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WP_Theme

WP_Theme Class

More Information

Role of WP_Theme

WP_Theme is a class that helps developers interact with a theme.

Methods and Properties

You shouldn’t alter the properties directly, but instead use the methods to interact with them. For complete list of methods and properties, refer the source code.

Properties

Name
WordPress Theme object.
ThemeURI
The URI of the theme’s webpage.
Description
The description of the theme
Author
The theme’s author
AuthorURI
The website of the theme author
Version
The version of the theme
Template
(Optional — used in a child theme) The folder name of the parent theme
Status
If the theme is published
Tags
Tags used to describe the theme
TextDomain
The text domain used in the theme for translation purposes
DomainPath
Path to the theme translation files

Methods

errors()
Returns WP_Error object with error information. If there isn’t any error information then it returns false
exists()
Boolean for if the theme exists
parent()
Returns parent WP_Theme object or false if there is no parent theme
cache_delete()
Clears the cache for the theme

Header Methods

get( $header )
Used to get a sanitized but unformatted theme header. Use the get_template() method to find the template, not the ‘Template’ header. Returns string on success and false on failure
display ( $header, $markup, $translate )
Gets the theme header then formats and translates it for display.

Path and URL Methods

get_stylesheet()
Returns a string with the directory name of the theme’s “stylesheet” files, inside the theme root. If this is a child theme it is the directory from the child theme.
get_template()
Returns a string with the directory name of the theme’s “template” file. If this is a child theme it is the directory from the parent theme.
get_stylesheet_directory()
Returns a string with the absolute path to a theme’s stylesheet files. If the theme is a child theme, the path will be to the child theme files.
get_template_directory()
Returns a string with the absolute path to a theme’s template files. If the theme is a child theme, the path will be to the parent theme files.
get_stylesheet_directory_uri()
Returns a string with the URL to the theme’s stylesheet files. If the theme is a child theme, the URL will be to the child theme files.
get_template_directory_uri()
Returns a string with the URL to the theme’s template files. If the theme is a child theme, the URL will be to the parent theme files.
get_theme_root()
Returns a string with the path to the directory of the theme root. This is typically the absolute path to the wp-content/themes folder.
get_theme_root_uri()
Returns a string with the URL to the directory of the theme root. This is typically the absolute URL to the wp-content/themes folder.

Files and Images

get_screenshot( $uri )
Returns the URL to the screenshot image for the theme. The $uri parameter determines the type of url to return. Passing ‘relative’ returns a relative URL otherwise it defaults to an absolute URL.
get_files( $type, $depth, $search_parent )
Returns an array of files in the theme’s directory.
get_page_templates()
Returns an array of page templates, keyed by the filename, with the value of the translated header name.

Permission Methods

is_allowed()
Boolean value for if a theme is allowed for the network. Always returns true if called on a single site.
get_allowed( $blog_id )
Returns an array of theme names that are allowed on the site or network. The $blog_id defaults to current blog. This method calls both get_allowed_on_network() and get_allowed_on_site( $blog_id ).
get_allowed_on_network ()
Returns an array of theme names that are allowed on the network.
get_allowed_on_site( $blog_id )
Returns an array of theme names that are allowed on the site.

Sorting

sort_by_name( $themes )
Sorts themes by name

Source

File: wp-includes/class-wp-theme.php

final class WP_Theme implements ArrayAccess {

	/**
	 * Whether the theme has been marked as updateable.
	 *
	 * @since 4.4.0
	 * @var bool
	 *
	 * @see WP_MS_Themes_List_Table
	 */
	public $update = false;

	/**
	 * Headers for style.css files.
	 *
	 * @since 3.4.0
	 * @since 5.4.0 Added `Requires at least` and `Requires PHP` headers.
	 * @var array
	 */
	private static $file_headers = array(
		'Name'        => 'Theme Name',
		'ThemeURI'    => 'Theme URI',
		'Description' => 'Description',
		'Author'      => 'Author',
		'AuthorURI'   => 'Author URI',
		'Version'     => 'Version',
		'Template'    => 'Template',
		'Status'      => 'Status',
		'Tags'        => 'Tags',
		'TextDomain'  => 'Text Domain',
		'DomainPath'  => 'Domain Path',
		'RequiresWP'  => 'Requires at least',
		'RequiresPHP' => 'Requires PHP',
	);

	/**
	 * Default themes.
	 *
	 * @var array
	 */
	private static $default_themes = array(
		'classic'         => 'WordPress Classic',
		'default'         => 'WordPress Default',
		'twentyten'       => 'Twenty Ten',
		'twentyeleven'    => 'Twenty Eleven',
		'twentytwelve'    => 'Twenty Twelve',
		'twentythirteen'  => 'Twenty Thirteen',
		'twentyfourteen'  => 'Twenty Fourteen',
		'twentyfifteen'   => 'Twenty Fifteen',
		'twentysixteen'   => 'Twenty Sixteen',
		'twentyseventeen' => 'Twenty Seventeen',
		'twentynineteen'  => 'Twenty Nineteen',
		'twentytwenty'    => 'Twenty Twenty',
	);

	/**
	 * Renamed theme tags.
	 *
	 * @var array
	 */
	private static $tag_map = array(
		'fixed-width'    => 'fixed-layout',
		'flexible-width' => 'fluid-layout',
	);

	/**
	 * Absolute path to the theme root, usually wp-content/themes
	 *
	 * @var string
	 */
	private $theme_root;

	/**
	 * Header data from the theme's style.css file.
	 *
	 * @var array
	 */
	private $headers = array();

	/**
	 * Header data from the theme's style.css file after being sanitized.
	 *
	 * @var array
	 */
	private $headers_sanitized;

	/**
	 * Header name from the theme's style.css after being translated.
	 *
	 * Cached due to sorting functions running over the translated name.
	 *
	 * @var string
	 */
	private $name_translated;

	/**
	 * Errors encountered when initializing the theme.
	 *
	 * @var WP_Error
	 */
	private $errors;

	/**
	 * The directory name of the theme's files, inside the theme root.
	 *
	 * In the case of a child theme, this is directory name of the child theme.
	 * Otherwise, 'stylesheet' is the same as 'template'.
	 *
	 * @var string
	 */
	private $stylesheet;

	/**
	 * The directory name of the theme's files, inside the theme root.
	 *
	 * In the case of a child theme, this is the directory name of the parent theme.
	 * Otherwise, 'template' is the same as 'stylesheet'.
	 *
	 * @var string
	 */
	private $template;

	/**
	 * A reference to the parent theme, in the case of a child theme.
	 *
	 * @var WP_Theme
	 */
	private $parent;

	/**
	 * URL to the theme root, usually an absolute URL to wp-content/themes
	 *
	 * @var string
	 */
	private $theme_root_uri;

	/**
	 * Flag for whether the theme's textdomain is loaded.
	 *
	 * @var bool
	 */
	private $textdomain_loaded;

	/**
	 * Stores an md5 hash of the theme root, to function as the cache key.
	 *
	 * @var string
	 */
	private $cache_hash;

	/**
	 * Flag for whether the themes cache bucket should be persistently cached.
	 *
	 * Default is false. Can be set with the {@see 'wp_cache_themes_persistently'} filter.
	 *
	 * @var bool
	 */
	private static $persistently_cache;

	/**
	 * Expiration time for the themes cache bucket.
	 *
	 * By default the bucket is not cached, so this value is useless.
	 *
	 * @var bool
	 */
	private static $cache_expiration = 1800;

	/**
	 * Constructor for WP_Theme.
	 *
	 * @since 3.4.0
	 *
	 * @global array $wp_theme_directories
	 *
	 * @param string        $theme_dir  Directory of the theme within the theme_root.
	 * @param string        $theme_root Theme root.
	 * @param WP_Theme|null $_child If this theme is a parent theme, the child may be passed for validation purposes.
	 */
	public function __construct( $theme_dir, $theme_root, $_child = null ) {
		global $wp_theme_directories;

		// Initialize caching on first run.
		if ( ! isset( self::$persistently_cache ) ) {
			/** This action is documented in wp-includes/theme.php */
			self::$persistently_cache = apply_filters( 'wp_cache_themes_persistently', false, 'WP_Theme' );
			if ( self::$persistently_cache ) {
				wp_cache_add_global_groups( 'themes' );
				if ( is_int( self::$persistently_cache ) ) {
					self::$cache_expiration = self::$persistently_cache;
				}
			} else {
				wp_cache_add_non_persistent_groups( 'themes' );
			}
		}

		$this->theme_root = $theme_root;
		$this->stylesheet = $theme_dir;

		// Correct a situation where the theme is 'some-directory/some-theme' but 'some-directory' was passed in as part of the theme root instead.
		if ( ! in_array( $theme_root, (array) $wp_theme_directories, true )
			&& in_array( dirname( $theme_root ), (array) $wp_theme_directories, true )
		) {
			$this->stylesheet = basename( $this->theme_root ) . '/' . $this->stylesheet;
			$this->theme_root = dirname( $theme_root );
		}

		$this->cache_hash = md5( $this->theme_root . '/' . $this->stylesheet );
		$theme_file       = $this->stylesheet . '/style.css';

		$cache = $this->cache_get( 'theme' );

		if ( is_array( $cache ) ) {
			foreach ( array( 'errors', 'headers', 'template' ) as $key ) {
				if ( isset( $cache[ $key ] ) ) {
					$this->$key = $cache[ $key ];
				}
			}
			if ( $this->errors ) {
				return;
			}
			if ( isset( $cache['theme_root_template'] ) ) {
				$theme_root_template = $cache['theme_root_template'];
			}
		} elseif ( ! file_exists( $this->theme_root . '/' . $theme_file ) ) {
			$this->headers['Name'] = $this->stylesheet;
			if ( ! file_exists( $this->theme_root . '/' . $this->stylesheet ) ) {
				$this->errors = new WP_Error(
					'theme_not_found',
					sprintf(
						/* translators: %s: Theme directory name. */
						__( 'The theme directory "%s" does not exist.' ),
						esc_html( $this->stylesheet )
					)
				);
			} else {
				$this->errors = new WP_Error( 'theme_no_stylesheet', __( 'Stylesheet is missing.' ) );
			}
			$this->template = $this->stylesheet;
			$this->cache_add(
				'theme',
				array(
					'headers'    => $this->headers,
					'errors'     => $this->errors,
					'stylesheet' => $this->stylesheet,
					'template'   => $this->template,
				)
			);
			if ( ! file_exists( $this->theme_root ) ) { // Don't cache this one.
				$this->errors->add( 'theme_root_missing', __( 'Error: The themes directory is either empty or doesn’t exist. Please check your installation.' ) );
			}
			return;
		} elseif ( ! is_readable( $this->theme_root . '/' . $theme_file ) ) {
			$this->headers['Name'] = $this->stylesheet;
			$this->errors          = new WP_Error( 'theme_stylesheet_not_readable', __( 'Stylesheet is not readable.' ) );
			$this->template        = $this->stylesheet;
			$this->cache_add(
				'theme',
				array(
					'headers'    => $this->headers,
					'errors'     => $this->errors,
					'stylesheet' => $this->stylesheet,
					'template'   => $this->template,
				)
			);
			return;
		} else {
			$this->headers = get_file_data( $this->theme_root . '/' . $theme_file, self::$file_headers, 'theme' );
			// Default themes always trump their pretenders.
			// Properly identify default themes that are inside a directory within wp-content/themes.
			$default_theme_slug = array_search( $this->headers['Name'], self::$default_themes, true );
			if ( $default_theme_slug ) {
				if ( basename( $this->stylesheet ) != $default_theme_slug ) {
					$this->headers['Name'] .= '/' . $this->stylesheet;
				}
			}
		}

		if ( ! $this->template && $this->stylesheet === $this->headers['Template'] ) {
			$this->errors = new WP_Error(
				'theme_child_invalid',
				sprintf(
					/* translators: %s: Template. */
					__( 'The theme defines itself as its parent theme. Please check the %s header.' ),
					'<code>Template</code>'
				)
			);
			$this->cache_add(
				'theme',
				array(
					'headers'    => $this->headers,
					'errors'     => $this->errors,
					'stylesheet' => $this->stylesheet,
				)
			);

			return;
		}

		// (If template is set from cache [and there are no errors], we know it's good.)
		if ( ! $this->template ) {
			$this->template = $this->headers['Template'];
		}

		if ( ! $this->template ) {
			$this->template = $this->stylesheet;
			if ( ! file_exists( $this->theme_root . '/' . $this->stylesheet . '/index.php' ) ) {
				$error_message = sprintf(
					/* translators: 1: index.php, 2: Documentation URL, 3: style.css */
					__( 'Template is missing. Standalone themes need to have a %1$s template file. <a href="%2$s">Child themes</a> need to have a Template header in the %3$s stylesheet.' ),
					'<code>index.php</code>',
					__( 'https://developer.wordpress.org/themes/advanced-topics/child-themes/' ),
					'<code>style.css</code>'
				);
				$this->errors = new WP_Error( 'theme_no_index', $error_message );
				$this->cache_add(
					'theme',
					array(
						'headers'    => $this->headers,
						'errors'     => $this->errors,
						'stylesheet' => $this->stylesheet,
						'template'   => $this->template,
					)
				);
				return;
			}
		}

		// If we got our data from cache, we can assume that 'template' is pointing to the right place.
		if ( ! is_array( $cache ) && $this->template != $this->stylesheet && ! file_exists( $this->theme_root . '/' . $this->template . '/index.php' ) ) {
			// If we're in a directory of themes inside /themes, look for the parent nearby.
			// wp-content/themes/directory-of-themes/*
			$parent_dir  = dirname( $this->stylesheet );
			$directories = search_theme_directories();

			if ( '.' !== $parent_dir && file_exists( $this->theme_root . '/' . $parent_dir . '/' . $this->template . '/index.php' ) ) {
				$this->template = $parent_dir . '/' . $this->template;
			} elseif ( $directories && isset( $directories[ $this->template ] ) ) {
				// Look for the template in the search_theme_directories() results, in case it is in another theme root.
				// We don't look into directories of themes, just the theme root.
				$theme_root_template = $directories[ $this->template ]['theme_root'];
			} else {
				// Parent theme is missing.
				$this->errors = new WP_Error(
					'theme_no_parent',
					sprintf(
						/* translators: %s: Theme directory name. */
						__( 'The parent theme is missing. Please install the "%s" parent theme.' ),
						esc_html( $this->template )
					)
				);
				$this->cache_add(
					'theme',
					array(
						'headers'    => $this->headers,
						'errors'     => $this->errors,
						'stylesheet' => $this->stylesheet,
						'template'   => $this->template,
					)
				);
				$this->parent = new WP_Theme( $this->template, $this->theme_root, $this );
				return;
			}
		}

		// Set the parent, if we're a child theme.
		if ( $this->template != $this->stylesheet ) {
			// If we are a parent, then there is a problem. Only two generations allowed! Cancel things out.
			if ( $_child instanceof WP_Theme && $_child->template == $this->stylesheet ) {
				$_child->parent = null;
				$_child->errors = new WP_Error(
					'theme_parent_invalid',
					sprintf(
						/* translators: %s: Theme directory name. */
						__( 'The "%s" theme is not a valid parent theme.' ),
						esc_html( $_child->template )
					)
				);
				$_child->cache_add(
					'theme',
					array(
						'headers'    => $_child->headers,
						'errors'     => $_child->errors,
						'stylesheet' => $_child->stylesheet,
						'template'   => $_child->template,
					)
				);
				// The two themes actually reference each other with the Template header.
				if ( $_child->stylesheet == $this->template ) {
					$this->errors = new WP_Error(
						'theme_parent_invalid',
						sprintf(
							/* translators: %s: Theme directory name. */
							__( 'The "%s" theme is not a valid parent theme.' ),
							esc_html( $this->template )
						)
					);
					$this->cache_add(
						'theme',
						array(
							'headers'    => $this->headers,
							'errors'     => $this->errors,
							'stylesheet' => $this->stylesheet,
							'template'   => $this->template,
						)
					);
				}
				return;
			}
			// Set the parent. Pass the current instance so we can do the crazy checks above and assess errors.
			$this->parent = new WP_Theme( $this->template, isset( $theme_root_template ) ? $theme_root_template : $this->theme_root, $this );
		}

		if ( wp_paused_themes()->get( $this->stylesheet ) && ( ! is_wp_error( $this->errors ) || ! isset( $this->errors->errors['theme_paused'] ) ) ) {
			$this->errors = new WP_Error( 'theme_paused', __( 'This theme failed to load properly and was paused within the admin backend.' ) );
		}

		// We're good. If we didn't retrieve from cache, set it.
		if ( ! is_array( $cache ) ) {
			$cache = array(
				'headers'    => $this->headers,
				'errors'     => $this->errors,
				'stylesheet' => $this->stylesheet,
				'template'   => $this->template,
			);
			// If the parent theme is in another root, we'll want to cache this. Avoids an entire branch of filesystem calls above.
			if ( isset( $theme_root_template ) ) {
				$cache['theme_root_template'] = $theme_root_template;
			}
			$this->cache_add( 'theme', $cache );
		}
	}

	/**
	 * When converting the object to a string, the theme name is returned.
	 *
	 * @since 3.4.0
	 *
	 * @return string Theme name, ready for display (translated)
	 */
	public function __toString() {
		return (string) $this->display( 'Name' );
	}

	/**
	 * __isset() magic method for properties formerly returned by current_theme_info()
	 *
	 * @since 3.4.0
	 *
	 * @param string $offset Property to check if set.
	 * @return bool Whether the given property is set.
	 */
	public function __isset( $offset ) {
		static $properties = array(
			'name',
			'title',
			'version',
			'parent_theme',
			'template_dir',
			'stylesheet_dir',
			'template',
			'stylesheet',
			'screenshot',
			'description',
			'author',
			'tags',
			'theme_root',
			'theme_root_uri',
		);

		return in_array( $offset, $properties, true );
	}

	/**
	 * __get() magic method for properties formerly returned by current_theme_info()
	 *
	 * @since 3.4.0
	 *
	 * @param string $offset Property to get.
	 * @return mixed Property value.
	 */
	public function __get( $offset ) {
		switch ( $offset ) {
			case 'name':
			case 'title':
				return $this->get( 'Name' );
			case 'version':
				return $this->get( 'Version' );
			case 'parent_theme':
				return $this->parent() ? $this->parent()->get( 'Name' ) : '';
			case 'template_dir':
				return $this->get_template_directory();
			case 'stylesheet_dir':
				return $this->get_stylesheet_directory();
			case 'template':
				return $this->get_template();
			case 'stylesheet':
				return $this->get_stylesheet();
			case 'screenshot':
				return $this->get_screenshot( 'relative' );
			// 'author' and 'description' did not previously return translated data.
			case 'description':
				return $this->display( 'Description' );
			case 'author':
				return $this->display( 'Author' );
			case 'tags':
				return $this->get( 'Tags' );
			case 'theme_root':
				return $this->get_theme_root();
			case 'theme_root_uri':
				return $this->get_theme_root_uri();
			// For cases where the array was converted to an object.
			default:
				return $this->offsetGet( $offset );
		}
	}

	/**
	 * Method to implement ArrayAccess for keys formerly returned by get_themes()
	 *
	 * @since 3.4.0
	 *
	 * @param mixed $offset
	 * @param mixed $value
	 */
	public function offsetSet( $offset, $value ) {}

	/**
	 * Method to implement ArrayAccess for keys formerly returned by get_themes()
	 *
	 * @since 3.4.0
	 *
	 * @param mixed $offset
	 */
	public function offsetUnset( $offset ) {}

	/**
	 * Method to implement ArrayAccess for keys formerly returned by get_themes()
	 *
	 * @since 3.4.0
	 *
	 * @param mixed $offset
	 * @return bool
	 */
	public function offsetExists( $offset ) {
		static $keys = array(
			'Name',
			'Version',
			'Status',
			'Title',
			'Author',
			'Author Name',
			'Author URI',
			'Description',
			'Template',
			'Stylesheet',
			'Template Files',
			'Stylesheet Files',
			'Template Dir',
			'Stylesheet Dir',
			'Screenshot',
			'Tags',
			'Theme Root',
			'Theme Root URI',
			'Parent Theme',
		);

		return in_array( $offset, $keys, true );
	}

	/**
	 * Method to implement ArrayAccess for keys formerly returned by get_themes().
	 *
	 * Author, Author Name, Author URI, and Description did not previously return
	 * translated data. We are doing so now as it is safe to do. However, as
	 * Name and Title could have been used as the key for get_themes(), both remain
	 * untranslated for back compatibility. This means that ['Name'] is not ideal,
	 * and care should be taken to use `$theme::display( 'Name' )` to get a properly
	 * translated header.
	 *
	 * @since 3.4.0
	 *
	 * @param mixed $offset
	 * @return mixed
	 */
	public function offsetGet( $offset ) {
		switch ( $offset ) {
			case 'Name':
			case 'Title':
				/*
				 * See note above about using translated data. get() is not ideal.
				 * It is only for backward compatibility. Use display().
				 */
				return $this->get( 'Name' );
			case 'Author':
				return $this->display( 'Author' );
			case 'Author Name':
				return $this->display( 'Author', false );
			case 'Author URI':
				return $this->display( 'AuthorURI' );
			case 'Description':
				return $this->display( 'Description' );
			case 'Version':
			case 'Status':
				return $this->get( $offset );
			case 'Template':
				return $this->get_template();
			case 'Stylesheet':
				return $this->get_stylesheet();
			case 'Template Files':
				return $this->get_files( 'php', 1, true );
			case 'Stylesheet Files':
				return $this->get_files( 'css', 0, false );
			case 'Template Dir':
				return $this->get_template_directory();
			case 'Stylesheet Dir':
				return $this->get_stylesheet_directory();
			case 'Screenshot':
				return $this->get_screenshot( 'relative' );
			case 'Tags':
				return $this->get( 'Tags' );
			case 'Theme Root':
				return $this->get_theme_root();
			case 'Theme Root URI':
				return $this->get_theme_root_uri();
			case 'Parent Theme':
				return $this->parent() ? $this->parent()->get( 'Name' ) : '';
			default:
				return null;
		}
	}

	/**
	 * Returns errors property.
	 *
	 * @since 3.4.0
	 *
	 * @return WP_Error|false WP_Error if there are errors, or false.
	 */
	public function errors() {
		return is_wp_error( $this->errors ) ? $this->errors : false;
	}

	/**
	 * Whether the theme exists.
	 *
	 * A theme with errors exists. A theme with the error of 'theme_not_found',
	 * meaning that the theme's directory was not found, does not exist.
	 *
	 * @since 3.4.0
	 *
	 * @return bool Whether the theme exists.
	 */
	public function exists() {
		return ! ( $this->errors() && in_array( 'theme_not_found', $this->errors()->get_error_codes(), true ) );
	}

	/**
	 * Returns reference to the parent theme.
	 *
	 * @since 3.4.0
	 *
	 * @return WP_Theme|false Parent theme, or false if the current theme is not a child theme.
	 */
	public function parent() {
		return isset( $this->parent ) ? $this->parent : false;
	}

	/**
	 * Adds theme data to cache.
	 *
	 * Cache entries keyed by the theme and the type of data.
	 *
	 * @since 3.4.0
	 *
	 * @param string       $key  Type of data to store (theme, screenshot, headers, post_templates)
	 * @param array|string $data Data to store
	 * @return bool Return value from wp_cache_add()
	 */
	private function cache_add( $key, $data ) {
		return wp_cache_add( $key . '-' . $this->cache_hash, $data, 'themes', self::$cache_expiration );
	}

	/**
	 * Gets theme data from cache.
	 *
	 * Cache entries are keyed by the theme and the type of data.
	 *
	 * @since 3.4.0
	 *
	 * @param string $key Type of data to retrieve (theme, screenshot, headers, post_templates)
	 * @return mixed Retrieved data
	 */
	private function cache_get( $key ) {
		return wp_cache_get( $key . '-' . $this->cache_hash, 'themes' );
	}

	/**
	 * Clears the cache for the theme.
	 *
	 * @since 3.4.0
	 */
	public function cache_delete() {
		foreach ( array( 'theme', 'screenshot', 'headers', 'post_templates' ) as $key ) {
			wp_cache_delete( $key . '-' . $this->cache_hash, 'themes' );
		}
		$this->template          = null;
		$this->textdomain_loaded = null;
		$this->theme_root_uri    = null;
		$this->parent            = null;
		$this->errors            = null;
		$this->headers_sanitized = null;
		$this->name_translated   = null;
		$this->headers           = array();
		$this->__construct( $this->stylesheet, $this->theme_root );
	}

	/**
	 * Get a raw, unformatted theme header.
	 *
	 * The header is sanitized, but is not translated, and is not marked up for display.
	 * To get a theme header for display, use the display() method.
	 *
	 * Use the get_template() method, not the 'Template' header, for finding the template.
	 * The 'Template' header is only good for what was written in the style.css, while
	 * get_template() takes into account where WordPress actually located the theme and
	 * whether it is actually valid.
	 *
	 * @since 3.4.0
	 *
	 * @param string $header Theme header. Name, Description, Author, Version, ThemeURI, AuthorURI, Status, Tags.
	 * @return string|array|false String or array (for Tags header) on success, false on failure.
	 */
	public function get( $header ) {
		if ( ! isset( $this->headers[ $header ] ) ) {
			return false;
		}

		if ( ! isset( $this->headers_sanitized ) ) {
			$this->headers_sanitized = $this->cache_get( 'headers' );
			if ( ! is_array( $this->headers_sanitized ) ) {
				$this->headers_sanitized = array();
			}
		}

		if ( isset( $this->headers_sanitized[ $header ] ) ) {
			return $this->headers_sanitized[ $header ];
		}

		// If themes are a persistent group, sanitize everything and cache it. One cache add is better than many cache sets.
		if ( self::$persistently_cache ) {
			foreach ( array_keys( $this->headers ) as $_header ) {
				$this->headers_sanitized[ $_header ] = $this->sanitize_header( $_header, $this->headers[ $_header ] );
			}
			$this->cache_add( 'headers', $this->headers_sanitized );
		} else {
			$this->headers_sanitized[ $header ] = $this->sanitize_header( $header, $this->headers[ $header ] );
		}

		return $this->headers_sanitized[ $header ];
	}

	/**
	 * Gets a theme header, formatted and translated for display.
	 *
	 * @since 3.4.0
	 *
	 * @param string $header    Theme header. Name, Description, Author, Version, ThemeURI, AuthorURI, Status, Tags.
	 * @param bool   $markup    Optional. Whether to mark up the header. Defaults to true.
	 * @param bool   $translate Optional. Whether to translate the header. Defaults to true.
	 * @return string|array|false Processed header. An array for Tags if `$markup` is false, string otherwise.
	 *                            False on failure.
	 */
	public function display( $header, $markup = true, $translate = true ) {
		$value = $this->get( $header );
		if ( false === $value ) {
			return false;
		}

		if ( $translate && ( empty( $value ) || ! $this->load_textdomain() ) ) {
			$translate = false;
		}

		if ( $translate ) {
			$value = $this->translate_header( $header, $value );
		}

		if ( $markup ) {
			$value = $this->markup_header( $header, $value, $translate );
		}

		return $value;
	}

	/**
	 * Sanitize a theme header.
	 *
	 * @since 3.4.0
	 * @since 5.4.0 Added support for `Requires at least` and `Requires PHP` headers.
	 *
	 * @param string $header Theme header. Accepts 'Name', 'Description', 'Author', 'Version',
	 *                       'ThemeURI', 'AuthorURI', 'Status', 'Tags', 'RequiresWP', 'RequiresPHP'.
	 * @param string $value  Value to sanitize.
	 * @return string|array An array for Tags header, string otherwise.
	 */
	private function sanitize_header( $header, $value ) {
		switch ( $header ) {
			case 'Status':
				if ( ! $value ) {
					$value = 'publish';
					break;
				}
				// Fall through otherwise.
			case 'Name':
				static $header_tags = array(
					'abbr'    => array( 'title' => true ),
					'acronym' => array( 'title' => true ),
					'code'    => true,
					'em'      => true,
					'strong'  => true,
				);

				$value = wp_kses( $value, $header_tags );
				break;
			case 'Author':
				// There shouldn't be anchor tags in Author, but some themes like to be challenging.
			case 'Description':
				static $header_tags_with_a = array(
					'a'       => array(
						'href'  => true,
						'title' => true,
					),
					'abbr'    => array( 'title' => true ),
					'acronym' => array( 'title' => true ),
					'code'    => true,
					'em'      => true,
					'strong'  => true,
				);

				$value = wp_kses( $value, $header_tags_with_a );
				break;
			case 'ThemeURI':
			case 'AuthorURI':
				$value = esc_url_raw( $value );
				break;
			case 'Tags':
				$value = array_filter( array_map( 'trim', explode( ',', strip_tags( $value ) ) ) );
				break;
			case 'Version':
			case 'RequiresWP':
			case 'RequiresPHP':
				$value = strip_tags( $value );
				break;
		}

		return $value;
	}

	/**
	 * Mark up a theme header.
	 *
	 * @since 3.4.0
	 *
	 * @param string       $header    Theme header. Name, Description, Author, Version, ThemeURI, AuthorURI, Status, Tags.
	 * @param string|array $value     Value to mark up. An array for Tags header, string otherwise.
	 * @param string       $translate Whether the header has been translated.
	 * @return string Value, marked up.
	 */
	private function markup_header( $header, $value, $translate ) {
		switch ( $header ) {
			case 'Name':
				if ( empty( $value ) ) {
					$value = esc_html( $this->get_stylesheet() );
				}
				break;
			case 'Description':
				$value = wptexturize( $value );
				break;
			case 'Author':
				if ( $this->get( 'AuthorURI' ) ) {
					$value = sprintf( '<a href="%1$s">%2$s</a>', $this->display( 'AuthorURI', true, $translate ), $value );
				} elseif ( ! $value ) {
					$value = __( 'Anonymous' );
				}
				break;
			case 'Tags':
				static $comma = null;
				if ( ! isset( $comma ) ) {
					/* translators: Used between list items, there is a space after the comma. */
					$comma = __( ', ' );
				}
				$value = implode( $comma, $value );
				break;
			case 'ThemeURI':
			case 'AuthorURI':
				$value = esc_url( $value );
				break;
		}

		return $value;
	}

	/**
	 * Translate a theme header.
	 *
	 * @since 3.4.0
	 *
	 * @param string       $header Theme header. Name, Description, Author, Version, ThemeURI, AuthorURI, Status, Tags.
	 * @param string|array $value  Value to translate. An array for Tags header, string otherwise.
	 * @return string|array Translated value. An array for Tags header, string otherwise.
	 */
	private function translate_header( $header, $value ) {
		switch ( $header ) {
			case 'Name':
				// Cached for sorting reasons.
				if ( isset( $this->name_translated ) ) {
					return $this->name_translated;
				}

				// phpcs:ignore WordPress.WP.I18n.LowLevelTranslationFunction,WordPress.WP.I18n.NonSingularStringLiteralText,WordPress.WP.I18n.NonSingularStringLiteralDomain
				$this->name_translated = translate( $value, $this->get( 'TextDomain' ) );

				return $this->name_translated;
			case 'Tags':
				if ( empty( $value ) || ! function_exists( 'get_theme_feature_list' ) ) {
					return $value;
				}

				static $tags_list;
				if ( ! isset( $tags_list ) ) {
					$tags_list = array(
						// As of 4.6, deprecated tags which are only used to provide translation for older themes.
						'black'             => __( 'Black' ),
						'blue'              => __( 'Blue' ),
						'brown'             => __( 'Brown' ),
						'gray'              => __( 'Gray' ),
						'green'             => __( 'Green' ),
						'orange'            => __( 'Orange' ),
						'pink'              => __( 'Pink' ),
						'purple'            => __( 'Purple' ),
						'red'               => __( 'Red' ),
						'silver'            => __( 'Silver' ),
						'tan'               => __( 'Tan' ),
						'white'             => __( 'White' ),
						'yellow'            => __( 'Yellow' ),
						'dark'              => __( 'Dark' ),
						'light'             => __( 'Light' ),
						'fixed-layout'      => __( 'Fixed Layout' ),
						'fluid-layout'      => __( 'Fluid Layout' ),
						'responsive-layout' => __( 'Responsive Layout' ),
						'blavatar'          => __( 'Blavatar' ),
						'photoblogging'     => __( 'Photoblogging' ),
						'seasonal'          => __( 'Seasonal' ),
					);

					$feature_list = get_theme_feature_list( false ); // No API.

					foreach ( $feature_list as $tags ) {
						$tags_list += $tags;
					}
				}

				foreach ( $value as &$tag ) {
					if ( isset( $tags_list[ $tag ] ) ) {
						$tag = $tags_list[ $tag ];
					} elseif ( isset( self::$tag_map[ $tag ] ) ) {
						$tag = $tags_list[ self::$tag_map[ $tag ] ];
					}
				}

				return $value;

			default:
				// phpcs:ignore WordPress.WP.I18n.LowLevelTranslationFunction,WordPress.WP.I18n.NonSingularStringLiteralText,WordPress.WP.I18n.NonSingularStringLiteralDomain
				$value = translate( $value, $this->get( 'TextDomain' ) );
		}
		return $value;
	}

	/**
	 * The directory name of the theme's "stylesheet" files, inside the theme root.
	 *
	 * In the case of a child theme, this is directory name of the child theme.
	 * Otherwise, get_stylesheet() is the same as get_template().
	 *
	 * @since 3.4.0
	 *
	 * @return string Stylesheet
	 */
	public function get_stylesheet() {
		return $this->stylesheet;
	}

	/**
	 * The directory name of the theme's "template" files, inside the theme root.
	 *
	 * In the case of a child theme, this is the directory name of the parent theme.
	 * Otherwise, the get_template() is the same as get_stylesheet().
	 *
	 * @since 3.4.0
	 *
	 * @return string Template
	 */
	public function get_template() {
		return $this->template;
	}

	/**
	 * Returns the absolute path to the directory of a theme's "stylesheet" files.
	 *
	 * In the case of a child theme, this is the absolute path to the directory
	 * of the child theme's files.
	 *
	 * @since 3.4.0
	 *
	 * @return string Absolute path of the stylesheet directory.
	 */
	public function get_stylesheet_directory() {
		if ( $this->errors() && in_array( 'theme_root_missing', $this->errors()->get_error_codes(), true ) ) {
			return '';
		}

		return $this->theme_root . '/' . $this->stylesheet;
	}

	/**
	 * Returns the absolute path to the directory of a theme's "template" files.
	 *
	 * In the case of a child theme, this is the absolute path to the directory
	 * of the parent theme's files.
	 *
	 * @since 3.4.0
	 *
	 * @return string Absolute path of the template directory.
	 */
	public function get_template_directory() {
		if ( $this->parent() ) {
			$theme_root = $this->parent()->theme_root;
		} else {
			$theme_root = $this->theme_root;
		}

		return $theme_root . '/' . $this->template;
	}

	/**
	 * Returns the URL to the directory of a theme's "stylesheet" files.
	 *
	 * In the case of a child theme, this is the URL to the directory of the
	 * child theme's files.
	 *
	 * @since 3.4.0
	 *
	 * @return string URL to the stylesheet directory.
	 */
	public function get_stylesheet_directory_uri() {
		return $this->get_theme_root_uri() . '/' . str_replace( '%2F', '/', rawurlencode( $this->stylesheet ) );
	}

	/**
	 * Returns the URL to the directory of a theme's "template" files.
	 *
	 * In the case of a child theme, this is the URL to the directory of the
	 * parent theme's files.
	 *
	 * @since 3.4.0
	 *
	 * @return string URL to the template directory.
	 */
	public function get_template_directory_uri() {
		if ( $this->parent() ) {
			$theme_root_uri = $this->parent()->get_theme_root_uri();
		} else {
			$theme_root_uri = $this->get_theme_root_uri();
		}

		return $theme_root_uri . '/' . str_replace( '%2F', '/', rawurlencode( $this->template ) );
	}

	/**
	 * The absolute path to the directory of the theme root.
	 *
	 * This is typically the absolute path to wp-content/themes.
	 *
	 * @since 3.4.0
	 *
	 * @return string Theme root.
	 */
	public function get_theme_root() {
		return $this->theme_root;
	}

	/**
	 * Returns the URL to the directory of the theme root.
	 *
	 * This is typically the absolute URL to wp-content/themes. This forms the basis
	 * for all other URLs returned by WP_Theme, so we pass it to the public function
	 * get_theme_root_uri() and allow it to run the {@see 'theme_root_uri'} filter.
	 *
	 * @since 3.4.0
	 *
	 * @return string Theme root URI.
	 */
	public function get_theme_root_uri() {
		if ( ! isset( $this->theme_root_uri ) ) {
			$this->theme_root_uri = get_theme_root_uri( $this->stylesheet, $this->theme_root );
		}
		return $this->theme_root_uri;
	}

	/**
	 * Returns the main screenshot file for the theme.
	 *
	 * The main screenshot is called screenshot.png. gif and jpg extensions are also allowed.
	 *
	 * Screenshots for a theme must be in the stylesheet directory. (In the case of child
	 * themes, parent theme screenshots are not inherited.)
	 *
	 * @since 3.4.0
	 *
	 * @param string $uri Type of URL to return, either 'relative' or an absolute URI. Defaults to absolute URI.
	 * @return string|false Screenshot file. False if the theme does not have a screenshot.
	 */
	public function get_screenshot( $uri = 'uri' ) {
		$screenshot = $this->cache_get( 'screenshot' );
		if ( $screenshot ) {
			if ( 'relative' === $uri ) {
				return $screenshot;
			}
			return $this->get_stylesheet_directory_uri() . '/' . $screenshot;
		} elseif ( 0 === $screenshot ) {
			return false;
		}

		foreach ( array( 'png', 'gif', 'jpg', 'jpeg' ) as $ext ) {
			if ( file_exists( $this->get_stylesheet_directory() . "/screenshot.$ext" ) ) {
				$this->cache_add( 'screenshot', 'screenshot.' . $ext );
				if ( 'relative' === $uri ) {
					return 'screenshot.' . $ext;
				}
				return $this->get_stylesheet_directory_uri() . '/' . 'screenshot.' . $ext;
			}
		}

		$this->cache_add( 'screenshot', 0 );
		return false;
	}

	/**
	 * Return files in the theme's directory.
	 *
	 * @since 3.4.0
	 *
	 * @param string[]|string $type          Optional. Array of extensions to find, string of a single extension,
	 *                                       or null for all extensions. Default null.
	 * @param int             $depth         Optional. How deep to search for files. Defaults to a flat scan (0 depth).
	 *                                       -1 depth is infinite.
	 * @param bool            $search_parent Optional. Whether to return parent files. Default false.
	 * @return string[] Array of files, keyed by the path to the file relative to the theme's directory, with the values
	 *                  being absolute paths.
	 */
	public function get_files( $type = null, $depth = 0, $search_parent = false ) {
		$files = (array) self::scandir( $this->get_stylesheet_directory(), $type, $depth );

		if ( $search_parent && $this->parent() ) {
			$files += (array) self::scandir( $this->get_template_directory(), $type, $depth );
		}

		return $files;
	}

	/**
	 * Returns the theme's post templates.
	 *
	 * @since 4.7.0
	 *
	 * @return string[] Array of page templates, keyed by filename and post type,
	 *                  with the value of the translated header name.
	 */
	public function get_post_templates() {
		// If you screw up your current theme and we invalidate your parent, most things still work. Let it slide.
		if ( $this->errors() && $this->errors()->get_error_codes() !== array( 'theme_parent_invalid' ) ) {
			return array();
		}

		$post_templates = $this->cache_get( 'post_templates' );

		if ( ! is_array( $post_templates ) ) {
			$post_templates = array();

			$files = (array) $this->get_files( 'php', 1, true );

			foreach ( $files as $file => $full_path ) {
				if ( ! preg_match( '|Template Name:(.*)$|mi', file_get_contents( $full_path ), $header ) ) {
					continue;
				}

				$types = array( 'page' );
				if ( preg_match( '|Template Post Type:(.*)$|mi', file_get_contents( $full_path ), $type ) ) {
					$types = explode( ',', _cleanup_header_comment( $type[1] ) );
				}

				foreach ( $types as $type ) {
					$type = sanitize_key( $type );
					if ( ! isset( $post_templates[ $type ] ) ) {
						$post_templates[ $type ] = array();
					}

					$post_templates[ $type ][ $file ] = _cleanup_header_comment( $header[1] );
				}
			}

			$this->cache_add( 'post_templates', $post_templates );
		}

		if ( $this->load_textdomain() ) {
			foreach ( $post_templates as &$post_type ) {
				foreach ( $post_type as &$post_template ) {
					$post_template = $this->translate_header( 'Template Name', $post_template );
				}
			}
		}

		return $post_templates;
	}

	/**
	 * Returns the theme's post templates for a given post type.
	 *
	 * @since 3.4.0
	 * @since 4.7.0 Added the `$post_type` parameter.
	 *
	 * @param WP_Post|null $post      Optional. The post being edited, provided for context.
	 * @param string       $post_type Optional. Post type to get the templates for. Default 'page'.
	 *                                If a post is provided, its post type is used.
	 * @return string[] Array of template header names keyed by the template file name.
	 */
	public function get_page_templates( $post = null, $post_type = 'page' ) {
		if ( $post ) {
			$post_type = get_post_type( $post );
		}

		$post_templates = $this->get_post_templates();
		$post_templates = isset( $post_templates[ $post_type ] ) ? $post_templates[ $post_type ] : array();

		/**
		 * Filters list of page templates for a theme.
		 *
		 * @since 4.9.6
		 *
		 * @param string[]     $post_templates Array of template header names keyed by the template file name.
		 * @param WP_Theme     $this           The theme object.
		 * @param WP_Post|null $post           The post being edited, provided for context, or null.
		 * @param string       $post_type      Post type to get the templates for.
		 */
		$post_templates = (array) apply_filters( 'theme_templates', $post_templates, $this, $post, $post_type );

		/**
		 * Filters list of page templates for a theme.
		 *
		 * The dynamic portion of the hook name, `$post_type`, refers to the post type.
		 *
		 * @since 3.9.0
		 * @since 4.4.0 Converted to allow complete control over the `$page_templates` array.
		 * @since 4.7.0 Added the `$post_type` parameter.
		 *
		 * @param string[]     $post_templates Array of template header names keyed by the template file name.
		 * @param WP_Theme     $this           The theme object.
		 * @param WP_Post|null $post           The post being edited, provided for context, or null.
		 * @param string       $post_type      Post type to get the templates for.
		 */
		$post_templates = (array) apply_filters( "theme_{$post_type}_templates", $post_templates, $this, $post, $post_type );

		return $post_templates;
	}

	/**
	 * Scans a directory for files of a certain extension.
	 *
	 * @since 3.4.0
	 *
	 * @param string            $path          Absolute path to search.
	 * @param array|string|null $extensions    Optional. Array of extensions to find, string of a single extension,
	 *                                         or null for all extensions. Default null.
	 * @param int               $depth         Optional. How many levels deep to search for files. Accepts 0, 1+, or
	 *                                         -1 (infinite depth). Default 0.
	 * @param string            $relative_path Optional. The basename of the absolute path. Used to control the
	 *                                         returned path for the found files, particularly when this function
	 *                                         recurses to lower depths. Default empty.
	 * @return string[]|false Array of files, keyed by the path to the file relative to the `$path` directory prepended
	 *                        with `$relative_path`, with the values being absolute paths. False otherwise.
	 */
	private static function scandir( $path, $extensions = null, $depth = 0, $relative_path = '' ) {
		if ( ! is_dir( $path ) ) {
			return false;
		}

		if ( $extensions ) {
			$extensions  = (array) $extensions;
			$_extensions = implode( '|', $extensions );
		}

		$relative_path = trailingslashit( $relative_path );
		if ( '/' === $relative_path ) {
			$relative_path = '';
		}

		$results = scandir( $path );
		$files   = array();

		/**
		 * Filters the array of excluded directories and files while scanning theme folder.
		 *
		 * @since 4.7.4
		 *
		 * @param string[] $exclusions Array of excluded directories and files.
		 */
		$exclusions = (array) apply_filters( 'theme_scandir_exclusions', array( 'CVS', 'node_modules', 'vendor', 'bower_components' ) );

		foreach ( $results as $result ) {
			if ( '.' === $result[0] || in_array( $result, $exclusions, true ) ) {
				continue;
			}
			if ( is_dir( $path . '/' . $result ) ) {
				if ( ! $depth ) {
					continue;
				}
				$found = self::scandir( $path . '/' . $result, $extensions, $depth - 1, $relative_path . $result );
				$files = array_merge_recursive( $files, $found );
			} elseif ( ! $extensions || preg_match( '~\.(' . $_extensions . ')$~', $result ) ) {
				$files[ $relative_path . $result ] = $path . '/' . $result;
			}
		}

		return $files;
	}

	/**
	 * Loads the theme's textdomain.
	 *
	 * Translation files are not inherited from the parent theme. TODO: If this fails for the
	 * child theme, it should probably try to load the parent theme's translations.
	 *
	 * @since 3.4.0
	 *
	 * @return bool True if the textdomain was successfully loaded or has already been loaded.
	 *  False if no textdomain was specified in the file headers, or if the domain could not be loaded.
	 */
	public function load_textdomain() {
		if ( isset( $this->textdomain_loaded ) ) {
			return $this->textdomain_loaded;
		}

		$textdomain = $this->get( 'TextDomain' );
		if ( ! $textdomain ) {
			$this->textdomain_loaded = false;
			return false;
		}

		if ( is_textdomain_loaded( $textdomain ) ) {
			$this->textdomain_loaded = true;
			return true;
		}

		$path       = $this->get_stylesheet_directory();
		$domainpath = $this->get( 'DomainPath' );
		if ( $domainpath ) {
			$path .= $domainpath;
		} else {
			$path .= '/languages';
		}

		$this->textdomain_loaded = load_theme_textdomain( $textdomain, $path );
		return $this->textdomain_loaded;
	}

	/**
	 * Whether the theme is allowed (multisite only).
	 *
	 * @since 3.4.0
	 *
	 * @param string $check   Optional. Whether to check only the 'network'-wide settings, the 'site'
	 *                        settings, or 'both'. Defaults to 'both'.
	 * @param int    $blog_id Optional. Ignored if only network-wide settings are checked. Defaults to current site.
	 * @return bool Whether the theme is allowed for the network. Returns true in single-site.
	 */
	public function is_allowed( $check = 'both', $blog_id = null ) {
		if ( ! is_multisite() ) {
			return true;
		}

		if ( 'both' === $check || 'network' === $check ) {
			$allowed = self::get_allowed_on_network();
			if ( ! empty( $allowed[ $this->get_stylesheet() ] ) ) {
				return true;
			}
		}

		if ( 'both' === $check || 'site' === $check ) {
			$allowed = self::get_allowed_on_site( $blog_id );
			if ( ! empty( $allowed[ $this->get_stylesheet() ] ) ) {
				return true;
			}
		}

		return false;
	}

	/**
	 * Determines the latest WordPress default theme that is installed.
	 *
	 * This hits the filesystem.
	 *
	 * @since 4.4.0
	 *
	 * @return WP_Theme|false Object, or false if no theme is installed, which would be bad.
	 */
	public static function get_core_default_theme() {
		foreach ( array_reverse( self::$default_themes ) as $slug => $name ) {
			$theme = wp_get_theme( $slug );
			if ( $theme->exists() ) {
				return $theme;
			}
		}
		return false;
	}

	/**
	 * Returns array of stylesheet names of themes allowed on the site or network.
	 *
	 * @since 3.4.0
	 *
	 * @param int $blog_id Optional. ID of the site. Defaults to the current site.
	 * @return string[] Array of stylesheet names.
	 */
	public static function get_allowed( $blog_id = null ) {
		/**
		 * Filters the array of themes allowed on the network.
		 *
		 * Site is provided as context so that a list of network allowed themes can
		 * be filtered further.
		 *
		 * @since 4.5.0
		 *
		 * @param string[] $allowed_themes An array of theme stylesheet names.
		 * @param int      $blog_id        ID of the site.
		 */
		$network = (array) apply_filters( 'network_allowed_themes', self::get_allowed_on_network(), $blog_id );
		return $network + self::get_allowed_on_site( $blog_id );
	}

	/**
	 * Returns array of stylesheet names of themes allowed on the network.
	 *
	 * @since 3.4.0
	 *
	 * @return string[] Array of stylesheet names.
	 */
	public static function get_allowed_on_network() {
		static $allowed_themes;
		if ( ! isset( $allowed_themes ) ) {
			$allowed_themes = (array) get_site_option( 'allowedthemes' );
		}

		/**
		 * Filters the array of themes allowed on the network.
		 *
		 * @since MU (3.0.0)
		 *
		 * @param string[] $allowed_themes An array of theme stylesheet names.
		 */
		$allowed_themes = apply_filters( 'allowed_themes', $allowed_themes );

		return $allowed_themes;
	}

	/**
	 * Returns array of stylesheet names of themes allowed on the site.
	 *
	 * @since 3.4.0
	 *
	 * @param int $blog_id Optional. ID of the site. Defaults to the current site.
	 * @return string[] Array of stylesheet names.
	 */
	public static function get_allowed_on_site( $blog_id = null ) {
		static $allowed_themes = array();

		if ( ! $blog_id || ! is_multisite() ) {
			$blog_id = get_current_blog_id();
		}

		if ( isset( $allowed_themes[ $blog_id ] ) ) {
			/**
			 * Filters the array of themes allowed on the site.
			 *
			 * @since 4.5.0
			 *
			 * @param string[] $allowed_themes An array of theme stylesheet names.
			 * @param int      $blog_id        ID of the site. Defaults to current site.
			 */
			return (array) apply_filters( 'site_allowed_themes', $allowed_themes[ $blog_id ], $blog_id );
		}

		$current = get_current_blog_id() == $blog_id;

		if ( $current ) {
			$allowed_themes[ $blog_id ] = get_option( 'allowedthemes' );
		} else {
			switch_to_blog( $blog_id );
			$allowed_themes[ $blog_id ] = get_option( 'allowedthemes' );
			restore_current_blog();
		}

		// This is all super old MU back compat joy.
		// 'allowedthemes' keys things by stylesheet. 'allowed_themes' keyed things by name.
		if ( false === $allowed_themes[ $blog_id ] ) {
			if ( $current ) {
				$allowed_themes[ $blog_id ] = get_option( 'allowed_themes' );
			} else {
				switch_to_blog( $blog_id );
				$allowed_themes[ $blog_id ] = get_option( 'allowed_themes' );
				restore_current_blog();
			}

			if ( ! is_array( $allowed_themes[ $blog_id ] ) || empty( $allowed_themes[ $blog_id ] ) ) {
				$allowed_themes[ $blog_id ] = array();
			} else {
				$converted = array();
				$themes    = wp_get_themes();
				foreach ( $themes as $stylesheet => $theme_data ) {
					if ( isset( $allowed_themes[ $blog_id ][ $theme_data->get( 'Name' ) ] ) ) {
						$converted[ $stylesheet ] = true;
					}
				}
				$allowed_themes[ $blog_id ] = $converted;
			}
			// Set the option so we never have to go through this pain again.
			if ( is_admin() && $allowed_themes[ $blog_id ] ) {
				if ( $current ) {
					update_option( 'allowedthemes', $allowed_themes[ $blog_id ] );
					delete_option( 'allowed_themes' );
				} else {
					switch_to_blog( $blog_id );
					update_option( 'allowedthemes', $allowed_themes[ $blog_id ] );
					delete_option( 'allowed_themes' );
					restore_current_blog();
				}
			}
		}

		/** This filter is documented in wp-includes/class-wp-theme.php */
		return (array) apply_filters( 'site_allowed_themes', $allowed_themes[ $blog_id ], $blog_id );
	}

	/**
	 * Enables a theme for all sites on the current network.
	 *
	 * @since 4.6.0
	 *
	 * @param string|string[] $stylesheets Stylesheet name or array of stylesheet names.
	 */
	public static function network_enable_theme( $stylesheets ) {
		if ( ! is_multisite() ) {
			return;
		}

		if ( ! is_array( $stylesheets ) ) {
			$stylesheets = array( $stylesheets );
		}

		$allowed_themes = get_site_option( 'allowedthemes' );
		foreach ( $stylesheets as $stylesheet ) {
			$allowed_themes[ $stylesheet ] = true;
		}

		update_site_option( 'allowedthemes', $allowed_themes );
	}

	/**
	 * Disables a theme for all sites on the current network.
	 *
	 * @since 4.6.0
	 *
	 * @param string|string[] $stylesheets Stylesheet name or array of stylesheet names.
	 */
	public static function network_disable_theme( $stylesheets ) {
		if ( ! is_multisite() ) {
			return;
		}

		if ( ! is_array( $stylesheets ) ) {
			$stylesheets = array( $stylesheets );
		}

		$allowed_themes = get_site_option( 'allowedthemes' );
		foreach ( $stylesheets as $stylesheet ) {
			if ( isset( $allowed_themes[ $stylesheet ] ) ) {
				unset( $allowed_themes[ $stylesheet ] );
			}
		}

		update_site_option( 'allowedthemes', $allowed_themes );
	}

	/**
	 * Sorts themes by name.
	 *
	 * @since 3.4.0
	 *
	 * @param WP_Theme[] $themes Array of theme objects to sort (passed by reference).
	 */
	public static function sort_by_name( &$themes ) {
		if ( 0 === strpos( get_user_locale(), 'en_' ) ) {
			uasort( $themes, array( 'WP_Theme', '_name_sort' ) );
		} else {
			foreach ( $themes as $key => $theme ) {
				$theme->translate_header( 'Name', $theme->headers['Name'] );
			}
			uasort( $themes, array( 'WP_Theme', '_name_sort_i18n' ) );
		}
	}

	/**
	 * Callback function for usort() to naturally sort themes by name.
	 *
	 * Accesses the Name header directly from the class for maximum speed.
	 * Would choke on HTML but we don't care enough to slow it down with strip_tags().
	 *
	 * @since 3.4.0
	 *
	 * @param WP_Theme $a First theme.
	 * @param WP_Theme $b Second theme.
	 * @return int Negative if `$a` falls lower in the natural order than `$b`. Zero if they fall equally.
	 *             Greater than 0 if `$a` falls higher in the natural order than `$b`. Used with usort().
	 */
	private static function _name_sort( $a, $b ) {
		return strnatcasecmp( $a->headers['Name'], $b->headers['Name'] );
	}

	/**
	 * Callback function for usort() to naturally sort themes by translated name.
	 *
	 * @since 3.4.0
	 *
	 * @param WP_Theme $a First theme.
	 * @param WP_Theme $b Second theme.
	 * @return int Negative if `$a` falls lower in the natural order than `$b`. Zero if they fall equally.
	 *             Greater than 0 if `$a` falls higher in the natural order than `$b`. Used with usort().
	 */
	private static function _name_sort_i18n( $a, $b ) {
		return strnatcasecmp( $a->name_translated, $b->name_translated );
	}
}

Methods

Changelog

Version Description
3.4.0 Introduced.

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Licensed under the GNU GPLv2+ License.
https://developer.wordpress.org/reference/classes/wp_theme