cxx/include/exception

// -*- C++ -*-
//===-------------------------- exception ---------------------------------===//
//
//                     The LLVM Compiler Infrastructure
//
// This file is dual licensed under the MIT and the University of Illinois Open
// Source Licenses. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//

#ifndef _LIBCPP_EXCEPTION
#define _LIBCPP_EXCEPTION

/*
    exception synopsis

namespace std
{

class exception
{
public:
    exception() noexcept;
    exception(const exception&) noexcept;
    exception& operator=(const exception&) noexcept;
    virtual ~exception() noexcept;
    virtual const char* what() const noexcept;
};

class bad_exception
    : public exception
{
public:
    bad_exception() noexcept;
    bad_exception(const bad_exception&) noexcept;
    bad_exception& operator=(const bad_exception&) noexcept;
    virtual ~bad_exception() noexcept;
    virtual const char* what() const noexcept;
};

typedef void (*unexpected_handler)();
unexpected_handler set_unexpected(unexpected_handler  f ) noexcept;
unexpected_handler get_unexpected() noexcept;
[[noreturn]] void unexpected();

typedef void (*terminate_handler)();
terminate_handler set_terminate(terminate_handler  f ) noexcept;
terminate_handler get_terminate() noexcept;
[[noreturn]] void terminate() noexcept;

bool uncaught_exception()  noexcept;
int  uncaught_exceptions() noexcept;  // C++17

typedef unspecified exception_ptr;

exception_ptr current_exception() noexcept;
void rethrow_exception [[noreturn]] (exception_ptr p);
template<class E> exception_ptr make_exception_ptr(E e) noexcept;

class nested_exception
{
public:
    nested_exception() noexcept;
    nested_exception(const nested_exception&) noexcept = default;
    nested_exception& operator=(const nested_exception&) noexcept = default;
    virtual ~nested_exception() = default;

    // access functions
    [[noreturn]] void rethrow_nested() const;
    exception_ptr nested_ptr() const noexcept;
};

template <class T> [[noreturn]] void throw_with_nested(T&& t);
template <class E> void rethrow_if_nested(const E& e);

}  // std

*/

#include <__config>
#include <cstddef>
#include <type_traits>

#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
#pragma GCC system_header
#endif

namespace std  // purposefully not using versioning namespace
{

class _LIBCPP_EXCEPTION_ABI exception
{
public:
    _LIBCPP_INLINE_VISIBILITY exception() _NOEXCEPT {}
    virtual ~exception() _NOEXCEPT;
    virtual const char* what() const _NOEXCEPT;
};

class _LIBCPP_EXCEPTION_ABI bad_exception
    : public exception
{
public:
    _LIBCPP_INLINE_VISIBILITY bad_exception() _NOEXCEPT {}
    virtual ~bad_exception() _NOEXCEPT;
    virtual const char* what() const _NOEXCEPT;
};

typedef void (*unexpected_handler)();
_LIBCPP_FUNC_VIS unexpected_handler set_unexpected(unexpected_handler) _NOEXCEPT;
_LIBCPP_FUNC_VIS unexpected_handler get_unexpected() _NOEXCEPT;
_LIBCPP_NORETURN _LIBCPP_FUNC_VIS void unexpected();

typedef void (*terminate_handler)();
_LIBCPP_FUNC_VIS terminate_handler set_terminate(terminate_handler) _NOEXCEPT;
_LIBCPP_FUNC_VIS terminate_handler get_terminate() _NOEXCEPT;
_LIBCPP_NORETURN _LIBCPP_FUNC_VIS void terminate() _NOEXCEPT;

_LIBCPP_FUNC_VIS bool uncaught_exception() _NOEXCEPT;
_LIBCPP_FUNC_VIS int uncaught_exceptions() _NOEXCEPT;

class _LIBCPP_TYPE_VIS exception_ptr;

_LIBCPP_FUNC_VIS exception_ptr current_exception() _NOEXCEPT;
_LIBCPP_NORETURN _LIBCPP_FUNC_VIS void rethrow_exception(exception_ptr);

class _LIBCPP_TYPE_VIS exception_ptr
{
    void* __ptr_;
public:
    _LIBCPP_INLINE_VISIBILITY exception_ptr() _NOEXCEPT : __ptr_() {}
    _LIBCPP_INLINE_VISIBILITY exception_ptr(nullptr_t) _NOEXCEPT : __ptr_() {}
    exception_ptr(const exception_ptr&) _NOEXCEPT;
    exception_ptr& operator=(const exception_ptr&) _NOEXCEPT;
    ~exception_ptr() _NOEXCEPT;

    _LIBCPP_INLINE_VISIBILITY
    _LIBCPP_EXPLICIT
        operator bool() const _NOEXCEPT {return __ptr_ != nullptr;}

    friend _LIBCPP_INLINE_VISIBILITY
    bool operator==(const exception_ptr& __x, const exception_ptr& __y) _NOEXCEPT
        {return __x.__ptr_ == __y.__ptr_;}
    friend _LIBCPP_INLINE_VISIBILITY
    bool operator!=(const exception_ptr& __x, const exception_ptr& __y) _NOEXCEPT
        {return !(__x == __y);}

    friend _LIBCPP_FUNC_VIS exception_ptr current_exception() _NOEXCEPT;
    friend _LIBCPP_FUNC_VIS void rethrow_exception(exception_ptr);
};

template<class _Ep>
exception_ptr
make_exception_ptr(_Ep __e) _NOEXCEPT
{
#ifndef _LIBCPP_NO_EXCEPTIONS
    try
    {
        throw __e;
    }
    catch (...)
    {
        return current_exception();
    }
#endif  // _LIBCPP_NO_EXCEPTIONS
}

// nested_exception

class _LIBCPP_EXCEPTION_ABI nested_exception
{
    exception_ptr __ptr_;
public:
    nested_exception() _NOEXCEPT;
//     nested_exception(const nested_exception&) noexcept = default;
//     nested_exception& operator=(const nested_exception&) noexcept = default;
    virtual ~nested_exception() _NOEXCEPT;

    // access functions
    _LIBCPP_NORETURN void rethrow_nested() const;
    _LIBCPP_INLINE_VISIBILITY exception_ptr nested_ptr() const _NOEXCEPT {return __ptr_;}
};

template <class _Tp>
struct __nested
    : public _Tp,
      public nested_exception
{
    _LIBCPP_INLINE_VISIBILITY explicit __nested(const _Tp& __t) : _Tp(__t) {}
};

template <class _Tp>
_LIBCPP_NORETURN
void
#ifndef _LIBCPP_HAS_NO_RVALUE_REFERENCES
throw_with_nested(_Tp&& __t, typename enable_if<
                  is_class<typename remove_reference<_Tp>::type>::value &&
                  !is_base_of<nested_exception, typename remove_reference<_Tp>::type>::value
                  && !__libcpp_is_final<typename remove_reference<_Tp>::type>::value
                                    >::type* = 0)
#else  // _LIBCPP_HAS_NO_RVALUE_REFERENCES
throw_with_nested (_Tp& __t, typename enable_if<
                  is_class<_Tp>::value && !is_base_of<nested_exception, _Tp>::value
                                    >::type* = 0)
#endif  // _LIBCPP_HAS_NO_RVALUE_REFERENCES
{
#ifndef _LIBCPP_NO_EXCEPTIONS
    throw __nested<typename remove_reference<_Tp>::type>(_VSTD::forward<_Tp>(__t));
#endif
}

template <class _Tp>
_LIBCPP_NORETURN
void
#ifndef _LIBCPP_HAS_NO_RVALUE_REFERENCES
throw_with_nested(_Tp&& __t, typename enable_if<
                  !is_class<typename remove_reference<_Tp>::type>::value ||
                  is_base_of<nested_exception, typename remove_reference<_Tp>::type>::value
                  || __libcpp_is_final<typename remove_reference<_Tp>::type>::value
                                    >::type* = 0)
#else  // _LIBCPP_HAS_NO_RVALUE_REFERENCES
throw_with_nested (_Tp& __t, typename enable_if<
                  !is_class<_Tp>::value || is_base_of<nested_exception, _Tp>::value
                                    >::type* = 0)
#endif  // _LIBCPP_HAS_NO_RVALUE_REFERENCES
{
#ifndef _LIBCPP_NO_EXCEPTIONS
    throw _VSTD::forward<_Tp>(__t);
#endif
}

template <class _Ep>
inline _LIBCPP_INLINE_VISIBILITY
void
rethrow_if_nested(const _Ep& __e, typename enable_if<
                                   is_polymorphic<_Ep>::value
                                                   >::type* = 0)
{
    const nested_exception* __nep = dynamic_cast<const nested_exception*>(_VSTD::addressof(__e));
    if (__nep)
        __nep->rethrow_nested();
}

template <class _Ep>
inline _LIBCPP_INLINE_VISIBILITY
void
rethrow_if_nested(const _Ep&, typename enable_if<
                                   !is_polymorphic<_Ep>::value
                                                   >::type* = 0)
{
}

}  // std

#endif  // _LIBCPP_EXCEPTION