| // Copyright 2018 The Rust Project Developers. See the COPYRIGHT |
| // file at the top-level directory of this distribution and at |
| // http://rust-lang.org/COPYRIGHT. |
| // |
| // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or |
| // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license |
| // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your |
| // option. This file may not be copied, modified, or distributed |
| // except according to those terms. |
| |
| use std::hash::Hash; |
| use std::hash::BuildHasher; |
| use std::hash::Hasher; |
| use std::collections::HashMap; |
| use std::collections::hash_map::RawEntryMut; |
| use std::borrow::Borrow; |
| |
| pub trait HashInterner<K: Eq + Hash> { |
| fn intern_ref<Q: ?Sized, F: FnOnce() -> K>(&mut self, value: &Q, make: F) -> K |
| where K: Borrow<Q>, |
| Q: Hash + Eq; |
| |
| fn intern<Q, F: FnOnce(Q) -> K>(&mut self, value: Q, make: F) -> K |
| where K: Borrow<Q>, |
| Q: Hash + Eq; |
| } |
| |
| impl<K: Eq + Hash + Copy, S: BuildHasher> HashInterner<K> for HashMap<K, (), S> { |
| #[inline] |
| fn intern_ref<Q: ?Sized, F: FnOnce() -> K>(&mut self, value: &Q, make: F) -> K |
| where K: Borrow<Q>, |
| Q: Hash + Eq |
| { |
| let mut hasher = self.hasher().build_hasher(); |
| value.hash(&mut hasher); |
| let hash = hasher.finish(); |
| let entry = self.raw_entry_mut().from_key_hashed_nocheck(hash, value); |
| |
| match entry { |
| RawEntryMut::Occupied(e) => *e.key(), |
| RawEntryMut::Vacant(e) => { |
| let v = make(); |
| e.insert_hashed_nocheck(hash, v, ()); |
| v |
| } |
| } |
| } |
| |
| #[inline] |
| fn intern<Q, F: FnOnce(Q) -> K>(&mut self, value: Q, make: F) -> K |
| where K: Borrow<Q>, |
| Q: Hash + Eq |
| { |
| let mut hasher = self.hasher().build_hasher(); |
| value.hash(&mut hasher); |
| let hash = hasher.finish(); |
| let entry = self.raw_entry_mut().from_key_hashed_nocheck(hash, &value); |
| |
| match entry { |
| RawEntryMut::Occupied(e) => *e.key(), |
| RawEntryMut::Vacant(e) => { |
| let v = make(value); |
| e.insert_hashed_nocheck(hash, v, ()); |
| v |
| } |
| } |
| } |
| } |