Reorganizing the code

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

src/ast/num_occurs.h

@@ -0,0 +1,55 @@
+/*++
+Copyright (c) 2006 Microsoft Corporation
+
+Module Name:
+
+    num_occurs.h
+
+Abstract:
+
+    <abstract>
+
+Author:
+
+    Leonardo de Moura (leonardo) 2008-01-27.
+
+Revision History:
+
+--*/
+#ifndef _NUM_OCCURS_H_
+#define _NUM_OCCURS_H_
+
+#include"ast.h"
+#include"obj_hashtable.h"
+
+/**
+   \brief Functor for computing the number of occurrences of each sub-expression in a expression F.
+*/
+class num_occurs { 
+protected:
+    bool m_ignore_ref_count1;
+    bool m_ignore_quantifiers;
+    obj_map<expr, unsigned>        m_num_occurs;
+
+    void process(expr * t, expr_fast_mark1 & visited);
+public:
+    num_occurs(bool ignore_ref_count1 = false, bool ignore_quantifiers = false):
+        m_ignore_ref_count1(ignore_ref_count1), 
+        m_ignore_quantifiers(ignore_quantifiers) {
+    }
+
+    void reset() { m_num_occurs.reset(); }
+    
+    void operator()(expr * t);
+    void operator()(unsigned num, expr * const * ts);
+
+    unsigned get_num_occs(expr * n) const { 
+        unsigned val;
+        if (m_num_occurs.find(n, val))
+            return val;
+        return 0;
+    }
+};
+
+#endif /* _NUM_OCCURS_H_ */
+