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

2022-10-18 00:46:59 +03:00
parent 21115121bb
commit 1e4c050d6c
3 changed files with 192 additions and 0 deletions
@@ -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();
+}