49 lines
1.1 KiB
JavaScript
49 lines
1.1 KiB
JavaScript
'use strict';
|
|
|
|
var toPosInt = require('es5-ext/number/to-pos-integer')
|
|
|
|
, create = Object.create, hasOwnProperty = Object.prototype.hasOwnProperty;
|
|
|
|
module.exports = function (limit) {
|
|
var size = 0, base = 1, queue = create(null), map = create(null), index = 0, del;
|
|
limit = toPosInt(limit);
|
|
return {
|
|
hit: function (id) {
|
|
var oldIndex = map[id], nuIndex = ++index;
|
|
queue[nuIndex] = id;
|
|
map[id] = nuIndex;
|
|
if (!oldIndex) {
|
|
++size;
|
|
if (size <= limit) return;
|
|
id = queue[base];
|
|
del(id);
|
|
return id;
|
|
}
|
|
delete queue[oldIndex];
|
|
if (base !== oldIndex) return;
|
|
while (!hasOwnProperty.call(queue, ++base)) continue; //jslint: skip
|
|
},
|
|
delete: del = function (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; //jslint: skip
|
|
},
|
|
clear: function () {
|
|
size = 0;
|
|
base = 1;
|
|
queue = create(null);
|
|
map = create(null);
|
|
index = 0;
|
|
}
|
|
};
|
|
};
|