Create placeholders to optimization methods

src/opt/optimize_objectives.cpp

@@ -0,0 +1,60 @@
+/*++
+Copyright (c) 2013 Microsoft Corporation
+
+Module Name:
+
+    optimize_objectives.cpp
+
+Abstract:
+   
+    Objective optimization method.
+
+Author:
+
+    Anh-Dung Phan (t-anphan) 2013-10-16
+
+Notes:
+
+--*/
+
+
+#include "optimize_objectives.h"
+
+namespace opt {
+
+    /*
+        Enumerate locally optimal assignments until fixedpoint.
+    */
+    lbool mathsat_style_opt(solver& s, 
+                          expr_ref_vector& objectives, svector<bool> const& is_max,
+                          vector<optional<rational> >& values) {
+        lbool is_sat;
+        is_sat = s.check_sat(0,0);
+        if (is_sat != l_true) {
+            return is_sat;
+        }
+        // assume that s is instrumented to produce locally optimal assignments.
+
+        while (is_sat != l_false) {
+            model_ref model;
+            s.get_model(model);
+            // extract values for objectives.
+            // store them in values.
+            // assert there must be something better.
+            is_sat = s.check_sat(0,0);
+        }
+        return l_true;
+
+    }
+
+    /**
+       Takes solver with hard constraints added.
+       Returns an optimal assignment to objective functions.
+    */
+    
+    lbool optimize_objectives(solver& s, 
+                          expr_ref_vector& objectives, svector<bool> const& is_max,
+                          vector<optional<rational> >& values) {
+        return mathsat_style_opt(s, objectives, is_max, values);
+    }
+}