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| // Copyright Joyent, Inc. and other Node contributors. | |
| // | |
| // 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. | |
| '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; |