add initial skeleton for xor-solver

src/sat/smt/xor_solver.h

@@ -0,0 +1,48 @@
+/*++
+Copyright (c) 2014 Microsoft Corporation
+
+Module Name:
+
+    xor_solver.h
+
+Abstract:
+
+    XOR solver.
+    Interface outline.
+
+--*/
+
+#pragma once
+
+#include "sat/smt/euf_solver.h"
+
+namespace xr {
+    class solver : public euf::th_solver {
+    public:
+        solver(euf::solver& ctx);
+        
+        th_solver* clone(euf::solver& ctx) override;
+
+        sat::literal internalize(expr* e, bool sign, bool root, bool redundant)  override { UNREACHABLE(); return sat::null_literal; }
+
+        void internalize(expr* e, bool redundant) override { UNREACHABLE(); }
+
+
+        void asserted(sat::literal l) override;
+        bool unit_propagate() override;
+        void get_antecedents(sat::literal l, sat::ext_justification_idx idx, sat::literal_vector & r, bool probing) override;
+
+        void pre_simplify() override;
+        void simplify() override;
+
+        sat::check_result check() override;
+        void push() override;
+        void pop(unsigned n) override;
+
+        std::ostream& display(std::ostream& out) const override;
+        std::ostream& display_justification(std::ostream& out, sat::ext_justification_idx idx) const override;
+        std::ostream& display_constraint(std::ostream& out, sat::ext_constraint_idx idx) const override;
+
+    };
+
+}