mirror of
https://github.com/matrix-construct/construct
synced 2024-11-30 10:42:47 +01:00
258 lines
11 KiB
C++
258 lines
11 KiB
C++
// Matrix Construct
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//
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// Copyright (C) Matrix Construct Developers, Authors & Contributors
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// Copyright (C) 2016-2018 Jason Volk <jason@zemos.net>
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//
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// Permission to use, copy, modify, and/or distribute this software for any
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// purpose with or without fee is hereby granted, provided that the above
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// copyright notice and this permission notice is present in all copies. The
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// full license for this software is available in the LICENSE file.
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#pragma once
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#define HAVE_IRCD_EXCEPTION_H
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/// Forward declarations for boost::system because it is not included here.
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namespace boost::system
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{
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struct error_code;
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struct error_category;
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struct system_error;
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namespace errc {}
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}
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namespace ircd
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{
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struct terminate;
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struct exception; // Root exception
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// util
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bool system_category(const std::error_category &) noexcept;
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bool system_category(const std::error_code &) noexcept;
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bool is(const std::error_code &, const std::errc &) noexcept;
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std::error_code make_error_code(const int &code = errno);
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std::error_code make_error_code(const std::error_code &);
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std::error_code make_error_code(const std::system_error &);
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std::error_code make_error_code(const boost::system::error_code &);
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std::error_code make_error_code(const boost::system::system_error &);
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std::system_error make_system_error(const int &code = errno);
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std::system_error make_system_error(const std::errc &);
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std::system_error make_system_error(const std::error_code &);
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std::system_error make_system_error(const boost::system::error_code &);
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std::system_error make_system_error(const boost::system::system_error &);
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template<class... args> std::exception_ptr make_system_eptr(args&&...);
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template<class... args> [[noreturn]] void throw_system_error(args&&...);
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template<class E, class... args> std::exception_ptr make_exception_ptr(args&&...);
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string_view string(const mutable_buffer &, const std::error_code &);
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string_view string(const mutable_buffer &, const std::system_error &);
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string_view string(const mutable_buffer &, const boost::system::error_code &);
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string_view string(const mutable_buffer &, const boost::system::system_error &);
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std::string string(const std::error_code &);
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std::string string(const std::system_error &);
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std::string string(const boost::system::error_code &);
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std::string string(const boost::system::system_error &);
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void panicking(const std::exception &) noexcept;
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void panicking(const std::exception_ptr &) noexcept;
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void _aborting_() noexcept;
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}
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/// The root exception type.
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///
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/// All exceptions in the project inherit from this type. We generally don't
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/// have catch blocks on this type. Instead we use `ircd::error` to catch
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/// project-specific exceptions. This gives us just a little more indirection
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/// to play with before inheriting from std::exception.
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///
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/// Not all exceptions are from project developer's code, such as
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/// `std::out_of_range`, etc. It's not necessarily bad to just catch
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/// `std::exception` and we do it often enough, but be considerate.
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///
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/// Remember: Not all exceptions have to inherit from `std::exception` either.
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/// We have only one example of this: ctx::terminated. To be sure nothing can
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/// possibly get through you can `catch(...)` but with extreme care that you
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/// are not discarding a termination which will hang the `ircd::ctx` you're on.
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///
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/// !!!
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/// NOTE: CONTEXT SWITCHES CANNOT OCCUR INSIDE CATCH BLOCKS UNLESS YOU USE THE
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/// MITIGATION TOOLS PROVIDED IN `ircd::ctx` WHICH RESULT IN THE LOSS OF THE
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/// ABILITY TO RETHROW THE EXCEPTION (i.e `throw` statement). BEST PRACTICE
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/// IS TO RETURN CONTROL FROM THE CATCH BLOCK BEFORE CONTEXT SWITCHING.
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/// !!!
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struct ircd::exception
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:virtual std::exception
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{
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static constexpr const size_t &BUFSIZE
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{
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512UL
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};
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protected:
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IRCD_OVERLOAD(generate_skip)
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char buf[BUFSIZE];
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ssize_t generate(const char *const &name, const string_view &fmt, const va_rtti &ap) noexcept;
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ssize_t generate(const string_view &fmt, const va_rtti &ap) noexcept;
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public:
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const char *what() const noexcept override
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{
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return buf;
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}
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exception(generate_skip_t = {}) noexcept
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{
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buf[0] = '\0';
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}
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exception(exception &&) = delete;
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exception(const exception &) = delete;
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exception &operator=(exception &&) = delete;
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exception &operator=(const exception &) = delete;
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};
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/// Always prefer ircd::terminate() to std::terminate() for all project code.
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struct ircd::terminate
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{
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[[noreturn]] terminate(const std::exception &) noexcept;
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[[noreturn]] terminate(std::exception_ptr) noexcept;
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[[noreturn]] terminate() noexcept;
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};
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/// Exception generator convenience macro
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///
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/// If you want to create your own exception type, you have found the right
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/// place! This macro allows creating an exception in the the hierarchy.
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///
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/// To create an exception, invoke this macro in your header. Examples:
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///
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/// IRCD_EXCEPTION(ircd::exception, my_exception)
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/// IRCD_EXCEPTION(my_exception, my_specific_exception)
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///
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/// Then your catch sequence can look like the following:
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///
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/// catch(const my_specific_exception &e)
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/// {
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/// log("something specifically bad happened: %s", e.what());
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/// }
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/// catch(const my_exception &e)
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/// {
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/// log("something generically bad happened: %s", e.what());
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/// }
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/// catch(const ircd::exception &e)
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/// {
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/// log("unrelated bad happened: %s", e.what());
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/// }
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/// catch(const std::exception &e)
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/// {
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/// log("unhandled bad happened: %s", e.what());
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/// }
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///
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/// Remember: the order of the catch blocks is important.
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///
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#define IRCD_EXCEPTION(parent, name) \
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struct name \
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:parent \
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{ \
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template<class... args> \
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name(const string_view &fmt = " ", args&&... ap) noexcept \
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:parent{generate_skip} \
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{ \
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generate(#name, fmt, ircd::va_rtti{std::forward<args>(ap)...}); \
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} \
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\
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name(generate_skip_t) noexcept \
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:parent{generate_skip} \
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{ \
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} \
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}; \
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/// Hides the name of the exception when generating a string
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#define IRCD_EXCEPTION_HIDENAME(parent, name) \
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struct name \
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:parent \
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{ \
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template<class... args> \
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name(const string_view &fmt = " ", args&&... ap) noexcept \
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:parent{generate_skip} \
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{ \
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generate(fmt, ircd::va_rtti{std::forward<args>(ap)...}); \
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} \
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\
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name(generate_skip_t = {}) noexcept \
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:parent{generate_skip} \
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{ \
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} \
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};
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/// Creates a panic-type exception.
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///
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/// Throwable which will terminate on construction in debug mode but throw
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/// normally in release mode. Ideally this should never be thrown in release
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/// mode because the termination in debug means a test can never pass and
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/// the triggering callsite should be eliminated. Nevertheless it throws
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/// normally in release mode for recovering at an exception handler.
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#define IRCD_PANICKING(parent, name) \
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struct name \
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:parent \
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{ \
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template<class... args> \
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name(const string_view &fmt = " ", args&&... ap) noexcept \
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:parent{generate_skip} \
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{ \
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generate(#name, fmt, ircd::va_rtti{std::forward<args>(ap)...}); \
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ircd::panicking(*this); \
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} \
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\
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name(generate_skip_t) \
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:parent{generate_skip} \
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{ \
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} \
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}; \
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namespace ircd
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{
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/// Root error exception type. Inherit from this.
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/// List your own exception somewhere else (unless you're overhauling libircd).
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/// example, in your namespace:
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///
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/// IRCD_EXCEPTION(ircd::error, error)
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///
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IRCD_EXCEPTION(exception, error) // throw ircd::error("something bad")
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IRCD_EXCEPTION(error, user_error) // throw ircd::user_error("something silly")
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// panic errors; see IRCD_PANICKING docs.
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IRCD_PANICKING(exception, panic)
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IRCD_PANICKING(panic, not_implemented)
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}
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template<class E,
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class... args>
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std::exception_ptr
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ircd::make_exception_ptr(args&&... a)
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try
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{
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throw E{std::forward<args>(a)...};
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}
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catch(const E &)
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{
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return std::current_exception();
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};
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template<class... args>
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void
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ircd::throw_system_error(args&&... a)
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{
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throw std::system_error
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{
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make_error_code(std::forward<args>(a)...)
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};
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}
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template<class... args>
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std::exception_ptr
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ircd::make_system_eptr(args&&... a)
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{
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return std::make_exception_ptr(make_system_error(std::forward<args>(a)...));
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}
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