gcdb::get_table_from_query()

	protected function get_table_from_query( $query ) {
		// Remove characters that can legally trail the table name.
		$query = rtrim( $query, ';/-#' );

		// Allow (select...) union [...] style queries. Use the first query's table name.
		$query = ltrim( $query, "rnt (" );

		// Strip everything between parentheses except nested selects.
		$query = preg_replace( '/((?!s*select)[^(]*?)/is', '()', $query );

		// Quickly match most common queries.
		if ( preg_match(
			'/^s*(?:'
				. 'SELECT.*?s+FROM'
				. '|INSERT(?:s+LOW_PRIORITY|s+DELAYED|s+HIGH_PRIORITY)?(?:s+IGNORE)?(?:s+INTO)?'
				. '|REPLACE(?:s+LOW_PRIORITY|s+DELAYED)?(?:s+INTO)?'
				. '|UPDATE(?:s+LOW_PRIORITY)?(?:s+IGNORE)?'
				. '|DELETE(?:s+LOW_PRIORITY|s+QUICK|s+IGNORE)*(?:.+?FROM)?'
			. ')s+((?:[0-9a-zA-Z$_.`-]|[xC2-xDF][x80-xBF])+)/is',
			$query,
			$maybe
		) ) {
			return str_replace( '`', '', $maybe[1] );
		}

		// SHOW TABLE STATUS and SHOW TABLES WHERE Name = 'gc_posts'
		if ( preg_match( '/^s*SHOWs+(?:TABLEs+STATUS|(?:FULLs+)?TABLES).+WHEREs+Names*=s*("|')((?:[0-9a-zA-Z$_.-]|[xC2-xDF][x80-xBF])+)\1/is', $query, $maybe ) ) {
			return $maybe[2];
		}

		/*
		 * SHOW TABLE STATUS LIKE and SHOW TABLES LIKE 'gc_123_%'
		 * This quoted LIKE operand seldom holds a full table name.
		 * It is usually a pattern for matching a prefix so we just
		 * strip the trailing % and unescape the _ to get 'gc_123_'
		 * which drop-ins can use for routing these SQL statements.
		 */
		if ( preg_match( '/^s*SHOWs+(?:TABLEs+STATUS|(?:FULLs+)?TABLES)s+(?:WHEREs+Names+)?LIKEs*("|')((?:[\\0-9a-zA-Z$_.-]|[xC2-xDF][x80-xBF])+)%?\1/is', $query, $maybe ) ) {
			return str_replace( '\_', '_', $maybe[2] );
		}

		// Big pattern for the rest of the table-related queries.
		if ( preg_match(
			'/^s*(?:'
				. '(?:EXPLAINs+(?:EXTENDEDs+)?)?SELECT.*?s+FROM'
				. '|DESCRIBE|DESC|EXPLAIN|HANDLER'
				. '|(?:LOCK|UNLOCK)s+TABLE(?:S)?'
				. '|(?:RENAME|OPTIMIZE|BACKUP|RESTORE|CHECK|CHECKSUM|ANALYZE|REPAIR).*s+TABLE'
				. '|TRUNCATE(?:s+TABLE)?'
				. '|CREATE(?:s+TEMPORARY)?s+TABLE(?:s+IFs+NOTs+EXISTS)?'
				. '|ALTER(?:s+IGNORE)?s+TABLE'
				. '|DROPs+TABLE(?:s+IFs+EXISTS)?'
				. '|CREATE(?:s+w+)?s+INDEX.*s+ON'
				. '|DROPs+INDEX.*s+ON'
				. '|LOADs+DATA.*INFILE.*INTOs+TABLE'
				. '|(?:GRANT|REVOKE).*ONs+TABLE'
				. '|SHOWs+(?:.*FROM|.*TABLE)'
			. ')s+(*s*((?:[0-9a-zA-Z$_.`-]|[xC2-xDF][x80-xBF])+)s*)*/is',
			$query,
			$maybe
		) ) {
			return str_replace( '`', '', $maybe[1] );
		}

		return false;
	}