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Special-case streams in operator<< and operator>>

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This commit is contained in:
Peter Dimov 2021-09-05 01:50:37 +03:00
parent 3a06c98e8d
commit e2251ab450
4 changed files with 89 additions and 3 deletions
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36
include/boost/lambda2/lambda2.hpp
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@ -10,6 +10,7 @@
#include <utility>
#include <tuple>
#include <cstddef>
#include <iosfwd>
// Same format as BOOST_VERSION:
// major * 100000 + minor * 100 + patch
@ -201,9 +202,6 @@ BOOST_LAMBDA2_UNARY_LAMBDA(~, std::bit_not<>)
// additional
BOOST_LAMBDA2_BINARY_LAMBDA(<<, lambda2_detail::left_shift)
BOOST_LAMBDA2_BINARY_LAMBDA(>>, lambda2_detail::right_shift)
BOOST_LAMBDA2_UNARY_LAMBDA(+, lambda2_detail::unary_plus)
BOOST_LAMBDA2_UNARY_LAMBDA(*, lambda2_detail::dereference)
@ -226,6 +224,38 @@ BOOST_LAMBDA2_BINARY_LAMBDA(^=, lambda2_detail::bit_xor_equal)
BOOST_LAMBDA2_BINARY_LAMBDA(<<=, lambda2_detail::left_shift_equal)
BOOST_LAMBDA2_BINARY_LAMBDA(>>=, lambda2_detail::right_shift_equal)
// operator<<
template<class A, class = std::enable_if_t<!std::is_convertible<A&, std::ios_base&>::value>,
class B, class = lambda2_detail::enable_binary_lambda<A, B>>
auto operator<<( A&& a, B&& b )
{
return std::bind( lambda2_detail::left_shift(), std::forward<A>(a), std::forward<B>(b) ); \
}
template<class A, class = std::enable_if_t<std::is_convertible<A&, std::ios_base&>::value>,
class B, class = lambda2_detail::enable_unary_lambda<B>>
auto operator<<( A& a, B&& b )
{
return std::bind( lambda2_detail::left_shift(), std::ref(a), std::forward<B>(b) );
}
// operator>>
template<class A, class = std::enable_if_t<!std::is_convertible<A&, std::ios_base&>::value>,
class B, class = lambda2_detail::enable_binary_lambda<A, B>>
auto operator>>( A&& a, B&& b )
{
return std::bind( lambda2_detail::right_shift(), std::forward<A>(a), std::forward<B>(b) ); \
}
template<class A, class = std::enable_if_t<std::is_convertible<A&, std::ios_base&>::value>,
class B, class = lambda2_detail::enable_unary_lambda<B>>
auto operator>>( A& a, B&& b )
{
return std::bind( lambda2_detail::right_shift(), std::ref(a), std::forward<B>(b) );
}
} // namespace lambda2
} // namespace boost

2
test/Jamfile
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@ -24,3 +24,5 @@ run placeholders.cpp ;
run increment.cpp ;
run subscript.cpp ;
run compound.cpp ;
run stream_insert.cpp ;
run stream_extract.cpp ;

28
test/stream_extract.cpp Normal file
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@ -0,0 +1,28 @@
// Copyright 2021 Peter Dimov
// Distributed under the Boost Software License, Version 1.0.
// https://www.boost.org/LICENSE_1_0.txt
#include <boost/lambda2.hpp>
#include <boost/core/lightweight_test.hpp>
#include <sstream>
#include <string>
template<class T> T from_string( std::string const& s )
{
using namespace boost::lambda2;
std::istringstream is( s );
T t{};
( is >> _1 )( t );
return t;
}
int main()
{
BOOST_TEST_EQ( from_string<int>( "123" ), 123 );
return boost::report_errors();
}

26
test/stream_insert.cpp Normal file
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@ -0,0 +1,26 @@
// Copyright 2021 Peter Dimov
// Distributed under the Boost Software License, Version 1.0.
// https://www.boost.org/LICENSE_1_0.txt
#include <boost/lambda2.hpp>
#include <boost/core/lightweight_test.hpp>
#include <sstream>
#include <string>
template<class T> std::string to_string( T const& t )
{
using namespace boost::lambda2;
std::ostringstream os;
( os << _1 )( t );
return os.str();
}
int main()
{
BOOST_TEST_EQ( to_string( 123 ), "123" );
return boost::report_errors();
}