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eqv.hpp

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00001 /* -*- mode: C++; c-basic-offset: 2; indent-tabs-mode: nil -*- */
00002 /*
00003  *  Main authors:
00004  *     Christian Schulte <schulte@gecode.org>
00005  *
00006  *  Copyright:
00007  *     Christian Schulte, 2004
00008  *
00009  *  Last modified:
00010  *     $Date: 2011-10-07 11:28:27 +0200 (Fri, 07 Oct 2011) $ by $Author: schulte $
00011  *     $Revision: 12427 $
00012  *
00013  *  This file is part of Gecode, the generic constraint
00014  *  development environment:
00015  *     http://www.gecode.org
00016  *
00017  *  Permission is hereby granted, free of charge, to any person obtaining
00018  *  a copy of this software and associated documentation files (the
00019  *  "Software"), to deal in the Software without restriction, including
00020  *  without limitation the rights to use, copy, modify, merge, publish,
00021  *  distribute, sublicense, and/or sell copies of the Software, and to
00022  *  permit persons to whom the Software is furnished to do so, subject to
00023  *  the following conditions:
00024  *
00025  *  The above copyright notice and this permission notice shall be
00026  *  included in all copies or substantial portions of the Software.
00027  *
00028  *  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
00029  *  EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
00030  *  MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
00031  *  NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
00032  *  LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
00033  *  OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
00034  *  WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
00035  *
00036  */
00037 
00038 namespace Gecode { namespace Int { namespace Bool {
00039 
00040   template<class BVA, class BVB, class BVC>
00041   forceinline
00042   Eqv<BVA,BVB,BVC>::Eqv(Home home, BVA b0, BVB b1, BVC b2)
00043     : BoolTernary<BVA,BVB,BVC>(home,b0,b1,b2) {}
00044 
00045   template<class BVA, class BVB, class BVC>
00046   forceinline
00047   Eqv<BVA,BVB,BVC>::Eqv(Space& home, bool share, Eqv<BVA,BVB,BVC>& p)
00048     : BoolTernary<BVA,BVB,BVC>(home,share,p) {}
00049 
00050   template<class BVA, class BVB, class BVC>
00051   inline ExecStatus
00052   Eqv<BVA,BVB,BVC>::post(Home home, BVA b0, BVB b1, BVC b2){
00053     switch (bool_test(b0,b1)) {
00054     case BT_SAME:
00055       GECODE_ME_CHECK(b2.one(home)); break;
00056     case BT_COMP:
00057       GECODE_ME_CHECK(b2.zero(home)); break;
00058     case BT_NONE:
00059       if (b2.one())
00060         return Eq<BVA,BVB>::post(home,b0,b1);
00061       if (b0.one()) {
00062         if (b1.one()) {
00063           GECODE_ME_CHECK(b2.one(home)); return ES_OK;
00064         } else if (b1.zero()) {
00065           GECODE_ME_CHECK(b2.zero(home)); return ES_OK;
00066         }
00067       }
00068       if (b0.zero()) {
00069         if (b1.one()) {
00070           GECODE_ME_CHECK(b2.zero(home)); return ES_OK;
00071         } else if (b1.zero()) {
00072           GECODE_ME_CHECK(b2.one(home)); return ES_OK;
00073         }
00074       }
00075       (void) new (home) Eqv(home,b0,b1,b2);
00076       break;
00077     default:
00078       GECODE_NEVER;
00079     }
00080     return ES_OK;
00081   }
00082 
00083   template<class BVA, class BVB, class BVC>
00084   Actor*
00085   Eqv<BVA,BVB,BVC>::copy(Space& home, bool share) {
00086     return new (home) Eqv<BVA,BVB,BVC>(home,share,*this);
00087   }
00088 
00089   template<class BVA, class BVB, class BVC>
00090   ExecStatus
00091   Eqv<BVA,BVB,BVC>::propagate(Space& home, const ModEventDelta&) {
00092 #define GECODE_INT_STATUS(S0,S1,S2) \
00093   ((BVA::S0<<(2*BVA::BITS))|(BVB::S1<<(1*BVB::BITS))|(BVC::S2<<(0*BVC::BITS)))
00094     switch ((x0.status() << (2*BVA::BITS)) | (x1.status() << (1*BVB::BITS)) |
00095             (x2.status() << (0*BVC::BITS))) {
00096     case GECODE_INT_STATUS(NONE,NONE,NONE):
00097       GECODE_NEVER;
00098     case GECODE_INT_STATUS(NONE,NONE,ZERO):
00099     case GECODE_INT_STATUS(NONE,NONE,ONE):
00100     case GECODE_INT_STATUS(NONE,ZERO,NONE):
00101       return ES_FIX;
00102     case GECODE_INT_STATUS(NONE,ZERO,ZERO):
00103       GECODE_ME_CHECK(x0.one_none(home)); break;
00104     case GECODE_INT_STATUS(NONE,ZERO,ONE):
00105       GECODE_ME_CHECK(x0.zero_none(home)); break;
00106     case GECODE_INT_STATUS(NONE,ONE,NONE):
00107       return ES_FIX;
00108     case GECODE_INT_STATUS(NONE,ONE,ZERO):
00109       GECODE_ME_CHECK(x0.zero_none(home)); break;
00110     case GECODE_INT_STATUS(NONE,ONE,ONE):
00111       GECODE_ME_CHECK(x0.one_none(home)); break;
00112     case GECODE_INT_STATUS(ZERO,NONE,NONE):
00113       return ES_FIX;
00114     case GECODE_INT_STATUS(ZERO,NONE,ZERO):
00115       GECODE_ME_CHECK(x1.one_none(home)); break;
00116     case GECODE_INT_STATUS(ZERO,NONE,ONE):
00117       GECODE_ME_CHECK(x1.zero_none(home)); break;
00118     case GECODE_INT_STATUS(ZERO,ZERO,NONE):
00119       GECODE_ME_CHECK(x2.one_none(home)); break;
00120     case GECODE_INT_STATUS(ZERO,ZERO,ZERO):
00121       return ES_FAILED;
00122     case GECODE_INT_STATUS(ZERO,ZERO,ONE):
00123       break;
00124     case GECODE_INT_STATUS(ZERO,ONE,NONE):
00125       GECODE_ME_CHECK(x2.zero_none(home)); break;
00126     case GECODE_INT_STATUS(ZERO,ONE,ZERO):
00127       break;
00128     case GECODE_INT_STATUS(ZERO,ONE,ONE):
00129       return ES_FAILED;
00130     case GECODE_INT_STATUS(ONE,NONE,NONE):
00131       return ES_FIX;
00132     case GECODE_INT_STATUS(ONE,NONE,ZERO):
00133       GECODE_ME_CHECK(x1.zero_none(home)); break;
00134     case GECODE_INT_STATUS(ONE,NONE,ONE):
00135       GECODE_ME_CHECK(x1.one_none(home)); break;
00136     case GECODE_INT_STATUS(ONE,ZERO,NONE):
00137       GECODE_ME_CHECK(x2.zero_none(home)); break;
00138     case GECODE_INT_STATUS(ONE,ZERO,ZERO):
00139       break;
00140     case GECODE_INT_STATUS(ONE,ZERO,ONE):
00141       return ES_FAILED;
00142     case GECODE_INT_STATUS(ONE,ONE,NONE):
00143       GECODE_ME_CHECK(x2.one_none(home)); break;
00144     case GECODE_INT_STATUS(ONE,ONE,ZERO):
00145       return ES_FAILED;
00146     case GECODE_INT_STATUS(ONE,ONE,ONE):
00147       break;
00148     default:
00149       GECODE_NEVER;
00150     }
00151     return home.ES_SUBSUMED(*this);
00152 #undef GECODE_INT_STATUS
00153   }
00154 
00155 
00156   /*
00157    * N-ary Boolean equivalence propagator
00158    *
00159    */
00160 
00161   forceinline
00162   NaryEqv::NaryEqv(Home home, ViewArray<BoolView>& x0, int pm20)
00163     : BinaryPropagator<BoolView,PC_BOOL_VAL>(home,x0[0],x0[1]), 
00164       x(x0), pm2(pm20) {
00165     assert(x.size() >= 2);
00166     x.drop_fst(2);
00167   }
00168 
00169   forceinline
00170   NaryEqv::NaryEqv(Space& home, bool share, NaryEqv& p)
00171     : BinaryPropagator<BoolView,PC_BOOL_VAL>(home,share,p), pm2(p.pm2) {
00172     x.update(home,share,p.x);
00173   }
00174 
00175   forceinline size_t
00176   NaryEqv::dispose(Space& home) {
00177     (void) BinaryPropagator<BoolView,PC_BOOL_VAL>::dispose(home);
00178     return sizeof(*this);
00179   }
00180 
00181   forceinline void
00182   NaryEqv::resubscribe(Space& home, BoolView& x0) {
00183     if (x0.assigned()) {
00184       pm2 ^= x0.val();
00185       int n = x.size();
00186       for (int i=n; i--; )
00187         if (x[i].assigned()) {
00188           pm2 ^= x[i].val();
00189           x[i] = x[--n];
00190         } else {
00191           // Move to x0 and subscribe
00192           x0=x[i]; x[i]=x[--n];
00193           x0.subscribe(home,*this,PC_BOOL_VAL,false);
00194           break;
00195         }
00196       x.size(n);
00197     }
00198   }
00199 
00200 }}}
00201 
00202 // STATISTICS: int-prop