WP_Rewrite::flush_rules()
Method: Removes rewrite rules and then recreate rewrite rules.
Source: wp-includes/class-wp-rewrite.php:1849
WP_Rewrite::get_search_permastruct()
Method: Retrieves the search permalink structure.
Source: wp-includes/class-wp-rewrite.php:691
{$permastructname}_rewrite_rules
Filter Hook: Filters rewrite rules used for individual permastructs.
Source: wp-includes/class-wp-rewrite.php:1432
flush_rewrite_rules_hard
Filter Hook: Filters whether a “hard” rewrite rule flush should be performed when requested.
Source: wp-includes/class-wp-rewrite.php:1876