321 lines
9.2 KiB
PHP
321 lines
9.2 KiB
PHP
<?php
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namespace OpenCloud\Common;
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/**
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* Provides an abstraction for working with ordered sets of objects
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*
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* Collection objects are used whenever there are multiples; for example,
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* multiple objects in a container, or multiple servers in a service.
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*
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* @since 1.0
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* @author Glen Campbell <glen.campbell@rackspace.com>
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* @author Jamie Hannaford <jamie.hannaford@rackspace.com>
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*/
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class Collection extends Base
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{
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private $service;
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private $itemclass;
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private $itemlist = array();
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private $pointer = 0;
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private $sortkey;
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private $next_page_class;
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private $next_page_callback;
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private $next_page_url;
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/**
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* A Collection is an array of objects
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*
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* Some assumptions:
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* * The `Collection` class assumes that there exists on its service
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* a factory method with the same name of the class. For example, if
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* you create a Collection of class `Foobar`, it will attempt to call
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* the method `parent::Foobar()` to create instances of that class.
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* * It assumes that the factory method can take an array of values, and
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* it passes that to the method.
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*
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* @param Service $service - the service associated with the collection
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* @param string $itemclass - the Class of each item in the collection
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* (assumed to be the name of the factory method)
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* @param array $arr - the input array
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*/
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public function __construct($service, $itemclass, $array)
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{
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$this->service = $service;
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$this->getLogger()->info(
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'Collection:service={class}, class={itemClass}, array={array}',
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array(
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'class' => get_class($service),
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'itemClass' => $itemclass,
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'array' => print_r($array, true)
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)
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);
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$this->next_page_class = $itemclass;
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if (false !== ($classNamePos = strrpos($itemclass, '\\'))) {
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$this->itemclass = substr($itemclass, $classNamePos + 1);
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} else {
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$this->itemclass = $itemclass;
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}
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if (!is_array($array)) {
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throw new Exceptions\CollectionError(
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Lang::translate('Cannot create a Collection without an array')
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);
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}
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// save the array of items
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$this->setItemList($array);
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}
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/**
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* Set the entire data array.
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*
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* @param array $array
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*/
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public function setItemList(array $array)
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{
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$this->itemlist = $array;
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}
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/**
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* Retrieve the entire data array.
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*
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* @return array
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*/
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public function getItemList()
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{
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return $this->itemlist;
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}
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/**
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* Returns the number of items in the collection
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*
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* For most services, this is the total number of items. If the Collection
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* is paginated, however, this only returns the count of items in the
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* current page of data.
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*
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* @return int
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*/
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public function count()
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{
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return count($this->itemlist);
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}
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/**
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* Pseudonym for count()
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*
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* @codeCoverageIgnore
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*/
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public function size()
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{
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return $this->count();
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}
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/**
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* Retrieves the service associated with the Collection
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*
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* @return Service
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*/
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public function service()
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{
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return $this->service;
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}
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/**
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* Resets the pointer to the beginning, but does NOT return the first item
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*
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* @api
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* @return void
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*/
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public function reset()
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{
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$this->pointer = 0;
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}
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/**
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* Resets the collection pointer back to the first item in the page
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* and returns it
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*
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* This is useful if you're only interested in the first item in the page.
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*
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* @api
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* @return Base the first item in the set
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*/
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public function first()
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{
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$this->reset();
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return $this->next();
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}
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/**
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* Returns the next item in the page
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*
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* @api
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* @return Base the next item or FALSE if at the end of the page
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*/
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public function next()
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{
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if ($this->pointer >= $this->count()) {
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return false;
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}
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$service = $this->service();
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if (method_exists($service, $this->itemclass)) {
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return $service->{$this->itemclass}($this->itemlist[$this->pointer++]);
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} elseif (method_exists($service, 'resource')) {
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return $service->resource($this->itemclass, $this->itemlist[$this->pointer++]);
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}
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// @codeCoverageIgnoreStart
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return false;
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// @codeCoverageIgnoreEnd
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}
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/**
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* sorts the collection on a specified key
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*
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* Note: only top-level keys can be used as the sort key. Note that this
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* only sorts the data in the current page of the Collection (for
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* multi-page data).
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*
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* @api
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* @param string $keyname the name of the field to use as the sort key
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* @return void
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*/
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public function sort($keyname = 'id')
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{
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$this->sortkey = $keyname;
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usort($this->itemlist, array($this, 'sortCompare'));
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}
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/**
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* selects only specified items from the Collection
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*
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* This provides a simple form of filtering on Collections. For each item
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* in the collection, it calls the callback function, passing it the item.
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* If the callback returns `TRUE`, then the item is retained; if it returns
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* `FALSE`, then the item is deleted from the collection.
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*
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* Note that this should not supersede server-side filtering; the
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* `Collection::Select()` method requires that *all* of the data for the
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* Collection be retrieved from the server before the filtering is
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* performed; this can be very inefficient, especially for large data
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* sets. This method is mostly useful on smaller-sized sets.
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*
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* Example:
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* <code>
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* $services = $connection->ServiceList();
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* $services->Select(function($item){ return $item->region=='ORD';});
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* // now the $services Collection only has items from the ORD region
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* </code>
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*
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* `Select()` is *destructive*; that is, it actually removes entries from
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* the collection. For example, if you use `Select()` to find items with
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* the ID > 10, then use it again to find items that are <= 10, it will
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* return an empty list.
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*
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* @api
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* @param callable $testfunc a callback function that is passed each item
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* in turn. Note that `Select()` performs an explicit test for
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* `FALSE`, so functions like `strpos()` need to be cast into a
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* boolean value (and not just return the integer).
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* @returns void
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* @throws DomainError if callback doesn't return a boolean value
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*/
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public function select($testfunc)
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{
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foreach ($this->getItemList() as $index => $item) {
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$test = call_user_func($testfunc, $item);
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if (!is_bool($test)) {
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throw new Exceptions\DomainError(
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Lang::translate('Callback function for Collection::Select() did not return boolean')
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);
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}
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if ($test === false) {
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unset($this->itemlist[$index]);
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}
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}
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}
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/**
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* returns the Collection object for the next page of results, or
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* FALSE if there are no more pages
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*
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* Generally, the structure for a multi-page collection will look like
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* this:
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*
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* $coll = $obj->Collection();
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* do {
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* while($item = $coll->Next()) {
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* // do something with the item
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* }
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* } while ($coll = $coll->NextPage());
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*
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* @api
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* @return Collection if there are more pages of results, otherwise FALSE
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*/
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public function nextPage()
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{
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if (isset($this->next_page_url)) {
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return call_user_func(
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$this->next_page_callback,
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$this->next_page_class,
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$this->next_page_url
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);
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}
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// @codeCoverageIgnoreStart
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return false;
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// @codeCoverageIgnoreEnd
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}
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/**
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* for paginated collection, sets the callback function and URL for
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* the next page
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*
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* The callback function should have the signature:
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*
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* function Whatever($class, $url, $parent)
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*
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* and the `$url` should be the URL of the next page of results
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*
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* @param callable $callback the name of the function (or array of
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* object, function name)
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* @param string $url the URL of the next page of results
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* @return void
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*/
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public function setNextPageCallback($callback, $url)
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{
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$this->next_page_callback = $callback;
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$this->next_page_url = $url;
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}
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/**
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* Compares two values of sort keys
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*/
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private function sortCompare($a, $b)
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{
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$key = $this->sortkey;
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// handle strings with strcmp()
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if (is_string($a->$key)) {
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return strcmp($a->$key, $b->$key);
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}
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// handle others with logical comparisons
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if ($a->$key == $b->$key) {
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return 0;
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}
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if ($a->$key < $b->$key) {
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return -1;
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} else {
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return 1;
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}
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}
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}
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