adding C++ API for optimization

Signed-off-by: Nikolaj Bjorner <nbjorner@microsoft.com>

src/api/c++/z3++.h

@@ -1479,6 +1479,66 @@ namespace z3 {
         }
     };
 
+    class optimize : public object {
+        Z3_optimize m_opt;
+    public:
+        class handle {
+            unsigned m_h;
+        public:
+            handle(unsigned h): m_h(h) {}
+            unsigned h() const { return m_h; }
+        };
+        optimize(context& c):object(c) { m_opt = Z3_mk_optimize(c); Z3_optimize_inc_ref(c, m_opt); }
+        ~optimize() { Z3_optimize_dec_ref(ctx(), m_opt); }
+        operator Z3_optimize() const { return m_opt; }
+
+        void add(expr const& e) {
+            assert(e.is_bool());
+            Z3_optimize_assert(ctx(), m_opt, e);
+        }
+        handle add(expr const& e, unsigned weight) {
+            assert(e.is_bool());
+            std::stringstream strm;
+            strm << weight; 
+            return handle(Z3_optimize_assert_soft(ctx(), m_opt, e, strm.str().c_str(), 0)); 
+        }
+        handle add(expr const& e, char const* weight) {
+            assert(e.is_bool());
+            return handle(Z3_optimize_assert_soft(ctx(), m_opt, e, weight, 0)); 
+        }
+        handle maximzie(expr const& e) {
+            return handle(Z3_optimize_maximize(ctx(), m_opt, e));
+        }
+        handle minimize(expr const& e) {
+            return handle(Z3_optimize_minimize(ctx(), m_opt, e));
+        }
+
+        check_result check() { Z3_lbool r = Z3_optimize_check(ctx(), m_opt); check_error(); return to_check_result(r); }
+
+        model get_model() const { Z3_model m = Z3_optimize_get_model(ctx(), m_opt); check_error(); return model(ctx(), m); }
+
+        void set(params const & p) { Z3_optimize_set_params(ctx(), m_opt, p); check_error(); }
+
+        expr lower(handle const& h) {
+            Z3_ast r = Z3_optimize_get_lower(ctx(), m_opt, h.h());
+            check_error();
+            return expr(ctx(), r);
+        }
+
+        expr upper(handle const& h) {
+            Z3_ast r = Z3_optimize_get_upper(ctx(), m_opt, h.h());
+            check_error();
+            return expr(ctx(), r);
+        }
+
+        stats statistics() const { Z3_stats r = Z3_optimize_get_statistics(ctx(), m_opt); check_error(); return stats(ctx(), r); }
+        
+        friend std::ostream & operator<<(std::ostream & out, optimize const & s) { out << Z3_optimize_to_string(s.ctx(), s.m_opt); return out; }
+
+        std::string help() const { char const * r = Z3_optimize_get_help(ctx(), m_opt); check_error();  return r; }
+        
+    };
+
     inline tactic fail_if(probe const & p) {
         Z3_tactic r = Z3_tactic_fail_if(p.ctx(), p);
         p.check_error();