Open Graph API helper in PHP

OpenGraph.php

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+<?php
+/*
+  Copyright 2010 Scott MacVicar
+
+   Licensed under the Apache License, Version 2.0 (the "License");
+   you may not use this file except in compliance with the License.
+   You may obtain a copy of the License at
+
+       http://www.apache.org/licenses/LICENSE-2.0
+
+   Unless required by applicable law or agreed to in writing, software
+   distributed under the License is distributed on an "AS IS" BASIS,
+   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+   See the License for the specific language governing permissions and
+   limitations under the License.
+*/
+
+class OpenGraph implements Iterator
+{
+  /**
+   * There are base schema's based on type, this is just
+   * a map so that the schema can be obtained
+   *
+   */
+	public static $TYPES = array(
+		'activity' => array('activity', 'sport'),
+		'business' => array('bar', 'company', 'cafe', 'hotel', 'restaurant'),
+		'group' => array('cause', 'sports_league', 'sports_team'),
+		'organization' => array('band', 'government', 'non_profit', 'school', 'university'),
+		'person' => array('actor', 'athlete', 'author', 'director', 'musician', 'politician', 'public_figure'),
+		'place' => array('city', 'country', 'landmark', 'state_province'),
+		'product' => array('album', 'book', 'drink', 'food', 'game', 'movie', 'product', 'song', 'tv_show'),
+		'website' => array('blog', 'website'),
+	);
+
+  /**
+   * Holds all the Open Graph values we've parsed from a page
+   *
+   */
+	private $_values = array();
+
+  /**
+   * Fetches a URI and parses it for Open Graph data, returns
+   * false on error.
+   *
+   * @param $URI    URI to page to parse for Open Graph data
+   * @return OpenGraph
+   */
+	static public function fetch($URI) {
+		return self::_parse(file_get_contents($URI));
+	}
+
+  /**
+   * Parses HTML and extracts Open Graph data, this assumes
+   * the document is at least well formed.
+   *
+   * @param $HTML    HTML to parse
+   * @return OpenGraph
+   */
+	static private function _parse($HTML) {
+		$old_libxml_error = libxml_use_internal_errors(true);
+
+		$doc = new DOMDocument();
+		$doc->loadHTML($HTML);
+
+		libxml_use_internal_errors($old_libxml_error);
+
+		$tags = $doc->getElementsByTagName('meta');
+		if (!$tags || $tags->length === 0) {
+			return false;
+		}
+
+		$page = new self();
+
+		foreach ($tags AS $tag) {
+			if ($tag->hasAttribute('property') &&
+			    strpos($tag->getAttribute('property'), 'og:') === 0) {
+				$key = strtr(substr($tag->getAttribute('property'), 3), '-', '_');
+				$page->_values[$key] = $tag->getAttribute('content');
+			}
+		}
+
+		if (empty($page->_values)) { return false; }
+
+		return $page;
+	}
+
+  /**
+   * Helper method to access attributes directly
+   * Example:
+   * $graph->title
+   *
+   * @param $key    Key to fetch from the lookup
+   */
+	public function __get($key) {
+		if (array_key_exists($key, $this->_values)) {
+			return $this->_values[$key];
+		}
+
+		if ($key === 'schema') {
+			foreach (self::$TYPES AS $schema => $types) {
+				if (array_search($this->_values['type'], $types)) {
+					return $schema;
+				}
+			}
+		}
+	}
+
+  /**
+   * Return all the keys found on the page
+   *
+   * @return array
+   */
+	public function keys() {
+		return array_keys($this->_values);
+	}
+
+  /**
+   * Helper method to check an attribute exists
+   *
+   * @param $key
+   */
+	public function __isset($key) {
+		return array_key_exists($key, $this->_values);
+	}
+
+  /**
+   * Will return true if the page has location data embedded
+   *
+   * @return boolean Check if the page has location data
+   */
+	public function hasLocation() {
+		if (array_key_exists('latitude', $this->_values) && array_key_exists('longitude', $this->_values)) {
+			return true;
+		}
+
+		$address_keys = array('street_address', 'locality', 'region', 'postal_code', 'country_name');
+		$valid_address = true;
+		foreach ($address_keys AS $key) {
+			$valid_address = ($valid_address && array_key_exists($key, $this->_values));
+		}
+		return $valid_address;
+	}
+
+  /**
+   * Iterator code
+   */
+	private $_position = 0;
+	public function rewind() { reset($this->_values); $this->_position = 0; }
+	public function current() { return current($this->_values); }
+	public function key() { return key($this->_values); }
+	public function next() { next($this->_values); ++$this->_position; }
+	public function valid() { return $this->_position < sizeof($this->_values); }
+}
+
+/* tests
+$test = OpenGraph::fetch('http://www.rottentomatoes.com/m/10011268-oceans/');
+var_dump($test->keys());
+foreach ($test AS $key => $value) {
+	var_dump($key, $value);
+}
+
+$test = OpenGraph::fetch('http://www.example.org');
+var_dump($test);
+*/

README.md

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+# Open Graph Protocol helper for PHP
+
+A small library for making accessing of Open Graph Protocol data easier
+
+## Note
+Keys with a dash (-) in the name are converted to _ for easy access as a property
+in PHP
+
+## Required Extensions
+* DOM for parsing
+
+## Usage
+	require_once('OpenGraph.php');
+
+	$graph = OpenGraph::fetch('http://www.rottentomatoes.com/m/10011268-oceans/');
+	var_dump($graph->keys());
+	var_dump($graph->schema);
+
+	foreach ($graph as $key => $value) {
+		echo "$key => $value";
+	}