12345678910111213141516171819202122232425262728293031323334353637383940414243444546474849505152535455565758596061626364656667686970717273747576777879808182838485868788899091929394959697 |
- /*
- *
- * (C) Copyright John Maddock 1999-2005.
- * Use, modification and distribution are subject to the
- * Boost Software License, Version 1.0. (See accompanying file
- * LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
- *
- * This file provides some example of type_traits usage -
- * by "optimising" various algorithms:
- *
- * opt::iter_swap - uses type_traits to determine whether the iterator is a proxy
- * in which case it uses a "safe" approach, otherwise calls swap
- * on the assumption that swap may be specialised for the pointed-to type.
- *
- */
- #include <iostream>
- #include <typeinfo>
- #include <algorithm>
- #include <iterator>
- #include <vector>
- #include <memory>
- #include <boost/test/included/prg_exec_monitor.hpp>
- #include <boost/type_traits.hpp>
- using std::cout;
- using std::endl;
- using std::cin;
- namespace opt{
- //
- // iter_swap:
- // tests whether iterator is a proxy iterator or not, and
- // uses optimal form accordingly:
- //
- namespace detail{
- template <typename I>
- static void do_swap(I one, I two, const boost::false_type&)
- {
- typedef typename std::iterator_traits<I>::value_type v_t;
- v_t v = *one;
- *one = *two;
- *two = v;
- }
- template <typename I>
- static void do_swap(I one, I two, const boost::true_type&)
- {
- using std::swap;
- swap(*one, *two);
- }
- }
- template <typename I1, typename I2>
- inline void iter_swap(I1 one, I2 two)
- {
- //
- // See is both arguments are non-proxying iterators,
- // and if both iterator the same type:
- //
- typedef typename std::iterator_traits<I1>::reference r1_t;
- typedef typename std::iterator_traits<I2>::reference r2_t;
- typedef boost::integral_constant<bool,
- ::boost::is_reference<r1_t>::value
- && ::boost::is_reference<r2_t>::value
- && ::boost::is_same<r1_t, r2_t>::value> truth_type;
- detail::do_swap(one, two, truth_type());
- }
- }; // namespace opt
- int cpp_main(int argc, char* argv[])
- {
- //
- // testing iter_swap
- // really just a check that it does in fact compile...
- std::vector<int> v1;
- v1.push_back(0);
- v1.push_back(1);
- std::vector<bool> v2;
- v2.push_back(0);
- v2.push_back(1);
- opt::iter_swap(v1.begin(), v1.begin()+1);
- opt::iter_swap(v2.begin(), v2.begin()+1);
- return 0;
- }
|