Reputation: 52365
Here is an example of a range adaptor based off of Implement a Range Adaptor with arguments:
#include <boost/range/join.hpp>
#include <boost/range/algorithm.hpp>
#include <boost/range/adaptors.hpp>
#include <boost/range/iterator_range.hpp>
#include <boost/iterator/permutation_iterator.hpp>
#include <vector>
#include <list>
#include <iterator>
#include <iostream>
template <typename Range, typename Index>
class permutation_range :
public boost::iterator_range<
boost::permutation_iterator<
typename boost::range_iterator<Range>::type,
typename boost::range_iterator<Index>::type>>
{
using value_type = typename boost::range_value<Range>::type;
using replaced_iterator = boost::permutation_iterator<
typename boost::range_iterator<Range>::type,
typename boost::range_iterator<Index>::type>;
using base_t = boost::iterator_range<replaced_iterator>;
public:
permutation_range(Range& r, Index& i)
: base_t(replaced_iterator(boost::begin(r), boost::begin(i)),
replaced_iterator(boost::end(r), boost::end(i)))
{}
};
template <typename Range, typename Index>
permutation_range<Range, Index>
permutation(Range& r, Index& i)
{
return permutation_range<Range, Index>(r, i);
}
int main()
{
std::vector<int> v1{99, 1, 99, 2, 99, 3};
std::list<int> indexer{1, 3, 5};
boost::copy(permutation(v1, indexer),
std::ostream_iterator<int>(std::cout, " "));
}
Output
1 2 3
I want to adapt the above to use boost::joined_range. In other words, take two vectors and then join them into one longer range inside of permutation_range
. The idea is simple:
Example which would output 2 4 6
:
int main()
{
std::vector<int> v1{1, 2, 3};
std::vector<int> v2{4, 5, 6};
std::list<int> indexer{1, 3, 5};
boost::copy(permutation(v1, v2, indexer),
std::ostream_iterator<int>(std::cout, " "));
}
All my attempts so far have ended in a huge list of compiler errors, I haven't showed the attempts because I may be way off. I don't know if it is possible, but could anyone help me out here?
FINAL EDIT (Solution with a little hack to get the range initialized before the base class)
#include <boost/range/join.hpp>
#include <boost/range/algorithm.hpp>
#include <boost/range/adaptors.hpp>
#include <boost/range/iterator_range.hpp>
#include <boost/iterator/permutation_iterator.hpp>
#include <vector>
#include <list>
#include <iterator>
#include <iostream>
template <typename R1, typename R2>
struct initialize_me_first
{
initialize_me_first(typename boost::range::joined_range<const R1, const R2> j)
: j_range(j)
{}
typename boost::range::joined_range<const R1, const R2> j_range;
};
template <typename Range1, typename Range2, typename Index>
class permutation_range :
public initialize_me_first<Range1, Range2>,
public boost::iterator_range<
boost::permutation_iterator<
typename boost::range_iterator<
boost::range::joined_range<Range1, Range2>>::type,
typename boost::range_iterator<Index>::type>>
{
using value_type = typename boost::range_value<Range1>::type;
using replaced_iterator = boost::permutation_iterator<
typename boost::range_iterator<
boost::range::joined_range<Range1, Range2>>::type,
typename boost::range_iterator<Index>::type>;
using base_t = boost::iterator_range<replaced_iterator>;
using init = initialize_me_first<Range1, Range2>;
public:
permutation_range(const Range1& r1, const Range2& r2, const Index& i)
: init(boost::join(r1, r2)),
base_t(replaced_iterator(boost::begin(init::j_range),
boost::begin(i)),
replaced_iterator(boost::end(init::j_range),
boost::end(i)))
{}
};
template <typename Range1, typename Range2, typename Index>
permutation_range<const Range1, const Range2, const Index>
permutation(const Range1& r1, const Range2& r2, const Index& i)
{
return permutation_range<const Range1,
const Range2,
const Index>(r1, r2, i);
}
int main()
{
std::vector<int> v1{1, 2, 3};
std::vector<int> v2{4, 5, 6};
std::list<int> indexer{1, 3, 5};
boost::copy(permutation(v1, v2, indexer),
std::ostream_iterator<int>(std::cout, " "));
}
Upvotes: 1
Views: 1356
Reputation: 163287
To join two ranges, use boost::join
:
#include <boost/range/join.hpp>
boost::copy(permutation(boost::join(v1, v2), indexer), ...
But change your Range
parameters to be passed by const reference instead of non-const reference. There's no reason to require modifiable versions of those arguments since you're not actually permuting their contents.
Upvotes: 2