/**
 * Make a map and return a function for checking if a key
 * is in that map.
 * IMPORTANT: all calls of this function must be prefixed with
 * \/\*#\_\_PURE\_\_\*\/
 * So that rollup can tree-shake them if necessary.
 */ export function makeMap ( str , expectsLowerCase ? ) { const map = Object . create ( null ) ; const list = str . split ( ',' ) ; for ( let i = 0 ; i < list . length ; i ++ ) { map [ list [ i ] ] = true ; } return expectsLowerCase ? val => ! ! map [ val . toLowerCase ( ) ] : val => ! ! map [ val ] ; }