Trait ref_map::ResultRefMap

pub trait ResultRefMap<'r, T: 'r, E: 'r> {
    fn ref_map<U, F>(&'r self, f: F) -> Result<U, &E>
    where
        F: FnOnce(&'r T) -> U + 'r;
    fn ref_map_err<D, F>(&'r self, f: F) -> Result<&T, D>
    where
        F: FnOnce(&'r E) -> D + 'r;
}

Adds the ref_map() and ref_map_err() extension methods onto Result.

The ref_map() method borrows the internal object and passes it to a closure to be mapped in some way. This allows convenient use of as_* type methods or calculations which require the borrowed internal value.

use ref_map::*;

let answer: Result<Vec<i8>, Error> = Ok(vec![4, 7, 9, 5, 6]);

let filtered = answer.ref_map(|v| &v[3..]);
let answer = &[5, 6];

assert_eq!(filtered, Ok(&answer[..]));

The ref_map_err() provides the same, but on the Err(_) variant instead of Ok(_).

let answer: Result<(), String> = Err("file not found".into());

let error = answer.ref_map_err(|s| s.as_str());

assert_eq!(error, Err("file not found"));

See the crate-level documentation for more information.

Required methods

fn ref_map<U, F>(&'r self, f: F) -> Result<U, &E> where
    F: FnOnce(&'r T) -> U + 'r, 

Borrows the value in the Ok variant and maps it using the provided closure.

fn ref_map_err<D, F>(&'r self, f: F) -> Result<&T, D> where
    F: FnOnce(&'r E) -> D + 'r, 

Borrows the value in the Err variant and maps it using the provided closure.

Implementations on Foreign Types

impl<'r, T: 'r, E: 'r> ResultRefMap<'r, T, E> for Result<T, E>

fn ref_map<U, F>(&'r self, f: F) -> Result<U, &E> where
    F: FnOnce(&'r T) -> U + 'r, 

fn ref_map_err<D, F>(&'r self, f: F) -> Result<&T, D> where
    F: FnOnce(&'r E) -> D + 'r, 

Implementors