ceph/src/boost/libs/hana/example/scan_left.cpp

   1 // Copyright Louis Dionne 2013-2016
   2 // Distributed under the Boost Software License, Version 1.0.
   3 // (See accompanying file LICENSE.md or copy at http://boost.org/LICENSE_1_0.txt)
   4
   5 #include <boost/hana/assert.hpp>
   6 #include <boost/hana/equal.hpp>
   7 #include <boost/hana/scan_left.hpp>
   8 #include <boost/hana/tuple.hpp>
   9
  10 #include <sstream>
  11 namespace hana = boost::hana;
  12
  13
  14 auto to_string = [](auto x) {
  15     std::ostringstream ss;
  16     ss << x;
  17     return ss.str();
  18 };
  19
  20 auto f = [](auto state, auto element) {
  21     return "f(" + to_string(state) + ", " + to_string(element) + ")";
  22 };
  23
  24 int main() {
  25     // with initial state
  26     BOOST_HANA_RUNTIME_CHECK(hana::scan_left(hana::make_tuple(2, "3", '4'), 1, f) == hana::make_tuple(
  27         1,
  28         "f(1, 2)",
  29         "f(f(1, 2), 3)",
  30         "f(f(f(1, 2), 3), 4)"
  31     ));
  32
  33     // without initial state
  34     BOOST_HANA_RUNTIME_CHECK(hana::scan_left(hana::make_tuple(1, "2", '3'), f) == hana::make_tuple(
  35         1,
  36         "f(1, 2)",
  37         "f(f(1, 2), 3)"
  38     ));
  39 }