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namespace Gecode { namespace Int { namespace Channel {
/** * \brief Combine view with information for domain propagation * */ template<class View, class Offset> class DomInfo { public: /// The view View view; /// Last propagated size unsigned int size; /// Last propagated minimum int min; /// Last propagated maximum int max; /// Initialize void init(View x, int n); /// Update during cloning void update(Space& home, DomInfo<View,Offset>& vcb); /// Check whether propagation for assignment is to be done bool doval(void) const; /// Check whether propagation for domain is to be done bool dodom(void) const; /// Record that view got assigned void assigned(void); /// Record that one value got removed void removed(int i); /// Update the size and bounds information after pruning void done(Offset& o); };
template<class View, class Offset> forceinline void DomInfo<View,Offset>::init(View x, int n) { view = x; size = static_cast<unsigned int>(n); min = 0; max = n-1; }
template<class View, class Offset> forceinline void DomInfo<View,Offset>::update(Space& home, DomInfo<View,Offset>& di) { view.update(home,di.view); size = di.size; min = di.min; max = di.max; }
template<class View, class Offset> forceinline bool DomInfo<View,Offset>::doval(void) const { return (size != 1) && view.assigned(); }
template<class View, class Offset> forceinline bool DomInfo<View,Offset>::dodom(void) const { return size != view.size(); }
template<class View, class Offset> forceinline void DomInfo<View,Offset>::assigned(void) { size = 1; }
template<class View, class Offset> forceinline void DomInfo<View,Offset>::removed(int i) { size--; if (i == min) min++; else if (i == max) max--; }
template<class View, class Offset> forceinline void DomInfo<View,Offset>::done(Offset& o) { size = view.size(); min = o(view).min(); max = o(view).max(); }
// Propagate domain information from x to y template<class View, class Offset> ExecStatus prop_dom(Space& home, int n, DomInfo<View,Offset>* x, Offset& ox, DomInfo<View,Offset>* y, Offset& oy, ProcessStack& ya) { for (int i=0; i<n; i++) // Only views with not yet propagated missing values if (x[i].dodom()) { // Iterate the values in the complement of x[i] ViewRanges<typename Offset::ViewType> xir(ox(x[i].view)); Iter::Ranges::ComplVal<ViewRanges<typename Offset::ViewType> > xirc(x[i].min,x[i].max,xir); Iter::Ranges::ToValues<Iter::Ranges::ComplVal< ViewRanges<typename Offset::ViewType> > > jv(xirc); while (jv()) { // j is not in the domain of x[i], so prune i from y[j] int j = jv.val(); ModEvent me = oy(y[j].view).nq(home,i); if (me_failed(me)) return ES_FAILED; if (me_modified(me)) { if (me == ME_INT_VAL) { // Record that y[j] has been assigned and must be propagated ya.push(j); } else { // Obvious as x[i] is different from j y[j].removed(i); } } ++jv; } // Update which values have been propagated and what are the new bounds x[i].done(ox); } return ES_OK; }
/* * The actual propagator * */ template<class View, class Offset, bool shared> forceinline Dom<View,Offset,shared>::Dom(Home home, int n, DomInfo<View,Offset>* xy, Offset& ox, Offset& oy) : Base<DomInfo<View,Offset>,Offset,PC_INT_DOM>(home,n,xy,ox,oy) {}
template<class View, class Offset, bool shared> forceinline Dom<View,Offset,shared>::Dom(Space& home, Dom<View,Offset,shared>& p) : Base<DomInfo<View,Offset>,Offset,PC_INT_DOM>(home,p) {}
template<class View, class Offset, bool shared> Actor* Dom<View,Offset,shared>::copy(Space& home) { return new (home) Dom<View,Offset,shared>(home,*this); }
template<class View, class Offset, bool shared> PropCost Dom<View,Offset,shared>::cost(const Space&, const ModEventDelta& med) const { if (View::me(med) == ME_INT_VAL) return PropCost::quadratic(PropCost::LO, 2*n); else return PropCost::quadratic(PropCost::HI, 2*n); }
template<class View, class Offset, bool shared> ExecStatus Dom<View,Offset,shared>::propagate(Space& home, const ModEventDelta& med) { // MSVC in non-permissive mode needs this, no idea why... const int n = this->n; Region r; ProcessStack xa(r,n); ProcessStack ya(r,n);
DomInfo<View,Offset>* x = xy; DomInfo<View,Offset>* y = xy+n;
if (View::me(med) == ME_INT_VAL) { // Scan x and y for assigned but not yet propagated views for (int i=0; i<n; i++) { if (x[i].doval()) xa.push(i); if (y[i].doval()) ya.push(i); }
if (shared) { do { // Propagate assigned views for x GECODE_ES_CHECK((prop_val<View,Offset,DomInfo<View,Offset> > (home,n,x,ox,y,oy,n_na,xa,ya))); // Propagate assigned views for y GECODE_ES_CHECK((prop_val<View,Offset,DomInfo<View,Offset> > (home,n,y,oy,x,ox,n_na,ya,xa))); assert(ya.empty()); } while (!xa.empty() || !ya.empty()); return home.ES_NOFIX_PARTIAL(*this,View::med(ME_INT_DOM)); } else { do { // Propagate assigned views for x GECODE_ES_CHECK((prop_val<View,Offset,DomInfo<View,Offset> > (home,n,x,ox,y,oy,n_na,xa,ya))); // Propagate assigned views for y GECODE_ES_CHECK((prop_val<View,Offset,DomInfo<View,Offset> > (home,n,y,oy,x,ox,n_na,ya,xa))); assert(ya.empty()); } while (!xa.empty()); return home.ES_FIX_PARTIAL(*this,View::med(ME_INT_DOM)); } }
// Process changed views for y // This propagates from y to x and possibly records xs that // got assigned GECODE_ES_CHECK(prop_dom(home,n,y,oy,x,ox,xa));
// Process assigned views for x GECODE_ES_CHECK((prop_val<View,Offset,DomInfo<View,Offset> > (home,n,x,ox,y,oy,n_na,xa,ya)));
// Perform domain consistent propagation for distinct on the x views if (dc.available()) { GECODE_ES_CHECK(dc.sync()); } else { ViewArray<View> xv(r,n); for (int i=0; i<n; i++) xv[i] = x[i].view; GECODE_ES_CHECK(dc.init(home,xv)); } bool assigned; GECODE_ES_CHECK(dc.propagate(home,assigned)); if (assigned) { // This has assigned some more views in x which goes unnoticed // (that is, not recorded in xa). This must be checked and propagated // to the y views, however the distinctness on x is already // propagated. for (int i=0; i<n; i++) if (x[i].doval()) { int j = ox(x[i].view).val(); // Assign the y variable to i (or test if already assigned!) ModEvent me = oy(y[j].view).eq(home,i); if (me_failed(me)) return ES_FAILED; if (me_modified(me)) { // Record that y[j] has been assigned and must be propagated assert(me == ME_INT_VAL); // Otherwise the modification event would not be ME_INT_VAL ya.push(j); } x[i].assigned(); n_na--; } }
// Process changed views for x // This propagates from x to y and possibly records ys that // got assigned GECODE_ES_CHECK(prop_dom(home,n,x,ox,y,oy,ya));
// Process assigned view again (some might have been found above) while (!xa.empty() || !ya.empty()) { // Process assigned views for x GECODE_ES_CHECK((prop_val<View,Offset,DomInfo<View,Offset> > (home,n,x,ox,y,oy,n_na,xa,ya))); // Process assigned views for y GECODE_ES_CHECK((prop_val<View,Offset,DomInfo<View,Offset> > (home,n,y,oy,x,ox,n_na,ya,xa))); };
if (shared) { for (int i=0; i<2*n; i++) if (!xy[i].view.assigned()) return ES_NOFIX; return home.ES_SUBSUMED(*this); } else { return (n_na == 0) ? home.ES_SUBSUMED(*this) : ES_FIX; } }
template<class View, class Offset, bool shared> ExecStatus Dom<View,Offset,shared>::post(Home home, int n, DomInfo<View,Offset>* xy, Offset& ox, Offset& oy) { assert(n > 0); if (n == 1) { GECODE_ME_CHECK(ox(xy[0].view).eq(home,0)); GECODE_ME_CHECK(oy(xy[1].view).eq(home,0)); return ES_OK; } for (int i=0; i<n; i++) { GECODE_ME_CHECK(ox(xy[i ].view).gq(home,0)); GECODE_ME_CHECK(ox(xy[i ].view).le(home,n)); GECODE_ME_CHECK(oy(xy[i+n].view).gq(home,0)); GECODE_ME_CHECK(oy(xy[i+n].view).le(home,n)); } (void) new (home) Dom<View,Offset,shared>(home,n,xy,ox,oy); return ES_OK; }
}}}
// STATISTICS: int-prop