print.cpp
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/*=============================================================================
Copyright (c) 2017 Paul Fultz II
print.cpp
Distributed under the Boost Software License, Version 1.0. (See accompanying
file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
==============================================================================*/
/*=============================================================================
Copyright (c) 2016 Paul Fultz II
print.cpp
Distributed under the Boost Software License, Version 1.0. (See accompanying
file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
==============================================================================*/
#include "example.h"
using namespace boost::hof;
// ADL Lookup for ranges
namespace adl {
using std::begin;
using std::end;
template<class R>
auto adl_begin(R&& r) BOOST_HOF_RETURNS(begin(r));
template<class R>
auto adl_end(R&& r) BOOST_HOF_RETURNS(end(r));
}
// Iterate over a tuple
BOOST_HOF_STATIC_LAMBDA_FUNCTION(for_each_tuple) = [](const auto& sequence, auto f)
{
return unpack(proj(f))(sequence);
};
#ifdef _MSC_VER
// On MSVC, trailing decltype doesn't work with generic lambdas, so seperate
// functions can be used instead.
template<class Self, class T>
auto print_with_cout(Self, const T& x) -> decltype(std::cout << x, void())
{
std::cout << x << std::endl;
}
template<class Self, class T>
auto print_with_range(Self self, const T& range) -> decltype(self(*adl::adl_begin(range)), void())
{
for(const auto& x:range) self(x);
}
template<class Self, class T>
auto print_with_tuple(Self self, const T& tuple) -> decltype(for_each_tuple(tuple, self), void())
{
for_each_tuple(tuple, self);
}
// Recursively print everything
BOOST_HOF_STATIC_FUNCTION(simple_print) = fix(first_of(
BOOST_HOF_LIFT(print_with_cout),
BOOST_HOF_LIFT(print_with_range),
BOOST_HOF_LIFT(print_with_tuple)
));
#else
// Recursively print everything
BOOST_HOF_STATIC_LAMBDA_FUNCTION(simple_print) = fix(first_of(
[](auto, const auto& x) -> decltype(std::cout << x, void())
{
std::cout << x << std::endl;
},
[](auto self, const auto& range) -> decltype(self(*adl::adl_begin(range)), void())
{
for(const auto& x:range) self(x);
},
[](auto self, const auto& tuple) -> decltype(for_each_tuple(tuple, self), void())
{
for_each_tuple(tuple, self);
}
));
#endif
// Make print function varidiac
BOOST_HOF_STATIC_LAMBDA_FUNCTION(print) = proj(simple_print);
int main()
{
print(5, "Hello world");
print(5);
std::vector<int> v = { 1, 2, 3, 4 };
print(v);
auto t = std::make_tuple(1, 2, 3, 4);
print(t);
auto m = std::make_tuple(3, v, t);
print(m);
}