old_params ==> front_end_params. Isolated abstract solver interface

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

src/front_end_params/nnf_params.h

@@ -0,0 +1,74 @@
+/*++
+Copyright (c) 2006 Microsoft Corporation
+
+Module Name:
+
+    nnf_params.h
+
+Abstract:
+
+    <abstract>
+
+Author:
+
+    Leonardo de Moura (leonardo) 2008-01-14.
+
+Revision History:
+
+--*/
+#ifndef _NNF_PARAMS_H_
+#define _NNF_PARAMS_H_
+
+#include"ini_file.h"
+
+/**
+   \brief NNF translation mode.  The cheapest mode is NNF_SKOLEM, and
+   the most expensive is NNF_FULL.
+*/
+enum nnf_mode {
+    NNF_SKOLEM, /* A subformula is put into NNF only if it contains
+                   quantifiers or labels. The result of the
+                   transformation will be in skolem normal form.
+                   If a formula is too expensive to be put into NNF,
+                   then nested quantifiers and labels are renamed.
+
+                   This mode is sufficient when using E-matching.
+                */
+    NNF_QUANT, /* A subformula is put into NNF if it contains
+                  quantifiers, labels, or is in the scope of a
+                  quantifier. The result of the transformation will be
+                  in skolem normal form, and the body of quantifiers
+                  will be in NNF. If a ground formula is too expensive to
+                  be put into NNF, then nested quantifiers and labels 
+                  are renamed.
+
+                  This mode is sufficient when using Superposition
+                  Calculus.
+
+                  Remark: If the problem does not contain quantifiers,
+                  then NNF_QUANT is identical to NNF_SKOLEM.
+               */
+    NNF_OPPORTUNISTIC, /* Similar to NNF_QUANT, but a subformula is
+                          also put into NNF, if it is
+                          cheap. Otherwise, the nested quantifiers and
+                          labels are renamed. */
+    NNF_FULL /* Everything is put into NNF. */
+};
+
+struct nnf_params {
+    nnf_mode m_nnf_mode;
+    unsigned m_nnf_factor;
+    bool     m_nnf_ignore_labels;
+    bool     m_nnf_sk_hack;
+    nnf_params():
+        m_nnf_mode(NNF_SKOLEM),
+        m_nnf_factor(4),
+        m_nnf_ignore_labels(false),
+        m_nnf_sk_hack(false) {
+    }
+    
+    void register_params(ini_params & p);
+};
+    
+#endif /* _NNF_PARAMS_H_ */
+