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175 lines
4.6 KiB
175 lines
4.6 KiB
<?php
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namespace FeedWriter;
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use \Iterator;
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use \Exception;
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use \stdClass;
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use \ArrayIterator;
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class Feed {
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const RSS1 = 'RSS 1.0';
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const RSS2 = 'RSS 2.0';
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const ATOM = 'ATOM';
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protected $_iter = null;
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protected $_map = [];
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protected $_views = [];
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/**
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* Generate one or more views of a collection from a given iterator or array.
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*
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* Takes a data source, an array describing a mapping from instances of the
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* collection to items in the view, and a list of views to generate.
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*
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* This all sounds more abstract than it actually is, so let's run through
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* some examples:
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*
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* <code>
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*
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* use \FeedWriter\Feed;
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* use \FeedWriter\View\Atom;
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*
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* // Here's an array of arrays describing some blog posts. These could also
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* // be objects with properties like $blog_posts->writer.
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*
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* $blog_posts = [
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* [ 'date_created' => '2013-02-14', 'writer' => 'Brennen Bearnes', 'text' => 'Hate.' ],
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* [ 'date_created' => '2013-07-04', 'writer' => 'Brennen Bearnes', 'text' => 'Explosions.' ],
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* [ 'date_created' => '2013-08-31', 'writer' => 'Brennen Bearnes', 'text' => 'A feed thingy.' ],
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* ];
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*
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* // Here's a map that explains how to find the properties we need for our
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* // view:
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* $entry_from_post = [
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* 'date' => 'date_created',
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* 'author' => 'writer',
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* 'content' => 'text'
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* ];
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*
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* $feed = new Feed($blog_posts, $entry_from_post, ['atom' => new Atom]);
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*
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* // If everything went ok, views are now available as properties of the feed.
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* if (! $feed->error())
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* echo $feed->atom->render();
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* else
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* echo 'error: ' . $feed->error();
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*
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* </code>
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*
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* @param $source mixed iterator or array
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* @param $map array describing mapping of fields to fields
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* @param $views array one or more views to generate
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*/
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public function __construct ($source, array $map, array $views)
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{
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if (is_array($source))
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$iter = new ArrayIterator($source);
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else
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$iter = $source;
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$this->setIter($iter);
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$this->setViewsAndMap($views, $map);
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$this->spin();
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}
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/**
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* Explode if anybody tries to set a property directly.
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*/
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public function __set ($name, $view)
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{
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throw new Exception("You can't directly set properties on Feed. See documentation for constructor.");
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}
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/**
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* Get a view.
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*/
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public function __get ($name)
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{
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return $this->_views[$name];
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}
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/**
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* Is a given view set?
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*/
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public function __isset ($name)
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{
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return isset($this->_views[$name]);
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}
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/**
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* Stash views and map, making sure that the map provides for anything
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* the view explicitly requires.
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*/
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protected function setViewsAndMap (array $views, array $map)
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{
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if (! count($views))
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throw new Exception('Feed requires that at least one view instance be passed in)');
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if (! is_array($map))
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throw new Exception('$map must be an array');
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if (! count($map))
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throw new Exception('$map must provide values');
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// Validate map for each view:
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foreach ($views as $name => $view) {
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if (! isset($view->require))
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continue;
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foreach ($view->require as $field) {
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if (! isset($map[ $field ])) {
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throw new Exception('$map should provide a mapping for ' . $field);
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}
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}
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}
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$this->_views = $views;
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$this->_map = $map;
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}
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protected function setIter (Iterator $iter)
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{
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if (! ($iter instanceof Iterator))
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throw new Exception('$iter must be an iterator');
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$this->_iter = $iter;
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}
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/**
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* Do the business of handing off values to views.
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*/
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protected function spin ()
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{
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$output_item = (object)[];
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while ($this->_iter->valid()) {
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$input_item = $this->_iter->current();
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if (is_array($input_item))
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$input_item = (object)$input_item;
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foreach ($this->_map as $output_key => &$input_key) {
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if (is_string($input_key))
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{
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// shorthand for "use this field on the object for the value"
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if (isset($input_item->$input_key))
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$output_item->$output_key = $input_item->$input_key;
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else
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throw new Exception("unable to access $input_key on input item: " . print_r($input_item, 1));
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}
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elseif (is_callable($input_key))
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{
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// if we have a function, pass it the item and expect it to
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// return a value for our output key
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$output_item->$output_key = $input_key($input_item);
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}
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}
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foreach ($this->_views as $name => $view) {
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$view->collect($output_item);
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}
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$this->_iter->next();
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}
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}
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}
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