76 lines
2.1 KiB
Rust
76 lines
2.1 KiB
Rust
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use core::hash::{BuildHasher, Hash};
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use super::{Equivalent, IndexMap};
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pub struct PrivateMarker {}
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/// Opt-in mutable access to keys.
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///
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/// These methods expose `&mut K`, mutable references to the key as it is stored
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/// in the map.
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/// You are allowed to modify the keys in the hashmap **if the modification
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/// does not change the key’s hash and equality**.
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///
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/// If keys are modified erroneously, you can no longer look them up.
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/// This is sound (memory safe) but a logical error hazard (just like
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/// implementing PartialEq, Eq, or Hash incorrectly would be).
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///
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/// `use` this trait to enable its methods for `IndexMap`.
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pub trait MutableKeys {
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type Key;
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type Value;
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/// Return item index, mutable reference to key and value
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fn get_full_mut2<Q: ?Sized>(
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&mut self,
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key: &Q,
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) -> Option<(usize, &mut Self::Key, &mut Self::Value)>
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where
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Q: Hash + Equivalent<Self::Key>;
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/// Scan through each key-value pair in the map and keep those where the
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/// closure `keep` returns `true`.
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///
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/// The elements are visited in order, and remaining elements keep their
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/// order.
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///
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/// Computes in **O(n)** time (average).
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fn retain2<F>(&mut self, keep: F)
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where
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F: FnMut(&mut Self::Key, &mut Self::Value) -> bool;
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/// This method is not useful in itself – it is there to “seal” the trait
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/// for external implementation, so that we can add methods without
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/// causing breaking changes.
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fn __private_marker(&self) -> PrivateMarker;
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}
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/// Opt-in mutable access to keys.
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///
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/// See [`MutableKeys`](trait.MutableKeys.html) for more information.
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impl<K, V, S> MutableKeys for IndexMap<K, V, S>
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where
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K: Eq + Hash,
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S: BuildHasher,
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{
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type Key = K;
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type Value = V;
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fn get_full_mut2<Q: ?Sized>(&mut self, key: &Q) -> Option<(usize, &mut K, &mut V)>
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where
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Q: Hash + Equivalent<K>,
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{
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self.get_full_mut2_impl(key)
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}
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fn retain2<F>(&mut self, keep: F)
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where
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F: FnMut(&mut K, &mut V) -> bool,
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{
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self.retain_mut(keep)
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}
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fn __private_marker(&self) -> PrivateMarker {
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PrivateMarker {}
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}
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}
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