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// -*- C++ -*-
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// Copyright (C) 2005 Free Software Foundation, Inc.
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//
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// This file is part of the GNU ISO C++ Library. This library is free
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// software; you can redistribute it and/or modify it under the
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// terms of the GNU General Public License as published by the
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// Free Software Foundation; either version 2, or (at your option)
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// any later version.
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// This library is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU General Public License for more details.
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// You should have received a copy of the GNU General Public License along
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// with this library; see the file COPYING. If not, write to the Free
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// Software Foundation, 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301,
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// USA.
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// As a special exception, you may use this file as part of a free software
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// library without restriction. Specifically, if other files instantiate
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// templates or use macros or inline functions from this file, or you compile
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// this file and link it with other files to produce an executable, this
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// file does not by itself cause the resulting executable to be covered by
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// the GNU General Public License. This exception does not however
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// invalidate any other reasons why the executable file might be covered by
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// the GNU General Public License.
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// Copyright (C) 2004 Ami Tavory and Vladimir Dreizin, IBM-HRL.
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// Permission to use, copy, modify, sell, and distribute this software
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// is hereby granted without fee, provided that the above copyright
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// notice appears in all copies, and that both that copyright notice and
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// this permission notice appear in supporting documentation. None of
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// the above authors, nor IBM Haifa Research Laboratories, make any
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// representation about the suitability of this software for any
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// purpose. It is provided "as is" without express or implied warranty.
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/**
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* @file gp_ht_map_resize_example.cpp
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* An example of setting an initial size for a container object.
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*/
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// For gp_hash_assoc_cntnr
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#include <ext/pb_assoc/assoc_cntnr.hpp>
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// For hash-related policies.
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#include <ext/pb_assoc/hash_policy.hpp>
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// For assert
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#include <cassert>
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/*
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* A simple hash functor.
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* std::hash could serve instead of this functor,
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* but it is not yet standard everywhere.
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*/
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struct int_hash : public std::unary_function<
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int,
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size_t>
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{
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inline size_t
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operator()(const int& r_i) const
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{
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return (r_i);
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}
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};
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int
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main()
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{
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// Resize policy type.
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typedef
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pb_assoc::hash_standard_resize_policy<
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// Size-policy type.
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pb_assoc::hash_exponential_size_policy<>,
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// Trigger-policy type.
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pb_assoc::hash_load_check_resize_trigger<>,
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/* Allow external access to size.
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* This is just used in this example for using the
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* get_actual_size method (which won't be accessible without
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* this flag.
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*/
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true>
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resize_policy_t;
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/*
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* A collision-probing hash table mapping ints to chars.
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*/
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typedef
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pb_assoc::gp_hash_assoc_cntnr<
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int,
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char,
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int_hash,
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std::equal_to<
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int>,
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// Combining function.
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pb_assoc::direct_mask_range_hashing<>,
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// Probe function.
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pb_assoc::linear_probe_fn<
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const int& >,
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// Resize policy.
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resize_policy_t>
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map_t;
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// A resize-policy object with suggested initial size 256.
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resize_policy_t res(pb_assoc::hash_exponential_size_policy<>(256));
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map_t g(int_hash(),
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std::equal_to<int>(),
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pb_assoc::direct_mask_range_hashing<>(),
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pb_assoc::linear_probe_fn<const int& >(),
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res);
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/*
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* Check the actual size of the container object. In this case,
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* this should be the initial size given by the size policy object.
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**/
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assert(g.get_actual_size() >= 256);
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assert(g.size() == 0);
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}
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