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/* ***** BEGIN LICENSE BLOCK *****
* Version: MIT/X11 License
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
* THE SOFTWARE.
*
* Contributor(s):
* Nils Maier <MaierMan@web.de>
* Erik Vold <erikvvold@gmail.com>
*
* ***** END LICENSE BLOCK ***** */
"use strict";
/**
* Decorate a function with a memoization wrapper, with a limited-size cache
* to reduce peak memory utilization.
*
* The memoized function may have any number of arguments, but they must be
* be serializable. It's safest to use this only on functions that accept
* primitives.
*
* A memoized function is not thread-safe, but so is JS, nor re-entrant-safe!
*
* @usage var foo = Scriptish_memoize(function foo(arg1, arg2) { ... complex operation ... });
* @param {Function} func The function to be memoized
* @param {Number} limit Optional. Cache size (default: 100)
* @param {Number} num_args Options. Number of arguments the function expects (default: func.length)
* @return {Function} Memoized function
*/
exports.memoize = function memoize(func, limit, num_args) {
limit = limit || 100;
num_args = num_args || func.length;
var cache = Object.create(null);
var keylist = [];
var args = [];
var key, result;
switch (num_args) {
case 0:
throw new Error("memoize does not support functions without arguments");
case 1:
return function memoize_one_arg(a) {
key = a.toString();
if (key in cache)
return cache[key];
result = func.call(null, a);
cache[key] = result;
if (keylist.push(key) > limit)
delete cache[keylist.shift()];
return result;
};
case 2:
return function memoize_two_args(a, b) {
args[0] = a; args[1] = b;
key = JSON.stringify(args);
args.length = 0;
if (key in cache)
return cache[key];
var result = func.call(null, a, b);
cache[key] = result;
if (keylist.push(key) > limit)
delete cache[keylist.shift()];
return result;
};
case 3:
return function memoize_three_args(a, b, c) {
args[0] = a; args[1] = b; args[2] = c;
key = JSON.stringify(args);
args.length = 0;
if (key in cache)
return cache[key];
var result = func.call(null, a, b, c);
cache[key] = result;
if (keylist.push(key) > limit)
delete cache[keylist.shift()];
return result;
};
case 4:
return function memoize_four_args(a, b, c, d) {
args[0] = a; args[1] = b; args[2] = c; args[3] = d;
key = JSON.stringify(args);
args.length = 0;
if (key in cache)
return cache[key];
var result = func.call(null, a, b, c, d);
cache[key] = result;
if (keylist.push(key) > limit)
delete cache[keylist.shift()];
return result;
};
default:
return function() {
var key = JSON.stringify(arguments);
if (key in cache)
return cache[key];
var result = func.apply(null, arguments);
cache[key] = result;
if (keylist.push(key) > limit)
delete cache[keylist.shift()];
return result;
};
}
}
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