ceph/src/boost/libs/coroutine/example/asymmetric/layout.cpp

   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 <iostream>
   8 #include <iomanip>
   9 #include <vector>
  10 #include <string>
  11 #include <utility>
  12
  13 #include <boost/assign/list_of.hpp>
  14 #include <boost/bind.hpp>
  15 #include <boost/coroutine/all.hpp>
  16 #include <boost/range.hpp>
  17
  18 struct FinalEOL
  19 {
  20     ~FinalEOL() { std::cout << std::endl; }
  21 };
  22
  23 void layout(boost::coroutines::asymmetric_coroutine<std::string>::pull_type& in, int num, int width)
  24 {
  25     // Finish the last line when we leave by whatever means
  26     FinalEOL eol;
  27
  28     // Pull values from upstream, lay them out 'num' to a line
  29     for (;;)
  30     {
  31         for (int i = 0; i < num; ++i)
  32         {
  33             // when we exhaust the input, stop
  34             if (! in)
  35                 return;
  36
  37             std::cout << std::setw(width) << in.get();
  38             // now that we've handled this item, advance to next
  39             in();
  40         }
  41         // after 'num' items, line break
  42         std::cout << std::endl;
  43     }
  44 }
  45
  46 int main(int argc, char *argv[])
  47 {
  48     std::vector<std::string> words = boost::assign::list_of
  49         ("peas")
  50         ("porridge")
  51         ("hot")
  52         ("peas")
  53         ("porridge")
  54         ("cold")
  55         ("peas")
  56         ("porridge")
  57         ("in")
  58         ("the")
  59         ("pot")
  60         ("nine")
  61         ("days")
  62         ("old")
  63     ;
  64
  65     boost::coroutines::asymmetric_coroutine<std::string>::push_type writer(
  66         boost::bind(layout, _1, 5, 15));
  67
  68     std::copy(boost::begin(words), boost::end(words), boost::begin(writer));
  69
  70     std::cout << "\nDone" << std::endl;
  71
  72     return EXIT_SUCCESS;
  73 }