test_builtin_casters.cpp

/*
    tests/test_builtin_casters.cpp -- Casters available without any additional headers

    Copyright (c) 2017 Wenzel Jakob <wenzel.jakob@epfl.ch>

    All rights reserved. Use of this source code is governed by a
    BSD-style license that can be found in the LICENSE file.
*/

#include <pybind11/complex.h>

#include "pybind11_tests.h"

struct ConstRefCasted {
    int tag;
};

PYBIND11_NAMESPACE_BEGIN(pybind11)
PYBIND11_NAMESPACE_BEGIN(detail)
template <>
class type_caster<ConstRefCasted> {
public:
    static constexpr auto name = const_name<ConstRefCasted>();

    // Input is unimportant, a new value will always be constructed based on the
    // cast operator.
    bool load(handle, bool) { return true; }

    explicit operator ConstRefCasted &&() {
        value = {1};
        // NOLINTNEXTLINE(performance-move-const-arg)
        return std::move(value);
    }
    explicit operator ConstRefCasted &() {
        value = {2};
        return value;
    }
    explicit operator ConstRefCasted *() {
        value = {3};
        return &value;
    }

    explicit operator const ConstRefCasted &() {
        value = {4};
        return value;
    }
    explicit operator const ConstRefCasted *() {
        value = {5};
        return &value;
    }

    // custom cast_op to explicitly propagate types to the conversion operators.
    template <typename T_>
    using cast_op_type =
        /// const
        conditional_t<
            std::is_same<remove_reference_t<T_>, const ConstRefCasted *>::value,
            const ConstRefCasted *,
            conditional_t<
                std::is_same<T_, const ConstRefCasted &>::value,
                const ConstRefCasted &,
                /// non-const
                conditional_t<std::is_same<remove_reference_t<T_>, ConstRefCasted *>::value,
                              ConstRefCasted *,
                              conditional_t<std::is_same<T_, ConstRefCasted &>::value,
                                            ConstRefCasted &,
                                            /* else */ ConstRefCasted &&>>>>;

private:
    ConstRefCasted value = {0};
};
PYBIND11_NAMESPACE_END(detail)
PYBIND11_NAMESPACE_END(pybind11)

TEST_SUBMODULE(builtin_casters, m) {
    // test_simple_string
    m.def("string_roundtrip", [](const char *s) { return s; });

    // test_unicode_conversion
    // Some test characters in utf16 and utf32 encodings.  The last one (the 𝐀) contains a null
    // byte
    char32_t a32 = 0x61 /*a*/, z32 = 0x7a /*z*/, ib32 = 0x203d /*‽*/, cake32 = 0x1f382 /*🎂*/,
             mathbfA32 = 0x1d400 /*𝐀*/;
    char16_t b16 = 0x62 /*b*/, z16 = 0x7a, ib16 = 0x203d, cake16_1 = 0xd83c, cake16_2 = 0xdf82,
             mathbfA16_1 = 0xd835, mathbfA16_2 = 0xdc00;
    std::wstring wstr;
    wstr.push_back(0x61);   // a
    wstr.push_back(0x2e18); // ⸘
    if (PYBIND11_SILENCE_MSVC_C4127(sizeof(wchar_t) == 2)) {
        wstr.push_back(mathbfA16_1);
        wstr.push_back(mathbfA16_2);
    } // 𝐀, utf16
    else {
        wstr.push_back((wchar_t) mathbfA32);
    }                     // 𝐀, utf32
    wstr.push_back(0x7a); // z

    m.def("good_utf8_string", []() {
        return std::string((const char *) u8"Say utf8\u203d \U0001f382 \U0001d400");
    }); // Say utf8‽ 🎂 𝐀
    m.def("good_utf16_string", [=]() {
        return std::u16string({b16, ib16, cake16_1, cake16_2, mathbfA16_1, mathbfA16_2, z16});
    }); // b‽🎂𝐀z
    m.def("good_utf32_string", [=]() {
        return std::u32string({a32, mathbfA32, cake32, ib32, z32});
    });                                                 // a𝐀🎂‽z
    m.def("good_wchar_string", [=]() { return wstr; }); // a‽𝐀z
    m.def("bad_utf8_string", []() {
        return std::string("abc\xd0"
                           "def");
    });
    m.def("bad_utf16_string", [=]() { return std::u16string({b16, char16_t(0xd800), z16}); });
    // Under Python 2.7, invalid unicode UTF-32 characters didn't appear to trigger
    // UnicodeDecodeError
    m.def("bad_utf32_string", [=]() { return std::u32string({a32, char32_t(0xd800), z32}); });
    if (PYBIND11_SILENCE_MSVC_C4127(sizeof(wchar_t) == 2)) {
        m.def("bad_wchar_string", [=]() {
            return std::wstring({wchar_t(0x61), wchar_t(0xd800)});
        });
    }
    m.def("u8_Z", []() -> char { return 'Z'; });
    m.def("u8_eacute", []() -> char { return '\xe9'; });
    m.def("u16_ibang", [=]() -> char16_t { return ib16; });
    m.def("u32_mathbfA", [=]() -> char32_t { return mathbfA32; });
    m.def("wchar_heart", []() -> wchar_t { return 0x2665; });

    // test_single_char_arguments
    m.attr("wchar_size") = py::cast(sizeof(wchar_t));
    m.def("ord_char", [](char c) -> int { return static_cast<unsigned char>(c); });
    m.def("ord_char_lv", [](char &c) -> int { return static_cast<unsigned char>(c); });
    m.def("ord_char16", [](char16_t c) -> uint16_t { return c; });
    m.def("ord_char16_lv", [](char16_t &c) -> uint16_t { return c; });
    m.def("ord_char32", [](char32_t c) -> uint32_t { return c; });
    m.def("ord_wchar", [](wchar_t c) -> int { return c; });

    // test_bytes_to_string
    m.def("strlen", [](char *s) { return strlen(s); });
    m.def("string_length", [](const std::string &s) { return s.length(); });

#ifdef PYBIND11_HAS_U8STRING
    m.attr("has_u8string") = true;
    m.def("good_utf8_u8string", []() {
        return std::u8string(u8"Say utf8\u203d \U0001f382 \U0001d400");
    }); // Say utf8‽ 🎂 𝐀
    m.def("bad_utf8_u8string", []() {
        return std::u8string((const char8_t *) "abc\xd0"
                                               "def");
    });

    m.def("u8_char8_Z", []() -> char8_t { return u8'Z'; });

    // test_single_char_arguments
    m.def("ord_char8", [](char8_t c) -> int { return static_cast<unsigned char>(c); });
    m.def("ord_char8_lv", [](char8_t &c) -> int { return static_cast<unsigned char>(c); });
#endif

    // test_string_view
#ifdef PYBIND11_HAS_STRING_VIEW
    m.attr("has_string_view") = true;
    m.def("string_view_print", [](std::string_view s) { py::print(s, s.size()); });
    m.def("string_view16_print", [](std::u16string_view s) { py::print(s, s.size()); });
    m.def("string_view32_print", [](std::u32string_view s) { py::print(s, s.size()); });
    m.def("string_view_chars", [](std::string_view s) {
        py::list l;
        for (auto c : s) {
            l.append((std::uint8_t) c);
        }
        return l;
    });
    m.def("string_view16_chars", [](std::u16string_view s) {
        py::list l;
        for (auto c : s) {
            l.append((int) c);
        }
        return l;
    });
    m.def("string_view32_chars", [](std::u32string_view s) {
        py::list l;
        for (auto c : s) {
            l.append((int) c);
        }
        return l;
    });
    m.def("string_view_return",
          []() { return std::string_view((const char *) u8"utf8 secret \U0001f382"); });
    m.def("string_view16_return",
          []() { return std::u16string_view(u"utf16 secret \U0001f382"); });
    m.def("string_view32_return",
          []() { return std::u32string_view(U"utf32 secret \U0001f382"); });

    // The inner lambdas here are to also test implicit conversion
    using namespace std::literals;
    m.def("string_view_bytes",
          []() { return [](py::bytes b) { return b; }("abc \x80\x80 def"sv); });
    m.def("string_view_str",
          []() { return [](py::str s) { return s; }("abc \342\200\275 def"sv); });
    m.def("string_view_from_bytes",
          [](const py::bytes &b) { return [](std::string_view s) { return s; }(b); });
    m.def("string_view_memoryview", []() {
        static constexpr auto val = "Have some \360\237\216\202"sv;
        return py::memoryview::from_memory(val);
    });

#    ifdef PYBIND11_HAS_U8STRING
    m.def("string_view8_print", [](std::u8string_view s) { py::print(s, s.size()); });
    m.def("string_view8_chars", [](std::u8string_view s) {
        py::list l;
        for (auto c : s)
            l.append((std::uint8_t) c);
        return l;
    });
    m.def("string_view8_return", []() { return std::u8string_view(u8"utf8 secret \U0001f382"); });
    m.def("string_view8_str", []() { return py::str{std::u8string_view{u8"abc ‽ def"}}; });
#    endif

    struct TypeWithBothOperatorStringAndStringView {
        // NOLINTNEXTLINE(google-explicit-constructor)
        operator std::string() const { return "success"; }
        // NOLINTNEXTLINE(google-explicit-constructor)
        operator std::string_view() const { return "failure"; }
    };
    m.def("bytes_from_type_with_both_operator_string_and_string_view",
          []() { return py::bytes(TypeWithBothOperatorStringAndStringView()); });
    m.def("str_from_type_with_both_operator_string_and_string_view",
          []() { return py::str(TypeWithBothOperatorStringAndStringView()); });
#endif

    // test_integer_casting
    m.def("i32_str", [](std::int32_t v) { return std::to_string(v); });
    m.def("u32_str", [](std::uint32_t v) { return std::to_string(v); });
    m.def("i64_str", [](std::int64_t v) { return std::to_string(v); });
    m.def("u64_str", [](std::uint64_t v) { return std::to_string(v); });

    // test_int_convert
    m.def("int_passthrough", [](int arg) { return arg; });
    m.def(
        "int_passthrough_noconvert", [](int arg) { return arg; }, py::arg{}.noconvert());

    // test_tuple
    m.def(
        "pair_passthrough",
        [](const std::pair<bool, std::string> &input) {
            return std::make_pair(input.second, input.first);
        },
        "Return a pair in reversed order");
    m.def(
        "tuple_passthrough",
        [](std::tuple<bool, std::string, int> input) {
            return std::make_tuple(std::get<2>(input), std::get<1>(input), std::get<0>(input));
        },
        "Return a triple in reversed order");
    m.def("empty_tuple", []() { return std::tuple<>(); });
    static std::pair<RValueCaster, RValueCaster> lvpair;
    static std::tuple<RValueCaster, RValueCaster, RValueCaster> lvtuple;
    static std::pair<RValueCaster, std::tuple<RValueCaster, std::pair<RValueCaster, RValueCaster>>>
        lvnested;
    m.def("rvalue_pair", []() { return std::make_pair(RValueCaster{}, RValueCaster{}); });
    m.def("lvalue_pair", []() -> const decltype(lvpair) & { return lvpair; });
    m.def("rvalue_tuple",
          []() { return std::make_tuple(RValueCaster{}, RValueCaster{}, RValueCaster{}); });
    m.def("lvalue_tuple", []() -> const decltype(lvtuple) & { return lvtuple; });
    m.def("rvalue_nested", []() {
        return std::make_pair(
            RValueCaster{},
            std::make_tuple(RValueCaster{}, std::make_pair(RValueCaster{}, RValueCaster{})));
    });
    m.def("lvalue_nested", []() -> const decltype(lvnested) & { return lvnested; });

    m.def(
        "int_string_pair",
        []() {
            // Using no-destructor idiom to side-step warnings from overzealous compilers.
            static auto *int_string_pair = new std::pair<int, std::string>{2, "items"};
            return int_string_pair;
        },
        py::return_value_policy::reference);

    // test_builtins_cast_return_none
    m.def("return_none_string", []() -> std::string * { return nullptr; });
    m.def("return_none_char", []() -> const char * { return nullptr; });
    m.def("return_none_bool", []() -> bool * { return nullptr; });
    m.def("return_none_int", []() -> int * { return nullptr; });
    m.def("return_none_float", []() -> float * { return nullptr; });
    m.def("return_none_pair", []() -> std::pair<int, int> * { return nullptr; });

    // test_none_deferred
    m.def("defer_none_cstring", [](char *) { return false; });
    m.def("defer_none_cstring", [](const py::none &) { return true; });
    m.def("defer_none_custom", [](UserType *) { return false; });
    m.def("defer_none_custom", [](const py::none &) { return true; });
    m.def("nodefer_none_void", [](void *) { return true; });
    m.def("nodefer_none_void", [](const py::none &) { return false; });

    // test_void_caster
    m.def("load_nullptr_t", [](std::nullptr_t) {}); // not useful, but it should still compile
    m.def("cast_nullptr_t", []() { return std::nullptr_t{}; });

    // [workaround(intel)] ICC 20/21 breaks with py::arg().stuff, using py::arg{}.stuff works.

    // test_bool_caster
    m.def("bool_passthrough", [](bool arg) { return arg; });
    m.def(
        "bool_passthrough_noconvert", [](bool arg) { return arg; }, py::arg{}.noconvert());

    // TODO: This should be disabled and fixed in future Intel compilers
#if !defined(__INTEL_COMPILER)
    // Test "bool_passthrough_noconvert" again, but using () instead of {} to construct py::arg
    // When compiled with the Intel compiler, this results in segmentation faults when importing
    // the module. Tested with icc (ICC) 2021.1 Beta 20200827, this should be tested again when
    // a newer version of icc is available.
    m.def(
        "bool_passthrough_noconvert2", [](bool arg) { return arg; }, py::arg().noconvert());
#endif

    // test_reference_wrapper
    m.def("refwrap_builtin", [](std::reference_wrapper<int> p) { return 10 * p.get(); });
    m.def("refwrap_usertype", [](std::reference_wrapper<UserType> p) { return p.get().value(); });
    m.def("refwrap_usertype_const",
          [](std::reference_wrapper<const UserType> p) { return p.get().value(); });

    m.def("refwrap_lvalue", []() -> std::reference_wrapper<UserType> {
        static UserType x(1);
        return std::ref(x);
    });
    m.def("refwrap_lvalue_const", []() -> std::reference_wrapper<const UserType> {
        static UserType x(1);
        return std::cref(x);
    });

    // Not currently supported (std::pair caster has return-by-value cast operator);
    // triggers static_assert failure.
    // m.def("refwrap_pair", [](std::reference_wrapper<std::pair<int, int>>) { });

    m.def(
        "refwrap_list",
        [](bool copy) {
            static IncType x1(1), x2(2);
            py::list l;
            for (const auto &f : {std::ref(x1), std::ref(x2)}) {
                l.append(py::cast(
                    f, copy ? py::return_value_policy::copy : py::return_value_policy::reference));
            }
            return l;
        },
        "copy"_a);

    m.def("refwrap_iiw", [](const IncType &w) { return w.value(); });
    m.def("refwrap_call_iiw", [](IncType &w, const py::function &f) {
        py::list l;
        l.append(f(std::ref(w)));
        l.append(f(std::cref(w)));
        IncType x(w.value());
        l.append(f(std::ref(x)));
        IncType y(w.value());
        auto r3 = std::ref(y);
        l.append(f(r3));
        return l;
    });

    // test_complex
    m.def("complex_cast", [](float x) { return "{}"_s.format(x); });
    m.def("complex_cast",
          [](std::complex<float> x) { return "({}, {})"_s.format(x.real(), x.imag()); });

    // test int vs. long (Python 2)
    m.def("int_cast", []() { return (int) 42; });
    m.def("long_cast", []() { return (long) 42; });
    m.def("longlong_cast", []() { return ULLONG_MAX; });

    /// test void* cast operator
    m.def("test_void_caster", []() -> bool {
        void *v = (void *) 0xabcd;
        py::object o = py::cast(v);
        return py::cast<void *>(o) == v;
    });

    // Tests const/non-const propagation in cast_op.
    m.def("takes", [](ConstRefCasted x) { return x.tag; });
    m.def("takes_move", [](ConstRefCasted &&x) { return x.tag; });
    m.def("takes_ptr", [](ConstRefCasted *x) { return x->tag; });
    m.def("takes_ref", [](ConstRefCasted &x) { return x.tag; });
    m.def("takes_ref_wrap", [](std::reference_wrapper<ConstRefCasted> x) { return x.get().tag; });
    m.def("takes_const_ptr", [](const ConstRefCasted *x) { return x->tag; });
    m.def("takes_const_ref", [](const ConstRefCasted &x) { return x.tag; });
    m.def("takes_const_ref_wrap",
          [](std::reference_wrapper<const ConstRefCasted> x) { return x.get().tag; });
}