diff -r 3d4e9c994f10 -r a86126ab1dd4 wp/wp-includes/sitemaps/class-wp-sitemaps-renderer.php
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/wp/wp-includes/sitemaps/class-wp-sitemaps-renderer.php	Tue Dec 15 13:49:49 2020 +0100
@@ -0,0 +1,274 @@
+<?php
+/**
+ * Sitemaps: WP_Sitemaps_Renderer class
+ *
+ * Responsible for rendering Sitemaps data to XML in accordance with sitemap protocol.
+ *
+ * @package WordPress
+ * @subpackage Sitemaps
+ * @since 5.5.0
+ */
+
+/**
+ * Class WP_Sitemaps_Renderer
+ *
+ * @since 5.5.0
+ */
+class WP_Sitemaps_Renderer {
+	/**
+	 * XSL stylesheet for styling a sitemap for web browsers.
+	 *
+	 * @since 5.5.0
+	 *
+	 * @var string
+	 */
+	protected $stylesheet = '';
+
+	/**
+	 * XSL stylesheet for styling a sitemap for web browsers.
+	 *
+	 * @since 5.5.0
+	 *
+	 * @var string
+	 */
+	protected $stylesheet_index = '';
+
+	/**
+	 * WP_Sitemaps_Renderer constructor.
+	 *
+	 * @since 5.5.0
+	 */
+	public function __construct() {
+		$stylesheet_url = $this->get_sitemap_stylesheet_url();
+
+		if ( $stylesheet_url ) {
+			$this->stylesheet = '<?xml-stylesheet type="text/xsl" href="' . esc_url( $stylesheet_url ) . '" ?>';
+		}
+
+		$stylesheet_index_url = $this->get_sitemap_index_stylesheet_url();
+
+		if ( $stylesheet_index_url ) {
+			$this->stylesheet_index = '<?xml-stylesheet type="text/xsl" href="' . esc_url( $stylesheet_index_url ) . '" ?>';
+		}
+	}
+
+	/**
+	 * Gets the URL for the sitemap stylesheet.
+	 *
+	 * @since 5.5.0
+	 *
+	 * @global WP_Rewrite $wp_rewrite WordPress rewrite component.
+	 *
+	 * @return string The sitemap stylesheet URL.
+	 */
+	public function get_sitemap_stylesheet_url() {
+		global $wp_rewrite;
+
+		$sitemap_url = home_url( '/wp-sitemap.xsl' );
+
+		if ( ! $wp_rewrite->using_permalinks() ) {
+			$sitemap_url = home_url( '/?sitemap-stylesheet=sitemap' );
+		}
+
+		/**
+		 * Filters the URL for the sitemap stylesheet.
+		 *
+		 * If a falsey value is returned, no stylesheet will be used and
+		 * the "raw" XML of the sitemap will be displayed.
+		 *
+		 * @since 5.5.0
+		 *
+		 * @param string $sitemap_url Full URL for the sitemaps XSL file.
+		 */
+		return apply_filters( 'wp_sitemaps_stylesheet_url', $sitemap_url );
+	}
+
+	/**
+	 * Gets the URL for the sitemap index stylesheet.
+	 *
+	 * @since 5.5.0
+	 *
+	 * @global WP_Rewrite $wp_rewrite WordPress rewrite component.
+	 *
+	 * @return string The sitemap index stylesheet URL.
+	 */
+	public function get_sitemap_index_stylesheet_url() {
+		global $wp_rewrite;
+
+		$sitemap_url = home_url( '/wp-sitemap-index.xsl' );
+
+		if ( ! $wp_rewrite->using_permalinks() ) {
+			$sitemap_url = home_url( '/?sitemap-stylesheet=index' );
+		}
+
+		/**
+		 * Filters the URL for the sitemap index stylesheet.
+		 *
+		 * If a falsey value is returned, no stylesheet will be used and
+		 * the "raw" XML of the sitemap index will be displayed.
+		 *
+		 * @since 5.5.0
+		 *
+		 * @param string $sitemap_url Full URL for the sitemaps index XSL file.
+		 */
+		return apply_filters( 'wp_sitemaps_stylesheet_index_url', $sitemap_url );
+	}
+
+	/**
+	 * Renders a sitemap index.
+	 *
+	 * @since 5.5.0
+	 *
+	 * @param array $sitemaps Array of sitemap URLs.
+	 */
+	public function render_index( $sitemaps ) {
+		header( 'Content-type: application/xml; charset=UTF-8' );
+
+		$this->check_for_simple_xml_availability();
+
+		$index_xml = $this->get_sitemap_index_xml( $sitemaps );
+
+		if ( ! empty( $index_xml ) ) {
+			// All output is escaped within get_sitemap_index_xml().
+			// phpcs:ignore WordPress.Security.EscapeOutput.OutputNotEscaped
+			echo $index_xml;
+		}
+	}
+
+	/**
+	 * Gets XML for a sitemap index.
+	 *
+	 * @since 5.5.0
+	 *
+	 * @param array $sitemaps Array of sitemap URLs.
+	 * @return string|false A well-formed XML string for a sitemap index. False on error.
+	 */
+	public function get_sitemap_index_xml( $sitemaps ) {
+		$sitemap_index = new SimpleXMLElement(
+			sprintf(
+				'%1$s%2$s%3$s',
+				'<?xml version="1.0" encoding="UTF-8" ?>',
+				$this->stylesheet_index,
+				'<sitemapindex xmlns="http://www.sitemaps.org/schemas/sitemap/0.9" />'
+			)
+		);
+
+		foreach ( $sitemaps as $entry ) {
+			$sitemap = $sitemap_index->addChild( 'sitemap' );
+
+			// Add each element as a child node to the <sitemap> entry.
+			foreach ( $entry as $name => $value ) {
+				if ( 'loc' === $name ) {
+					$sitemap->addChild( $name, esc_url( $value ) );
+				} elseif ( 'lastmod' === $name ) {
+					$sitemap->addChild( $name, esc_xml( $value ) );
+				} else {
+					_doing_it_wrong(
+						__METHOD__,
+						sprintf(
+							/* translators: %s: List of element names. */
+							__( 'Fields other than %s are not currently supported for the sitemap index.' ),
+							implode( ',', array( 'loc', 'lastmod' ) )
+						),
+						'5.5.0'
+					);
+				}
+			}
+		}
+
+		return $sitemap_index->asXML();
+	}
+
+	/**
+	 * Renders a sitemap.
+	 *
+	 * @since 5.5.0
+	 *
+	 * @param array $url_list Array of URLs for a sitemap.
+	 */
+	public function render_sitemap( $url_list ) {
+		header( 'Content-type: application/xml; charset=UTF-8' );
+
+		$this->check_for_simple_xml_availability();
+
+		$sitemap_xml = $this->get_sitemap_xml( $url_list );
+
+		if ( ! empty( $sitemap_xml ) ) {
+			// All output is escaped within get_sitemap_xml().
+			// phpcs:ignore WordPress.Security.EscapeOutput.OutputNotEscaped
+			echo $sitemap_xml;
+		}
+	}
+
+	/**
+	 * Gets XML for a sitemap.
+	 *
+	 * @since 5.5.0
+	 *
+	 * @param array $url_list Array of URLs for a sitemap.
+	 * @return string|false A well-formed XML string for a sitemap index. False on error.
+	 */
+	public function get_sitemap_xml( $url_list ) {
+		$urlset = new SimpleXMLElement(
+			sprintf(
+				'%1$s%2$s%3$s',
+				'<?xml version="1.0" encoding="UTF-8" ?>',
+				$this->stylesheet,
+				'<urlset xmlns="http://www.sitemaps.org/schemas/sitemap/0.9" />'
+			)
+		);
+
+		foreach ( $url_list as $url_item ) {
+			$url = $urlset->addChild( 'url' );
+
+			// Add each element as a child node to the <url> entry.
+			foreach ( $url_item as $name => $value ) {
+				if ( 'loc' === $name ) {
+					$url->addChild( $name, esc_url( $value ) );
+				} elseif ( in_array( $name, array( 'lastmod', 'changefreq', 'priority' ), true ) ) {
+					$url->addChild( $name, esc_xml( $value ) );
+				} else {
+					_doing_it_wrong(
+						__METHOD__,
+						sprintf(
+							/* translators: %s: List of element names. */
+							__( 'Fields other than %s are not currently supported for sitemaps.' ),
+							implode( ',', array( 'loc', 'lastmod', 'changefreq', 'priority' ) )
+						),
+						'5.5.0'
+					);
+				}
+			}
+		}
+
+		return $urlset->asXML();
+	}
+
+	/**
+	 * Checks for the availability of the SimpleXML extension and errors if missing.
+	 *
+	 * @since 5.5.0
+	 */
+	private function check_for_simple_xml_availability() {
+		if ( ! class_exists( 'SimpleXMLElement' ) ) {
+			add_filter(
+				'wp_die_handler',
+				static function () {
+					return '_xml_wp_die_handler';
+				}
+			);
+
+			wp_die(
+				sprintf(
+					/* translators: %s: SimpleXML */
+					esc_xml( __( 'Could not generate XML sitemap due to missing %s extension' ) ),
+					'SimpleXML'
+				),
+				esc_xml( __( 'WordPress &rsaquo; Error' ) ),
+				array(
+					'response' => 501, // "Not implemented".
+				)
+			);
+		}
+	}
+}