
public function popScope()
{
$this->localIndex = $this->popIndex;
$this->resetLocalScope();
return $this;
}
public function next()
{
if (!$this->item) {
return false;
}
if (!$this->itemIterator) {
if (is_array($this->item)) {
$this->itemIterator = new ArrayIterator($this->item);
} else {
$this->itemIterator = $this->item->getIterator();
}
$this->itemStack[$this->localIndex][SSViewer_Scope::ITEM_ITERATOR] = $this->itemIterator;
$this->itemIteratorTotal = iterator_count($this->itemIterator); //count the total number of items
$this->itemStack[$this->localIndex][SSViewer_Scope::ITEM_ITERATOR_TOTAL] = $this->itemIteratorTotal;
$this->itemIterator->rewind();
} else {
$this->itemIterator->next();
}
$this->resetLocalScope();
if (!$this->itemIterator->valid()) {
return false;
}
return $this->itemIterator->key();
}
public function __call($name, $arguments)
{
$on = $this->itemIterator ? $this->itemIterator->current() : $this->item;
$retval = $on ? call_user_func_array(array($on, $name), $arguments) : null;
$this->resetLocalScope();
return $retval;
}
/**
* @return array
*/
protected function getItemStack()
{
return $this->itemStack;
}
/**
* @param array
*/
protected function setItemStack(array $stack)
{
$this->itemStack = $stack;
}
/**
* @return int|null
*/
protected function getUpIndex()
{
return $this->upIndex;
}
}