| 1 | <?php |
| 2 | /*************************************************************************** |
| 3 | * Copyright (C) 2003-2010 Polytechnique.org * |
| 4 | * http://opensource.polytechnique.org/ * |
| 5 | * * |
| 6 | * This program is free software; you can redistribute it and/or modify * |
| 7 | * it under the terms of the GNU General Public License as published by * |
| 8 | * the Free Software Foundation; either version 2 of the License, or * |
| 9 | * (at your option) any later version. * |
| 10 | * * |
| 11 | * This program is distributed in the hope that it will be useful, * |
| 12 | * but WITHOUT ANY WARRANTY; without even the implied warranty of * |
| 13 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the * |
| 14 | * GNU General Public License for more details. * |
| 15 | * * |
| 16 | * You should have received a copy of the GNU General Public License * |
| 17 | * along with this program; if not, write to the Free Software * |
| 18 | * Foundation, Inc., * |
| 19 | * 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA * |
| 20 | ***************************************************************************/ |
| 21 | |
| 22 | /** Implements a heap. The order of the elements is determined by the given |
| 23 | * comparator: the smaller element is the head of the heap. |
| 24 | */ |
| 25 | class PlHeap |
| 26 | { |
| 27 | private $comparator; |
| 28 | private $content = array(); |
| 29 | |
| 30 | public function __construct($comparator) |
| 31 | { |
| 32 | $this->comparator = $comparator; |
| 33 | } |
| 34 | |
| 35 | public function pop() |
| 36 | { |
| 37 | if (empty($this->content)) { |
| 38 | return null; |
| 39 | } |
| 40 | return array_shift($this->content); |
| 41 | } |
| 42 | |
| 43 | public function push($elt) |
| 44 | { |
| 45 | $start = 0; |
| 46 | $end = count($this->content); |
| 47 | |
| 48 | while ($start < $end) { |
| 49 | $middle = floor(($start + $end) / 2); |
| 50 | $comp = call_user_func($this->comparator, $elt, $this->content[$middle]); |
| 51 | if ($comp < 0) { |
| 52 | $end = $middle; |
| 53 | } else if ($comp > 0) { |
| 54 | $start = $middle + 1; |
| 55 | } else { |
| 56 | array_splice($this->content, $middle, 0, array($elt)); |
| 57 | return; |
| 58 | } |
| 59 | } |
| 60 | array_splice($this->content, $start, 0, array($elt)); |
| 61 | } |
| 62 | |
| 63 | public function count() |
| 64 | { |
| 65 | return count($this->content); |
| 66 | } |
| 67 | |
| 68 | public function iterator() |
| 69 | { |
| 70 | return PlIteratorUtils::fromArray($this->content, 1, true); |
| 71 | } |
| 72 | } |
| 73 | |
| 74 | // vim:set et sw=4 sts=4 sws=4 foldmethod=marker enc=utf-8: |
| 75 | ?> |