error_utils Namespace Reference

Contains utilities for error handling and classification. More...

Classes
class	Error
	A wrapper class for system error codes with additional context. More...

Typedefs
template<typename T = void>
using	Result = std::expected<T, Error>
	A specialization of std::expected for the Error type.
using	VoidResult = Result<>
	Result type for void (std::expected<void, Error>)
using	StringResult = Result<std::string>
	Result type for strings (std::expected<std::string, Error>)
using	IntResult = Result<int>
	Result type for integers (std::expected<int, Error>)
using	BoolResult = Result<bool>
	Result type for booleans (std::expected<bool, Error>)

Enumerations
enum class	ExtraError {   invalid_argument = 1 , length_error , logic_error , value_too_small ,   nonexistent_local_time , ambiguous_local_time , format_error , runtime_error ,   bad_alloc , bad_typeid , bad_cast , bad_optional_access ,   bad_expected_access , bad_variant_access , bad_weak_ptr , bad_function_call ,   bad_exception , exception , unknown_exception , unknown_error }
	Represents specific error codes for exception handling and error classification. More...
enum class	ExtraErrorCondition {   logic_error = 1 , runtime_error , resource_error , access_error ,   other_error }
	Represents categories of error conditions for error handling and classification. More...

Functions
constexpr std::error_code	make_error_code (ExtraError e)
	Create an error code from an ExtraError enum value.
constexpr std::error_condition	make_error_condition (ExtraErrorCondition e)
	Create an error condition from an ExtraErrorCondition enum value.
template<typename T, typename E, typename Ctx = std::string_view> requires detail::convertible_to_error_code<E>
constexpr Result< T >	make_error (E &&code, Ctx &&context={})
	Create an error result of the specified type.
template<typename T>
constexpr Result< T >	make_error (const std::error_code &code, const std::string_view context={})
	Create an error result of the specified type from a std::error_code.
template<typename T>
constexpr Result< T >	make_error (const std::regex_constants::error_type code, std::string_view context={})
	Create an error result of the specified type from a std::regex_constants::error_type.
std::error_code	last_error () noexcept
	Retrieve the last system error code and reset errno.
template<typename T>
Result< T >	make_error_from_errno (const std::string_view context={})
	Create an error result from the current errno value.
template<typename Func, typename R = std::invoke_result_t<Func>>
auto	with_errno (Func &&func, const std::string_view error_context={}) -> Result< R >
	Execute a function that may set errno, capturing the result and any error.
template<typename Func> requires std::is_nothrow_invocable_v<Func>
IntResult	invoke_with_syscall_api (Func &&func, const std::string_view error_context={}) noexcept
	Execute a function that may set errno, capturing the result and any error.
template<typename Func, typename R = std::invoke_result_t<Func>>
constexpr auto	try_catch (Func &&func, std::string_view context={}) -> Result< R >
	Execute a function and catch common exceptions, converting them to errors.
template<typename T>
constexpr Result< T >	first_of (std::initializer_list< Result< T > > results)
	Return first success result from multiple alternatives.

Detailed Description

Contains utilities for error handling and classification.

Typedef Documentation

BoolResult

using error_utils::BoolResult = Result<bool>

Result type for booleans (std::expected<bool, Error>)

IntResult

using error_utils::IntResult = Result<int>

Result type for integers (std::expected<int, Error>)

Result

template<typename T = void>

using error_utils::Result = std::expected<T, Error>

A specialization of std::expected for the Error type.

Template Parameters

T	The type of the expected value. Defaults to void

StringResult

using error_utils::StringResult = Result<std::string>

Result type for strings (std::expected<std::string, Error>)

VoidResult

using error_utils::VoidResult = Result<>

Result type for void (std::expected<void, Error>)

Enumeration Type Documentation

ExtraError

enum class error_utils::ExtraError

strong

Represents specific error codes for exception handling and error classification.

This scoped enumeration defines detailed error codes that map to specific C++ standard library exceptions, providing a unified way to handle various error types.

It is designed to work with the standard error handling facilities and integrates with std::error_code and std::error_condition

Enumerator
invalid_argument	std::invalid_argument exception.
length_error	std::length_error exception.
logic_error	std::logic_error base exception.
value_too_small	std::underflow_error exception.
nonexistent_local_time	std::chrono::nonexistent_local_time exception.
ambiguous_local_time	std::chrono::ambiguous_local_time exception.
format_error	std::format_error exception.
runtime_error	std::runtime_error base exception.
bad_alloc	std::bad_alloc exception.
bad_typeid	std::bad_typeid exception.
bad_cast	std::bad_cast exception.
bad_optional_access	std::bad_optional_access exception.
bad_expected_access	std::bad_expected_access exception.
bad_variant_access	std::bad_variant_access exception.
bad_weak_ptr	std::bad_weak_ptr exception.
bad_function_call	std::bad_function_call exception.
bad_exception	std::bad_exception exception.
exception	all std::exception exceptions.
unknown_exception	catch-all for any other exceptions.
unknown_error	Unknown error (not related to exceptions).

ExtraErrorCondition

enum class error_utils::ExtraErrorCondition

strong

Represents categories of error conditions for error handling and classification.

This enumeration defines broad categories of errors that can occur in the system, which are used to group specific error codes into more general error conditions.

Enumerator
logic_error	Errors related to program logic and invalid operations.
runtime_error	Errors occurring during program execution.
resource_error	Errors related to resource allocation and management.
access_error	Errors related to invalid access of data structures.
other_error	Other errors that do not fit into the above categories.

Function Documentation

first_of()

template<typename T>

Result< T > error_utils::first_of ( std::initializer_list< Result< T > > results )

nodiscardconstexpr

Return first success result from multiple alternatives.

Parameters

results

Multiple results of the same type

Template Parameters

T	The type of the result

Returns

First successful result or combined error

invoke_with_syscall_api()

template<typename Func>
requires std::is_nothrow_invocable_v<Func>

IntResult error_utils::invoke_with_syscall_api ( Func && func, const std::string_view error_context = {} )

nodiscardnoexcept

Execute a function that may set errno, capturing the result and any error.

This function is intended for use with system calls that return an integer result, where a return value of -1 indicates an error.

Parameters

func	Function that may set errno. Expected to return an integral type convertible to int.

Template Parameters

Func	Type of the function to execute

Parameters

error_context

Context to use if an error occurs

Template Parameters

Func	The type of the function to execute

Returns

Result of the function or an error if errno was set

Note

The errno value is reset before and after the function call.

The function must be noexcept to ensure that it does not throw exceptions.

Notice that the function must be invocable with no arguments.

Use a lambda or std::bind to wrap the function.

last_error()

std::error_code error_utils::last_error ( )

inlinenodiscardnoexcept

Retrieve the last system error code and reset errno.

Returns

The last system error code as std::error_code

make_error() [1/3]

template<typename T>

Result< T > error_utils::make_error ( const std::error_code & code, const std::string_view context = {} )

nodiscardconstexpr

Create an error result of the specified type from a std::error_code.

Parameters

code	The std::error_code error code
context	Optional context information

Template Parameters

T	The type of the result

Returns

An unexpected result with the error.

make_error() [2/3]

template<typename T>

Result< T > error_utils::make_error ( const std::regex_constants::error_type code, std::string_view context = {} )

nodiscardconstexpr

Create an error result of the specified type from a std::regex_constants::error_type.

Parameters

code	The regex error code
context	Optional context information

Template Parameters

T	The type of the result

Returns

An unexpected result with the regex error.

make_error() [3/3]

template<typename T, typename E, typename Ctx = std::string_view>
requires detail::convertible_to_error_code<E>

Result< T > error_utils::make_error ( E && code, Ctx && context = {} )

nodiscardconstexpr

Create an error result of the specified type.

Parameters

code	The error code
context	Optional context information

Template Parameters

T	The type of the result
E	The type of the error code
Ctx	The type of the context information

Returns

An unexpected result with the error.

make_error_code()

std::error_code error_utils::make_error_code ( ExtraError e )

constexpr

Create an error code from an ExtraError enum value.

Parameters

e	The ExtraError enum value

make_error_condition()

std::error_condition error_utils::make_error_condition ( ExtraErrorCondition e )

constexpr

Create an error condition from an ExtraErrorCondition enum value.

Parameters

e	The ExtraErrorCondition enum value

make_error_from_errno()

template<typename T>

Result< T > error_utils::make_error_from_errno ( const std::string_view context = {} )

nodiscard

Create an error result from the current errno value.

Parameters

context

Optional context information

Template Parameters

T	The type of the result

Returns

An unexpected result with the current errno

try_catch()

template<typename Func, typename R = std::invoke_result_t<Func>>

auto error_utils::try_catch ( Func && func, std::string_view context = {} ) -> Result<R>

nodiscardconstexpr

Execute a function and catch common exceptions, converting them to errors.

Parameters

func	Function to execute
context	Error context

Template Parameters

Func	The type of the function to execute
R	The return type of the function. Automatically deduced.

Returns

Result of the function or an error from caught exceptions

with_errno()

template<typename Func, typename R = std::invoke_result_t<Func>>

auto error_utils::with_errno ( Func && func, const std::string_view error_context = {} ) -> Result<R>

nodiscard

Execute a function that may set errno, capturing the result and any error.

Note

The errno value is reset before and after the function call.

Parameters

func	Function that may set errno
error_context	Context to use if an error occurs

Template Parameters

Func	The type of the function to execute
R	The return type of the function. Automatically deduced.

Returns

Result of the function or an error if errno was set