nl_tokens: Private function used in filterUnusedRules .
pl_tokens: function filterUnusedSelectors ( selectors , ignore , usedSelectors ) { /* There are some selectors not supported for matching, like
       *   :before, :after
       * They should be removed only if the parent is not found.
       * Example: '.clearfix:before' should be removed only if there
       *          is no '.clearfix'
       */ return selectors . filter ( ( selector ) => { selector = dePseudify ( selector ) ; /* TODO: process @-rules */ if ( selector [ 0 ] === '@' ) { return true ; } for ( let i = 0 , len = ignore . length ; i < len ; ++ i ) { if ( _ . isRegExp ( ignore [ i ] ) && ignore [ i ] . test ( selector ) ) { return <mask> ; } if ( ignore [ i ] === selector ) { return true ; } } return usedSelectors . indexOf ( selector ) !== - 1 ; } ) ; }