Ticket #37825: 37825.2.diff

src/wp-includes/category.php

@@ -333 +333 @@
 }
 
 /**
+ * Checks to see if more than one category has associated posts.
+ *
+ * @since 5.0.0
+ *
+ * @return bool Whether or not we have more than one categories.
+ */
+function wp_has_multiple_categories() {
+        return wp_has_multiple_terms( 'category' );
+}
+
+/**
+ * Checks to see if more than one tag has associated posts.
+ *
+ * @since 5.0.0
+ *
+ * @return bool Whether or not we have more than one tags.
+ */
+function wp_has_multiple_tags() {
+        return wp_has_multiple_terms( 'post_tag' );
+}
+
+/**
  * Update category structure to old pre 2.3 from new taxonomy structure.
  *
  * This function was added for the taxonomy support to update the new category

src/wp-includes/default-filters.php

@@ -491 +491 @@
 
 // Taxonomy
 add_action( 'init', 'create_initial_taxonomies', 0 ); // highest priority
+add_action( 'edit_term', '_clear_multi_taxonomy_cache_for_term', 10, 3 );
+add_action( 'save_post', '_clear_multi_taxonomy_cache_for_post', 10, 1 );
 add_action( 'change_locale', 'create_initial_taxonomies' );
 
 // Canonical

src/wp-includes/taxonomy.php

@@ -4515 +4515 @@
 
         return $parent;
 }
+
+/**
+ * Checks to see if more than one term of a given taxonomy has associated posts.
+ *
+ * @since 5.0.0
+ *
+ * @param string $taxonomy Taxonomy name.
+ * @return bool Whether or not we have more than one term of the given taxonomy.
+ */
+function wp_has_multiple_terms( $taxonomy ) {
+        if ( false === ( $is_multi_taxonomy = get_transient( 'is_multi_taxonomy_' . $taxonomy ) ) ) {
+                $is_multi_taxonomy = get_terms( array(
+                        'taxonomy'   => $taxonomy,
+                        'fields'     => 'count',
+                        'number'     => 2,
+                ) );
+                $is_multi_taxonomy = $is_multi_taxonomy > 1 ? 1 : 0;
+                set_transient( 'is_multi_taxonomy_' . $taxonomy, $is_multi_taxonomy );
+        }
+
+        /**
+         * Filters whether the site has more than one term of the given taxonomy with associated posts.
+         *
+         * @since 4.7.0
+         *
+         * @param bool   $is_multi_taxonomy Whether $is_multi_taxonomy should evaluate as true.
+         * @param string $taxonomy          Taxonomy name.
+         */
+        return apply_filters( 'is_multi_taxonomy', (bool) $is_multi_taxonomy, $taxonomy );
+}
+
+/**
+ * Helper function to clear the cache for a number of taxonomy terms.
+ *
+ * @since 5.0.0
+ * @access private
+ *
+ * @param string|array $taxonomies One or more taxonomy names.
+ */
+function _clear_multi_taxonomy_cache( $taxonomies ) {
+        $taxonomies = (array) $taxonomies;
+
+        foreach ( $taxonomies as $taxonomy ) {
+                delete_transient( 'is_multi_taxonomy_' . $taxonomy );
+        }
+}
+
+/**
+ * Helper function to clear the $is_multi_taxonomy cache for a term.
+ *
+ * @since 4.7.0
+ * @access private
+ *
+ * @param int    $term_id  Term ID.
+ * @param int    $tt_id    Term taxonomy ID.
+ * @param string $taxonomy Taxonomy name.
+ */
+function _clear_multi_taxonomy_cache_for_term( $term_id, $tt_id, $taxonomy ) {
+        _clear_multi_taxonomy_cache( $taxonomy );
+}
+
+/**
+ * Helper function to clear the $is_multi_taxonomy cache for a post.
+ *
+ * @since 4.7.0
+ * @access private
+ *
+ * @param int $post_id Post ID.
+ */
+function _clear_multi_taxonomy_cache_for_post( $post_id ) {
+        _clear_multi_taxonomy_cache( get_object_taxonomies( get_post( $post_id ) ) );
+}