gment to append to the main JOIN clause.
	 *     @type string $where SQL fragment to append to the main WHERE clause.
	 * }
	 */
	protected function get_sql_clauses() {
		/*
		 * $queries are passed by reference to get_sql_for_query() for recursion.
		 * To keep $this->queries unaltered, pass a copy.
		 */
		$queries = $this->queries;
		$sql     = $this->get_sql_for_query( $queries );

		if ( ! empty( $sql['where'] ) ) {
			$sql['where'] = ' AND ' . $sql['where'];
		}

		return $sql;
	}

	/**
	 * Generates SQL clauses for a single query array.
	 *
	 * If nested subqueries are found, this method recurses the tree to
	 * produce the properly nested SQL.
	 *
	 * @since 4.1.0
	 *
	 * @param array $query Query to parse (passed by reference).
	 * @param int   $depth Optional. Number of tree levels deep we currently are.
	 *                     Used to calculate indentation. Default 0.
	 * @return string[] {
	 *     Array containing JOIN and WHERE SQL clauses to append to a single query array.
	 *
	 *     @type string $join  SQL fragment to append to the main JOIN clause.
	 *     @type string $where SQL fragment to append to the main WHERE clause.
	 * }
	 */
	protected function get_sql_for_query( &$query, $depth = 0 ) {
		$sql_chunks = array(
			'join'  => array(),
			'where' => array(),
		);

		$sql = array(
			'join'  => '',
			'where' => '',
		);

		$indent = '';
		for ( $i = 0; $i < $depth; $i++ ) {
			$indent .= '  ';
		}

		foreach ( $query as $key => &$clause ) {
			if ( 'relation' === $key ) {
				$relation = $query['relation'];
			} elseif ( is_array( $clause ) ) {

				// This is a first-order clause.
				if ( $this->is_first_order_clause( $clause ) ) {
					$clause_sql = $this->get_sql_for_clause( $clause, $query );

					$where_count = count( $clause_sql['where'] );
					if ( ! $where_count ) {
						$sql_chunks['where'][] = '';
					} elseif ( 1 === $where_count ) {
						$sql_chunks['where'][] = $clause_sql['where'][0];
					} else {
						$sql_chunks['where'][] = '( ' . implode( ' AND ', $clause_sql['where'] ) . ' )';
					}

					$sql_chunks['join'] = array_merge( $sql_chunks['join'], $clause_sql['join'] );
					// This is a subquery, so we recurse.
				} else {
					$clause_sql = $this->get_sql_for_query( $clause, $depth + 1 );

					$sql_chunks['where'][] = $clause_sql['where'];
					$sql_chunks['join'][]  = $clause_sql['join'];
				}
			}
		}

		// Filter to remove empties.
		$sql_chunks['join']  = array_filter( $sql_chunks['join'] );
		$sql_chunks['where'] = array_filter( $sql_chunks['where'] );

		if ( empty( $relation ) ) {
			$relation = 'AND';
		}

		// Filter duplicate JOIN clauses and combine into a single string.
		if ( ! empty( $sql_chunks['join'] ) ) {
			$sql['join'] = implode( ' ', array_unique( $sql_chunks['join'] ) );
		}

		// Generate a single WHERE clause with proper brackets and indentation.
		if ( ! empty( $sql_chunks['where'] ) ) {
			$sql['where'] = '( ' . "\n  " . $indent . implode( ' ' . "\n  " . $indent . $relation . ' ' . "\n  " . $indent, $sql_chunks['where'] ) . "\n" . $indent . ')';
		}

		return $sql;
	}

	/**
	 * Generates SQL JOIN and WHERE clauses for a "first-order" query clause.
	 *
	 * @since 4.1.0
	 *
	 * @global wpdb $wpdb The WordPress database abstraction object.
	 *
	 * @param array $clause       Query clause (passed by reference).
	 * @param array $parent_query Parent query array.
	 * @return array {
	 *     Array containing JOIN and WHERE SQL clauses to append to a first-order query.
	 *
	 *     @type string[] $join  Array of SQL fragments to append to the main JOIN clause.
	 *     @type string[] $where Array of SQL fragments to append to the main WHERE clause.
	 * }
	 */
	public function get_sql_for_clause( &$clause, $parent_query ) {
		global $wpdb;

		$sql = array(
			'where' => array(),
			'join'  => array(),
		);

		$join  = '';
		$where = '';

		$this->clean_query( $clause );

		if ( is_wp_error( $clause ) ) {
			return self::$no_results;
		}

		$terms    = $clause['terms'];
		$operator = strtoupper( $clause['operator'] );

		if ( 'IN' === $operator ) {

			if ( empty( $terms ) ) {
				return self::$no_results;
			}

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

			/*
			 * Before creating another table join, see if this clause has a
			 * sibling with an existing join that can be shared.
			 */
			$alias = $this->find_compatible_table_alias( $clause, $parent_query );
			if ( false === $alias ) {
				$i     = count( $this->table_aliases );
				$alias = $i ? 'tt' . $i : $wpdb->term_relationships;

				// Store the alias as part of a flat array to build future iterators.
				$this->table_aliases[] = $alias;

				// Store the alias with this clause, so later siblings can use it.
				$clause['alias'] = $alias;

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

			$where = "$alias.term_taxonomy_id $operator ($terms)";

		} elseif ( 'NOT IN' === $operator ) {

			if ( empty( $terms ) ) {
				return $sql;
			}

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

			$where = "$this->primary_table.$this->primary_id_column NOT IN (
				SELECT object_id
				FROM $wpdb->term_relationships
				WHERE term_taxonomy_id IN ($terms)
			)";

		} elseif ( 'AND' === $operator ) {

			if ( empty( $terms ) ) {
				return $sql;
			}

			$num_terms = count( $terms );

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

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

		} elseif ( 'NOT EXISTS' === $operator || 'EXISTS' === $operator ) {

			$where = $wpdb->prepare(
				"$operator (
					SELECT 1
					FROM $wpdb->term_relationships
					INNER JOIN $wpdb->term_taxonomy
					ON $wpdb->term_taxonomy.term_taxonomy_id = $wpdb->term_relationships.term_taxonomy_id
					WHERE $wpdb->term_taxonomy.taxonomy = %s
					AND $wpdb->term_relationships.object_id = $this->primary_table.$this->primary_id_column
				)",
				$clause['taxonomy']
			);

		}

		$sql['join'][]  = $join;
		$sql['where'][] = $where;
		return $sql;
	}

	/**
	 * Identifies an existing table alias that is compatible with the current query clause.
	 *
	 * We avoid unnecessary table joins by allowing each clause to look for
	 * an existing table alias that is compatible with the query that it
	 * needs to perform.
	 *
	 * An existing alias is compatible if (a) it is a sibling of `$clause`
	 * (ie, it's under the scope of the same relation), and (b) the combination
	 * of operator and relation between the clauses allows for a shared table
	 * join. In the case of WP_Tax_Query, this only applies to 'IN'
	 * clauses that are connected by the relation 'OR'.
	 *
	 * @since 4.1.0
	 *
	 * @param array $clause       Query clause.
	 * @param array $parent_query Parent query of $clause.
	 * @return string|false Table alias if found, otherwise false.
	 */
	protected function find_compatible_table_alias( $clause, $parent_query ) {
		$alias = false;

		// Sanity check. Only IN queries use the JOIN syntax.
		if ( ! isset( $clause['operator'] ) || 'IN' !== $clause['operator'] ) {
			return $alias;
		}

		// Since we're only checking IN queries, we're only concerned with OR relations.
		if ( ! isset( $parent_query['relation'] ) || 'OR' !== $parent_query['relation'] ) {
			return $alias;
		}

		$compatible_operators = array( 'IN' );

		foreach ( $parent_query as $sibling ) {
			if ( ! is_array( $sibling ) || ! $this->is_first_order_clause( $sibling ) ) {
				continue;
			}

			if ( empty( $sibling['alias'] ) || empty( $sibling['operator'] ) ) {
				continue;
			}

			// The sibling must both have compatible operator to share its alias.
			if ( in_array( strtoupper( $sibling['operator'] ), $compatible_operators, true ) ) {
				$alias = preg_replace( '/\W/', '_', $sibling['alias'] );
				break;
			}
		}

		return $alias;
	}

	/**
	 * Validates a single query.
	 *
	 * @since 3.2.0
	 *
	 * @param array $query The single query. Passed by reference.
	 */
	private function clean_query( &$query ) {
		if ( empty( $query['taxonomy'] ) ) {
			if ( 'term_taxonomy_id' !== $query['field'] ) {
				$query = new WP_Error( 'invalid_taxonomy', __( 'Invalid taxonomy.' ) );
				return;
			}

			// So long as there are shared terms, 'include_children' requires that a taxonomy is set.
			$query['include_children'] = false;
		} elseif ( ! taxonomy_exists( $query['taxonomy'] ) ) {
			$query = new WP_Error( 'invalid_taxonomy', __( 'Invalid taxonomy.' ) );
			return;
		}

		if ( 'slug' === $query['field'] || 'name' === $query['field'] ) {
			$query['terms'] = array_unique( (array) $query['terms'] );
		} else {
			$query['terms'] = wp_parse_id_list( $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.
	 *
	 * Operates on the `$query` object by reference. In the case of error,
	 * `$query` is converted to a WP_Error object.
	 *
	 * @since 3.2.0
	 *
	 * @param array  $query           The single query. Passed by reference.
	 * @param string $resulting_field The resulting field. Accepts 'slug', 'name', 'term_taxonomy_id',
	 *                                or 'term_id'. Default 'term_id'.
	 */
	public function transform_query( &$query, $resulting_field ) {
		if ( empty( $query['terms'] ) ) {
			return;
		}

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

		$resulting_field = sanitize_key( $resulting_field );

		// Empty 'terms' always results in a null transformation.
		$terms = array_filter( $query['terms'] );
		if ( empty( $terms ) ) {
			$query['terms'] = array();
			$query['field'] = $resulting_field;
			return;
		}

		$args = array(
			'get'                    => 'all',
			'number'                 => 0,
			'taxonomy'               => $query['taxonomy'],
			'update_term_meta_cache' => false,
			'orderby'                => 'none',
		);

		// Term query parameter name depends on the 'field' being searched on.
		switch ( $query['field'] ) {
			case 'slug':
				$args['slug'] = $terms;
				break;
			case 'name':
				$args['name'] = $terms;
				break;
			case 'term_taxonomy_id':
				$args['term_taxonomy_id'] = $terms;
				break;
			default:
				$args['include'] = wp_parse_id_list( $terms );
				break;
		}

		if ( ! is_taxonomy_hierarchical( $query['taxonomy'] ) ) {
			$args['number'] = count( $terms );
		}

		$term_query = new WP_Term_Query();
		$term_list  = $term_query->query( $args );

		if ( is_wp_error( $term_list ) ) {
			$query = $term_list;
			return;
		}

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

		$query['terms'] = wp_list_pluck( $term_list, $resulting_field );
		$query['field'] = $resulting_field;
	}
}
is a block theme.
 *
 * @since 6.0.0
 * @return bool
 */
function wc_current_theme_is_fse_theme() {
	if ( function_exists( 'wp_is_block_theme' ) ) {
		return (bool) wp_is_block_theme();
	}
	if ( function_exists( 'gutenberg_is_fse_theme' ) ) {
		return (bool) gutenberg_is_fse_theme();
	}

	return false;
}

/**
 * Check if the current theme has WooCommerce support or is a FSE theme.
 *
 * @since 6.0.0
 * @return bool
 */
function wc_current_theme_supports_woocommerce_or_fse() {
	return (bool) current_theme_supports( 'woocommerce' ) || wc_current_theme_is_fse_theme();
}

/**
 * Given an element name, returns a class name.
 *
 * If the WP-related function is not defined, return empty string.
 *
 * @param string $element The name of the element.
 *
 * @since 7.0.1
 * @return string
 */
function wc_wp_theme_get_element_class_name( $element ) {
	if ( function_exists( 'wp_theme_get_element_class_name' ) ) {
		return wp_theme_get_element_class_name( $element );
	}

	return '';
}