From c70a2e38bf3068e4f2b7d58c18d299e665354ee4 Mon Sep 17 00:00:00 2001
From: Sylvain Pion <Sylvain.Pion@sophia.inria.fr>
Date: Sun, 25 Jun 2000 18:48:55 +0000
Subject: [PATCH] - New file.  Definition of the class Interval_base.

---
 .../include/CGAL/Interval_base.h              | 162 ++++++++++++++++++
 1 file changed, 162 insertions(+)
 create mode 100644 Packages/Interval_arithmetic/include/CGAL/Interval_base.h

diff --git a/Packages/Interval_arithmetic/include/CGAL/Interval_base.h b/Packages/Interval_arithmetic/include/CGAL/Interval_base.h
new file mode 100644
index 00000000000..e2b8f95bd43
--- /dev/null
+++ b/Packages/Interval_arithmetic/include/CGAL/Interval_base.h
@@ -0,0 +1,162 @@
+// ============================================================================
+//
+// Copyright (c) 2000 The CGAL Consortium
+//
+// This software and related documentation is part of an INTERNAL release
+// of the Computational Geometry Algorithms Library (CGAL). It is not
+// intended for general use.
+//
+// ----------------------------------------------------------------------------
+//
+// release       :
+// release_date  :
+//
+// file          : include/CGAL/Interval_base.h
+// revision      : $Revision$
+// revision_date : $Date$
+// package       : Interval Arithmetic
+// author(s)     : Sylvain Pion
+// coordinator   : INRIA Sophia-Antipolis (<Mariette.Yvinec@sophia.inria.fr>)
+//
+// ============================================================================
+
+#ifndef CGAL_INTERVAL_BASE_H
+#define CGAL_INTERVAL_BASE_H
+
+// This file contains the description of the Interval_base class, which is used
+// by the number types Interval_nt<>.
+
+#include <CGAL/basic.h>
+#include <CGAL/Interval_arithmetic/_FPU.h>
+#include <utility>				// Relational operators.
+
+CGAL_BEGIN_NAMESPACE
+
+struct Interval_base
+{
+  typedef Interval_base IA;
+  struct unsafe_comparison {};		// Exception class.
+  static unsigned number_of_failures;	// Number of filter failures.
+  static const IA Smallest, Largest;	// Useful constant intervals.
+
+  Interval_base () {}
+
+  // To stop constant propagation, I need these CGAL_IA_STOP_CPROP().
+  // Ideally, these barriers should be placed just before the critical
+  // operations.
+  Interval_base (const double d)
+  {
+    _inf = _sup = CGAL_IA_STOP_CPROP(d);
+  }
+
+  Interval_base (const double i, const double s)
+  {
+    CGAL_assertion_msg(i<=s,
+	      " Variable used before being initialized (or CGAL bug)");
+    _inf = CGAL_IA_STOP_CPROP(i);
+    _sup = CGAL_IA_STOP_CPROP(s);
+  }
+
+  static void overlap_action() // throw (unsafe_comparison)
+  {
+    number_of_failures++;
+    throw unsafe_comparison();
+  }
+
+  bool operator<  (const IA &d) const
+  {
+    if (_sup  < d._inf) return true;
+    if (_inf >= d._sup) return false;
+    overlap_action();
+    return false;
+  }
+
+  bool operator<= (const IA &d) const
+  {
+    if (_sup <= d._inf) return true;
+    if (_inf >  d._sup) return false;
+    overlap_action();
+    return false;
+  }
+
+  bool operator>= (const IA &d) const
+  {
+    return d <= *this;
+  }
+
+  bool operator== (const IA &d) const
+  {
+    if (d._inf >  _sup || d._sup  < _inf) return false;
+    if (d._inf == _sup && d._sup == _inf) return true;
+    overlap_action();
+    return false;
+  }
+
+  bool is_point() const
+  {
+    return _sup == _inf;
+  }
+
+  bool is_same (const IA & d) const
+  {
+    return _inf == d._inf && _sup == d._sup;
+  }
+
+  bool overlap (const IA & d) const
+  {
+    return !(d._inf > _sup || d._sup < _inf);
+  }
+
+  double inf() const { return _inf; }
+  double sup() const { return _sup; }
+
+// protected:
+  double _inf, _sup;	// "_inf" stores the lower bound, "_sup" the upper.
+};
+
+inline
+double
+to_double (const Interval_base & d)
+{
+  return (d._sup + d._inf) * 0.5;
+}
+
+inline
+bool
+is_valid (const Interval_base & d)
+{
+#if defined _MSC_VER || defined __sgi || defined __BORLANDC__
+  return is_valid(d._inf) && is_valid(d._sup) && d._inf <= d._sup;
+#else
+  // The 2 first is_valid() are implicitely done by the 3rd test ;-)
+  return d._inf <= d._sup;
+#endif
+}
+
+inline
+bool
+is_finite (const Interval_base & d)
+{
+  return is_finite(d._inf) && is_finite(d._sup);
+}
+
+inline
+io_Operator
+io_tag (const Interval_base &)
+{
+  return io_Operator();
+}
+
+inline
+Number_tag
+number_type_tag (const Interval_base &)
+{
+  return Number_tag();
+}
+
+std::ostream & operator<< (std::ostream &, const Interval_base &);
+std::istream & operator>> (std::istream &, Interval_base &);
+
+CGAL_END_NAMESPACE
+
+#endif // CGAL_INTERVAL_BASE_H