mirror of https://github.com/CGAL/cgal
74 lines
2.0 KiB
C++
74 lines
2.0 KiB
C++
// Copyright (c) 2002 Utrecht University (The Netherlands),
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// ETH Zurich (Switzerland), Freie Universitaet Berlin (Germany),
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// INRIA Sophia-Antipolis (France), Martin-Luther-University Halle-Wittenberg
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// (Germany), Max-Planck-Institute Saarbruecken (Germany), RISC Linz (Austria),
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// and Tel-Aviv University (Israel). All rights reserved.
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//
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// This file is part of CGAL (www.cgal.org); you can redistribute it and/or
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// modify it under the terms of the GNU Lesser General Public License as
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// published by the Free Software Foundation; version 2.1 of the License.
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// See the file LICENSE.LGPL distributed with CGAL.
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//
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// Licensees holding a valid commercial license may use this file in
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// accordance with the commercial license agreement provided with the software.
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//
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// This file is provided AS IS with NO WARRANTY OF ANY KIND, INCLUDING THE
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// WARRANTY OF DESIGN, MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
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//
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// $URL$
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// $Id$
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//
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//
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// Author(s) : Sylvain Pion
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#ifndef CGAL_IS_A_PREDICATE_H
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#define CGAL_IS_A_PREDICATE_H
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// How to determine if a kernel functor is a predicate or a construction.
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#include <CGAL/basic.h>
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#include <CGAL/enum.h>
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CGAL_BEGIN_NAMESPACE
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namespace CGALi {
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// By default it's a construction
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template <typename Return_type>
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struct Return_type_of_predicate {
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typedef CGAL::Tag_false type;
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};
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// Specializations for predicates
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template <>
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struct Return_type_of_predicate<bool> {
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typedef CGAL::Tag_true type;
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};
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template <>
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struct Return_type_of_predicate<CGAL::Sign> {
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typedef CGAL::Tag_true type;
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};
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template <>
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struct Return_type_of_predicate<CGAL::Bounded_side> {
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typedef CGAL::Tag_true type;
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};
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template <>
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struct Return_type_of_predicate<CGAL::Angle> {
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typedef CGAL::Tag_true type;
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};
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} // namespace CGALi
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template <typename Functor>
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struct Is_a_predicate {
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typedef typename CGALi::Return_type_of_predicate<
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typename Functor::result_type>::type type;
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};
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CGAL_END_NAMESPACE
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#endif // CGAL_IS_A_PREDICATE_H
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