container/detail/next_capacity.hpp

0001 //////////////////////////////////////////////////////////////////////////////
0002 //
0003 // (C) Copyright Ion Gaztanaga 2014-2015. Distributed under the Boost
0004 // Software License, Version 1.0. (See accompanying file
0005 // LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
0006 //
0007 // See http://www.boost.org/libs/container for documentation.
0008 //
0009 //////////////////////////////////////////////////////////////////////////////
0010 #ifndef BOOST_CONTAINER_DETAIL_NEXT_CAPACITY_HPP
0011 #define BOOST_CONTAINER_DETAIL_NEXT_CAPACITY_HPP
0012
0013 #ifndef BOOST_CONFIG_HPP
0014 #  include <boost/config.hpp>
0015 #endif
0016
0017 #if defined(BOOST_HAS_PRAGMA_ONCE)
0018 #  pragma once
0019 #endif
0020
0021 #include <boost/container/detail/config_begin.hpp>
0022 #include <boost/container/detail/workaround.hpp>
0023
0024 // container
0025 #include <boost/container/throw_exception.hpp>
0026 // container/detail
0027 #include <boost/container/detail/min_max.hpp>
0028
0029 namespace boost {
0030 namespace container {
0031 namespace dtl {
0032
0033 template<unsigned Minimum, unsigned Numerator, unsigned Denominator>
0034 struct grow_factor_ratio
0035 {
0036    BOOST_CONTAINER_STATIC_ASSERT(Numerator > Denominator);
0037    BOOST_CONTAINER_STATIC_ASSERT(Numerator   < 100);
0038    BOOST_CONTAINER_STATIC_ASSERT(Denominator < 100);
0039    BOOST_CONTAINER_STATIC_ASSERT(Denominator == 1 || (0 != Numerator % Denominator));
0040
0041    template<class SizeType>
0042    SizeType operator()(const SizeType cur_cap, const SizeType add_min_cap, const SizeType max_cap) const
0043    {
0044       const SizeType overflow_limit  = ((SizeType)-1) / Numerator;
0045
0046       SizeType new_cap = 0;
0047
0048       if(cur_cap <= overflow_limit){
0049          new_cap = SizeType(cur_cap * Numerator / Denominator);
0050       }
0051       else if(Denominator == 1 || (SizeType(new_cap = cur_cap) / Denominator) > overflow_limit){
0052          new_cap = (SizeType)-1;
0053       }
0054       else{
0055          new_cap = SizeType(new_cap*Numerator);
0056       }
0057       return max_value<SizeType>
0058                ( SizeType(Minimum)
0059                , max_value<SizeType>
0060                   ( SizeType(cur_cap+add_min_cap)
0061                   , min_value<SizeType>(max_cap, new_cap))
0062                );
0063    }
0064 };
0065
0066 }  //namespace dtl {
0067
0068 struct growth_factor_50
0069    : dtl::grow_factor_ratio<0, 3, 2>
0070 {};
0071
0072 struct growth_factor_60
0073    : dtl::grow_factor_ratio<0, 8, 5>
0074 {};
0075
0076 struct growth_factor_100
0077    : dtl::grow_factor_ratio<0, 2, 1>
0078 {};
0079
0080 template<class SizeType>
0081 inline void clamp_by_stored_size_type(SizeType &, SizeType)
0082 {}
0083
0084 template<class SizeType, class SomeStoredSizeType>
0085 inline void clamp_by_stored_size_type(SizeType &s, SomeStoredSizeType)
0086 {
0087    if (s >= SomeStoredSizeType(-1) )
0088       s = SomeStoredSizeType(-1);
0089 }
0090
0091 }  //namespace container {
0092 }  //namespace boost {
0093
0094 #include <boost/container/detail/config_end.hpp>
0095
0096 #endif   //#ifndef BOOST_CONTAINER_DETAIL_NEXT_CAPACITY_HPP