97 lines
2.7 KiB
C++
97 lines
2.7 KiB
C++
/* Boost.MultiIndex example of use of multi_index_container::ctor_args_list.
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*
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* Copyright 2003-2008 Joaquin M Lopez Munoz.
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* Distributed under the Boost Software License, Version 1.0.
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* (See accompanying file LICENSE_1_0.txt or copy at
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* http://www.boost.org/LICENSE_1_0.txt)
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*
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* See http://www.boost.org/libs/multi_index for library home page.
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*/
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#if !defined(NDEBUG)
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#define BOOST_MULTI_INDEX_ENABLE_INVARIANT_CHECKING
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#define BOOST_MULTI_INDEX_ENABLE_SAFE_MODE
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#endif
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#include <boost/multi_index_container.hpp>
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#include <boost/multi_index/identity.hpp>
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#include <boost/multi_index/ordered_index.hpp>
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#include <algorithm>
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#include <iostream>
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#include <iterator>
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using boost::multi_index_container;
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using namespace boost::multi_index;
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/* modulo_less order numbers according to their division residual.
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* For instance, if modulo==10 then 22 is less than 15 as 22%10==2 and
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* 15%10==5.
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*/
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template<typename IntegralType>
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struct modulo_less
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{
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modulo_less(IntegralType m):modulo(m){}
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bool operator()(IntegralType x,IntegralType y)const
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{
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return (x%modulo)<(y%modulo);
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}
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private:
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IntegralType modulo;
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};
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/* multi_index_container of unsigned ints holding a "natural" index plus
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* an ordering based on modulo_less.
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*/
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typedef multi_index_container<
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unsigned int,
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indexed_by<
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ordered_unique<identity<unsigned int> >,
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ordered_non_unique<identity<unsigned int>, modulo_less<unsigned int> >
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>
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> modulo_indexed_set;
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int main()
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{
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/* define a modulo_indexed_set with modulo==10 */
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modulo_indexed_set::ctor_args_list args_list=
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boost::make_tuple(
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/* ctor_args for index #0 is default constructible */
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nth_index<modulo_indexed_set,0>::type::ctor_args(),
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/* first parm is key_from_value, second is our sought for key_compare */
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boost::make_tuple(identity<unsigned int>(),modulo_less<unsigned int>(10))
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);
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modulo_indexed_set m(args_list);
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/* this could have be written online without the args_list variable,
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* left as it is for explanatory purposes. */
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/* insert some numbers */
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unsigned int numbers[]={0,1,20,40,33,68,11,101,60,34,88,230,21,4,7,17};
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const std::size_t numbers_length(sizeof(numbers)/sizeof(numbers[0]));
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m.insert(&numbers[0],&numbers[numbers_length]);
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/* lists all numbers in order, along with their "equivalence class", that is,
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* the equivalent numbers under modulo_less
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*/
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for(modulo_indexed_set::iterator it=m.begin();it!=m.end();++it){
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std::cout<<*it<<" -> ( ";
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nth_index<modulo_indexed_set,1>::type::iterator it0,it1;
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boost::tie(it0,it1)=get<1>(m).equal_range(*it);
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std::copy(it0,it1,std::ostream_iterator<unsigned int>(std::cout," "));
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std::cout<<")"<<std::endl;
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}
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return 0;
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}
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