add accessors for implied values to API

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

src/solver/combined_solver.cpp

@@ -184,6 +184,28 @@ public:
         return m_solver1->get_scope_level();
     }
 
+    expr_ref get_implied_value(expr* e) override {
+        if (m_use_solver1_results)
+            return m_solver1->get_implied_value(e);
+        else
+            return m_solver2->get_implied_value(e);
+    }
+    
+    expr_ref get_implied_lower_bound(expr* e) override {
+        if (m_use_solver1_results)
+            return m_solver1->get_implied_lower_bound(e);
+        else
+            return m_solver2->get_implied_lower_bound(e);
+    }
+    
+    expr_ref get_implied_upper_bound(expr* e) override {
+        if (m_use_solver1_results)
+            return m_solver1->get_implied_upper_bound(e);
+        else
+            return m_solver2->get_implied_upper_bound(e);
+    }
+
+
     lbool get_consequences(expr_ref_vector const& asms, expr_ref_vector const& vars, expr_ref_vector& consequences) override {
         switch_inc_mode();
         m_use_solver1_results = false;

src/solver/solver.h

@@ -226,6 +226,19 @@ public:
 
     virtual expr_ref_vector cube(expr_ref_vector& vars, unsigned backtrack_level) = 0;
 
+    /**
+       \brief retrieve fixed value assignment in current solver state, if it is implied.
+    */
+    virtual expr_ref get_implied_value(expr* e) = 0;
+
+    /**
+       \brief retrieve upper/lower bound for arithmetic term, if it is implied.
+    */
+    virtual expr_ref get_implied_lower_bound(expr* e) = 0;
+
+    virtual expr_ref get_implied_upper_bound(expr* e) = 0;
+
+
     /**
        \brief Display the content of this solver.
     */

src/solver/solver_pool.cpp

@@ -127,6 +127,18 @@ public:
         return m_base->get_trail();
     }
 
+    expr_ref get_implied_value(expr* e) override {
+        return expr_ref(e, m);
+    }
+
+    expr_ref get_implied_lower_bound(expr* e) override {
+        return expr_ref(e, m);
+    }
+
+    expr_ref get_implied_upper_bound(expr* e) override {
+        return expr_ref(e, m);
+    }
+
     lbool check_sat_core2(unsigned num_assumptions, expr * const * assumptions) override {
         SASSERT(!m_pushed || get_scope_level() > 0);
         m_proof.reset();

src/solver/tactic2solver.cpp

@@ -97,6 +97,17 @@ public:
         throw default_exception("cannot retrieve trail from solvers created using tactcis");
     }
 
+    expr_ref get_implied_value(expr* e) override {
+        return expr_ref(e, m);
+    }
+
+    expr_ref get_implied_lower_bound(expr* e) override {
+        return expr_ref(e, m);
+    }
+
+    expr_ref get_implied_upper_bound(expr* e) override {
+        return expr_ref(e, m);
+    }
 
 };