working on named assertions support

Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>

src/solver/solver_na2as.h

@@ -0,0 +1,55 @@
+/*++
+Copyright (c) 2012 Microsoft Corporation
+
+Module Name:
+
+    solver_na2as.h
+
+Abstract:
+
+    Solver that implements "named" assertions using assumptions (aka answer literals).
+    That is, a named assertion assert_expr(t, a) is mapped into
+          a implies t
+    and 'a' is used as an extra assumption for check_sat.
+
+Author:
+
+    Leonardo (leonardo) 2012-11-02
+
+Notes:
+
+--*/
+#ifndef _SOLVER_NA2AS_H_
+#define _SOLVER_NA2AS_H_
+
+#include"solver.h"
+
+class solver_na2as : public solver {
+    ast_manager *      m_manager;
+    ptr_vector<expr>   m_assumptions;
+    unsigned_vector    m_scopes;
+    void restore_assumptions(unsigned old_sz);
+public:
+    solver_na2as();
+    virtual ~solver_na2as();
+
+    virtual void assert_expr(expr * t, expr * a);
+    virtual void assert_expr(expr * t) = 0;
+    
+    // Subclasses of solver_na2as should redefine the following *_core methods instead of these ones.
+    virtual void init(ast_manager & m, symbol const & logic);
+    virtual lbool check_sat(unsigned num_assumptions, expr * const * assumptions);
+    virtual void push();
+    virtual void pop(unsigned n);
+    virtual unsigned get_scope_level() const;
+    virtual void reset();
+protected:
+    virtual void init_core(ast_manager & m, symbol const & logic) = 0;
+    virtual lbool check_sat_core(unsigned num_assumptions, expr * const * assumptions) = 0;
+    virtual void push_core() = 0;
+    virtual void pop_core(unsigned n) = 0;
+    virtual void reset_core() = 0;
+};
+
+
+#endif