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
19struct FinalEOL
20{
21 ~FinalEOL() { std::cout << std::endl; }
22};
23
24void 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
47int main(int argc, char *argv[])
48{
49 std::vector<std::string> words = boost::assign::list_of
50 (t: "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(f: layout, a1: _1, a2: 5, a3: 15));
68
69 std::copy(first: boost::begin(r&: words), last: boost::end(r&: words), result: boost::begin(r&: writer));
70
71 std::cout << "\nDone" << std::endl;
72
73 return EXIT_SUCCESS;
74}
75

source code of boost/libs/coroutine/example/asymmetric/layout.cpp