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dekker.one
1/* -*- mode: C++; c-basic-offset: 2; indent-tabs-mode: nil -*- */
2/*
3 * Main authors:
4 * Christian Schulte <schulte@gecode.org>
5 * Guido Tack <tack@gecode.org>
6 *
7 * Copyright:
8 * Christian Schulte, 2010
9 * Guido Tack, 2010
10 *
11 * This file is part of Gecode, the generic constraint
12 * development environment:
13 * http://www.gecode.org
14 *
15 * Permission is hereby granted, free of charge, to any person obtaining
16 * a copy of this software and associated documentation files (the
17 * "Software"), to deal in the Software without restriction, including
18 * without limitation the rights to use, copy, modify, merge, publish,
19 * distribute, sublicense, and/or sell copies of the Software, and to
20 * permit persons to whom the Software is furnished to do so, subject to
21 * the following conditions:
22 *
23 * The above copyright notice and this permission notice shall be
24 * included in all copies or substantial portions of the Software.
25 *
26 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
27 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
28 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
29 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
30 * LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
31 * OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
32 * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
33 *
34 */
35
36namespace Gecode { namespace Int { namespace Cumulative {
37
38 /// Sort order for tasks by decreasing capacity
39 template<class Task>
40 class TaskByDecCap {
41 public:
42 /// Sort order
43 bool operator ()(const Task& t1, const Task& t2) const;
44 };
45
46 template<class Task>
47 forceinline bool
48 TaskByDecCap<Task>::operator ()(const Task& t1, const Task& t2) const {
49 return t1.c() > t2.c();
50 }
51
52 // Basic propagation (timetabling)
53 template<class Task, class Cap>
54 forceinline ExecStatus
55 timetabling(Space& home, Propagator& p, Cap c, TaskArray<Task>& t) {
56 int ccur = c.max();
57 int cmax = ccur;
58 int cmin = ccur;
59
60 // Sort tasks by decreasing capacity
61 TaskByDecCap<Task> tbdc;
62 Support::quicksort(&t[0], t.size(), tbdc);
63
64 Region r;
65
66 bool assigned;
67 if (Event* e = Event::events(r,t,assigned)) {
68 // Set of current but not required tasks
69 Support::BitSet<Region> tasks(r,static_cast<unsigned int>(t.size()));
70
71 // Process events, use ccur as the capacity that is still free
72 do {
73 // Current time
74 int time = e->time();
75
76 // Process events for completion of required part
77 for ( ; (e->type() == Event::LRT) && (e->time() == time); e++)
78 if (t[e->idx()].mandatory()) {
79 tasks.set(static_cast<unsigned int>(e->idx()));
80 ccur += t[e->idx()].c();
81 }
82 // Process events for completion of task
83 for ( ; (e->type() == Event::LCT) && (e->time() == time); e++)
84 tasks.clear(static_cast<unsigned int>(e->idx()));
85 // Process events for start of task
86 for ( ; (e->type() == Event::EST) && (e->time() == time); e++)
87 tasks.set(static_cast<unsigned int>(e->idx()));
88 // Process events for zero-length task
89 for ( ; (e->type() == Event::ZRO) && (e->time() == time); e++) {
90 ccur -= t[e->idx()].c();
91 if (ccur < cmin) cmin=ccur;
92 if (ccur < 0)
93 return ES_FAILED;
94 ccur += t[e->idx()].c();
95 }
96
97 // norun start time
98 int nrstime = time;
99 // Process events for start of required part
100 for ( ; (e->type() == Event::ERT) && (e->time() == time); e++)
101 if (t[e->idx()].mandatory()) {
102 tasks.clear(static_cast<unsigned int>(e->idx()));
103 ccur -= t[e->idx()].c();
104 if (ccur < cmin) cmin=ccur;
105 nrstime = time+1;
106 if (ccur < 0)
107 return ES_FAILED;
108 } else if (t[e->idx()].optional() && (t[e->idx()].c() > ccur)) {
109 GECODE_ME_CHECK(t[e->idx()].excluded(home));
110 }
111
112 // Exploit that tasks are sorted according to capacity
113 for (Iter::Values::BitSet<Support::BitSet<Region> > j(tasks);
114 j() && (t[j.val()].c() > ccur); ++j)
115 // Task j cannot run from zltime to next time - 1
116 if (t[j.val()].mandatory())
117 GECODE_ME_CHECK(t[j.val()].norun(home, nrstime, e->time() - 1));
118 } while (e->type() != Event::END);
119
120 GECODE_ME_CHECK(c.gq(home,cmax-cmin));
121 }
122
123 if (assigned)
124 return home.ES_SUBSUMED(p);
125 return ES_NOFIX;
126 }
127
128}}}
129
130// STATISTICS: int-prop