/wp-includes/taxonomy.php

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<?php
/**
 * Taxonomy API
 *
 * @package WordPress
 * @subpackage Taxonomy
 * @since 2.3.0
 */

//
// Taxonomy Registration
//

/**
 * Creates the initial taxonomies.
 *
 * This function fires twice: in wp-settings.php before plugins are loaded (for
 * backwards compatibility reasons), and again on the 'init' action. We must avoid
 * registering rewrite rules before the 'init' action.
 */
function create_initial_taxonomies() {
	global $wp_rewrite;

	if ( ! did_action( 'init' ) ) {
		$rewrite = array( 'category' => false, 'post_tag' => false, 'post_format' => false );
	} else {
		$post_format_base = apply_filters( 'post_format_rewrite_base', 'type' );
		$rewrite = array(
			'category' => array(
				'hierarchical' => true,
				'slug' => get_option('category_base') ? get_option('category_base') : 'category',
				'with_front' => ! get_option('category_base') || $wp_rewrite->using_index_permalinks(),
				'ep_mask' => EP_CATEGORIES,
			),
			'post_tag' => array(
				'slug' => get_option('tag_base') ? get_option('tag_base') : 'tag',
				'with_front' => ! get_option('tag_base') || $wp_rewrite->using_index_permalinks(),
				'ep_mask' => EP_TAGS,
			),
			'post_format' => $post_format_base ? array( 'slug' => $post_format_base ) : false,
		);
	}

	register_taxonomy( 'category', 'post', array(
		'hierarchical' => true,
		'query_var' => 'category_name',
		'rewrite' => $rewrite['category'],
		'public' => true,
		'show_ui' => true,
		'show_admin_column' => true,
		'_builtin' => true,
	) );

	register_taxonomy( 'post_tag', 'post', array(
	 	'hierarchical' => false,
		'query_var' => 'tag',
		'rewrite' => $rewrite['post_tag'],
		'public' => true,
		'show_ui' => true,
		'show_admin_column' => true,
		'_builtin' => true,
	) );

	register_taxonomy( 'nav_menu', 'nav_menu_item', array(
		'public' => false,
		'hierarchical' => false,
		'labels' => array(
			'name' => __( 'Navigation Menus' ),
			'singular_name' => __( 'Navigation Menu' ),
		),
		'query_var' => false,
		'rewrite' => false,
		'show_ui' => false,
		'_builtin' => true,
		'show_in_nav_menus' => false,
	) );

	register_taxonomy( 'link_category', 'link', array(
		'hierarchical' => false,
		'labels' => array(
			'name' => __( 'Link Categories' ),
			'singular_name' => __( 'Link Category' ),
			'search_items' => __( 'Search Link Categories' ),
			'popular_items' => null,
			'all_items' => __( 'All Link Categories' ),
			'edit_item' => __( 'Edit Link Category' ),
			'update_item' => __( 'Update Link Category' ),
			'add_new_item' => __( 'Add New Link Category' ),
			'new_item_name' => __( 'New Link Category Name' ),
			'separate_items_with_commas' => null,
			'add_or_remove_items' => null,
			'choose_from_most_used' => null,
		),
		'capabilities' => array(
			'manage_terms' => 'manage_links',
			'edit_terms'   => 'manage_links',
			'delete_terms' => 'manage_links',
			'assign_terms' => 'manage_links',
		),
		'query_var' => false,
		'rewrite' => false,
		'public' => false,
		'show_ui' => false,
		'_builtin' => true,
	) );

	register_taxonomy( 'post_format', 'post', array(
		'public' => true,
		'hierarchical' => false,
		'labels' => array(
			'name' => _x( 'Format', 'post format' ),
			'singular_name' => _x( 'Format', 'post format' ),
		),
		'query_var' => true,
		'rewrite' => $rewrite['post_format'],
		'show_ui' => false,
		'_builtin' => true,
		'show_in_nav_menus' => current_theme_supports( 'post-formats' ),
	) );
}
add_action( 'init', 'create_initial_taxonomies', 0 ); // highest priority

/**
 * Get a list of registered taxonomy objects.
 *
 * @package WordPress
 * @subpackage Taxonomy
 * @since 3.0.0
 * @uses $wp_taxonomies
 * @see register_taxonomy
 *
 * @param array $args An array of key => value arguments to match against the taxonomy objects.
 * @param string $output The type of output to return, either taxonomy 'names' or 'objects'. 'names' is the default.
 * @param string $operator The logical operation to perform. 'or' means only one element
 *  from the array needs to match; 'and' means all elements must match. The default is 'and'.
 * @return array A list of taxonomy names or objects
 */
function get_taxonomies( $args = array(), $output = 'names', $operator = 'and' ) {
	global $wp_taxonomies;

	$field = ('names' == $output) ? 'name' : false;

	return wp_filter_object_list($wp_taxonomies, $args, $operator, $field);
}

/**
 * Return all of the taxonomy names that are of $object_type.
 *
 * It appears that this function can be used to find all of the names inside of
 * $wp_taxonomies global variable.
 *
 * <code><?php $taxonomies = get_object_taxonomies('post'); ?></code> Should
 * result in <code>Array('category', 'post_tag')</code>
 *
 * @package WordPress
 * @subpackage Taxonomy
 * @since 2.3.0
 *
 * @uses $wp_taxonomies
 *
 * @param array|string|object $object Name of the type of taxonomy object, or an object (row from posts)
 * @param string $output The type of output to return, either taxonomy 'names' or 'objects'. 'names' is the default.
 * @return array The names of all taxonomy of $object_type.
 */
function get_object_taxonomies($object, $output = 'names') {
	global $wp_taxonomies;

	if ( is_object($object) ) {
		if ( $object->post_type == 'attachment' )
			return get_attachment_taxonomies($object);
		$object = $object->post_type;
	}

	$object = (array) $object;

	$taxonomies = array();
	foreach ( (array) $wp_taxonomies as $tax_name => $tax_obj ) {
		if ( array_intersect($object, (array) $tax_obj->object_type) ) {
			if ( 'names' == $output )
				$taxonomies[] = $tax_name;
			else
				$taxonomies[ $tax_name ] = $tax_obj;
		}
	}

	return $taxonomies;
}

/**
 * Retrieves the taxonomy object of $taxonomy.
 *
 * The get_taxonomy function will first check that the parameter string given
 * is a taxonomy object and if it is, it will return it.
 *
 * @package WordPress
 * @subpackage Taxonomy
 * @since 2.3.0
 *
 * @uses $wp_taxonomies
 * @uses taxonomy_exists() Checks whether taxonomy exists
 *
 * @param string $taxonomy Name of taxonomy object to return
 * @return object|bool The Taxonomy Object or false if $taxonomy doesn't exist
 */
function get_taxonomy( $taxonomy ) {
	global $wp_taxonomies;

	if ( ! taxonomy_exists( $taxonomy ) )
		return false;

	return $wp_taxonomies[$taxonomy];
}

/**
 * Checks that the taxonomy name exists.
 *
 * Formerly is_taxonomy(), introduced in 2.3.0.
 *
 * @package WordPress
 * @subpackage Taxonomy
 * @since 3.0.0
 *
 * @uses $wp_taxonomies
 *
 * @param string $taxonomy Name of taxonomy object
 * @return bool Whether the taxonomy exists.
 */
function taxonomy_exists( $taxonomy ) {
	global $wp_taxonomies;

	return isset( $wp_taxonomies[$taxonomy] );
}

/**
 * Whether the taxonomy object is hierarchical.
 *
 * Checks to make sure that the taxonomy is an object first. Then Gets the
 * object, and finally returns the hierarchical value in the object.
 *
 * A false return value might also mean that the taxonomy does not exist.
 *
 * @package WordPress
 * @subpackage Taxonomy
 * @since 2.3.0
 *
 * @uses taxonomy_exists() Checks whether taxonomy exists
 * @uses get_taxonomy() Used to get the taxonomy object
 *
 * @param string $taxonomy Name of taxonomy object
 * @return bool Whether the taxonomy is hierarchical
 */
function is_taxonomy_hierarchical($taxonomy) {
	if ( ! taxonomy_exists($taxonomy) )
		return false;

	$taxonomy = get_taxonomy($taxonomy);
	return $taxonomy->hierarchical;
}

/**
 * Create or modify a taxonomy object. Do not use before init.
 *
 * A simple function for creating or modifying a taxonomy object based on the
 * parameters given. The function will accept an array (third optional
 * parameter), along with strings for the taxonomy name and another string for
 * the object type.
 *
 * Nothing is returned, so expect error maybe or use taxonomy_exists() to check
 * whether taxonomy exists.
 *
 * Optional $args contents:
 *
 * - label - Name of the taxonomy shown in the menu. Usually plural. If not set, labels['name'] will be used.
 * - labels - An array of labels for this taxonomy.
 *     * By default tag labels are used for non-hierarchical types and category labels for hierarchical ones.
 *     * You can see accepted values in {@link get_taxonomy_labels()}.
 * - description - A short descriptive summary of what the taxonomy is for. Defaults to blank.
 * - public - If the taxonomy should be publicly queryable; //@TODO not implemented.
 *     * Defaults to true.
 * - hierarchical - Whether the taxonomy is hierarchical (e.g. category). Defaults to false.
 * - show_ui -Whether to generate a default UI for managing this taxonomy in the admin.
 *     * If not set, the default is inherited from public.
 * - show_in_menu - Where to show the taxonomy in the admin menu.
 *     * If true, the taxonomy is shown as a submenu of the object type menu.
 *     * If false, no menu is shown.
 *     * show_ui must be true.
 *     * If not set, the default is inherited from show_ui.
 * - show_in_nav_menus - Makes this taxonomy available for selection in navigation menus.
 *     * If not set, the default is inherited from public.
 * - show_tagcloud - Whether to list the taxonomy in the Tag Cloud Widget.
 *     * If not set, the default is inherited from show_ui.
 * - meta_box_cb - Provide a callback function for the meta box display. Defaults to
 *     post_categories_meta_box for hierarchical taxonomies and post_tags_meta_box for non-hierarchical.
 * - capabilities - Array of capabilities for this taxonomy.
 *     * You can see accepted values in this function.
 * - rewrite - Triggers the handling of rewrites for this taxonomy. Defaults to true, using $taxonomy as slug.
 *     * To prevent rewrite, set to false.
 *     * To specify rewrite rules, an array can be passed with any of these keys
 *         * 'slug' => string Customize the permastruct slug. Defaults to $taxonomy key
 *         * 'with_front' => bool Should the permastruct be prepended with WP_Rewrite::$front. Defaults to true.
 *         * 'hierarchical' => bool Either hierarchical rewrite tag or not. Defaults to false.
 *         * 'ep_mask' => const Assign an endpoint mask.
 *             * If not specified, defaults to EP_NONE.
 * - query_var - Sets the query_var key for this taxonomy. Defaults to $taxonomy key
 *     * If false, a taxonomy cannot be loaded at ?{query_var}={term_slug}
 *     * If specified as a string, the query ?{query_var_string}={term_slug} will be valid.
 * - update_count_callback - Works much like a hook, in that it will be called when the count is updated.
 *     * Defaults to _update_post_term_count() for taxonomies attached to post types, which then confirms
 *       that the objects are published before counting them.
 *     * Defaults to _update_generic_term_count() for taxonomies attached to other object types, such as links.
 * - _builtin - true if this taxonomy is a native or "built-in" taxonomy. THIS IS FOR INTERNAL USE ONLY!
 *
 * @since 2.3.0
 * @uses $wp_taxonomies Inserts new taxonomy object into the list
 * @uses $wp Adds query vars
 *
 * @param string $taxonomy Taxonomy key, must not exceed 32 characters.
 * @param array|string $object_type Name of the object type for the taxonomy object.
 * @param array|string $args See optional args description above.
 * @return null|WP_Error WP_Error if errors, otherwise null.
 */
function register_taxonomy( $taxonomy, $object_type, $args = array() ) {
	global $wp_taxonomies, $wp;

	if ( ! is_array( $wp_taxonomies ) )
		$wp_taxonomies = array();

	$defaults = array(
		'labels'                => array(),
		'description'           => '',
		'public'                => true,
		'hierarchical'          => false,
		'show_ui'               => null,
		'show_in_menu'          => null,
		'show_in_nav_menus'     => null,
		'show_tagcloud'         => null,
		'meta_box_cb'           => null,
		'capabilities'          => array(),
		'rewrite'               => true,
		'query_var'             => $taxonomy,
		'update_count_callback' => '',
		'_builtin'              => false,
	);
	$args = wp_parse_args( $args, $defaults );

	if ( strlen( $taxonomy ) > 32 )
		return new WP_Error( 'taxonomy_too_long', __( 'Taxonomies cannot exceed 32 characters in length' ) );

	if ( false !== $args['query_var'] && ! empty( $wp ) ) {
		if ( true === $args['query_var'] )
			$args['query_var'] = $taxonomy;
		else
			$args['query_var'] = sanitize_title_with_dashes( $args['query_var'] );
		$wp->add_query_var( $args['query_var'] );
	}

	if ( false !== $args['rewrite'] && ( is_admin() || '' != get_option( 'permalink_structure' ) ) ) {
		$args['rewrite'] = wp_parse_args( $args['rewrite'], array(
			'with_front' => true,
			'hierarchical' => false,
			'ep_mask' => EP_NONE,
		) );

		if ( empty( $args['rewrite']['slug'] ) )
			$args['rewrite']['slug'] = sanitize_title_with_dashes( $taxonomy );

		if ( $args['hierarchical'] && $args['rewrite']['hierarchical'] )
			$tag = '(.+?)';
		else
			$tag = '([^/]+)';

		add_rewrite_tag( "%$taxonomy%", $tag, $args['query_var'] ? "{$args['query_var']}=" : "taxonomy=$taxonomy&term=" );
		add_permastruct( $taxonomy, "{$args['rewrite']['slug']}/%$taxonomy%", $args['rewrite'] );
	}

	// If not set, default to the setting for public.
	if ( null === $args['show_ui'] )
		$args['show_ui'] = $args['public'];

	// If not set, default to the setting for show_ui.
	if ( null === $args['show_in_menu' ] || ! $args['show_ui'] )
		$args['show_in_menu' ] = $args['show_ui'];

	// If not set, default to the setting for public.
	if ( null === $args['show_in_nav_menus'] )
		$args['show_in_nav_menus'] = $args['public'];

	// If not set, default to the setting for show_ui.
	if ( null === $args['show_tagcloud'] )
		$args['show_tagcloud'] = $args['show_ui'];

	$default_caps = array(
		'manage_terms' => 'manage_categories',
		'edit_terms'   => 'manage_categories',
		'delete_terms' => 'manage_categories',
		'assign_terms' => 'edit_posts',
	);
	$args['cap'] = (object) array_merge( $default_caps, $args['capabilities'] );
	unset( $args['capabilities'] );

	$args['name'] = $taxonomy;
	$args['object_type'] = array_unique( (array) $object_type );

	$args['labels'] = get_taxonomy_labels( (object) $args );
	$args['label'] = $args['labels']->name;

	// If not set, use the default meta box
	if ( null === $args['meta_box_cb'] ) {
		if ( $args['hierarchical'] )
			$args['meta_box_cb'] = 'post_categories_meta_box';
		else
			$args['meta_box_cb'] = 'post_tags_meta_box';
	}

	$wp_taxonomies[ $taxonomy ] = (object) $args;

	// register callback handling for metabox
 	add_filter( 'wp_ajax_add-' . $taxonomy, '_wp_ajax_add_hierarchical_term' );

	do_action( 'registered_taxonomy', $taxonomy, $object_type, $args );
}

/**
 * Builds an object with all taxonomy labels out of a taxonomy object
 *
 * Accepted keys of the label array in the taxonomy object:
 * - name - general name for the taxonomy, usually plural. The same as and overridden by $tax->label. Default is Tags/Categories
 * - singular_name - name for one object of this taxonomy. Default is Tag/Category
 * - search_items - Default is Search Tags/Search Categories
 * - popular_items - This string isn't used on hierarchical taxonomies. Default is Popular Tags
 * - all_items - Default is All Tags/All Categories
 * - parent_item - This string isn't used on non-hierarchical taxonomies. In hierarchical ones the default is Parent Category
 * - parent_item_colon - The same as <code>parent_item</code>, but with colon <code>:</code> in the end
 * - edit_item - Default is Edit Tag/Edit Category
 * - view_item - Default is View Tag/View Category
 * - update_item - Default is Update Tag/Update Category
 * - add_new_item - Default is Add New Tag/Add New Category
 * - new_item_name - Default is New Tag Name/New Category Name
 * - separate_items_with_commas - This string isn't used on hierarchical taxonomies. Default is "Separate tags with commas", used in the meta box.
 * - add_or_remove_items - This string isn't used on hierarchical taxonomies. Default is "Add or remove tags", used in the meta box when JavaScript is disabled.
 * - choose_from_most_used - This string isn't used on hierarchical taxonomies. Default is "Choose from the most used tags", used in the meta box.
 * - not_found - This string isn't used on hierarchical taxonomies. Default is "No tags found", used in the meta box.
 *
 * Above, the first default value is for non-hierarchical taxonomies (like tags) and the second one is for hierarchical taxonomies (like categories).
 *
 * @since 3.0.0
 * @param object $tax Taxonomy object
 * @return object object with all the labels as member variables
 */

function get_taxonomy_labels( $tax ) {
	$tax->labels = (array) $tax->labels;

	if ( isset( $tax->helps ) && empty( $tax->labels['separate_items_with_commas'] ) )
		$tax->labels['separate_items_with_commas'] = $tax->helps;

	if ( isset( $tax->no_tagcloud ) && empty( $tax->labels['not_found'] ) )
		$tax->labels['not_found'] = $tax->no_tagcloud;

	$nohier_vs_hier_defaults = array(
		'name' => array( _x( 'Tags', 'taxonomy general name' ), _x( 'Categories', 'taxonomy general name' ) ),
		'singular_name' => array( _x( 'Tag', 'taxonomy singular name' ), _x( 'Category', 'taxonomy singular name' ) ),
		'search_items' => array( __( 'Search Tags' ), __( 'Search Categories' ) ),
		'popular_items' => array( __( 'Popular Tags' ), null ),
		'all_items' => array( __( 'All Tags' ), __( 'All Categories' ) ),
		'parent_item' => array( null, __( 'Parent Category' ) ),
		'parent_item_colon' => array( null, __( 'Parent Category:' ) ),
		'edit_item' => array( __( 'Edit Tag' ), __( 'Edit Category' ) ),
		'view_item' => array( __( 'View Tag' ), __( 'View Category' ) ),
		'update_item' => array( __( 'Update Tag' ), __( 'Update Category' ) ),
		'add_new_item' => array( __( 'Add New Tag' ), __( 'Add New Category' ) ),
		'new_item_name' => array( __( 'New Tag Name' ), __( 'New Category Name' ) ),
		'separate_items_with_commas' => array( __( 'Separate tags with commas' ), null ),
		'add_or_remove_items' => array( __( 'Add or remove tags' ), null ),
		'choose_from_most_used' => array( __( 'Choose from the most used tags' ), null ),
		'not_found' => array( __( 'No tags found.' ), null ),
	);
	$nohier_vs_hier_defaults['menu_name'] = $nohier_vs_hier_defaults['name'];

	return _get_custom_object_labels( $tax, $nohier_vs_hier_defaults );
}

/**
 * Add an already registered taxonomy to an object type.
 *
 * @package WordPress
 * @subpackage Taxonomy
 * @since 3.0.0
 * @uses $wp_taxonomies Modifies taxonomy object
 *
 * @param string $taxonomy Name of taxonomy object
 * @param string $object_type Name of the object type
 * @return bool True if successful, false if not
 */
function register_taxonomy_for_object_type( $taxonomy, $object_type) {
	global $wp_taxonomies;

	if ( !isset($wp_taxonomies[$taxonomy]) )
		return false;

	if ( ! get_post_type_object($object_type) )
		return false;

	if ( ! in_array( $object_type, $wp_taxonomies[$taxonomy]->object_type ) )
		$wp_taxonomies[$taxonomy]->object_type[] = $object_type;

	return true;
}

/**
 * Remove an already registered taxonomy from an object type.
 *
 * @since 3.7.0
 *
 * @param string $taxonomy    Name of taxonomy object.
 * @param string $object_type Name of the object type.
 * @return bool True if successful, false if not.
 */
function unregister_taxonomy_for_object_type( $taxonomy, $object_type ) {
	global $wp_taxonomies;

	if ( ! isset( $wp_taxonomies[ $taxonomy ] ) )
		return false;

	if ( ! get_post_type_object( $object_type ) )
		return false;

	$key = array_search( $object_type, $wp_taxonomies[ $taxonomy ]->object_type, true );
	if ( false === $key )
		return false;

	unset( $wp_taxonomies[ $taxonomy ]->object_type[ $key ] );
	return true;
}

//
// Term API
//

/**
 * Retrieve object_ids of valid taxonomy and term.
 *
 * The strings of $taxonomies must exist before this function will continue. On
 * failure of finding a valid taxonomy, it will return an WP_Error class, kind
 * of like Exceptions in PHP 5, except you can't catch them. Even so, you can
 * still test for the WP_Error class and get the error message.
 *
 * The $terms aren't checked the same as $taxonomies, but still need to exist
 * for $object_ids to be returned.
 *
 * It is possible to change the order that object_ids is returned by either
 * using PHP sort family functions or using the database by using $args with
 * either ASC or DESC array. The value should be in the key named 'order'.
 *
 * @package WordPress
 * @subpackage Taxonomy
 * @since 2.3.0
 *
 * @uses $wpdb
 * @uses wp_parse_args() Creates an array from string $args.
 *
 * @param int|array $term_ids Term id or array of term ids of terms that will be used
 * @param string|array $taxonomies String of taxonomy name or Array of string values of taxonomy names
 * @param array|string $args Change the order of the object_ids, either ASC or DESC
 * @return WP_Error|array If the taxonomy does not exist, then WP_Error will be returned. On success
 *	the array can be empty meaning that there are no $object_ids found or it will return the $object_ids found.
 */
function get_objects_in_term( $term_ids, $taxonomies, $args = array() ) {
	global $wpdb;

	if ( ! is_array( $term_ids ) )
		$term_ids = array( $term_ids );

	if ( ! is_array( $taxonomies ) )
		$taxonomies = array( $taxonomies );

	foreach ( (array) $taxonomies as $taxonomy ) {
		if ( ! taxonomy_exists( $taxonomy ) )
			return new WP_Error( 'invalid_taxonomy', __( 'Invalid taxonomy' ) );
	}

	$defaults = array( 'order' => 'ASC' );
	$args = wp_parse_args( $args, $defaults );
	extract( $args, EXTR_SKIP );

	$order = ( 'desc' == strtolower( $order ) ) ? 'DESC' : 'ASC';

	$term_ids = array_map('intval', $term_ids );

	$taxonomies = "'" . implode( "', '", $taxonomies ) . "'";
	$term_ids = "'" . implode( "', '", $term_ids ) . "'";

	$object_ids = $wpdb->get_col("SELECT tr.object_id FROM $wpdb->term_relationships AS tr INNER JOIN $wpdb->term_taxonomy AS tt ON tr.term_taxonomy_id = tt.term_taxonomy_id WHERE tt.taxonomy IN ($taxonomies) AND tt.term_id IN ($term_ids) ORDER BY tr.object_id $order");

	if ( ! $object_ids )
		return array();

	return $object_ids;
}

/**
 * Given a taxonomy query, generates SQL to be appended to a main query.
 *
 * @since 3.1.0
 *
 * @see WP_Tax_Query
 *
 * @param array $tax_query A compact tax query
 * @param string $primary_table
 * @param string $primary_id_column
 * @return array
 */
function get_tax_sql( $tax_query, $primary_table, $primary_id_column ) {
	$tax_query_obj = new WP_Tax_Query( $tax_query );
	return $tax_query_obj->get_sql( $primary_table, $primary_id_column );
}

/**
 * Container class for a multiple taxonomy query.
 *
 * @since 3.1.0
 */
class WP_Tax_Query {

	/**
	 * List of taxonomy queries. A single taxonomy query is an associative array:
	 * - 'taxonomy' string The taxonomy being queried
	 * - 'terms' string|array The list of terms
	 * - 'field' string (optional) Which term field is being used.
	 *		Possible values: 'term_id', 'slug' or 'name'
	 *		Default: 'term_id'
	 * - 'operator' string (optional)
	 *		Possible values: 'AND', 'IN' or 'NOT IN'.
	 *		Default: 'IN'
	 * - 'include_children' bool (optional) Whether to include child terms.
	 *		Default: true
	 *
	 * @since 3.1.0
	 * @access public
	 * @var array
	 */
	public $queries = array();

	/**
	 * The relation between the queries. Can be one of 'AND' or 'OR'.
	 *
	 * @since 3.1.0
	 * @access public
	 * @var string
	 */
	public $relation;

	/**
	 * Standard response when the query should not return any rows.
	 *
	 * @since 3.2.0
	 * @access private
	 * @var string
	 */
	private static $no_results = array( 'join' => '', 'where' => ' AND 0 = 1' );

	/**
	 * Constructor.
	 *
	 * Parses a compact tax query and sets defaults.
	 *
	 * @since 3.1.0
	 * @access public
	 *
	 * @param array $tax_query A compact tax query:
	 *  array(
	 *    'relation' => 'OR',
	 *    array(
	 *      'taxonomy' => 'tax1',
	 *      'terms' => array( 'term1', 'term2' ),
	 *      'field' => 'slug',
	 *    ),
	 *    array(
	 *      'taxonomy' => 'tax2',
	 *      'terms' => array( 'term-a', 'term-b' ),
	 *      'field' => 'slug',
	 *    ),
	 *  )
	 */
	public function __construct( $tax_query ) {
		if ( isset( $tax_query['relation'] ) && strtoupper( $tax_query['relation'] ) == 'OR' ) {
			$this->relation = 'OR';
		} else {
			$this->relation = 'AND';
		}

		$defaults = array(
			'taxonomy' => '',
			'terms' => array(),
			'include_children' => true,
			'field' => 'term_id',
			'operator' => 'IN',
		);

		foreach ( $tax_query as $query ) {
			if ( ! is_array( $query ) )
				continue;

			$query = array_merge( $defaults, $query );

			$query['terms'] = (array) $query['terms'];

			$this->queries[] = $query;
		}
	}

	/**
	 * Generates SQL clauses to be appended to a main query.
	 *
	 * @since 3.1.0
	 * @access public
	 *
	 * @param string $primary_table
	 * @param string $primary_id_column
	 * @return array
	 */
	public function get_sql( $primary_table, $primary_id_column ) {
		global $wpdb;

		$join = '';
		$where = array();
		$i = 0;
		$count = count( $this->queries );

		foreach ( $this->queries as $index => $query ) {
			$this->clean_query( $query );

			if ( is_wp_error( $query ) )
				return self::$no_results;

			extract( $query );

			if ( 'IN' == $operator ) {

				if ( empty( $terms ) ) {
					if ( 'OR' == $this->relation ) {
						if ( ( $index + 1 === $count ) && empty( $where ) )
							return self::$no_results;
						continue;
					} else {
						return self::$no_results;
					}
				}

				$terms = implode( ',', $terms );

				$alias = $i ? 'tt' . $i : $wpdb->term_relationships;

				$join .= " INNER JOIN $wpdb->term_relationships";
				$join .= $i ? " AS $alias" : '';
				$join .= " ON ($primary_table.$primary_id_column = $alias.object_id)";

				$where[] = "$alias.term_taxonomy_id $operator ($terms)";
			} elseif ( 'NOT IN' == $operator ) {

				if ( empty( $terms ) )
					continue;

				$terms = implode( ',', $terms );

				$where[] = "$primary_table.$primary_id_column NOT IN (
					SELECT object_id
					FROM $wpdb->term_relationships
					WHERE term_taxonomy_id IN ($terms)
				)";
			} elseif ( 'AND' == $operator ) {

				if ( empty( $terms ) )
					continue;

				$num_terms = count( $terms );

				$terms = implode( ',', $terms );

				$where[] = "(
					SELECT COUNT(1)
					FROM $wpdb->term_relationships
					WHERE term_taxonomy_id IN ($terms)
					AND object_id = $primary_table.$primary_id_column
				) = $num_terms";
			}

			$i++;
		}

		if ( ! empty( $where ) )
			$where = ' AND ( ' . implode( " $this->relation ", $where ) . ' )';
		else
			$where = '';

		return compact( 'join', 'where' );
	}

	/**
	 * Validates a single query.
	 *
	 * @since 3.2.0
	 * @access private
	 *
	 * @param array &$query The single query
	 */
	private function clean_query( &$query ) {
		if ( ! taxonomy_exists( $query['taxonomy'] ) ) {
			$query = new WP_Error( 'Invalid taxonomy' );
			return;
		}

		$query['terms'] = array_unique( (array) $query['terms'] );

		if ( is_taxonomy_hierarchical( $query['taxonomy'] ) && $query['include_children'] ) {
			$this->transform_query( $query, 'term_id' );

			if ( is_wp_error( $query ) )
				return;

			$children = array();
			foreach ( $query['terms'] as $term ) {
				$children = array_merge( $children, get_term_children( $term, $query['taxonomy'] ) );
				$children[] = $term;
			}
			$query['terms'] = $children;
		}

		$this->transform_query( $query, 'term_taxonomy_id' );
	}

	/**
	 * Transforms a single query, from one field to another.
	 *
	 * @since 3.2.0
	 *
	 * @param array &$query The single query
	 * @param string $resulting_field The resulting field
	 */
	public function transform_query( &$query, $resulting_field ) {
		global $wpdb;

		if ( empty( $query['terms'] ) )
			return;

		if ( $query['field'] == $resulting_field )
			return;

		$resulting_field = sanitize_key( $resulting_field );

		switch ( $query['field'] ) {
			case 'slug':
			case 'name':
				$terms = "'" . implode( "','", array_map( 'sanitize_title_for_query', $query['terms'] ) ) . "'";
				$terms = $wpdb->get_col( "
					SELECT $wpdb->term_taxonomy.$resulting_field
					FROM $wpdb->term_taxonomy
					INNER JOIN $wpdb->terms USING (term_id)
					WHERE taxonomy = '{$query['taxonomy']}'
					AND $wpdb->terms.{$query['field']} IN ($terms)
				" );
				break;
			case 'term_taxonomy_id':
				$terms = implode( ',', array_map( 'intval', $query['terms'] ) );
				$terms = $wpdb->get_col( "
					SELECT $resulting_field
					FROM $wpdb->term_taxonomy
					WHERE term_taxonomy_id IN ($terms)
				" );
				break;
			default:
				$terms = implode( ',', array_map( 'intval', $query['terms'] ) );
				$terms = $wpdb->get_col( "
					SELECT $resulting_field
					FROM $wpdb->term_taxonomy
					WHERE taxonomy = '{$query['taxonomy']}'
					AND term_id IN ($terms)
				" );
		}

		if ( 'AND' == $query['operator'] && count( $terms ) < count( $query['terms'] ) ) {
			$query = new WP_Error( 'Inexistent terms' );
			return;
		}

		$query['terms'] = $terms;
		$query['field'] = $resulting_field;
	}
}

/**
 * Get all Term data from database by Term ID.
 *
 * The usage of the get_term function is to apply filters to a term object. It
 * is possible to get a term object from the database before applying the
 * filters.
 *
 * $term ID must be part of $taxonomy, to get from the database. Failure, might
 * be able to be captured by the hooks. Failure would be the same value as $wpdb
 * returns for the get_row method.
 *
 * There are two hooks, one is specifically for each term, named 'get_term', and
 * the second is for the taxonomy name, 'term_$taxonomy'. Both hooks gets the
 * term object, and the taxonomy name as parameters. Both hooks are expected to
 * return a Term object.
 *
 * 'get_term' hook - Takes two parameters the term Object and the taxonomy name.
 * Must return term object. Used in get_term() as a catch-all filter for every
 * $term.
 *
 * 'get_$taxonomy' hook - Takes two parameters the term Object and the taxonomy
 * name. Must return term object. $taxonomy will be the taxonomy name, so for
 * example, if 'category', it would be 'get_category' as the filter name. Useful
 * for custom taxonomies or plugging into default taxonomies.
 *
 * @package WordPress
 * @subpackage Taxonomy
 * @since 2.3.0
 *
 * @uses $wpdb
 * @uses sanitize_term() Cleanses the term based on $filter context before returning.
 * @see sanitize_term_field() The $context param lists the available values for get_term_by() $filter param.
 *
 * @param int|object $term If integer, will get from database. If object will apply filters and return $term.
 * @param string $taxonomy Taxonomy name that $term is part of.
 * @param string $output Constant OBJECT, ARRAY_A, or ARRAY_N
 * @param string $filter Optional, default is raw or no WordPress defined filter will applied.
 * @return mixed|null|WP_Error Term Row from database. Will return null if $term is empty. If taxonomy does not
 * exist then WP_Error will be returned.
 */
function get_term($term, $taxonomy, $output = OBJECT, $filter = 'raw') {
	global $wpdb;
	$null = null;

	if ( empty($term) ) {
		$error = new WP_Error('invalid_term', __('Empty Term'));
		return $error;
	}

	if ( ! taxonomy_exists($taxonomy) ) {
		$error = new WP_Error('invalid_taxonomy', __('Invalid taxonomy'));
		return $error;
	}

	if ( is_object($term) && empty($term->filter) ) {
		wp_cache_add($term->term_id, $term, $taxonomy);
		$_term = $term;
	} else {
		if ( is_object($term) )
			$term = $term->term_id;
		if ( !$term = (int) $term )
			return $null;
		if ( ! $_term = wp_cache_get($term, $taxonomy) ) {
			$_term = $wpdb->get_row( $wpdb->prepare( "SELECT t.*, tt.* FROM $wpdb->terms AS t INNER JOIN $wpdb->term_taxonomy AS tt ON t.term_id = tt.term_id WHERE tt.taxonomy = %s AND t.term_id = %d LIMIT 1", $taxonomy, $term) );
			if ( ! $_term )
				return $null;
			wp_cache_add($term, $_term, $taxonomy);
		}
	}

	$_term = apply_filters('get_term', $_term, $taxonomy);
	$_term = apply_filters("get_$taxonomy", $_term, $taxonomy);
	$_term = sanitize_term($_term, $taxonomy, $filter);

	if ( $output == OBJECT ) {
		return $_term;
	} elseif ( $output == ARRAY_A ) {
		$__term = get_object_vars($_term);
		return $__term;
	} elseif ( $output == ARRAY_N ) {
		$__term = array_values(get_object_vars($_term));
		return $__term;
	} else {
		return $_term;
	}
}

/**
 * Get all Term data from database by Term field and data.
 *
 * Warning: $value is not escaped for 'name' $field. You must do it yourself, if
 * required.
 *
 * The default $field is 'id', therefore it is possible to also use null for
 * field, but not recommended that you do so.
 *
 * If $value does not exist, the return value will be false. If $taxonomy exists
 * and $field and $value combinations exist, the Term will be returned.
 *
 * @package WordPress
 * @subpackage Taxonomy
 * @since 2.3.0
 *
 * @uses $wpdb
 * @uses sanitize_term() Cleanses the term based on $filter context before returning.
 * @see sanitize_term_field() The $context param lists the available values for get_term_by() $filter param.
 *
 * @param string $field Either 'slug', 'name', 'id' (term_id), or 'term_taxonomy_id'
 * @param string|int $value Search for this term value
 * @param string $taxonomy Taxonomy Name
 * @param string $output Constant OBJECT, ARRAY_A, or ARRAY_N
 * @param string $filter Optional, default is raw or no WordPress defined filter will applied.
 * @return mixed Term Row from database. Will return false if $taxonomy does not exist or $term was not found.
 */
function get_term_by($field, $value, $taxonomy, $output = OBJECT, $filter = 'raw') {
	global $wpdb;

	if ( ! taxonomy_exists($taxonomy) )
		return false;

	if ( 'slug' == $field ) {
		$field = 't.slug';
		$value = sanitize_title($value);
		if ( empty($value) )
			return false;
	} else if ( 'name' == $field ) {
		// Assume already escaped
		$value = wp_unslash($value);
		$field = 't.name';
	} else if ( 'term_taxonomy_id' == $field ) {
		$value = (int) $value;
		$field = 'tt.term_taxonomy_id';
	} else {
		$term = get_term( (int) $value, $taxonomy, $output, $filter);
		if ( is_wp_error( $term ) )
			$term = false;
		return $term;
	}

	$term = $wpdb->get_row( $wpdb->prepare( "SELECT t.*, tt.* FROM $wpdb->terms AS t INNER JOIN $wpdb->term_taxonomy AS tt ON t.term_id = tt.term_id WHERE tt.taxonomy = %s AND $field = %s LIMIT 1", $taxonomy, $value) );
	if ( !$term )
		return false;

	wp_cache_add($term->term_id, $term, $taxonomy);

	$term = apply_filters('get_term', $term, $taxonomy);
	$term = apply_filters("get_$taxonomy", $term, $taxonomy);
	$term = sanitize_term($term, $taxonomy, $filter);

	if ( $output == OBJECT ) {
		return $term;
	} elseif ( $output == ARRAY_A ) {
		return get_object_vars($term);
	} elseif ( $output == ARRAY_N ) {
		return array_values(get_object_vars($term));
	} else {
		return $term;
	}
}

/**
 * Merge all term children into a single array of their IDs.
 *
 * This recursive function will merge all of the children of $term into the same
 * array of term IDs. Only useful for taxonomies which are hierarchical.
 *
 * Will return an empty array if $term does not exist in $taxonomy.
 *
 * @package WordPress
 * @subpackage Taxonomy
 * @since 2.3.0
 *
 * @uses $wpdb
 * @uses _get_term_hierarchy()
 * @uses get_term_children() Used to get the children of both $taxonomy and the parent $term
 *
 * @param string $term_id ID of Term to get children
 * @param string $taxonomy Taxonomy Name
 * @return array|WP_Error List of Term Objects. WP_Error returned if $taxonomy does not exist
 */
function get_term_children( $term_id, $taxonomy ) {
	if ( ! taxonomy_exists($taxonomy) )
		return new WP_Error('invalid_taxonomy', __('Invalid taxonomy'));

	$term_id = intval( $term_id );

	$terms = _get_term_hierarchy($taxonomy);

	if ( ! isset($terms[$term_id]) )
		return array();

	$children = $terms[$term_id];

	foreach ( (array) $terms[$term_id] as $child ) {
		if ( isset($terms[$child]) )
			$children = array_merge($children, get_term_children($child, $taxonomy));
	}

	return $children;
}

/**
 * Get sanitized Term field.
 *
 * Does checks for $term, based on the $taxonomy. The function is for contextual
 * reasons and for simplicity of usage. See sanitize_term_field() for more
 * information.
 *
 * @package WordPress
 * @subpackage Taxonomy
 * @since 2.3.0
 *
 * @uses sanitize_term_field() Passes the return value in sanitize_term_field on success.
 *
 * @param string $field Term field to fetch
 * @param int $term Term ID
 * @param string $taxonomy Taxonomy Name
 * @param string $context Optional, default is display. Look at sanitize_term_field() for available options.
 * @return mixed Will return an empty string if $term is not an object or if $field is not set in $term.
 */
function get_term_field( $field, $term, $taxonomy, $context = 'display' ) {
	$term = (int) $term;
	$term = get_term( $term, $taxonomy );
	if ( is_wp_error($term) )
		return $term;

	if ( !is_object($term) )
		return '';

	if ( !isset($term->$field) )
		return '';

	return sanitize_term_field($field, $term->$field, $term->term_id, $taxonomy, $context);
}

/**
 * Sanitizes Term for editing.
 *
 * Return value is sanitize_term() and usage is for sanitizing the term for
 * editing. Function is for contextual and simplicity.
 *
 * @package WordPress
 * @subpackage Taxonomy
 * @since 2.3.0
 *
 * @uses sanitize_term() Passes the return value on success
 *
 * @param int|object $id Term ID or Object
 * @param string $taxonomy Taxonomy Name
 * @return mixed|null|WP_Error Will return empty string if $term is not an object.
 */
function get_term_to_edit( $id, $taxonomy ) {
	$term = get_term( $id, $taxonomy );

	if ( is_wp_error($term) )
		return $term;

	if ( !is_object($term) )
		return '';

	return sanitize_term($term, $taxonomy, 'edit');
}

/**
 * Retrieve the terms in a given taxonomy or list of taxonomies.
 *
 * You can fully inject any customizations to the query before it is sent, as
 * well as control the output with a filter.
 *
 * The 'get_terms' filter will be called when the cache has the term and will
 * pass the found term along with the array of $taxonomies and array of $args.
 * This filter is also called before the array of terms is passed and will pass
 * the array of terms, along with the $taxonomies and $args.
 *
 * The 'list_terms_exclusions' filter passes the compiled exclusions along with
 * the $args.
 *
 * The 'get_terms_orderby' filter passes the ORDER BY clause for the query
 * along with the $args array.
 *
 * The 'get_terms_fields' filter passes the fields for the SELECT query
 * along with the $args array.
 *
 * The list of arguments that $args can contain, which will overwrite the defaults:
 *
 * orderby - Default is 'name'. Can be name, count, term_group, slug or nothing
 * (will use term_id), Passing a custom value other than these will cause it to
 * order based on the custom value.
 *
 * order - Default is ASC. Can use DESC.
 *
 * hide_empty - Default is true. Will not return empty terms, which means
 * terms whose count is 0 according to the given taxonomy.
 *
 * exclude - Default is an empty array. An array, comma- or space-delimited string
 * of term ids to exclude from the return array. If 'include' is non-empty,
 * 'exclude' is ignored.
 *
 * exclude_tree - Default is an empty array. An array, comma- or space-delimited
 * string of term ids to exclude from the return array, along with all of their
 * descendant terms according to the primary taxonomy. If 'include' is non-empty,
 * 'exclude_tree' is ignored.
 *
 * include - Default is an empty array. An array, comma- or space-delimited string
 * of term ids to include in the return array.
 *
 * number - The maximum number of terms to return. Default is to return them all.
 *
 * offset - The number by which to offset the terms query.
 *
 * fields - Default is 'all', which returns an array of term objects.
 * If 'fields' is 'ids' or 'names', returns an array of
 * integers or strings, respectively.
 *
 * slug - Returns terms whose "slug" matches this value. Default is empty string.
 *
 * hierarchical - Whether to include terms that have non-empty descendants
 * (even if 'hide_empty' is set to true).
 *
 * search - Returned terms' names will contain the value of 'search',
 * case-insensitive. Default is an empty string.
 *
 * name__like - Returned terms' names will contain the value of 'name__like',
 * case-insensitive. Default is empty string.
 *
 * description__like - Returned terms' descriptions will contain the value of
 *  'description__like', case-insensitive. Default is empty string.
 *
 * The argument 'pad_counts', if set to true will include the quantity of a term's
 * children in the quantity of each term's "count" object variable.
 *
 * The 'get' argument, if set to 'all' instead of its default empty string,
 * returns terms regardless of ancestry or whether the terms are empty.
 *
 * The 'child_of' argument, when used, should be set to the integer of a term ID. Its default
 * is 0. If set to a non-zero value, all returned terms will be descendants
 * of that term according to the given taxonomy. Hence 'child_of' is set to 0
 * if more than one taxonomy is passed in $taxonomies, because multiple taxonomies
 * make term ancestry ambiguous.
 *
 * The 'parent' argument, when used, should be set to the integer of a term ID. Its default is
 * the empty string '', which has a different meaning from the integer 0.
 * If set to an integer value, all returned terms will have as an immediate
 * ancestor the term whose ID is specified by that integer according to the given taxonomy.
 * The 'parent' argument is different from 'child_of' in that a term X is considered a 'parent'
 * of term Y only if term X is the father of term Y, not its grandfather or great-grandfather, etc.
 *
 * The 'cache_domain' argument enables a unique cache key to be produced when this query is stored
 * in object cache. For instance, if you are using one of this function's filters to modify the
 * query (such as 'terms_clauses'), setting 'cache_domain' to a unique value will not overwrite
 * the cache for similar queries. Default value is 'core'.
 *
 * @package WordPress
 * @subpackage Taxonomy
 * @since 2.3.0
 *
 * @uses $wpdb
 * @uses wp_parse_args() Merges the defaults with those defined by $args and allows for strings.
 *
 * @param string|array $taxonomies Taxonomy name or list of Taxonomy names
 * @param string|array $args The values of what to search for when returning terms
 * @return array|WP_Error List of Term Objects and their children. Will return WP_Error, if any of $taxonomies do not exist.
 */
function get_terms($taxonomies, $args = '') {
	global $wpdb;
	$empty_array = array();

	$single_taxonomy = ! is_array( $taxonomies ) || 1 === count( $taxonomies );
	if ( ! is_array( $taxonomies ) )
		$taxonomies = array( $taxonomies );

	foreach ( $taxonomies as $taxonomy ) {
		if ( ! taxonomy_exists($taxonomy) ) {
			$error = new WP_Error('invalid_taxonomy', __('Invalid taxonomy'));
			return $error;
		}
	}

	$defaults = array('orderby' => 'name', 'order' => 'ASC',
		'hide_empty' => true, 'exclude' => array(), 'exclude_tree' => array(), 'include' => array(),
		'number' => '', 'fields' => 'all', 'slug' => '', 'parent' => '',
		'hierarchical' => true, 'child_of' => 0, 'get' => '', 'name__like' => '', 'description__like' => '',
		'pad_counts' => false, 'offset' => '', 'search' => '', 'cache_domain' => 'core' );
	$args = wp_parse_args( $args, $defaults );
	$args['number'] = absint( $args['number'] );
	$args['offset'] = absint( $args['offset'] );
	if ( !$single_taxonomy || ! is_taxonomy_hierarchical( reset( $taxonomies ) ) ||
		'' !== $args['parent'] ) {
		$args['child_of'] = 0;
		$args['hierarchical'] = false;
		$args['pad_counts'] = false;
	}

	if ( 'all' == $args['get'] ) {
		$args['child_of'] = 0;
		$args['hide_empty'] = 0;
		$args['hierarchical'] = false;
		$args['pad_counts'] = false;
	}

	$args = apply_filters( 'get_terms_args', $args, $taxonomies );

	extract($args, EXTR_SKIP);

	if ( $child_of ) {
		$hierarchy = _get_term_hierarchy( reset( $taxonomies ) );
		if ( ! isset( $hierarchy[ $child_of ] ) )
			return $empty_array;
	}

	if ( $parent ) {
		$hierarchy = _get_term_hierarchy( reset( $taxonomies ) );
		if ( ! isset( $hierarchy[ $parent ] ) )
			return $empty_array;
	}

	// $args can be whatever, only use the args defined in defaults to compute the key
	$filter_key = ( has_filter('list_terms_exclusions') ) ? serialize($GLOBALS['wp_filter']['list_terms_exclusions']) : '';
	$key = md5( serialize( compact(array_keys($defaults)) ) . serialize( $taxonomies ) . $filter_key );
	$last_changed = wp_cache_get( 'last_changed', 'terms' );
	if ( ! $last_changed ) {
		$last_changed = microtime();
		wp_cache_set( 'last_changed', $last_changed, 'terms' );
	}
	$cache_key = "get_terms:$key:$last_changed";
	$cache = wp_cache_get( $cache_key, 'terms' );
	if ( false !== $cache ) {
		$cache = apply_filters('get_terms', $cache, $taxonomies, $args);
		return $cache;
	}

	$_orderby = strtolower($orderby);
	if ( 'count' == $_orderby )
		$orderby = 'tt.count';
	else if ( 'name' == $_orderby )
		$orderby = 't.name';
	else if ( 'slug' == $_orderby )
		$orderby = 't.slug';
	else if ( 'term_group' == $_orderby )
		$orderby = 't.term_group';
	else if ( 'none' == $_orderby )
		$orderby = '';
	elseif ( empty($_orderby) || 'id' == $_orderby )
		$orderby = 't.term_id';
	else
		$orderby = 't.name';

	$orderby = apply_filters( 'get_terms_orderby', $orderby, $args, $taxonomies );

	if ( !empty($orderby) )
		$orderby = "ORDER BY $orderby";
	else
		$order = '';

	$order = strtoupper( $order );
	if ( '' !== $order && !in_array( $order, array( 'ASC', 'DESC' ) ) )
		$order = 'ASC';

	$where = "tt.taxonomy IN ('" . implode("', '", $taxonomies) . "')";
	$inclusions = '';
	if ( ! empty( $include ) ) {
		$exclude = '';
		$exclude_tree = '';
		$inclusions = implode( ',', wp_parse_id_list( $include ) );
	}

	if ( ! empty( $inclusions ) ) {
		$inclusions = ' AND t.term_id IN ( ' . $inclusions . ' )';
		$where .= $inclusions;
	}

	$exclusions = '';
	if ( ! empty( $exclude_tree ) ) {
		$exclude_tree = wp_parse_id_list( $exclude_tree );
		$excluded_children = $exclude_tree;
		foreach ( $exclude_tree as $extrunk ) {
			$excluded_children = array_merge(
				$excluded_children,
				(array) get_terms( $taxonomies[0], array( 'child_of' => intval( $extrunk ), 'fields' => 'ids', 'hide_empty' => 0 ) )
			);
		}
		$exclusions = implode( ',', array_map( 'intval', $excluded_children ) );
	}

	if ( ! empty( $exclude ) ) {
		$exterms = wp_parse_id_list( $exclude );
		if ( empty( $exclusions ) )
			$exclusions = implode( ',', $exterms );
		else
			$exclusions .= ', ' . implode( ',', $exterms );
	}

	if ( ! empty( $exclusions ) )
		$exclusions = ' AND t.term_id NOT IN (' . $exclusions . ')';

	$exclusions = apply_filters( 'list_terms_exclusions', $exclusions, $args, $taxonomies );

	if ( ! empty( $exclusions ) )
		$where .= $exclusions;

	if ( !empty($slug) ) {
		$slug = sanitize_title($slug);
		$where .= " AND t.slug = '$slug'";
	}

	if ( !empty($name__like) ) {
		$name__like = like_escape( $name__like );
		$where .= $wpdb->prepare( " AND t.name LIKE %s", '%' . $name__like . '%' );
	}

	if ( ! empty( $description__like ) ) {
		$description__like = like_escape( $description__like );
		$where .= $wpdb->prepare( " AND tt.description LIKE %s", '%' . $description__like . '%' );
	}

	if ( '' !== $parent ) {
		$parent = (int) $parent;
		$where .= " AND tt.parent = '$parent'";
	}

	if ( 'count' == $fields )
		$hierarchical = false;

	if ( $hide_empty && !$hierarchical )
		$where .= ' AND tt.count > 0';

	// don't limit the query results when we have to descend the family tree
	if ( $number && ! $hierarchical && ! $child_of && '' === $parent ) {
		if ( $offset )
			$limits = 'LIMIT ' . $offset . ',' . $number;
		else
			$limits = 'LIMIT ' . $number;
	} else {
		$limits = '';
	}

	if ( ! empty( $search ) ) {
		$search = like_escape( $search );
		$where .= $wpdb->prepare( ' AND ((t.name LIKE %s) OR (t.slug LIKE %s))', '%' . $search . '%', '%' . $search . '%' );
	}

	$selects = array();
	switch ( $fields ) {
		case 'all':
			$selects = array( 't.*', 'tt.*' );
			break;
		case 'ids':
		case 'id=>parent':
			$selects = array( 't.term_id', 'tt.parent', 'tt.count' );
			break;
		case 'names':
			$selects = array( 't.term_id', 'tt.parent', 'tt.count', 't.name' );
			break;
		case 'count':
			$orderby = '';
			$order = '';
			$selects = array( 'COUNT(*)' );
			break;
		case 'id=>name':
			$selects = array( 't.term_id', 't.name' );
			break;
		case 'id=>slug':
			$selects = array( 't.term_id', 't.slug' );
			break;
	}

	$_fields = $fields;

	$fields = implode( ', ', apply_filters( 'get_terms_fields', $selects, $args, $taxonomies ) );

	$join = "INNER JOIN $wpdb->term_taxonomy AS tt ON t.term_id = tt.term_id";

	$pieces = array( 'fields', 'join', 'where', 'orderby', 'order', 'limits' );
	$clauses = apply_filters( 'terms_clauses', compact( $pieces ), $taxonomies, $args );
	foreach ( $pieces as $piece )
		$$piece = isset( $clauses[ $piece ] ) ? $clauses[ $piece ] : '';

	$query = "SELECT $fields FROM $wpdb->terms AS t $join WHERE $where $orderby $order $limits";

	$fields = $_fields;

	if ( 'count' == $fields ) {
		$term_count = $wpdb->get_var($query);
		return $term_count;
	}

	$terms = $wpdb->get_results($query);
	if ( 'all' == $fields ) {
		update_term_cache($terms);
	}

	if ( empty($terms) ) {
		wp_cache_add( $cache_key, array(), 'terms', DAY_IN_SECONDS );
		$terms = apply_filters('get_terms', array(), $taxonomies, $args);
		return $terms;
	}

	if ( $child_of ) {
		$children = _get_term_hierarchy( reset( $taxonomies ) );
		if ( ! empty( $children ) )
			$terms = _get_term_children( $child_of, $terms, reset( $taxonomies ) );
	}

	// Update term counts to include children.
	if ( $pad_counts && 'all' == $fields )
		_pad_term_counts( $terms, reset( $taxonomies ) );

	// Make sure we show empty categories that have children.
	if …