1
2 // Copyright Nat Goodspeed 2013.
3 // Distributed under the Boost Software License, Version 1.0.
4 // (See accompanying file LICENSE_1_0.txt or copy at
5 // http://www.boost.org/LICENSE_1_0.txt)
6
7 #include <boost/coroutine/all.hpp>
8
9 #include <iostream>
10 #include <iomanip>
11 #include <vector>
12 #include <string>
13 #include <utility>
14
15 #include <boost/assign/list_of.hpp>
16 #include <boost/bind.hpp>
17 #include <boost/range.hpp>
18
19 struct FinalEOL
20 {
~FinalEOLFinalEOL21 ~FinalEOL() { std::cout << std::endl; }
22 };
23
layout(boost::coroutines::asymmetric_coroutine<std::string>::pull_type & in,int num,int width)24 void layout(boost::coroutines::asymmetric_coroutine<std::string>::pull_type& in, int num, int width)
25 {
26 // Finish the last line when we leave by whatever means
27 FinalEOL eol;
28
29 // Pull values from upstream, lay them out 'num' to a line
30 for (;;)
31 {
32 for (int i = 0; i < num; ++i)
33 {
34 // when we exhaust the input, stop
35 if (! in)
36 return;
37
38 std::cout << std::setw(width) << in.get();
39 // now that we've handled this item, advance to next
40 in();
41 }
42 // after 'num' items, line break
43 std::cout << std::endl;
44 }
45 }
46
main(int argc,char * argv[])47 int main(int argc, char *argv[])
48 {
49 std::vector<std::string> words = boost::assign::list_of
50 ("peas")
51 ("porridge")
52 ("hot")
53 ("peas")
54 ("porridge")
55 ("cold")
56 ("peas")
57 ("porridge")
58 ("in")
59 ("the")
60 ("pot")
61 ("nine")
62 ("days")
63 ("old")
64 ;
65
66 boost::coroutines::asymmetric_coroutine<std::string>::push_type writer(
67 boost::bind(layout, _1, 5, 15));
68
69 std::copy(boost::begin(words), boost::end(words), boost::begin(writer));
70
71 std::cout << "\nDone" << std::endl;
72
73 return EXIT_SUCCESS;
74 }
75