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/// Defining an error with set of reason.
/// # Usage
/// ```
/// use error_ex::{create_error};
/// create_error!(ErrorType => ErrorReason1, ErrorReason2, ErrorReason3);
/// ```
/// ## Examples
///
/// ```
/// use error_ex::{create_error};
///
/// create_error!(InputError => IllegalArgument, InvalidInput, MissingArgument);
/// //Now, you can use the following code to instantiate this error
/// InputError::illegal_argument(format!("Your message here"));
///
/// ```
///
/// ## Error Mapping
///
/// The explicit way
/// ```
/// use std::fs;
/// use error_ex::{create_error};
///
/// create_error!(FileError => IoError);
/// create_error!(SchemaError => ParseError);
///
/// let error: Result<(), FileError> = Err(FileError::io_error("".to_string()));
///
/// let mapped = error.map_err(|error| {
/// SchemaError::parse_error(format!("SchemaError::ParseError error {error}"))
/// });
///
/// ```
/// ## Function wrapper
/// The above code can be simplified using `map_to__error!`
/// macro using the build in lower order function
/// ```
///
/// use std::fs;
/// use std::io::Error;
/// use error_ex::{create_error};
///
/// create_error!(FileError => IoError);
/// create_error!(SchemaError => ParseError);
///
/// let error: Result<(), FileError> = Err(FileError::io_error("".to_string()));
///
/// let mapped = error.map_err(SchemaError::map_to_parse_error);
///
/// ```
///
#[macro_export]
macro_rules! create_error {
( $error:ident => $( $error_reason:ident ),* ) => {
paste::paste! {
#[derive(Debug, Clone, PartialEq, Eq)]
pub struct $error {
pub reason: [<$error Reason>],
pub message: String,
}
#[derive(Debug, Clone, PartialEq, Eq)]
#[allow(unused_qualifications)]
pub enum [<$error Reason>] {
$(
[<$error_reason>],
)*
}
impl $error {
$(
#[allow(unused_qualifications)]
pub fn [<$error_reason:snake>](message: String) -> $error {
$error {
reason: [<$error Reason>]::$error_reason,
message,
}
}
)*
$(
#[allow(unused_qualifications)]
pub fn [<map_to_ $error_reason:snake>]<E>(error: E) -> $error
where
E: std::error::Error,
{
let error_name = stringify!($error);
let error_reason_name = stringify!($error_reason);
let error_string =
format!("{}::{} caused by {}", error_name, error_reason_name, error);
$error {
reason: [<$error Reason>]::$error_reason,
message: error_string,
}
}
)*
}
impl std::error::Error for $error {}
impl std::fmt::Display for $error {
fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
let error_name = stringify!([<$error:camel>]);
write!(
f,
"{:#?} error, reason: {:#?}, message {:#?}",
error_name,
self.reason,
self.message
)
}
}
}
};
}