mpd/src/util/Exception.hxx
2023-03-06 14:59:48 +01:00

118 lines
2.4 KiB
C++

// SPDX-License-Identifier: BSD-2-Clause
// author: Max Kellermann <max.kellermann@gmail.com>
#ifndef EXCEPTION_HXX
#define EXCEPTION_HXX
#include <exception>
#include <string>
#include <utility>
/**
* Throws the specified exception. There is an overload for
* std::exception_ptr which throws the contained exception instead of
* the std::exception_ptr itself.
*/
template<typename T>
[[noreturn]]
inline void
ThrowException(T &&t)
{
throw std::forward<T>(t);
}
[[noreturn]]
inline void
ThrowException(std::exception_ptr ep)
{
std::rethrow_exception(ep);
}
/**
* Create a nested exception, wrapping #ep inside the
* std::current_exception().
*/
template<typename T>
inline std::exception_ptr
NestCurrentException(T &&t) noexcept
{
try {
std::throw_with_nested(std::forward<T>(t));
} catch (...) {
return std::current_exception();
}
}
/**
* Create a nested exception, wrapping #ep inside (a copy of) #t.
*/
template<typename T>
inline std::exception_ptr
NestException(std::exception_ptr ep, T &&t) noexcept
{
try {
std::rethrow_exception(ep);
} catch (...) {
return NestCurrentException(std::forward<T>(t));
}
}
/**
* Find an instance of #T in the nested exception chain, and return a
* pointer. Returns nullptr if no such instance was found.
*/
template<typename T>
[[gnu::pure]]
inline const T *
FindNested(std::exception_ptr ep) noexcept
{
try {
std::rethrow_exception(ep);
} catch (const T &t) {
return &t;
} catch (const std::nested_exception &ne) {
return FindNested<T>(ne.nested_ptr());
} catch (...) {
}
return nullptr;
}
/**
* Find an instance of #T in the nested exception chain, and rethrow
* it. Does nothing if no such instance was found.
*/
template<typename T>
inline void
FindRetrowNested(std::exception_ptr ep)
{
try {
std::rethrow_exception(ep);
} catch (const T &t) {
throw;
} catch (const std::nested_exception &ne) {
FindRetrowNested<T>(ne.nested_ptr());
} catch (...) {
}
}
/**
* Obtain the full concatenated message of an exception and its nested
* chain.
*/
std::string
GetFullMessage(const std::exception &e,
const char *fallback="Unknown exception",
const char *separator="; ") noexcept;
/**
* Obtain the full concatenated message of an exception and its nested
* chain.
*/
std::string
GetFullMessage(std::exception_ptr ep,
const char *fallback="Unknown exception",
const char *separator="; ") noexcept;
#endif