64 lines
1.3 KiB
JavaScript
64 lines
1.3 KiB
JavaScript
|
// (c) 2018, Mariusz Nowak
|
||
|
|
// SPDX-License-Identifier: ISC
|
||
|
|
// Derived from https://github.com/medikoo/lru-queue
|
||
|
|
export function lruQueue(limit) {
|
||
|
|
var size = 0;
|
||
|
|
var base = 1;
|
||
|
|
var queue = Object.create(null);
|
||
|
|
var map = Object.create(null);
|
||
|
|
var index = 0;
|
||
|
|
|
||
|
|
var del = function del(id) {
|
||
|
|
var oldIndex = map[id];
|
||
|
|
if (!oldIndex) return;
|
||
|
|
delete queue[oldIndex];
|
||
|
|
delete map[id];
|
||
|
|
--size;
|
||
|
|
if (base !== oldIndex) return;
|
||
|
|
|
||
|
|
if (!size) {
|
||
|
|
index = 0;
|
||
|
|
base = 1;
|
||
|
|
return;
|
||
|
|
}
|
||
|
|
|
||
|
|
while (!hasOwnProperty.call(queue, ++base)) {
|
||
|
|
continue;
|
||
|
|
}
|
||
|
|
};
|
||
|
|
|
||
|
|
limit = Math.abs(limit);
|
||
|
|
return {
|
||
|
|
hit: function hit(id) {
|
||
|
|
var oldIndex = map[id];
|
||
|
|
var nuIndex = ++index;
|
||
|
|
queue[nuIndex] = id;
|
||
|
|
map[id] = nuIndex;
|
||
|
|
|
||
|
|
if (!oldIndex) {
|
||
|
|
++size;
|
||
|
|
if (size <= limit) return undefined;
|
||
|
|
id = queue[base];
|
||
|
|
del(id);
|
||
|
|
return id;
|
||
|
|
}
|
||
|
|
|
||
|
|
delete queue[oldIndex];
|
||
|
|
if (base !== oldIndex) return undefined;
|
||
|
|
|
||
|
|
while (!hasOwnProperty.call(queue, ++base)) {
|
||
|
|
continue;
|
||
|
|
}
|
||
|
|
|
||
|
|
return undefined;
|
||
|
|
},
|
||
|
|
delete: del,
|
||
|
|
clear: function clear() {
|
||
|
|
size = index = 0;
|
||
|
|
base = 1;
|
||
|
|
queue = Object.create(null);
|
||
|
|
map = Object.create(null);
|
||
|
|
}
|
||
|
|
};
|
||
|
|
}
|
||
|
|
;
|