add rule unfolding transformation

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

lib/dl_mk_unfold.h

@@ -0,0 +1,54 @@
+/*++
+Copyright (c) 2012 Microsoft Corporation
+
+Module Name:
+
+    dl_mk_unfold.h
+
+Abstract:
+
+    Unfold rules once, return the unfolded set of rules.
+
+Author:
+
+    Nikolaj Bjorner (nbjorner) 2012-10-15
+
+Revision History:
+
+--*/
+#ifndef _DL_MK_UNFOLD_H_
+#define _DL_MK_UNFOLD_H_
+
+#include"dl_context.h"
+#include"dl_rule_set.h"
+#include"uint_set.h"
+#include"dl_rule_transformer.h"
+#include"dl_mk_rule_inliner.h"
+
+namespace datalog {
+
+    /**
+       \brief Implements an unfolding transformation.
+    */
+    class mk_unfold : public rule_transformer::plugin {
+        context&        m_ctx;
+        ast_manager&    m;
+        rule_manager&   rm;
+        rule_unifier    m_unify;
+        replace_proof_converter* m_pc;
+
+        void expand_tail(rule& r, unsigned tail_idx, rule_set const& src, rule_set& dst);
+
+    public:
+        /**
+           \brief Create unfold rule transformer.
+         */
+        mk_unfold(context & ctx);
+        
+        rule_set * operator()(rule_set const & source, model_converter_ref& mc, proof_converter_ref& pc);
+    };
+
+};
+
+#endif /* _DL_MK_UNFOLD_H_ */
+