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<?php
/*
* Copyright 2016 Google LLC
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are
* met:
*
* * Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* * Redistributions in binary form must reproduce the above
* copyright notice, this list of conditions and the following disclaimer
* in the documentation and/or other materials provided with the
* distribution.
* * Neither the name of Google Inc. nor the names of its
* contributors may be used to endorse or promote products derived from
* this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
* OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
namespace Google\ApiCore;
use Generator;
use InvalidArgumentException;
use IteratorAggregate;
use LengthException;
/**
* A collection of elements retrieved using one or more API calls. The
* collection will attempt to retrieve a fixed number of elements, and
* will make API calls until that fixed number is reached, or there
* are no more elements to retrieve.
*/
class FixedSizeCollection implements IteratorAggregate
{
private $collectionSize;
private $pageList;
/**
* FixedSizeCollection constructor.
* @param Page $initialPage
* @param integer $collectionSize
*/
public function __construct($initialPage, $collectionSize)
{
if ($collectionSize <= 0) {
throw new InvalidArgumentException(
"collectionSize must be > 0. collectionSize: $collectionSize"
);
}
if ($collectionSize < $initialPage->getPageElementCount()) {
$ipc = $initialPage->getPageElementCount();
throw new InvalidArgumentException(
"collectionSize must be greater than or equal to the number of " .
"elements in initialPage. collectionSize: $collectionSize, " .
"initialPage size: $ipc"
);
}
$this->collectionSize = $collectionSize;
$this->pageList = FixedSizeCollection::createPageArray($initialPage, $collectionSize);
}
/**
* Returns the number of elements in the collection. This will be
* equal to the collectionSize parameter used at construction
* unless there are no elements remaining to be retrieved.
*
* @return int
*/
public function getCollectionSize()
{
$size = 0;
foreach ($this->pageList as $page) {
$size += $page->getPageElementCount();
}
return $size;
}
/**
* Returns true if there are more elements that can be retrieved
* from the API.
*
* @return bool
*/
public function hasNextCollection()
{
return $this->getLastPage()->hasNextPage();
}
/**
* Returns a page token that can be passed into the API list
* method to retrieve additional elements.
*
* @return string
*/
public function getNextPageToken()
{
return $this->getLastPage()->getNextPageToken();
}
/**
* Retrieves the next FixedSizeCollection using one or more API calls.
*
* @return FixedSizeCollection
*/
public function getNextCollection()
{
$lastPage = $this->getLastPage();
$nextPage = $lastPage->getNextPage($this->collectionSize);
return new FixedSizeCollection($nextPage, $this->collectionSize);
}
/**
* Returns an iterator over the elements of the collection.
*
* @return Generator
*/
public function getIterator()
{
foreach ($this->pageList as $page) {
foreach ($page as $element) {
yield $element;
}
}
}
/**
* Returns an iterator over FixedSizeCollections, starting with this
* and making API calls as required until all of the elements have
* been retrieved.
*
* @return Generator|FixedSizeCollection[]
*/
public function iterateCollections()
{
$currentCollection = $this;
yield $this;
while ($currentCollection->hasNextCollection()) {
$currentCollection = $currentCollection->getNextCollection();
yield $currentCollection;
}
}
private function getLastPage()
{
$pageList = $this->pageList;
// Get last element in array...
$lastPage = end($pageList);
reset($pageList);
return $lastPage;
}
/**
* @param Page $initialPage
* @param integer $collectionSize
* @return Page[]
*/
private static function createPageArray($initialPage, $collectionSize)
{
$pageList = [$initialPage];
$currentPage = $initialPage;
$itemCount = $currentPage->getPageElementCount();
while ($itemCount < $collectionSize && $currentPage->hasNextPage()) {
$remainingCount = $collectionSize - $itemCount;
$currentPage = $currentPage->getNextPage($remainingCount);
$rxElementCount = $currentPage->getPageElementCount();
if ($rxElementCount > $remainingCount) {
throw new LengthException("API returned a number of elements " .
"exceeding the specified page size limit. page size: " .
"$remainingCount, elements received: $rxElementCount");
}
array_push($pageList, $currentPage);
$itemCount += $rxElementCount;
}
return $pageList;
}
}
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