Add alternate for multi-lang sitemap

classes/Kohana/Sitemap/URL.php

@@ -9,6 +9,7 @@ abstract class Kohana_Sitemap_URL implements Kohana_Sitemap_Interface
 		'changefreq' => NULL,
 		'priority'   => NULL,
 	);
+	private $alternates = array();
 
 	/**
 	 * URL of the page. This URL must begin with the protocol (such as http) and end
@@ -92,6 +93,31 @@ public function set_priority($priority)
 
 		return $this;
 	}
+	/**
+	 * Submit rel-alternate-hreflang annotations in a Sitemap
+	 * @see https://support.google.com/webmasters/answer/2620865?hl=en
+	 * @param string $lang
+	 * @param string $location 
+	 */
+	public function set_alternate($lang,$location)
+	{
+		if ( ! Valid::max_length($location, 2048))
+		{
+			throw new LengthException('The location was too long, maximum length of 2,048 characters.');
+		}
+
+		$location = Sitemap::encode($location);
+
+		if ( ! Valid::url($location))
+		{
+			throw new InvalidArgumentException('The location was not a valid URL');
+		}
+
+		$alternate = array('lang' => $lang,'location' => $location);
+		$this->alternates[] = $alternate;
+
+		return $this;
+	}
 
 	/**
 	 * @var Kohana_Sitemap_Interface
@@ -130,6 +156,16 @@ public function create()
 				$url_node->appendChild(new DOMElement($name, $value));
 			}
 		}
+		if ($this->alternates != NULL)
+		{
+			foreach($this->alternates as $k => $alternate)
+			{
+				$xhtmllink = $url_node->appendChild(new DOMElement('link'));
+				$xhtmllink->setAttributeNode(new DOMAttr('rel', 'alternate'));
+				$xhtmllink->setAttributeNode(new DOMAttr('hreflang', $alternate['lang']));
+				$xhtmllink->setAttributeNode(new DOMAttr('href', $alternate['location']));
+			}
+		}
 
 		// If a specialised sitemap was used, import it's data here.
 		if (NULL !== $this->driver)

guide/sitemap/sitemap.basic.md

@@ -41,9 +41,37 @@ The above example should output the following
 # Requirements
 
 | Argument         | Requirements                                                                                                    |
-|------------------|-----------------------------------------------------------------------------------------------------------------|
+|------------------------------------------------------------------------------------------------------------------------------------|
 | loc              | Maximum length of 2,048 characters.                                                                             |
 |                  | Must pass Validate::url                                                                                         |
 | last mod         | Unixtime stamp                                                                                                  |
 | change frequency | Must be one of the following: **always**, **hourly**, **daily**, **weekly**, **monthly**, **yearly**, **never** |
-| priority         | Must be a numeric value between **0 (zero)** and **1 (one)** and is **inclusive**.                              |
+| priority         | Must be a numeric value between **0 (zero)** and **1 (one)** and is **inclusive**.                              |
+| alternate        | lang , location (see loc)                                                                                       |
+
+
+# Alternate
+
+You can add alternate for multi-lingual page. Ex:
+
+    $url->set_alternate('fr-fr','http://google.fr');
+
+Output: 
+
+	<urlset xmlns="http://www.sitemaps.org/schemas/sitemap/0.9">
+		<url>
+			<loc>http://google.com</loc>
+			<lastmod>2010-06-17T19:48:12+01:00</lastmod>
+			<changefreq>daily</changefreq>
+			<priority>1</priority>
+			<link rel="alternate" hreflang="fr-fr" href="http://google.fr"/>
+		</url>
+	</urlset>
+
+Don't forget to add a set_alternate for the current page:
+
+      $url->set_alternate('en','http://google.com');
+
+As said here:
+
+https://support.google.com/webmasters/answer/2620865?hl=en