use std::borrow::Borrow;
use std::collections::HashMap;
use std::hash::Hash;
/// An interface to the hash map operations used by
/// [`KeyNodeList`](crate::KeyNodeList).
///
/// Any data structure that implements this trait can be used as the
/// underlying hash map for [`KeyNodeList`](crate::KeyNodeList).
pub trait Map<K, V> {
/// Returns the number of elements in the map.
///
/// This operation should compute in *O*(1) time.
fn len(&self) -> usize;
/// Returns `true` if the map contains no elements.
///
/// This operation should compute in *O*(1) time.
#[inline]
fn is_empty(&self) -> bool {
self.len() == 0
}
/// Clears the map, removing all key-value pairs.
/// Keeps the allocated memory for reuse.
fn clear(&mut self);
/// Returns `true` if the map contains a value for the specified key.
///
/// The key may be any borrowed form of the map’s key type, but [`Hash`]
/// and [`Eq`] on the borrowed form must match those for the key type.
///
/// This operation should compute in *O*(1) time on average.
#[inline]
fn contains_key<Q: ?Sized>(&self, k: &Q) -> bool
where
K: Hash + Eq + Borrow<Q>,
Q: Hash + Eq,
{
self.get(k).is_some()
}
/// Returns a reference to the value corresponding to the key.
///
/// The key may be any borrowed form of the map’s key type, but [`Hash`]
/// and [`Eq`] on the borrowed form must match those for the key type.
///
/// This operation should compute in *O*(1) time on average.
fn get<Q: ?Sized>(&self, k: &Q) -> Option<&V>
where
K: Hash + Eq + Borrow<Q>,
Q: Hash + Eq;
/// Returns a mutable reference to the value corresponding to the key.
///
/// The key may be any borrowed form of the map’s key type, but [`Hash`]
/// and [`Eq`] on the borrowed form must match those for the key type.
///
/// This operation should compute in *O*(1) time on average.
fn get_mut<Q: ?Sized>(&mut self, k: &Q) -> Option<&mut V>
where
K: Hash + Eq + Borrow<Q>,
Q: Hash + Eq;
/// Inserts a key-value pair into the map.
///
/// If the map did have this key present, returns an error containing the
/// key and the value.
///
/// If the map did not have this key present, the key-value pair is
/// inserted, and [`Ok(())`](Ok) is returned.
///
/// This operation should compute in *O*(1) time on average.
fn insert<T: Into<V>>(&mut self, k: K, v: T) -> Result<(), (K, T)>
where
K: Hash + Eq;
/// Removes a key from the map, returning the value at the key if the key
/// was previously in the map.
///
/// The key may be any borrowed form of the map’s key type, but [`Hash`]
/// and [`Eq`] on the borrowed form must match those for the key type.
///
/// This operation should compute in *O*(1) time on average.
#[inline]
fn remove<Q: ?Sized>(&mut self, k: &Q) -> Option<V>
where
K: Hash + Eq + Borrow<Q>,
Q: Hash + Eq,
{
self.remove_entry(k).map(|(_, v)| v)
}
/// Removes a key from the map, returning the stored key and value if the
/// key was previously in the map.
///
/// The key may be any borrowed form of the map’s key type, but [`Hash`]
/// and [`Eq`] on the borrowed form must match those for the key type.
///
/// This operation should compute in *O*(1) time on average.
fn remove_entry<Q: ?Sized>(&mut self, k: &Q) -> Option<(K, V)>
where
K: Hash + Eq + Borrow<Q>,
Q: Hash + Eq;
}
impl<K, V> Map<K, V> for HashMap<K, V> {
#[inline]
fn len(&self) -> usize {
self.len()
}
#[inline]
fn clear(&mut self) {
self.clear()
}
#[inline]
fn get<Q: ?Sized>(&self, k: &Q) -> Option<&V>
where
K: Hash + Eq + Borrow<Q>,
Q: Hash + Eq,
{
self.get(k)
}
#[inline]
fn get_mut<Q: ?Sized>(&mut self, k: &Q) -> Option<&mut V>
where
K: Hash + Eq + Borrow<Q>,
Q: Hash + Eq,
{
self.get_mut(k)
}
#[inline]
#[allow(clippy::map_entry)]
fn insert<T: Into<V>>(&mut self, k: K, v: T) -> Result<(), (K, T)>
where
K: Hash + Eq,
{
if self.contains_key(&k) {
Err((k, v))
} else {
self.insert(k, v.into());
Ok(())
}
}
#[inline]
fn remove_entry<Q: ?Sized>(&mut self, k: &Q) -> Option<(K, V)>
where
K: Hash + Eq + Borrow<Q>,
Q: Hash + Eq,
{
self.remove_entry(k)
}
}