(function () { 'use strict';
function init(list) {
list._idleNext = list;
list._idlePrev = list;
}
exports.init = init;
// show the most idle item
function peek(list) {
if (list._idlePrev == list) return null;
return list._idlePrev;
}
exports.peek = peek;
// remove the most idle item from the list
function shift(list) {
var first = list._idlePrev;
remove(first);
return first;
}
exports.shift = shift;
// remove a item from its list
function remove(item) {
if (item._idleNext) {
item._idleNext._idlePrev = item._idlePrev;
}
if (item._idlePrev) {
item._idlePrev._idleNext = item._idleNext;
}
item._idleNext = null;
item._idlePrev = null;
}
exports.remove = remove;
// remove a item from its list and place at the end.
function append(list, item) {
remove(item);
item._idleNext = list._idleNext;
list._idleNext._idlePrev = item;
item._idlePrev = list;
list._idleNext = item;
}
exports.append = append;
function isEmpty(list) {
return list._idleNext === list;
}
exports.isEmpty = isEmpty;
}());
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