/// `Finish` is a type that represents a value which
/// may have an error occurred during the computation.
///
/// Logically, `Finish<T, E>` is equivalent to `Result<T, (T, E)>`.
#[derive(Debug, Default, Clone, PartialOrd, Ord, PartialEq, Eq, Hash)]
pub struct Finish<T, E> {
value: T,
error: Option<E>,
}
impl<T, E> Finish<T, E> {
/// Makes a new instance.
///
/// # Examples
/// ```
/// use libflate::Finish;
///
/// // The result value of a succeeded computation
/// let succeeded = Finish::new("value", None as Option<()>);
/// assert_eq!(succeeded.into_result(), Ok("value"));
///
/// // The result value of a failed computation
/// let failed = Finish::new("value", Some("error"));
/// assert_eq!(failed.into_result(), Err("error"));
/// ```
pub fn new(value: T, error: Option<E>) -> Self {
Finish {
value: value,
error: error,
}
}
/// Unwraps the instance.
///
/// # Examples
/// ```
/// use libflate::Finish;
///
/// let succeeded = Finish::new("value", None as Option<()>);
/// assert_eq!(succeeded.unwrap(), ("value", None));
///
/// let failed = Finish::new("value", Some("error"));
/// assert_eq!(failed.unwrap(), ("value", Some("error")));
/// ```
pub fn unwrap(self) -> (T, Option<E>) {
(self.value, self.error)
}
/// Converts from `Finish<T, E>` to `Result<T, E>`.
///
/// # Examples
/// ```
/// use libflate::Finish;
///
/// let succeeded = Finish::new("value", None as Option<()>);
/// assert_eq!(succeeded.into_result(), Ok("value"));
///
/// let failed = Finish::new("value", Some("error"));
/// assert_eq!(failed.into_result(), Err("error"));
/// ```
pub fn into_result(self) -> Result<T, E> {
if let Some(e) = self.error {
Err(e)
} else {
Ok(self.value)
}
}
/// Converts from `Finish<T, E>` to `Result<&T, &E>`.
///
/// # Examples
/// ```
/// use libflate::Finish;
///
/// let succeeded = Finish::new("value", None as Option<()>);
/// assert_eq!(succeeded.as_result(), Ok(&"value"));
///
/// let failed = Finish::new("value", Some("error"));
/// assert_eq!(failed.as_result(), Err(&"error"));
/// ```
pub fn as_result(&self) -> Result<&T, &E> {
if let Some(ref e) = self.error {
Err(e)
} else {
Ok(&self.value)
}
}
}