updeep-remeda/lib/util/curry.js
2016-01-13 08:19:56 -08:00

129 lines
3.3 KiB
JavaScript

/* eslint no-shadow:0, no-param-reassign:0 */
export const _ = '@@updeep/placeholder';
function countArguments(args, max) {
let n = args.length;
if (n > max) n = max;
while (args[n - 1] === _) {
n--;
}
return n;
}
export function curry1(fn) {
return function curried(a, ...args) {
const [b, c] = args;
const n = countArguments(arguments);
if (n >= 1) return fn(a, b, c);
return curried;
};
}
export function curry2(fn) {
return function curried(a, b, ...args) {
const [c, d] = args;
const n = countArguments(arguments, 2);
if (b === _ || c === _ || d === _) {
throw new Error('Can only use placeholder on first argument of this function.');
}
if (n >= 2) {
if (a === _) return curry1((a, c, d) => fn(a, b, c, d));
return fn(a, b, c, d);
}
if (n === 1) return curry1((b, c, d) => fn(a, b, c, d));
return curried;
};
}
export function curry3(fn) {
return function curried(a, b, c, ...args) {
const [d, e] = args;
const n = countArguments(arguments, 3);
if (c === _ || d === _ || e === _) {
throw new Error('Can only use placeholder on first or second argument of this function.');
}
if (n >= 3) {
if (a === _) {
if (b === _) return curry2((a, b, d, e) => fn(a, b, c, d, e));
return curry1((a, d, e) => fn(a, b, c, d, e));
}
if (b === _) return curry1((b, d, e) => fn(a, b, c, d, e));
return fn(a, b, c, d, e);
}
if (n === 2) {
if (a === _) return curry2((a, c, d, e) => fn(a, b, c, d, e));
return curry1((c, d, e) => fn(a, b, c, d, e));
}
if (n === 1) return curry2((b, c, d, e) => fn(a, b, c, d, e));
return curried;
};
}
export function curry4(fn) {
return function curried(a, b, c, d, ...args) {
const [e, f] = args;
const n = countArguments(arguments, 4);
if (d === _ || e === _ || f === _) {
throw new Error(
'Can only use placeholder on first, second or third argument of this function.'
);
}
if (n >= 4) {
if (a === _) {
if (b === _) {
if (c === _) return curry3((a, b, c, e, f) => fn(a, b, c, d, e, f));
return curry2((a, b, e, f) => fn(a, b, c, d, e, f));
}
if (c === _) return curry2((a, c, e, f) => fn(a, b, c, d, e, f));
return curry1((a, e, f) => fn(a, b, c, d, e, f));
}
if (b === _) {
if (c === _) return curry2((b, c, e, f) => fn(a, b, c, d, e, f));
return curry1((b, e, f) => fn(a, b, c, d, e, f));
}
if (c === _) return curry1((c, e, f) => fn(a, b, c, d, e, f));
return fn(a, b, c, d, e, f);
}
if (n === 3) {
if (a === _) {
if (b === _) return curry3((a, b, d, e, f) => fn(a, b, c, d, e, f));
return curry2((a, d, e, f) => fn(a, b, c, d, e, f));
}
if (b === _) return curry2((b, d, e, f) => fn(a, b, c, d, e, f));
return curry1((d, e, f) => fn(a, b, c, d, e, f));
}
if (n === 2) {
if (a === _) return curry3((a, c, d, e, f) => fn(a, b, c, d, e, f));
return curry2((c, d, e, f) => fn(a, b, c, d, e, f));
}
if (n === 1) return curry3((b, c, d, e, f) => fn(a, b, c, d, e, f));
return curried;
};
}
export default function curry(fn, length = fn.length) {
return [
fn,
curry1,
curry2,
curry3,
curry4,
][length](fn);
}