add demodulator tactic based on demodulator-simplifier

- some handling for commutative operators
- fix bug in demodulator_index where fwd and bwd are swapped

src/tactic/core/CMakeLists.txt

@@ -32,6 +32,7 @@ z3_add_component(core_tactics
     cofactor_term_ite_tactic.h
     collect_statistics_tactic.h
     ctx_simplify_tactic.h
+    demodulator_tactic.h
     der_tactic.h
     distribute_forall_tactic.h
     dom_simplify_tactic.h

src/tactic/core/demodulator_tactic.h

@@ -0,0 +1,40 @@
+/*++
+Copyright (c) 2022 Microsoft Corporation
+
+Module Name:
+
+    demodulator_tactic.h
+
+Abstract:
+
+    Tactic for solving variables
+
+Author:
+
+    Nikolaj Bjorner (nbjorner) 2022-10-30
+
+--*/
+#pragma once
+
+#include "util/params.h"
+#include "tactic/tactic.h"
+#include "tactic/dependent_expr_state_tactic.h"
+#include "ast/simplifiers/demodulator_simplifier.h"
+
+
+class demodulator_tactic_factory : public dependent_expr_simplifier_factory {
+public:
+    dependent_expr_simplifier* mk(ast_manager& m, params_ref const& p, dependent_expr_state& s) override {
+        return alloc(demodulator_simplifier, m, p, s);
+    }
+};
+
+inline tactic * mk_demodulator_tactic(ast_manager& m, params_ref const& p = params_ref()) {
+    return alloc(dependent_expr_state_tactic, m, p, alloc(demodulator_tactic_factory));
+}
+
+/*
+  ADD_TACTIC("demodulator", "solve for variables.", "mk_demodulator_tactic(m, p)")
+*/
+
+