/** * Memoize a given function by caching the computed result. * The cache of a memoized function can be cleared by
deleting the cache * property of the function. @param
{function} fn The function to be memoized. * Must be a pure function. * @param
{function(args: Array)} [hasher] A custom hash builder. * Is JSON.stringify by default. * @return {function} Returns the memoized function
export function memoize(fn, hasher) {
return function memoize() {
if (typeof memoize.cache !== "object") {
memoize.cache = {};
}
const args = [];
for (let i = 0; i < arguments.length; i++) {
args[i] = arguments[i];
}
const hash = hasher ? hasher(args) : JSON.stringify(args);
if (!(hash in memoize.cache)) {
memoize.cache[hash] = fn.apply(fn, args);
}
return memoize.cache[hash];
};
}/** * Memoize a given function by caching all results and the arguments, * and comparing against the arguments of
previous results before * executing again. * This is less perormant than memoize which calculates a
hash, * which is very fast to compare. Use memoizeCompae only when it is * not possible to create a
unique serializable hash from the function * arguments. * The isEqual function must compare two sets of arguments *
and return true when equal (can be a deep equality check for example). * @param
{function} fn * @param {function(a: , b: ) : boolean} isEqual * @returns {function}
export function memoizeCompare(fn, isEqual) {
const memoize = function memoize() {
const args = [];
for (let i = 0; i < arguments.length; i++) {
args[i] = arguments[i];
}
for (let c = 0; c < memoize.cache.length; c++) {
const cached = memoize.cache[c];
if (isEqual(args, cached.args)) {
// TODO: move this cache entry to the top so recently used entries move
up?
return cached.res;
}
}
const res = fn.apply(fn, args);
memoize.cache.unshift({ args, res });
return res;
};
memoize.cache = [];
return memoize;
}/** * Find the maximum number of arguments expected by a typed function. * @param {function} fn A typed function * @return {number} Returns the maximum number of expected arguments. * Returns -1 when no signatures where found on the function.