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Add result<>::emplace (refs #85)

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This commit is contained in:
Peter Dimov
2022-10-18 00:46:59 +03:00
parent 21115121bb
commit 1e4c050d6c
3 changed files with 192 additions and 0 deletions
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15
include/boost/system/result.hpp
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@@ -401,6 +401,14 @@ public:
return has_error()? variant2::unsafe_get<1>( v_ ): E(); return has_error()? variant2::unsafe_get<1>( v_ ): E();
} }
// emplace
template<class... A>
BOOST_CXX14_CONSTEXPR T& emplace( A&&... a )
{
return v_.template emplace<0>( std::forward<A>(a)... );
}
// swap // swap
BOOST_CXX14_CONSTEXPR void swap( result& r ) BOOST_CXX14_CONSTEXPR void swap( result& r )
@@ -573,6 +581,13 @@ public:
return has_error()? variant2::unsafe_get<1>( v_ ): E(); return has_error()? variant2::unsafe_get<1>( v_ ): E();
} }
// emplace
BOOST_CXX14_CONSTEXPR void emplace()
{
v_.template emplace<0>();
}
// swap // swap
BOOST_CXX14_CONSTEXPR void swap( result& r ) BOOST_CXX14_CONSTEXPR void swap( result& r )

1
test/Jamfile.v2
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@@ -183,3 +183,4 @@ run result_convert_construct.cpp : : : $(CPP11) ;
run result_typedefs.cpp : : : $(CPP11) ; run result_typedefs.cpp : : : $(CPP11) ;
run result_value_construct3.cpp : : : $(CPP11) ; run result_value_construct3.cpp : : : $(CPP11) ;
run result_error_construct3.cpp : : : $(CPP11) ; run result_error_construct3.cpp : : : $(CPP11) ;
run result_emplace.cpp : : : $(CPP11) ;

176
test/result_emplace.cpp Normal file
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@@ -0,0 +1,176 @@
// Copyright 2017, 2021, 2022 Peter Dimov.
// Distributed under the Boost Software License, Version 1.0.
// https://www.boost.org/LICENSE_1_0.txt
#include <boost/system/result.hpp>
#include <boost/core/lightweight_test.hpp>
#include <cerrno>
using namespace boost::system;
struct X
{
static int instances;
int v_;
explicit X( int v ): v_( v ) { ++instances; }
X( int v1, int v2 ): v_( v1+v2 ) { ++instances; }
X( int v1, int v2, int v3 ): v_( v1+v2+v3 ) { ++instances; }
X( X const& ) = delete;
X& operator=( X const& ) = delete;
~X() { --instances; }
};
int X::instances = 0;
struct Y
{
static int instances;
Y() noexcept { ++instances; }
Y( Y const& ) noexcept { ++instances; }
Y& operator=( Y const& ) = default;
~Y() { --instances; }
};
int Y::instances = 0;
int main()
{
{
result<int> r;
BOOST_TEST( r.has_value() );
r.emplace( 1 );
BOOST_TEST( r.has_value() );
BOOST_TEST_EQ( r.value(), 1 );
}
{
result<int> r( ENOENT, generic_category() );
BOOST_TEST( !r.has_value() );
r.emplace( 1 );
BOOST_TEST( r.has_value() );
BOOST_TEST_EQ( r.value(), 1 );
}
BOOST_TEST_EQ( X::instances, 0 );
{
result<X> r( 0 );
BOOST_TEST( r.has_value() );
BOOST_TEST_EQ( r.value().v_, 0 );
BOOST_TEST_EQ( X::instances, 1 );
r.emplace( 1 );
BOOST_TEST( r.has_value() );
BOOST_TEST_EQ( r.value().v_, 1 );
BOOST_TEST_EQ( X::instances, 1 );
r.emplace( 1, 2 );
BOOST_TEST( r.has_value() );
BOOST_TEST_EQ( r.value().v_, 1+2 );
BOOST_TEST_EQ( X::instances, 1 );
r.emplace( 1, 2, 3 );
BOOST_TEST( r.has_value() );
BOOST_TEST_EQ( r.value().v_, 1+2+3 );
BOOST_TEST_EQ( X::instances, 1 );
}
BOOST_TEST_EQ( X::instances, 0 );
{
result<X> r( ENOENT, generic_category() );
BOOST_TEST( !r.has_value() );
BOOST_TEST_EQ( X::instances, 0 );
r.emplace( 1, 2 );
BOOST_TEST( r.has_value() );
BOOST_TEST_EQ( r.value().v_, 1+2 );
BOOST_TEST_EQ( X::instances, 1 );
}
BOOST_TEST_EQ( X::instances, 0 );
BOOST_TEST_EQ( Y::instances, 0 );
{
result<int, Y> r( Y{} );
BOOST_TEST( !r.has_value() );
BOOST_TEST_EQ( Y::instances, 1 );
r.emplace( 1 );
BOOST_TEST( r.has_value() );
BOOST_TEST_EQ( *r, 1 );
BOOST_TEST_EQ( Y::instances, 0 );
}
BOOST_TEST_EQ( X::instances, 0 );
BOOST_TEST_EQ( Y::instances, 0 );
{
result<X, Y> r( in_place_error );
BOOST_TEST( !r.has_value() );
BOOST_TEST_EQ( X::instances, 0 );
BOOST_TEST_EQ( Y::instances, 1 );
r.emplace( 1, 2, 3 );
BOOST_TEST( r.has_value() );
BOOST_TEST_EQ( r->v_, 1+2+3 );
BOOST_TEST_EQ( X::instances, 1 );
BOOST_TEST_EQ( Y::instances, 0 );
}
BOOST_TEST_EQ( X::instances, 0 );
BOOST_TEST_EQ( Y::instances, 0 );
{
result<void> r;
BOOST_TEST( r.has_value() );
r.emplace();
BOOST_TEST( r.has_value() );
}
{
result<void> r( ENOENT, generic_category() );
BOOST_TEST( !r.has_value() );
r.emplace();
BOOST_TEST( r.has_value() );
}
BOOST_TEST_EQ( Y::instances, 0 );
{
result<void, Y> r( in_place_error );
BOOST_TEST( !r.has_value() );
BOOST_TEST_EQ( Y::instances, 1 );
r.emplace();
BOOST_TEST( r.has_value() );
BOOST_TEST_EQ( Y::instances, 0 );
}
return boost::report_errors();
}