Trait copse::SortableBy

pub trait SortableBy<O: ?Sized + TotalOrder> {
    // Required method
    fn sort_key(&self) -> &O::OrderedType;
}

A type that is sortable by its sort_key under total orders of type parameter O.

Note that if you wish to use O::OrderedType itself with copse’s collections, you must explicitly implement SortableBy<O> for it even though that implementation will typically be a no-op. This case cannot currently be provided for you by way of a blanket implementation because that would conflict with the blanket borrowing implementation that is provided for the default OrdTotalOrder; implementations for O::OrderedType that are not no-ops are strongly discouraged, as they are prone to causing considerable confusion—for any such use-case, consider defining a distinct TotalOrder instead.

Example

use copse::{BTreeSet, SortableBy, TotalOrder};
use std::cmp::Ordering;

struct MyOrdering;

impl TotalOrder for MyOrdering {
    type OrderedType = str;
    fn cmp(&self, this: &str, that: &str) -> Ordering { this.cmp(that) }
}

impl SortableBy<MyOrdering> for String {
    fn sort_key(&self) -> &str { self.as_str() }
}
impl SortableBy<MyOrdering> for str {
    fn sort_key(&self) -> &str { self }
}

let mut set = BTreeSet::new(MyOrdering);
set.insert(String::from("a"));
assert!(set.contains("a"));

Required Methods

fn sort_key(&self) -> &O::OrderedType

Extract the sort key by which self is ordered under total orders of type O.

Implementors

impl<T: ?Sized + Ord, K: ?Sized + Borrow<T>> SortableBy<OrdTotalOrder<T>> for K