wpdb::placeholder_escape(): string

2405	public function placeholder_escape() {2406		static $placeholder;2407 2408		if ( ! $placeholder ) {2409			// If ext/hash is not present, compat.php's hash_hmac() does not support sha256.2410			$algo = function_exists( 'hash' ) ? 'sha256' : 'sha1';2411			// Old WP installs may not have AUTH_SALT defined.2412			$salt = defined( 'AUTH_SALT' ) && AUTH_SALT ? AUTH_SALT : (string) rand();2413 2414			$placeholder = '{' . hash_hmac( $algo, uniqid( $salt, true ), $salt ) . '}';2415		}2416 2417		/*2418		 * Add the filter to remove the placeholder escaper. Uses priority 0, so that anything2419		 * else attached to this filter will receive the query with the placeholder string removed.2420		 */2421		if ( false === has_filter( 'query', array( $this, 'remove_placeholder_escape' ) ) ) {2422			add_filter( 'query', array( $this, 'remove_placeholder_escape' ), 0 );2423		}2424 2425		return $placeholder;2426	}