Containers: STL compatibility for Optional.

mosra · Jan 26, 2019 · 69e6593 · 69e6593
1 parent 9eb8e3c
commit 69e6593
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Showing 10 changed files with 373 additions and 3 deletions.
diff --git a/doc/corrade-changelog.dox b/doc/corrade-changelog.dox
@@ -60,6 +60,8 @@ namespace Corrade {
     initialization
 -   Added r-value overloads to @ref Containers::Optional::operator*() allowing
     you to easily take the value out of a r-value optional
+-   Opt-in STL compatibility for @ref Containers::Optional, allowing for
+    *explicit* conversion from and to @cpp std::optional @ce in C++17.
 -   New @ref Containers::arrayCast(StridedArrayView<T>) overload for casting
     strided array views
 

diff --git a/doc/snippets/CMakeLists.txt b/doc/snippets/CMakeLists.txt
@@ -39,6 +39,20 @@ add_library(snippets STATIC
 target_link_libraries(snippets PRIVATE CorradeUtility)
 set_target_properties(snippets PROPERTIES FOLDER "Corrade/doc/snippets")
 
+# Copied verbatim from src/Corrade/Test/CMakeLists.txt, please keep in sync
+# (especially for AppleClang)
+if((CMAKE_CXX_COMPILER_ID STREQUAL "GNU" AND NOT CMAKE_CXX_COMPILER_VERSION VERSION_LESS "7.0") OR
+   (CMAKE_CXX_COMPILER_ID STREQUAL "Clang" AND NOT CMAKE_CXX_COMPILER_VERSION VERSION_LESS "5.0") OR
+  #(CMAKE_CXX_COMPILER_ID STREQUAL "AppleClang" AND NOT CMAKE_CXX_COMPILER_VERSION VERSION_LESS "10.0") OR
+   (CMAKE_CXX_COMPILER_ID STREQUAL "MSVC" AND NOT CMAKE_CXX_COMPILER_VERSION VERSION_LESS "19.10"))
+    add_library(snippets-cpp17 STATIC
+        Containers-stl17.cpp)
+    target_link_libraries(snippets-cpp17 PRIVATE CorradeUtility)
+    set_target_properties(snippets-cpp17 PROPERTIES
+        CORRADE_CXX_STANDARD 17
+        FOLDER "Corrade/doc/snippets")
+endif()
+
 if(WITH_INTERCONNECT)
     add_library(snippets-Interconnect STATIC Interconnect.cpp)
     target_link_libraries(snippets-Interconnect PRIVATE CorradeInterconnect)

diff --git a/doc/snippets/Containers-stl17.cpp b/doc/snippets/Containers-stl17.cpp
@@ -0,0 +1,39 @@
+/*
+    This file is part of Corrade.
+
+    Copyright © 2007, 2008, 2009, 2010, 2011, 2012, 2013, 2014, 2015, 2016,
+                2017, 2018, 2019 Vladimír Vondruš <mosra@centrum.cz>
+
+    Permission is hereby granted, free of charge, to any person obtaining a
+    copy of this software and associated documentation files (the "Software"),
+    to deal in the Software without restriction, including without limitation
+    the rights to use, copy, modify, merge, publish, distribute, sublicense,
+    and/or sell copies of the Software, and to permit persons to whom the
+    Software is furnished to do so, subject to the following conditions:
+
+    The above copyright notice and this permission notice shall be included
+    in all copies or substantial portions of the Software.
+
+    THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+    IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+    FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
+    THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+    LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+    FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
+    DEALINGS IN THE SOFTWARE.
+*/
+
+#include "Corrade/Containers/OptionalStl.h"
+
+using namespace Corrade;
+
+int main() {
+{
+/* [Optional] */
+std::optional<int> a{5};
+Containers::Optional<int> b(a);
+
+std::optional<std::string> c(Containers::optional<std::string>("hello"));
+/* [Optional] */
+}
+}
diff --git a/src/Corrade/Containers/CMakeLists.txt b/src/Corrade/Containers/CMakeLists.txt
@@ -31,6 +31,7 @@ set(CorradeContainers_HEADERS
     EnumSet.hpp
     LinkedList.h
     Optional.h
+    OptionalStl.h
     Pointer.h
     PointerStl.h
     Reference.h

diff --git a/src/Corrade/Containers/Optional.h b/src/Corrade/Containers/Optional.h
@@ -27,6 +27,7 @@
 
 /** @file
  * @brief Class @ref Corrade::Containers::Optional, tag type @ref Corrade::Containers::NullOptT, tag @ref Corrade::Containers::NullOpt, function @ref Corrade::Containers::optional()
+ * @see @ref Corrade/Containers/OptionalStl.h
  */
 
 #include <new>
@@ -41,6 +42,10 @@
 
 namespace Corrade { namespace Containers {
 
+namespace Implementation {
+    template<class> struct OptionalConverter;
+}
+
 /**
 @brief Null optional initialization tag type
 
@@ -80,6 +85,18 @@ Unlike `std::optional`, this class does not provide a @cpp constexpr @ce
 implementation or ordering operators, which makes it fairly simple and
 lightweight. If you need the extra features, use the standard `std::optional`.
 
+@section Containers-Optional-stl STL compatibility
+
+Instances of @ref Optional are *explicitly* copy- and move-convertible to and
+from @cpp std::optional @ce if you include @ref Corrade/Containers/OptionalStl.h
+and build your code with C++17 enabled. The conversion is provided in a
+separate header to avoid unconditional @cpp #include <optional> @ce, which
+significantly affects compile times. Example:
+
+@snippet Containers-stl17.cpp Optional
+
+<b></b>
+
 @m_class{m-block m-success}
 
 @par Single-header version
@@ -132,6 +149,12 @@ template<class T> class Optional {
             new(&_value.v) T{std::forward<Args>(args)...};
         }
 
+        /** @brief Copy-construct an optional from external representation */
+        template<class U, class = decltype(Implementation::OptionalConverter<U>::from(std::declval<const U&>()))> explicit Optional(const U& other) noexcept(std::is_nothrow_copy_constructible<T>::value): Optional{Implementation::OptionalConverter<U>::from(other)} {}
+
+        /** @brief Move-construct an optional from external representation */
+        template<class U, class = decltype(Implementation::OptionalConverter<U>::from(std::declval<U&&>()))> explicit Optional(U&& other) noexcept(std::is_nothrow_move_constructible<T>::value): Optional{Implementation::OptionalConverter<U>::from(std::move(other))} {}
+
         /** @brief Copy constructor */
         Optional(const Optional<T>& other) noexcept(std::is_nothrow_copy_constructible<T>::value);
 
@@ -156,6 +179,16 @@ template<class T> class Optional {
          */
         Optional<T>& operator=(Optional<T>&& other) noexcept(std::is_nothrow_move_assignable<T>::value);
 
+        /** @brief Copy-convert the optional to external representation */
+        template<class U, class = decltype(Implementation::OptionalConverter<U>::to(std::declval<const Optional<T>&>()))> explicit operator U() const & {
+            return Implementation::OptionalConverter<U>::to(*this);
+        }
+
+        /** @brief Move-convert the optional to external representation */
+        template<class U, class = decltype(Implementation::OptionalConverter<U>::to(std::declval<Optional<T>&&>()))> explicit operator U() && {
+            return Implementation::OptionalConverter<U>::to(std::move(*this));
+        }
+
         /**
          * @brief Clear the contained value
          *

diff --git a/src/Corrade/Containers/OptionalStl.h b/src/Corrade/Containers/OptionalStl.h
@@ -0,0 +1,66 @@
+#ifndef Corrade_Containers_PointerStl_h
+#define Corrade_Containers_PointerStl_h
+/*
+    This file is part of Corrade.
+
+    Copyright © 2007, 2008, 2009, 2010, 2011, 2012, 2013, 2014, 2015, 2016,
+                2017, 2018, 2019 Vladimír Vondruš <mosra@centrum.cz>
+
+    Permission is hereby granted, free of charge, to any person obtaining a
+    copy of this software and associated documentation files (the "Software"),
+    to deal in the Software without restriction, including without limitation
+    the rights to use, copy, modify, merge, publish, distribute, sublicense,
+    and/or sell copies of the Software, and to permit persons to whom the
+    Software is furnished to do so, subject to the following conditions:
+
+    The above copyright notice and this permission notice shall be included
+    in all copies or substantial portions of the Software.
+
+    THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+    IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+    FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
+    THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+    LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+    FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
+    DEALINGS IN THE SOFTWARE.
+*/
+
+/** @file
+@brief STL compatibility for @ref Corrade::Containers::Optional
+
+Including this header allows you to *explicitly* convert between
+@ref Corrade::Containers::Optional and @cpp std::optional @ce using copy / move
+construction and assignment. See @ref Containers-Optional-stl for more
+information.
+*/
+
+#include <optional>
+
+#include "Corrade/Containers/Optional.h"
+
+/* Listing these namespaces doesn't anything to the docs, so don't */
+#ifndef DOXYGEN_GENERATING_OUTPUT
+namespace Corrade { namespace Containers { namespace Implementation {
+
+template<class T> struct OptionalConverter<std::optional<T>> {
+    static Optional<T> from(const std::optional<T>& other) {
+        return other ? Optional<T>{*other} : Containers::NullOpt;
+    }
+
+    static Optional<T> from(std::optional<T>&& other) {
+        return other ? Optional<T>{*std::move(other)} : Containers::NullOpt;
+    }
+
+    static std::optional<T> to(const Optional<T>& other) {
+        return other ? std::optional<T>{*other} : std::nullopt;
+    }
+
+    static std::optional<T> to(Optional<T>&& other) {
+        return other ? std::optional<T>{*std::move(other)} : std::nullopt;
+    }
+};
+
+}}}
+#endif
+
+#endif
diff --git a/src/Corrade/Containers/Test/CMakeLists.txt b/src/Corrade/Containers/Test/CMakeLists.txt
@@ -63,3 +63,15 @@ set_target_properties(
     ContainersStridedArrayViewTest
     ContainersTagsTest
     PROPERTIES FOLDER "Corrade/Containers/Test")
+
+# Copied verbatim from src/Corrade/Test/CMakeLists.txt, please keep in sync
+# (especially for AppleClang)
+if((CMAKE_CXX_COMPILER_ID STREQUAL "GNU" AND NOT CMAKE_CXX_COMPILER_VERSION VERSION_LESS "7.0") OR
+   (CMAKE_CXX_COMPILER_ID STREQUAL "Clang" AND NOT CMAKE_CXX_COMPILER_VERSION VERSION_LESS "5.0") OR
+  #(CMAKE_CXX_COMPILER_ID STREQUAL "AppleClang" AND NOT CMAKE_CXX_COMPILER_VERSION VERSION_LESS "10.0") OR
+   (CMAKE_CXX_COMPILER_ID STREQUAL "MSVC" AND NOT CMAKE_CXX_COMPILER_VERSION VERSION_LESS "19.10"))
+    corrade_add_test(ContainersOptionalStlTest OptionalStlTest.cpp)
+    set_target_properties(ContainersOptionalStlTest PROPERTIES
+        CORRADE_CXX_STANDARD 17
+        FOLDER "Corrade/Containers/Test")
+endif()
diff --git a/src/Corrade/Containers/Test/OptionalStlTest.cpp b/src/Corrade/Containers/Test/OptionalStlTest.cpp
@@ -0,0 +1,103 @@
+
+/*
+    This file is part of Corrade.
+
+    Copyright © 2007, 2008, 2009, 2010, 2011, 2012, 2013, 2014, 2015, 2016,
+                2017, 2018, 2019 Vladimír Vondruš <mosra@centrum.cz>
+
+    Permission is hereby granted, free of charge, to any person obtaining a
+    copy of this software and associated documentation files (the "Software"),
+    to deal in the Software without restriction, including without limitation
+    the rights to use, copy, modify, merge, publish, distribute, sublicense,
+    and/or sell copies of the Software, and to permit persons to whom the
+    Software is furnished to do so, subject to the following conditions:
+
+    The above copyright notice and this permission notice shall be included
+    in all copies or substantial portions of the Software.
+
+    THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+    IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+    FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
+    THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+    LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+    FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
+    DEALINGS IN THE SOFTWARE.
+*/
+
+#include "Corrade/Containers/OptionalStl.h"
+#include "Corrade/Containers/Pointer.h"
+#include "Corrade/TestSuite/Tester.h"
+
+namespace Corrade { namespace Containers { namespace Test { namespace {
+
+struct OptionalStlTest: TestSuite::Tester {
+    explicit OptionalStlTest();
+
+    void convertCopy();
+    void convertCopyNull();
+    void convertMove();
+    void convertMoveNull();
+};
+
+OptionalStlTest::OptionalStlTest() {
+    addTests({&OptionalStlTest::convertCopy,
+              &OptionalStlTest::convertCopyNull,
+              &OptionalStlTest::convertMove,
+              &OptionalStlTest::convertMoveNull});
+}
+
+void OptionalStlTest::convertCopy() {
+    std::optional<int> a = 5;
+    CORRADE_VERIFY(a);
+    CORRADE_COMPARE(*a, 5);
+
+    Optional<int> b{a};
+    CORRADE_VERIFY(b);
+    CORRADE_COMPARE(*b, 5);
+
+    std::optional<int> c{b};
+    CORRADE_VERIFY(c);
+    CORRADE_COMPARE(*c, 5);
+}
+
+void OptionalStlTest::convertCopyNull() {
+    std::optional<int> a;
+    CORRADE_VERIFY(!a);
+
+    Optional<int> b(a);
+    CORRADE_VERIFY(!b);
+
+    std::optional<int> c(b);
+    CORRADE_VERIFY(!c);
+}
+
+void OptionalStlTest::convertMove() {
+    std::optional<Pointer<int>> a{pointer(new int{15})};
+    CORRADE_VERIFY(a);
+    CORRADE_COMPARE(**a, 15);
+
+    Optional<Pointer<int>> b(std::move(a));
+    CORRADE_VERIFY(b);
+    CORRADE_VERIFY(!*a);
+    CORRADE_COMPARE(**b, 15);
+
+    std::optional<Pointer<int>> c(std::move(b));
+    CORRADE_VERIFY(c);
+    CORRADE_VERIFY(!*b);
+    CORRADE_COMPARE(**c, 15);
+}
+
+void OptionalStlTest::convertMoveNull() {
+    std::optional<Pointer<int>> a;
+    CORRADE_VERIFY(!a);
+
+    Optional<Pointer<int>> b(std::move(a));
+    CORRADE_VERIFY(!b);
+
+    std::optional<Pointer<int>> c(std::move(b));
+    CORRADE_VERIFY(!c);
+}
+
+}}}}
+
+CORRADE_TEST_MAIN(Corrade::Containers::Test::OptionalStlTest)