385 lines
9.6 KiB
C++
385 lines
9.6 KiB
C++
// Copyright (c) 1997-2000
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// Utrecht University (The Netherlands),
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// ETH Zurich (Switzerland),
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// INRIA Sophia-Antipolis (France),
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// Max-Planck-Institute Saarbruecken (Germany),
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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)
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//
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// $URL: https://github.com/CGAL/cgal/blob/v5.1/Hash_map/include/CGAL/Tools/chained_map.h $
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// $Id: chained_map.h 0779373 2020-03-26T13:31:46+01:00 Sébastien Loriot
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// SPDX-License-Identifier: LGPL-3.0-or-later OR LicenseRef-Commercial
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//
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//
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// Author(s) : Courtesy of LEDA
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#ifndef CGAL_CHAINED_MAP_H
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#define CGAL_CHAINED_MAP_H
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#include <CGAL/memory.h>
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#include <iostream>
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namespace CGAL {
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namespace internal {
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template <typename T, typename Allocator = CGAL_ALLOCATOR(T) > class chained_map;
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template <typename T> class chained_map_elem;
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template <typename T>
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class chained_map_elem
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{
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template<typename T2, typename Alloc> friend class chained_map;
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std::size_t k; T i;
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chained_map_elem<T>* succ;
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};
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template <typename T, typename Allocator>
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class chained_map
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{
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const std::size_t nullptrKEY;
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const std::size_t NONnullptrKEY;
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chained_map_elem<T> STOP;
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chained_map_elem<T>* table;
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chained_map_elem<T>* table_end;
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chained_map_elem<T>* free;
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std::size_t table_size;
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std::size_t table_size_1;
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chained_map_elem<T>* old_table;
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chained_map_elem<T>* old_table_end;
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chained_map_elem<T>* old_free;
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std::size_t old_table_size;
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std::size_t old_table_size_1;
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std::size_t old_index;
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typedef std::allocator_traits<Allocator> Allocator_traits;
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typedef typename Allocator_traits::template rebind_alloc<chained_map_elem<T> > allocator_type;
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allocator_type alloc;
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public:
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T& xdef() { return STOP.i; }
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const T& cxdef() const { return STOP.i; }
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private:
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void init_inf(T& x) const { x = STOP.i; }
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chained_map_elem<T>* HASH(std::size_t x) const
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{ return table + (x & table_size_1); }
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void init_table(std::size_t t);
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void rehash();
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void del_old_table();
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inline void insert(std::size_t x, T y);
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void destroy(chained_map_elem<T>* item)
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{
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typedef std::allocator_traits<allocator_type> Allocator_type_traits;
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Allocator_type_traits::destroy(alloc,item);
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}
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public:
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typedef chained_map_elem<T>* chained_map_item;
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typedef chained_map_item item;
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std::size_t index(chained_map_item it) const { return it->k; }
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T& inf(chained_map_item it) const { return it->i; }
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chained_map(std::size_t n = 1);
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chained_map(const chained_map<T, Allocator>& D);
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chained_map& operator=(const chained_map<T, Allocator>& D);
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void clear_entries();
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void clear();
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~chained_map()
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{
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if (old_table)
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{
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for (chained_map_item item = old_table ; item != old_table_end ; ++item)
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destroy(item);
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alloc.deallocate(old_table, old_table_end - old_table);
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}
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for (chained_map_item item = table ; item != table_end ; ++item)
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destroy(item);
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alloc.deallocate(table, table_end - table);
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}
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T& access(chained_map_item p, std::size_t x);
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T& access(std::size_t x);
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chained_map_item lookup(std::size_t x) const;
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chained_map_item first_item() const;
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chained_map_item next_item(chained_map_item it) const;
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void statistics() const;
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};
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template <typename T, typename Allocator>
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inline T& chained_map<T, Allocator>::access(std::size_t x)
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{ chained_map_item p = HASH(x);
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if (old_table) del_old_table();
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if ( p->k == x ) {
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old_index = x;
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return p->i;
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}
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else {
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if ( p->k == nullptrKEY ) {
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p->k = x;
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init_inf(p->i); // initializes p->i to xdef
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old_index = x;
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return p->i;
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} else
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return access(p,x);
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}
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}
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template <typename T, typename Allocator>
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void chained_map<T, Allocator>::init_table(std::size_t t)
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{
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table_size = t;
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table_size_1 = t-1;
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table = alloc.allocate(t + t/2);
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for (std::size_t i = 0 ; i < t + t/2 ; ++i){
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std::allocator_traits<allocator_type>::construct(alloc,table + i);
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}
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free = table + t;
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table_end = table + t + t/2;
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for (chained_map_item p = table; p < free; p++)
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{ p->succ = &STOP;
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p->k = nullptrKEY;
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}
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table->k = NONnullptrKEY;
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}
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template <typename T, typename Allocator>
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inline void chained_map<T, Allocator>::insert(std::size_t x, T y)
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{ chained_map_item q = HASH(x);
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if ( q->k == nullptrKEY ) {
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q->k = x;
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q->i = y;
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} else {
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free->k = x;
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free->i = y;
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free->succ = q->succ;
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q->succ = free++;
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}
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}
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template <typename T, typename Allocator>
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void chained_map<T, Allocator>::rehash()
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{
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old_table = table;
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old_table_end = table_end;
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old_table_size = table_size;
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old_table_size_1 = table_size_1;
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old_free = free;
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chained_map_item old_table_mid = table + table_size;
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init_table(2*table_size);
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chained_map_item p;
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for(p = old_table + 1; p < old_table_mid; p++)
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{ std::size_t x = p->k;
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if ( x != nullptrKEY ) // list p is non-empty
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{ chained_map_item q = HASH(x);
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q->k = x;
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q->i = p->i;
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}
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}
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while (p < old_table_end)
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{ std::size_t x = p->k;
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insert(x,p->i);
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p++;
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}
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}
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template <typename T, typename Allocator>
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void chained_map<T, Allocator>::del_old_table()
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{
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chained_map_item save_table = table;
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chained_map_item save_table_end = table_end;
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chained_map_item save_free = free;
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std::size_t save_table_size = table_size;
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std::size_t save_table_size_1 = table_size_1;
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table = old_table;
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table_end = old_table_end;
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table_size = old_table_size;
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table_size_1 = old_table_size_1;
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free = old_free;
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old_table = 0;
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T p = access(old_index);
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for (chained_map_item item = table ; item != table_end ; ++item)
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destroy(item);
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alloc.deallocate(table, table_end - table);
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table = save_table;
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table_end = save_table_end;
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table_size = save_table_size;
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table_size_1 = save_table_size_1;
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free = save_free;
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access(old_index) = p;
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}
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template <typename T, typename Allocator>
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T& chained_map<T, Allocator>::access(chained_map_item p, std::size_t x)
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{
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STOP.k = x;
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chained_map_item q = p->succ;
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while (q->k != x) q = q->succ;
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if (q != &STOP)
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{ old_index = x;
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return q->i;
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}
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// index x not present, insert it
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if (free == table_end) // table full: rehash
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{ rehash();
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p = HASH(x);
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}
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if (p->k == nullptrKEY)
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{ p->k = x;
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init_inf(p->i); // initializes p->i to xdef
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return p->i;
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}
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q = free++;
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q->k = x;
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init_inf(q->i); // initializes q->i to xdef
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q->succ = p->succ;
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p->succ = q;
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return q->i;
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}
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template <typename T, typename Allocator>
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chained_map<T, Allocator>::chained_map(std::size_t n) :
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nullptrKEY(0), NONnullptrKEY(1), old_table(0)
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{
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if (n < 512)
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init_table(512);
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else {
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std::size_t ts = 1;
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while (ts < n) ts <<= 1;
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init_table(ts);
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}
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}
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template <typename T, typename Allocator>
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chained_map<T, Allocator>::chained_map(const chained_map<T, Allocator>& D) :
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nullptrKEY(0), NONnullptrKEY(1), old_table(0)
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{
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init_table(D.table_size);
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STOP.i = D.STOP.i; // xdef
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for(chained_map_item p = D.table + 1; p < D.free; p++)
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{ if (p->k != nullptrKEY || p >= D.table + D.table_size)
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{ insert(p->k,p->i);
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//D.copy_inf(p->i); // see chapter Implementation
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}
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}
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}
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template <typename T, typename Allocator>
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chained_map<T, Allocator>& chained_map<T, Allocator>::operator=(const chained_map<T, Allocator>& D)
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{
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clear_entries();
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for (chained_map_item item = table ; item != table_end ; ++item)
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destroy(item);
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alloc.deallocate(table, table_end - table);
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init_table(D.table_size);
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STOP.i = D.STOP.i; // xdef
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for(chained_map_item p = D.table + 1; p < D.free; p++)
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{ if (p->k != nullptrKEY || p >= D.table + D.table_size)
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{ insert(p->k,p->i);
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//copy_inf(p->i); // see chapter Implementation
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}
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}
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return *this;
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}
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template <typename T, typename Allocator>
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void chained_map<T, Allocator>::clear_entries()
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{ for(chained_map_item p = table + 1; p < free; p++)
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if (p->k != nullptrKEY || p >= table + table_size)
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p->i = T();
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}
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template <typename T, typename Allocator>
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void chained_map<T, Allocator>::clear()
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{
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clear_entries();
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for (chained_map_item item = table ; item != table_end ; ++item)
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destroy(item);
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alloc.deallocate(table, table_end - table);
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init_table(512);
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}
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template <typename T, typename Allocator>
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typename chained_map<T, Allocator>::chained_map_item
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chained_map<T, Allocator>::lookup(std::size_t x) const
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{ chained_map_item p = HASH(x);
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((std::size_t &)STOP.k) = x; // cast away const
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while (p->k != x)
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{ p = p->succ; }
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return (p == &STOP) ? 0 : p;
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}
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template <typename T, typename Allocator>
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typename chained_map<T, Allocator>::chained_map_item
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chained_map<T, Allocator>::first_item() const
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{ return next_item(table); }
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template <typename T, typename Allocator>
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typename chained_map<T, Allocator>::chained_map_item
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chained_map<T, Allocator>::next_item(chained_map_item it) const
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{ if (it == 0) return 0;
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do it++; while (it < table + table_size && it->k == nullptrKEY);
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return (it < free ? it : 0);
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}
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template <typename T, typename Allocator>
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void chained_map<T, Allocator>::statistics() const
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{ std::cout << "table_size: " << table_size <<"\n";
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std::size_t n = 0;
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for (chained_map_item p = table + 1; p < table + table_size; p++)
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if (p ->k != nullptrKEY) n++;
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std::size_t used_in_overflow = free - (table + table_size );
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n += used_in_overflow;
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std::cout << "number of entries: " << n << "\n";
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std::cout << "fraction of entries in first position: " <<
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((double) (n - used_in_overflow))/n <<"\n";
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std::cout << "fraction of empty lists: " <<
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((double) (n - used_in_overflow))/table_size<<"\n";
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}
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} // namespace internal
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} //namespace CGAL
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#endif // CGAL_CHAINED_MAP_H
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