| // 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. |
| |
| 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; |