include/exception

// -*- C++ -*-
//===----------------------------------------------------------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//

#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 <__assert> // all public C++ headers provide the assertion handler
#include <__availability>
#include <__config>
#include <__memory/addressof.h>
#include <cstddef>
#include <cstdlib>
#include <type_traits>
#include <version>

// <vcruntime_exception.h> defines its own std::exception and std::bad_exception types,
// which we use in order to be ABI-compatible with other STLs on Windows.
#if defined(_LIBCPP_ABI_VCRUNTIME)
#  include <vcruntime_exception.h>
#endif

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

namespace std  // purposefully not using versioning namespace
{

#if defined(_LIBCPP_ABI_VCRUNTIME) && (!defined(_HAS_EXCEPTIONS) || _HAS_EXCEPTIONS != 0)
// The std::exception class was already included above, but we're explicit about this condition here for clarity.

#elif defined(_LIBCPP_ABI_VCRUNTIME) && _HAS_EXCEPTIONS == 0
// However, <vcruntime_exception.h> does not define std::exception and std::bad_exception
// when _HAS_EXCEPTIONS == 0.
//
// Since libc++ still wants to provide the std::exception hierarchy even when _HAS_EXCEPTIONS == 0
// (after all those are simply types like any other), we define an ABI-compatible version
// of the VCRuntime std::exception and std::bad_exception types in that mode.

struct __std_exception_data {
  char const* _What;
  bool _DoFree;
};

class exception { // base of all library exceptions
public:
  exception() _NOEXCEPT : _Data() {}

  explicit exception(char const* __message) _NOEXCEPT : _Data() {
    _Data._What = __message;
    _Data._DoFree = true;
  }

  exception(exception const&) _NOEXCEPT {}

  exception& operator=(exception const&) _NOEXCEPT { return *this; }

  virtual ~exception() _NOEXCEPT {}

  virtual char const* what() const _NOEXCEPT { return _Data._What ? _Data._What : "Unknown exception"; }

private:
  __std_exception_data _Data;
};

class bad_exception : public exception {
public:
  bad_exception() _NOEXCEPT : exception("bad exception") {}
};

#else // !defined(_LIBCPP_ABI_VCRUNTIME)
// On all other platforms, we define our own std::exception and std::bad_exception types
// regardless of whether exceptions are turned on as a language feature.

class _LIBCPP_EXCEPTION_ABI exception {
public:
  _LIBCPP_INLINE_VISIBILITY exception() _NOEXCEPT {}
  _LIBCPP_INLINE_VISIBILITY exception(const exception&) _NOEXCEPT = default;

  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;
};
#endif // !_LIBCPP_ABI_VCRUNTIME

#if _LIBCPP_STD_VER <= 14 \
    || defined(_LIBCPP_ENABLE_CXX17_REMOVED_UNEXPECTED_FUNCTIONS) \
    || defined(_LIBCPP_BUILDING_LIBRARY)
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();
#endif

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 _LIBCPP_AVAILABILITY_UNCAUGHT_EXCEPTIONS 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);

#ifndef _LIBCPP_ABI_MICROSOFT

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 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>
_LIBCPP_INLINE_VISIBILITY exception_ptr
make_exception_ptr(_Ep __e) _NOEXCEPT
{
#ifndef _LIBCPP_NO_EXCEPTIONS
    try
    {
        throw __e;
    }
    catch (...)
    {
        return current_exception();
    }
#else
    ((void)__e);
    _VSTD::abort();
#endif
}

#else // _LIBCPP_ABI_MICROSOFT

class _LIBCPP_TYPE_VIS exception_ptr
{
_LIBCPP_DIAGNOSTIC_PUSH
_LIBCPP_CLANG_DIAGNOSTIC_IGNORED("-Wunused-private-field")
    void* __ptr1_;
    void* __ptr2_;
_LIBCPP_DIAGNOSTIC_POP
public:
    exception_ptr() _NOEXCEPT;
    exception_ptr(nullptr_t) _NOEXCEPT;
    exception_ptr(const exception_ptr& __other) _NOEXCEPT;
    exception_ptr& operator=(const exception_ptr& __other) _NOEXCEPT;
    exception_ptr& operator=(nullptr_t) _NOEXCEPT;
    ~exception_ptr() _NOEXCEPT;
    explicit operator bool() const _NOEXCEPT;
};

_LIBCPP_FUNC_VIS
bool operator==(const exception_ptr& __x, const exception_ptr& __y) _NOEXCEPT;

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

_LIBCPP_FUNC_VIS void swap(exception_ptr&, exception_ptr&) _NOEXCEPT;

_LIBCPP_FUNC_VIS exception_ptr __copy_exception_ptr(void *__except, const void* __ptr);
_LIBCPP_FUNC_VIS exception_ptr current_exception() _NOEXCEPT;
_LIBCPP_NORETURN _LIBCPP_FUNC_VIS void rethrow_exception(exception_ptr);

// This is a built-in template function which automagically extracts the required
// information.
template <class _E> void *__GetExceptionInfo(_E);

template<class _Ep>
_LIBCPP_INLINE_VISIBILITY exception_ptr
make_exception_ptr(_Ep __e) _NOEXCEPT
{
  return __copy_exception_ptr(_VSTD::addressof(__e), __GetExceptionInfo(__e));
}

#endif // _LIBCPP_ABI_MICROSOFT
// 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) {}
};

#ifndef _LIBCPP_NO_EXCEPTIONS
template <class _Tp, class _Up, bool>
struct __throw_with_nested;

template <class _Tp, class _Up>
struct __throw_with_nested<_Tp, _Up, true> {
    _LIBCPP_NORETURN static inline _LIBCPP_INLINE_VISIBILITY void
    __do_throw(_Tp&& __t)
    {
        throw __nested<_Up>(static_cast<_Tp&&>(__t));
    }
};

template <class _Tp, class _Up>
struct __throw_with_nested<_Tp, _Up, false> {
    _LIBCPP_NORETURN static inline _LIBCPP_INLINE_VISIBILITY void
#ifndef _LIBCPP_CXX03_LANG
    __do_throw(_Tp&& __t)
#else
    __do_throw (_Tp& __t)
#endif // _LIBCPP_CXX03_LANG
    {
        throw static_cast<_Tp&&>(__t);
    }
};
#endif

template <class _Tp>
_LIBCPP_NORETURN _LIBCPP_HIDE_FROM_ABI
void
throw_with_nested(_Tp&& __t)
{
#ifndef _LIBCPP_NO_EXCEPTIONS
    typedef typename decay<_Tp>::type _Up;
    static_assert( is_copy_constructible<_Up>::value, "type thrown must be CopyConstructible");
    __throw_with_nested<_Tp, _Up,
        is_class<_Up>::value &&
        !is_base_of<nested_exception, _Up>::value &&
        !__libcpp_is_final<_Up>::value>::
            __do_throw(static_cast<_Tp&&>(__t));
#else
    ((void)__t);
    // FIXME: Make this abort
#endif
}

template <class _From, class _To>
struct __can_dynamic_cast : _BoolConstant<
              is_polymorphic<_From>::value &&
                 (!is_base_of<_To, _From>::value ||
                   is_convertible<const _From*, const _To*>::value)> {};

template <class _Ep>
inline _LIBCPP_INLINE_VISIBILITY
void
rethrow_if_nested(const _Ep& __e,
                  __enable_if_t< __can_dynamic_cast<_Ep, nested_exception>::value>* = 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&,
                  __enable_if_t<!__can_dynamic_cast<_Ep, nested_exception>::value>* = 0)
{
}

} // namespace std

#endif // _LIBCPP_EXCEPTION