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Add support for boost::variant in C++11 mode
In C++11 mode, `boost::apply_visitor` requires an explicit `result_type`. This also adds optional tests for `boost::variant` in C++11/14, if boost is available. In C++17 mode, `std::variant` is tested instead.
This commit is contained in:
Dean Moldovan
parent
e06077bf47
commit
7918bcc95b
@ -28,8 +28,12 @@ matrix:
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install:
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- ps: |
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if ($env:PLATFORM -eq "x64") { $env:CMAKE_ARCH = "x64" }
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if ($env:APPVEYOR_JOB_NAME -like "*Visual Studio 2017*") { $env:CMAKE_GENERATOR = "Visual Studio 15 2017" }
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else { $env:CMAKE_GENERATOR = "Visual Studio 14 2015" }
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if ($env:APPVEYOR_JOB_NAME -like "*Visual Studio 2017*") {
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$env:CMAKE_GENERATOR = "Visual Studio 15 2017"
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$env:CMAKE_INCLUDE_PATH = "C:\Libraries\boost_1_64_0"
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} else {
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$env:CMAKE_GENERATOR = "Visual Studio 14 2015"
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}
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if ($env:PYTHON) {
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if ($env:PLATFORM -eq "x64") { $env:PYTHON = "$env:PYTHON-x64" }
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$env:PATH = "C:\Python$env:PYTHON\;C:\Python$env:PYTHON\Scripts\;$env:PATH"
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@ -45,7 +49,7 @@ install:
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- ps: |
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Start-FileDownload 'http://bitbucket.org/eigen/eigen/get/3.3.3.zip'
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7z x 3.3.3.zip -y > $null
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$env:CMAKE_INCLUDE_PATH = "eigen-eigen-67e894c6cd8f"
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$env:CMAKE_INCLUDE_PATH = "eigen-eigen-67e894c6cd8f;$env:CMAKE_INCLUDE_PATH"
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build_script:
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- cmake -G "%CMAKE_GENERATOR%" -A "%CMAKE_ARCH%"
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-DPYBIND11_CPP_STANDARD=/std:c++%CPP%
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@ -150,7 +150,7 @@ install:
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$SCRIPT_RUN_PREFIX sh -c "for s in 0 15; do sleep \$s; \
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apt-get -qy --no-install-recommends install \
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$PY_DEBUG python$PYTHON-dev python$PY-pytest python$PY-scipy \
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libeigen3-dev cmake make ${COMPILER_PACKAGES} && break; done"
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libeigen3-dev libboost-dev cmake make ${COMPILER_PACKAGES} && break; done"
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else
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if [ "$CLANG" = "4.0" ]; then
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@ -60,8 +60,7 @@ for custom variant types:
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template <>
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struct visit_helper<boost::variant> {
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template <typename... Args>
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static auto call(Args &&...args)
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-> decltype(boost::apply_visitor(args...)) {
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static auto call(Args &&...args) -> decltype(boost::apply_visitor(args...)) {
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return boost::apply_visitor(args...);
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}
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};
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@ -71,6 +70,13 @@ The ``visit_helper`` specialization is not required if your ``name::variant`` pr
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a ``name::visit()`` function. For any other function name, the specialization must be
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included to tell pybind11 how to visit the variant.
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.. note::
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pybind11 only supports the modern implementation of ``boost::variant``
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which makes use of variadic templates. This requires Boost 1.56 or newer.
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Additionally, on Windows, MSVC 2017 is required because ``boost::variant``
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falls back to the old non-variadic implementation on MSVC 2015.
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.. _opaque:
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Making opaque types
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@ -292,8 +292,10 @@ struct variant_caster_visitor {
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return_value_policy policy;
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handle parent;
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using result_type = handle; // required by boost::variant in C++11
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template <typename T>
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handle operator()(T &&src) const {
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result_type operator()(T &&src) const {
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return make_caster<T>::cast(std::forward<T>(src), policy, parent);
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}
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};
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@ -112,6 +112,9 @@ if(PYBIND11_TEST_FILES_EIGEN_I GREATER -1)
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endif()
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endif()
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# Optional dependency for some tests
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find_package(Boost)
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# Compile with compiler warnings turned on
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function(pybind11_enable_warnings target_name)
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if(MSVC)
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@ -141,37 +144,40 @@ foreach(t ${PYBIND11_CROSS_MODULE_TESTS})
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endforeach()
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set(testdir ${CMAKE_CURRENT_SOURCE_DIR})
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foreach(tgt ${test_targets})
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foreach(target ${test_targets})
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set(test_files ${PYBIND11_TEST_FILES})
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if(NOT tgt STREQUAL "pybind11_tests")
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if(NOT target STREQUAL "pybind11_tests")
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set(test_files "")
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endif()
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# Create the binding library
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pybind11_add_module(${tgt} THIN_LTO ${tgt}.cpp
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${test_files} ${PYBIND11_HEADERS})
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pybind11_enable_warnings(${tgt})
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pybind11_add_module(${target} THIN_LTO ${target}.cpp ${test_files} ${PYBIND11_HEADERS})
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pybind11_enable_warnings(${target})
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if(MSVC)
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target_compile_options(${tgt} PRIVATE /utf-8)
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target_compile_options(${target} PRIVATE /utf-8)
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endif()
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if(EIGEN3_FOUND)
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if (PYBIND11_EIGEN_VIA_TARGET)
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target_link_libraries(${tgt} PRIVATE Eigen3::Eigen)
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target_link_libraries(${target} PRIVATE Eigen3::Eigen)
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else()
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target_include_directories(${tgt} PRIVATE ${EIGEN3_INCLUDE_DIR})
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target_include_directories(${target} PRIVATE ${EIGEN3_INCLUDE_DIR})
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endif()
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target_compile_definitions(${tgt} PRIVATE -DPYBIND11_TEST_EIGEN)
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target_compile_definitions(${target} PRIVATE -DPYBIND11_TEST_EIGEN)
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endif()
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if(Boost_FOUND)
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target_include_directories(${target} PRIVATE ${Boost_INCLUDE_DIRS})
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target_compile_definitions(${target} PRIVATE -DPYBIND11_TEST_BOOST)
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endif()
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# Always write the output file directly into the 'tests' directory (even on MSVC)
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if(NOT CMAKE_LIBRARY_OUTPUT_DIRECTORY)
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set_target_properties(${tgt} PROPERTIES LIBRARY_OUTPUT_DIRECTORY ${testdir})
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set_target_properties(${target} PROPERTIES LIBRARY_OUTPUT_DIRECTORY ${testdir})
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foreach(config ${CMAKE_CONFIGURATION_TYPES})
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string(TOUPPER ${config} config)
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set_target_properties(${tgt} PROPERTIES LIBRARY_OUTPUT_DIRECTORY_${config} ${testdir})
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set_target_properties(${target} PROPERTIES LIBRARY_OUTPUT_DIRECTORY_${config} ${testdir})
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endforeach()
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endif()
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endforeach()
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@ -10,6 +10,27 @@
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#include "pybind11_tests.h"
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#include <pybind11/stl.h>
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// Test with `std::variant` in C++17 mode, or with `boost::variant` in C++11/14
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#if PYBIND11_HAS_VARIANT
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using std::variant;
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#elif PYBIND11_TEST_BOOST
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# include <boost/variant.hpp>
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# define PYBIND11_HAS_VARIANT 1
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using boost::variant;
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namespace pybind11 { namespace detail {
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template <typename... Ts>
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struct type_caster<boost::variant<Ts...>> : variant_caster<boost::variant<Ts...>> {};
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template <>
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struct visit_helper<boost::variant> {
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template <typename... Args>
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static auto call(Args &&...args) -> decltype(boost::apply_visitor(args...)) {
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return boost::apply_visitor(args...);
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}
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};
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}} // namespace pybind11::detail
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#endif
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/// Issue #528: templated constructor
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struct TplCtorClass {
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@ -162,22 +183,27 @@ TEST_SUBMODULE(stl, m) {
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#endif
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#ifdef PYBIND11_HAS_VARIANT
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static_assert(std::is_same<py::detail::variant_caster_visitor::result_type, py::handle>::value,
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"visitor::result_type is required by boost::variant in C++11 mode");
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struct visitor {
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const char *operator()(int) { return "int"; }
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const char *operator()(std::string) { return "std::string"; }
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const char *operator()(double) { return "double"; }
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const char *operator()(std::nullptr_t) { return "std::nullptr_t"; }
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using result_type = const char *;
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result_type operator()(int) { return "int"; }
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result_type operator()(std::string) { return "std::string"; }
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result_type operator()(double) { return "double"; }
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result_type operator()(std::nullptr_t) { return "std::nullptr_t"; }
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};
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// test_variant
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m.def("load_variant", [](std::variant<int, std::string, double, std::nullptr_t> v) {
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return std::visit(visitor(), v);
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m.def("load_variant", [](variant<int, std::string, double, std::nullptr_t> v) {
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return py::detail::visit_helper<variant>::call(visitor(), v);
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});
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m.def("load_variant_2pass", [](std::variant<double, int> v) {
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return std::visit(visitor(), v);
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m.def("load_variant_2pass", [](variant<double, int> v) {
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return py::detail::visit_helper<variant>::call(visitor(), v);
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});
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m.def("cast_variant", []() {
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using V = std::variant<int, std::string>;
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using V = variant<int, std::string>;
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return py::make_tuple(V(5), V("Hello"));
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});
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#endif
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