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Add support for boost::variant in C++11 mode

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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 2017-08-08 16:02:31 +02:00
parent e06077bf47
commit 7918bcc95b
6 changed files with 72 additions and 28 deletions
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10
.appveyor.yml
View File

@ -28,8 +28,12 @@ matrix:
install:
- ps: |
if ($env:PLATFORM -eq "x64") { $env:CMAKE_ARCH = "x64" }
if ($env:APPVEYOR_JOB_NAME -like "*Visual Studio 2017*") { $env:CMAKE_GENERATOR = "Visual Studio 15 2017" }
else { $env:CMAKE_GENERATOR = "Visual Studio 14 2015" }
if ($env:APPVEYOR_JOB_NAME -like "*Visual Studio 2017*") {
$env:CMAKE_GENERATOR = "Visual Studio 15 2017"
$env:CMAKE_INCLUDE_PATH = "C:\Libraries\boost_1_64_0"
} else {
$env:CMAKE_GENERATOR = "Visual Studio 14 2015"
}
if ($env:PYTHON) {
if ($env:PLATFORM -eq "x64") { $env:PYTHON = "$env:PYTHON-x64" }
$env:PATH = "C:\Python$env:PYTHON\;C:\Python$env:PYTHON\Scripts\;$env:PATH"
@ -45,7 +49,7 @@ install:
- ps: |
Start-FileDownload 'http://bitbucket.org/eigen/eigen/get/3.3.3.zip'
7z x 3.3.3.zip -y > $null
$env:CMAKE_INCLUDE_PATH = "eigen-eigen-67e894c6cd8f"
$env:CMAKE_INCLUDE_PATH = "eigen-eigen-67e894c6cd8f;$env:CMAKE_INCLUDE_PATH"
build_script:
- cmake -G "%CMAKE_GENERATOR%" -A "%CMAKE_ARCH%"
-DPYBIND11_CPP_STANDARD=/std:c++%CPP%

2
.travis.yml
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@ -150,7 +150,7 @@ install:
$SCRIPT_RUN_PREFIX sh -c "for s in 0 15; do sleep \$s; \
apt-get -qy --no-install-recommends install \
$PY_DEBUG python$PYTHON-dev python$PY-pytest python$PY-scipy \
libeigen3-dev cmake make ${COMPILER_PACKAGES} && break; done"
libeigen3-dev libboost-dev cmake make ${COMPILER_PACKAGES} && break; done"
else
if [ "$CLANG" = "4.0" ]; then

10
docs/advanced/cast/stl.rst
View File

@ -60,8 +60,7 @@ for custom variant types:
template <>
struct visit_helper<boost::variant> {
template <typename... Args>
static auto call(Args &&...args)
-> decltype(boost::apply_visitor(args...)) {
static auto call(Args &&...args) -> decltype(boost::apply_visitor(args...)) {
return boost::apply_visitor(args...);
}
};
@ -71,6 +70,13 @@ The ``visit_helper`` specialization is not required if your ``name::variant`` pr
a ``name::visit()`` function. For any other function name, the specialization must be
included to tell pybind11 how to visit the variant.
.. note::
pybind11 only supports the modern implementation of ``boost::variant``
which makes use of variadic templates. This requires Boost 1.56 or newer.
Additionally, on Windows, MSVC 2017 is required because ``boost::variant``
falls back to the old non-variadic implementation on MSVC 2015.
.. _opaque:
Making opaque types

4
include/pybind11/stl.h
View File

@ -292,8 +292,10 @@ struct variant_caster_visitor {
return_value_policy policy;
handle parent;
using result_type = handle; // required by boost::variant in C++11
template <typename T>
handle operator()(T &&src) const {
result_type operator()(T &&src) const {
return make_caster<T>::cast(std::forward<T>(src), policy, parent);
}
};

30
tests/CMakeLists.txt
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@ -112,6 +112,9 @@ if(PYBIND11_TEST_FILES_EIGEN_I GREATER -1)
endif()
endif()
# Optional dependency for some tests
find_package(Boost)
# Compile with compiler warnings turned on
function(pybind11_enable_warnings target_name)
if(MSVC)
@ -141,37 +144,40 @@ foreach(t ${PYBIND11_CROSS_MODULE_TESTS})
endforeach()
set(testdir ${CMAKE_CURRENT_SOURCE_DIR})
foreach(tgt ${test_targets})
foreach(target ${test_targets})
set(test_files ${PYBIND11_TEST_FILES})
if(NOT tgt STREQUAL "pybind11_tests")
if(NOT target STREQUAL "pybind11_tests")
set(test_files "")
endif()
# Create the binding library
pybind11_add_module(${tgt} THIN_LTO ${tgt}.cpp
${test_files} ${PYBIND11_HEADERS})
pybind11_enable_warnings(${tgt})
pybind11_add_module(${target} THIN_LTO ${target}.cpp ${test_files} ${PYBIND11_HEADERS})
pybind11_enable_warnings(${target})
if(MSVC)
target_compile_options(${tgt} PRIVATE /utf-8)
target_compile_options(${target} PRIVATE /utf-8)
endif()
if(EIGEN3_FOUND)
if (PYBIND11_EIGEN_VIA_TARGET)
target_link_libraries(${tgt} PRIVATE Eigen3::Eigen)
target_link_libraries(${target} PRIVATE Eigen3::Eigen)
else()
target_include_directories(${tgt} PRIVATE ${EIGEN3_INCLUDE_DIR})
target_include_directories(${target} PRIVATE ${EIGEN3_INCLUDE_DIR})
endif()
target_compile_definitions(${tgt} PRIVATE -DPYBIND11_TEST_EIGEN)
target_compile_definitions(${target} PRIVATE -DPYBIND11_TEST_EIGEN)
endif()
if(Boost_FOUND)
target_include_directories(${target} PRIVATE ${Boost_INCLUDE_DIRS})
target_compile_definitions(${target} PRIVATE -DPYBIND11_TEST_BOOST)
endif()
# Always write the output file directly into the 'tests' directory (even on MSVC)
if(NOT CMAKE_LIBRARY_OUTPUT_DIRECTORY)
set_target_properties(${tgt} PROPERTIES LIBRARY_OUTPUT_DIRECTORY ${testdir})
set_target_properties(${target} PROPERTIES LIBRARY_OUTPUT_DIRECTORY ${testdir})
foreach(config ${CMAKE_CONFIGURATION_TYPES})
string(TOUPPER ${config} config)
set_target_properties(${tgt} PROPERTIES LIBRARY_OUTPUT_DIRECTORY_${config} ${testdir})
set_target_properties(${target} PROPERTIES LIBRARY_OUTPUT_DIRECTORY_${config} ${testdir})
endforeach()
endif()
endforeach()

44
tests/test_stl.cpp
View File

@ -10,6 +10,27 @@
#include "pybind11_tests.h"
#include <pybind11/stl.h>
// Test with `std::variant` in C++17 mode, or with `boost::variant` in C++11/14
#if PYBIND11_HAS_VARIANT
using std::variant;
#elif PYBIND11_TEST_BOOST
# include <boost/variant.hpp>
# define PYBIND11_HAS_VARIANT 1
using boost::variant;
namespace pybind11 { namespace detail {
template <typename... Ts>
struct type_caster<boost::variant<Ts...>> : variant_caster<boost::variant<Ts...>> {};
template <>
struct visit_helper<boost::variant> {
template <typename... Args>
static auto call(Args &&...args) -> decltype(boost::apply_visitor(args...)) {
return boost::apply_visitor(args...);
}
};
}} // namespace pybind11::detail
#endif
/// Issue #528: templated constructor
struct TplCtorClass {
@ -162,22 +183,27 @@ TEST_SUBMODULE(stl, m) {
#endif
#ifdef PYBIND11_HAS_VARIANT
static_assert(std::is_same<py::detail::variant_caster_visitor::result_type, py::handle>::value,
"visitor::result_type is required by boost::variant in C++11 mode");
struct visitor {
const char *operator()(int) { return "int"; }
const char *operator()(std::string) { return "std::string"; }
const char *operator()(double) { return "double"; }
const char *operator()(std::nullptr_t) { return "std::nullptr_t"; }
using result_type = const char *;
result_type operator()(int) { return "int"; }
result_type operator()(std::string) { return "std::string"; }
result_type operator()(double) { return "double"; }
result_type operator()(std::nullptr_t) { return "std::nullptr_t"; }
};
// test_variant
m.def("load_variant", [](std::variant<int, std::string, double, std::nullptr_t> v) {
return std::visit(visitor(), v);
m.def("load_variant", [](variant<int, std::string, double, std::nullptr_t> v) {
return py::detail::visit_helper<variant>::call(visitor(), v);
});
m.def("load_variant_2pass", [](std::variant<double, int> v) {
return std::visit(visitor(), v);
m.def("load_variant_2pass", [](variant<double, int> v) {
return py::detail::visit_helper<variant>::call(visitor(), v);
});
m.def("cast_variant", []() {
using V = std::variant<int, std::string>;
using V = variant<int, std::string>;
return py::make_tuple(V(5), V("Hello"));
});
#endif