1 // Copyright (C) 2004 Jeremy Siek <jsiek@cs.indiana.edu>
2 // Distributed under the Boost Software License, Version 1.0. (See
3 // accompanying file LICENSE_1_0.txt or copy at
4 // http://www.boost.org/LICENSE_1_0.txt)
5
6 #include <iostream>
7 #include <vector>
8 #include <deque>
9 #include <algorithm>
10 #include <boost/iterator/permutation_iterator.hpp>
11 #include <boost/cstdlib.hpp>
12 #include <assert.h>
13
14
main()15 int main() {
16 using namespace boost;
17 int i = 0;
18
19 typedef std::vector< int > element_range_type;
20 typedef std::deque< int > index_type;
21
22 static const int element_range_size = 10;
23 static const int index_size = 4;
24
25 element_range_type elements( element_range_size );
26 for(element_range_type::iterator el_it = elements.begin() ; el_it != elements.end() ; ++el_it)
27 *el_it = std::distance(elements.begin(), el_it);
28
29 index_type indices( index_size );
30 for(index_type::iterator i_it = indices.begin() ; i_it != indices.end() ; ++i_it )
31 *i_it = element_range_size - index_size + std::distance(indices.begin(), i_it);
32 std::reverse( indices.begin(), indices.end() );
33
34 typedef permutation_iterator< element_range_type::iterator, index_type::iterator > permutation_type;
35 permutation_type begin = make_permutation_iterator( elements.begin(), indices.begin() );
36 permutation_type it = begin;
37 permutation_type end = make_permutation_iterator( elements.begin(), indices.end() );
38
39 std::cout << "The original range is : ";
40 std::copy( elements.begin(), elements.end(), std::ostream_iterator< int >( std::cout, " " ) );
41 std::cout << "\n";
42
43 std::cout << "The reindexing scheme is : ";
44 std::copy( indices.begin(), indices.end(), std::ostream_iterator< int >( std::cout, " " ) );
45 std::cout << "\n";
46
47 std::cout << "The permutated range is : ";
48 std::copy( begin, end, std::ostream_iterator< int >( std::cout, " " ) );
49 std::cout << "\n";
50
51 std::cout << "Elements at even indices in the permutation : ";
52 it = begin;
53 for(i = 0; i < index_size / 2 ; ++i, it+=2 ) std::cout << *it << " ";
54 std::cout << "\n";
55
56 std::cout << "Permutation backwards : ";
57 it = begin + (index_size);
58 assert( it != begin );
59 for( ; it-- != begin ; ) std::cout << *it << " ";
60 std::cout << "\n";
61
62 std::cout << "Iterate backward with stride 2 : ";
63 it = begin + (index_size - 1);
64 for(i = 0 ; i < index_size / 2 ; ++i, it-=2 ) std::cout << *it << " ";
65 std::cout << "\n";
66
67 return boost::exit_success;
68 }
69