Solver: Implement visitor pattern.

Fixes #238

Author: schvarcz

src/strategy/ibex_Solver.cpp

@@ -1,5 +1,5 @@
 //============================================================================
-//                                  I B E X                                   
+//                                  I B E X
 // File        : ibex_Solver.cpp
 // Author      : Gilles Chabert
 // Copyright   : Ecole des Mines de Nantes (France)
@@ -17,12 +17,16 @@ using namespace std;
 namespace ibex {
 
 Solver::Solver(Ctc& ctc, Bsc& bsc, CellBuffer& buffer) :
-		  ctc(ctc), bsc(bsc), buffer(buffer), time_limit(-1), cell_limit(-1), trace(0), time(0), impact(BitSet::all(ctc.nb_var)) {
+		  ctc(ctc), visitor(NULL), bsc(bsc), buffer(buffer), time_limit(-1), cell_limit(-1), trace(0), time(0), impact(BitSet::all(ctc.nb_var)) {
 
 	nb_cells=0;
 
 }
 
+void Solver::setVistor(SolverVisitor *visitor) {
+    this->visitor = visitor;
+}
+
 void Solver::start(const IntervalVector& init_box) {
 	buffer.flush();
 
@@ -35,18 +39,12 @@ void Solver::start(const IntervalVector& init_box) {
 
 	// add data required by the bisector
 	bsc.add_backtrackable(*root);
-
 	buffer.push(root);
 
-	int nb_var=init_box.size();
-
-	IntervalVector tmpbox(ctc.nb_var);
-
 	Timer::start();
-
 }
 
-bool Solver::next(std::vector<IntervalVector>& sols) {
+void Solver::iterate(std::vector<IntervalVector>& sols) {
 	try  {
 		while (!buffer.empty()) {
 
@@ -61,6 +59,9 @@ bool Solver::next(std::vector<IntervalVector>& sols) {
 			else                                // root node : impact set to 1 for all variables
 				impact.fill(0,ctc.nb_var-1);
 
+			if(visitor != NULL)
+					visitor->visit(c->box,EMPTY_BOOL);
+
 			ctc.contract(c->box,impact);
 
 			if (c->box.is_empty()) {
@@ -87,38 +88,32 @@ bool Solver::next(std::vector<IntervalVector>& sols) {
 				if (cell_limit >=0 && nb_cells>=cell_limit) throw CellLimitException();}
 
 			catch (NoBisectableVariableException&) {
-				new_sol(sols, c->box);
-				delete buffer.pop();
-				return !buffer.empty();
-				// note that we skip time_limit_check() here.
-				// In the case where "next" is called by "solve",
-				// and if time has exceeded, the exception will be raised by the
-				// very next call to "next" anyway. This holds, unless "next" finds
-				// new solutions again and again endlessly. So there is a little risk
-				// of uncaught timeout in this case (but this case is probably already
-				// an error case).
+        if(visitor != NULL)
+            visitor->visit(c->box,MAYBE);
+
+        sols.push_back(c->box);
+        delete buffer.pop();
 			}
 			time_limit_check();
 		}
 	}
 	catch (TimeOutException&) {
-		cout << "time limit " << time_limit << "s. reached " << endl; return false;
+		cout << "time limit " << time_limit << "s. reached " << endl;
 	}
 	catch (CellLimitException&) {
 		cout << "cell limit " << cell_limit << " reached " << endl;
 	}
 
 	Timer::stop();
 	time+= Timer::VIRTUAL_TIMELAPSE();
-
-	return false;
-
 }
 
 vector<IntervalVector> Solver::solve(const IntervalVector& init_box) {
 	vector<IntervalVector> sols;
+
 	start(init_box);
-	while (next(sols)) { }
+  iterate(sols);
+
 	return sols;
 }
 
@@ -129,12 +124,4 @@ void Solver::time_limit_check () {
 	Timer::start();
 }
 
-
-void Solver::new_sol (vector<IntervalVector> & sols, IntervalVector & box) {
-	sols.push_back(box);
-	cout.precision(12);
-	if (trace >=1)
-		cout << " sol " << sols.size() << " nb_cells " <<  nb_cells << " "  << sols[sols.size()-1] <<   endl;
-}
-
 } // end namespace ibex

src/strategy/ibex_Solver.h

@@ -1,5 +1,5 @@
 //============================================================================
-//                                  I B E X                                   
+//                                  I B E X
 // File        : ibex_Solver.h
 // Author      : Gilles Chabert
 // Copyright   : Ecole des Mines de Nantes (France)
@@ -34,49 +34,60 @@ namespace ibex {
 
 class CellLimitException : public Exception {} ;
 
+/**
+ * \ingroup set
+ * \brief Sivia visitor
+ */
+class SolverVisitor {
+public:
+    /**
+     * \brief Delete this.
+     */
+    virtual ~SolverVisitor() { }
+
+    /**
+     * \brief Visit
+     */
+    virtual void visit(const IntervalVector& box, BoolInterval status)=0;
+
+};
+
 class Solver {
 public:
 	/**
 	 * \brief Build a solver.
 	 *
-	 * \param ctc  -  the contractor (for contracting each node of the search tree) 
+	 * \param ctc  -  the contractor (for contracting each node of the search tree)
 	 * \param bsc  -  the bisector   (for branching). Contains the stop criterion.
 	 * \param buffer - the cell buffer (a CellStack in a depth first search strategy)
 	 */
 	Solver(Ctc& ctc, Bsc& bsc, CellBuffer& buffer);
 
-	/**
-	 * \brief Solve the system (non-interactive mode).
-	 *
-	 * \param init_box - the initial box (the search space)
-	 * 
-	 * Return :the vector of solutions (small boxes with the required precision) found by the solver.
-	 */
-	std::vector<IntervalVector> solve(const IntervalVector& init_box);
 
-	/**
-	 * \brief Start solving (interactive mode).
-	 *
-	 * Can also be used to restart a new search.
-	 */
-	void start(const IntervalVector& init_box);
+    /**
+     * \brief Solve the system.
+     *
+     * \param init_box - the initial box (the search space)
+     *
+     * Return :the vector of solutions (small boxes with the required precision) found by the solver.
+     */
+    std::vector<IntervalVector> solve(const IntervalVector& init_box);
 
-	/**
-	 * \brief Continue solving (interactive mode).
-	 *
-	 * Look for the next solution and push it into the vector.
-	 * \return false if the search is over (true otherwise).
-	 */
-	bool next(std::vector<IntervalVector>& sols);
 
+    /**
+     * \brief Set a visitor to provide visibility to Solver process.
+     *
+     * \param visitor - The visitor to be reported.
+     */
+    void setVistor(SolverVisitor *visitor);
 
 	/**
-	 * \brief  The contractor 
+	 * \brief  The contractor
 	 *
-	 * contractor used by the solver for contracting the current box at each node : 
+	 * contractor used by the solver for contracting the current box at each node :
 	 * generally, a sequence (with or without fixpoint) of different contractors (hc4 , acid, Newton , a linear relaxation )
 	 *
-	 */ 
+	 */
 	Ctc& ctc;
 
 	/** Bisector (tests also precision of boxes). */
@@ -100,10 +111,10 @@ class Solver {
 	/**
 	 * \brief Trace level
 	 *
-	 *  the trace level. 
+	 *  the trace level.
 	 *  0  : no trace  (default value)
 	 *  1   the solutions are printed each time a new solution is found
-	 *  2   the solutions are printed each time a new solution is found and the current box is printed at each node of the branch and prune algorithm 
+	 *  2   the solutions are printed each time a new solution is found and the current box is printed at each node of the branch and prune algorithm
 	 */
 	int trace;
 
@@ -116,11 +127,25 @@ class Solver {
 
 protected :
 
-	void time_limit_check();
+	/**
+	 * \brief Start solving.
+	 *
+	 * Can also be used to restart a new search.
+	 */
+	void start(const IntervalVector& init_box);
+
+	/**
+	 * \brief Continue solving.
+	 *
+	 * Look for the next solution and push it into the vector.
+	 * \return false if the search is over (true otherwise).
+	 */
+	void iterate(std::vector<IntervalVector>& sols);
 
-	void new_sol(std::vector<IntervalVector> & sols, IntervalVector & box);
+	void time_limit_check();
 
 	BitSet impact;
+  SolverVisitor *visitor;
 
 };