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index.js.flow
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/
index.js.flow
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// @flow strict
type Numberlike = number | string | null | void;
type Declensions = [string, string, string];
type Plural = (number: ?number) => string;
// N - number parameter (e.g. or ?number)
// R - retyrn type
type Formatter = <N, R>(number: N, word: string) => R;
function _absInt(number: Numberlike): number {
const int = Math.abs(parseInt(number, 10) || 0);
if (Number.isNaN(int)) {
throw new TypeError('Invalid number');
}
return int;
}
function _declensions(one: string, _two?: string, _five?: string): Declensions {
const two = typeof _two === 'undefined' ? one : _two;
const five = typeof _five === 'undefined' ? two : _five;
return [one, two, five];
}
function _pluralize(int: number, declensions: Declensions) {
return declensions[
int % 100 > 4 && int % 100 < 20
? 2
: [2, 0, 1, 1, 1, 2][int % 10 < 5 ? int % 10 : 5]
];
}
export function plural(one: string, two?: string, five?: string): Plural {
return (number: Numberlike) =>
_pluralize(_absInt(number), _declensions(one, two, five));
}
export function format(
formatter: Formatter,
one: string,
two?: string,
five?: string,
) {
return (number: ?number) => formatter(number, plural(one, two, five)(number));
}
export function defaultFormat(one: string, two?: string, five?: string) {
return (number: ?number) =>
[number, plural(one, two, five)(number)].join(' ');
}
export default defaultFormat;