ceph/src/boost/libs/yap/test/transform.cpp

   1 // Copyright (C) 2016-2018 T. Zachary Laine
   2 //
   3 // Distributed under the Boost Software License, Version 1.0. (See
   4 // accompanying file LICENSE_1_0.txt or copy at
   5 // http://www.boost.org/LICENSE_1_0.txt)
   6 #include <boost/yap/yap.hpp>
   7
   8 #include <boost/mpl/assert.hpp>
   9
  10 #include <boost/core/lightweight_test.hpp>
  11
  12 #include <sstream>
  13
  14
  15 template<typename T>
  16 using term = boost::yap::terminal<boost::yap::minimal_expr, T>;
  17
  18 namespace yap = boost::yap;
  19 namespace bh = boost::hana;
  20
  21
  22 struct iota_terminal_transform
  23 {
  24     template<typename T>
  25     auto operator()(boost::yap::expr_tag<boost::yap::expr_kind::terminal>, T && t)
  26     {
  27         return boost::yap::make_terminal(index_++);
  28     }
  29
  30     template<typename CallableExpr, typename... Arg>
  31     auto operator()(boost::yap::expr_tag<boost::yap::expr_kind::call>,
  32                     CallableExpr callable, Arg &&... arg)
  33     {
  34         return boost::yap::make_expression<boost::yap::expr_kind::call>(
  35             callable, boost::yap::transform(arg, *this)...);
  36     }
  37
  38     int index_;
  39 };
  40
  41 struct plus_expr_t
  42 {
  43     static yap::expr_kind const kind = yap::expr_kind::plus;
  44
  45     bh::tuple<term<int>, term<int>> elements;
  46 };
  47
  48 int main()
  49 {
  50     // Each node instantiated from from yap::expression.
  51     {
  52         auto plus_expr = yap::terminal<yap::expression, int>{{5}} + 6;
  53
  54         BOOST_TEST(yap::evaluate(plus_expr) == 11);
  55
  56         BOOST_TEST(
  57             yap::evaluate(
  58                 yap::transform(plus_expr, iota_terminal_transform{0})) == 1);
  59     }
  60
  61     // Each node instantiated from from yap::minimal_expr.
  62     {
  63         yap::minimal_expr<yap::expr_kind::plus, bh::tuple<term<int>, term<int>>>
  64             plus_expr;
  65
  66         yap::evaluate(yap::transform(plus_expr, iota_terminal_transform{0}), 1);
  67     }
  68
  69     // Leaves are instantiated from from yap::minimal_expr; nonterminal
  70     // expr_kind::plus does not even come from a template.
  71     {
  72         plus_expr_t plus_expr;
  73
  74         yap::evaluate(yap::transform(plus_expr, iota_terminal_transform{0}), 1);
  75     }
  76
  77     return boost::report_errors();
  78 }