137 lines
3.8 KiB
C++
Executable File
137 lines
3.8 KiB
C++
Executable File
// Copyright (c) 2014 GeometryFactory Sarl (France)
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// 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; either version 3 of the License,
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// or (at your option) any later version.
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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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// SPDX-License-Identifier: LGPL-3.0+
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//
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// Author(s) : Jane Tournois
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#ifndef CGAL_TIME_STAMPER_H
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#define CGAL_TIME_STAMPER_H
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#include <CGAL/Has_timestamp.h>
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namespace CGAL {
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template <typename T>
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struct Time_stamper
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{
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Time_stamper()
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: time_stamp_(0) {}
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Time_stamper(const Time_stamper& ts)
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: time_stamp_(ts.time_stamp_) {}
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static void initialize_time_stamp(T* pt) {
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pt->set_time_stamp(std::size_t(-1));
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}
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void set_time_stamp(T* pt) {
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if(pt->time_stamp() == std::size_t(-1))
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pt->set_time_stamp(time_stamp_++);
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else {
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// else: the time stamp is re-used
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// Enforces that the time stamp is greater than the current value.
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// That is used when a TDS_3 is copied.
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time_stamp_ = (std::max)(time_stamp_, pt->time_stamp() + 1);
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}
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}
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static std::size_t time_stamp(const T* pt)
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{
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if(pt == NULL){
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return std::size_t(-1);
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}
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return pt->time_stamp();
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}
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static std::size_t hash_value(const T* p) {
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if(NULL == p)
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return std::size_t(-1);
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else
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return p->time_stamp();
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}
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static bool less(const T* p_t1, const T* p_t2) {
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if(p_t1 == NULL) return (p_t2 != NULL);
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else if(p_t2 == NULL) return false;
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else {
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CGAL_assertion((p_t1 == p_t2) ==
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(p_t1->time_stamp() == p_t2->time_stamp()));
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return p_t1->time_stamp() < p_t2->time_stamp();
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}
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}
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void reset() {
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time_stamp_ = 0;
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}
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private:
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std::size_t time_stamp_;
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}; // end class template Time_stamper<T>
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template <typename T>
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struct No_time_stamp
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{
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public:
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void set_time_stamp(T*) {}
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static bool less(const T* p_t1,const T* p_t2) {
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return p_t1 < p_t2;
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}
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static void initialize_time_stamp(T*) {
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}
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static std::size_t time_stamp(const T*)
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{
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return 0;
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}
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static std::size_t hash_value(const T* p) {
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return reinterpret_cast<std::size_t>(p)/sizeof(T);
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}
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void reset() {}
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}; // end class template No_time_stamp<T>
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// That class template is an auxiliary class. It has a
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// specialization for the case where `T::Has_timestamp` does not exists.
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// The non-specialized template, when `T::Has_timestamp` exists, derives
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// from `Time_stamper<T>` or `No_time_stamp<T>` depending on the
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// value of the Boolean constant `T::Has_timestamp`.
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// The declaration of that class template requires `T` to be a complete type.
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template <class T, bool has_timestamp = internal::Has_timestamp<T>::value>
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struct Get_time_stamper{
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typedef Time_stamper<T> type;
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};
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// Specialization when `T::Has_timestamp` does not exist, derives from
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// `TimeStamper_`, or from `No_time_stamp<T>`.
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template <class T>
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struct Get_time_stamper<T,false>{
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typedef No_time_stamp<T> type;
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};
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// Implementation of the timestamp policy. It is very important that the
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// declaration of that class template does not require `T` to be a complete
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// type. That way, the declaration of a pointer of type `Time_stamper_impl<T, Ts>
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// in `Compact_container` for example is possible with an incomplete type.
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template <class T>
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struct Time_stamper_impl : public Get_time_stamper<T>::type {};
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} //end of namespace CGAL
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#endif // CGAL_TIME_STAMPER_H
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