Trait core_extensions::option_result_ext::OptionExt[−][src]

pub trait OptionExt<T>: ResultLike + TypeIdentity<Type = Option<T>> + Sized {
    fn filter_<F>(self, predicate: F) -> Option<T>
    where
        F: FnOnce(&T) -> bool,
    { ... }

    fn map_ref<'a, U, F>(&'a self, f: F) -> Option<U>
    where
        T: 'a,
        F: FnOnce(&'a T) -> U,
    { ... }

    fn map_mut<'a, U, F>(&'a mut self, f: F) -> Option<U>
    where
        T: 'a,
        F: FnOnce(&'a mut T) -> U,
    { ... }
}

Extension trait for Option.

Provided Methods

Allows using Option::filter before Rust 1.27.

Example

use core_extensions::OptionExt;

let text="what the ";
 
assert_eq!(Some(text).filter_(|x| x.len()==9 ).is_some(),true);
 
assert_eq!(
    text.split_whitespace().next()
        .filter_(|x| x.len()==4 ),
    Some("what"));

assert_eq!(Some(text).filter_(|x| x.len()==20 ),None);
 
assert_eq!(
    text.split_whitespace().next()
        .filter_(|x| x.len()==10 ),
    None);

Maps as reference to the contents.

Example

use core_extensions::OptionExt;
 
struct User{
    name:String,
    surname:String,
}
 
let user=Some(User{name:"Matt".into(),surname:"Parker".into()});
let name   =user.map_ref(|v| v.name.as_str() );
let surname=user.map_ref(|v| v.surname.as_str() );
 
assert_eq!(name,Some("Matt"));
assert_eq!(surname,Some("Parker"));

Maps as mutable reference to the contents.

Example

use core_extensions::OptionExt;
 
struct User{
    name:String,
    surname:String,
}
 
let mut user=Some(User{name:"Matt".into(),surname:"Parker".into()});
{
    let name   =user.map_mut(|v|{
        v.name.push_str("hew") ;
        v.name.as_str()
    });
     
    assert_eq!(name,Some("Matthew"));
}
assert_eq!(user.unwrap().name,"Matthew");

Implementations on Foreign Types

impl<T> OptionExt<T> for Option<T>
[src]

Implementors