src/raw.rs - anymap blob - Chris Morgan’s Git repositories

   1 //! The raw form of a `Map`, allowing untyped access.
   2 //!
   3 //! All relevant details are in the `RawMap` struct.
   4
   5 use std::any::TypeId;
   6 use std::borrow::Borrow;
   7 use std::collections::hash_map::{self, HashMap};
   8 use std::hash::Hash;
   9 use std::hash::{Hasher, BuildHasherDefault};
  10 use std::mem;
  11 use std::ops::{Index, IndexMut};
  12 use std::ptr;
  13
  14 use any::{Any, UncheckedAnyExt};
  15
  16 #[derive(Default)]
  17 struct TypeIdHasher {
  18     value: u64,
  19 }
  20
  21 impl Hasher for TypeIdHasher {
  22     #[inline]
  23     fn write(&mut self, bytes: &[u8]) {
  24         // This expects to receive one and exactly one 64-bit value
  25         debug_assert!(bytes.len() == 8);
  26         unsafe {
  27             ptr::copy_nonoverlapping(mem::transmute(&bytes[0]), &mut self.value, 1)
  28         }
  29     }
  30
  31     #[inline]
  32     fn finish(&self) -> u64 { self.value }
  33 }
  34
  35 #[test]
  36 fn type_id_hasher() {
  37     fn verify_hashing_with(type_id: TypeId) {
  38         let mut hasher = TypeIdHasher::default();
  39         type_id.hash(&mut hasher);
  40         assert_eq!(hasher.finish(), unsafe { mem::transmute::<TypeId, u64>(type_id) });
  41     }
  42     // Pick a variety of types, just to demonstrate it’s all sane. Normal, zero-sized, unsized, &c.
  43     verify_hashing_with(TypeId::of::<usize>());
  44     verify_hashing_with(TypeId::of::<()>());
  45     verify_hashing_with(TypeId::of::<str>());
  46     verify_hashing_with(TypeId::of::<&str>());
  47     verify_hashing_with(TypeId::of::<Vec<u8>>());
  48 }
  49
  50 /// The raw, underlying form of a `Map`.
  51 ///
  52 /// At its essence, this is a wrapper around `HashMap<TypeId, Box<Any>>`, with the portions that
  53 /// would be memory-unsafe removed or marked unsafe. Normal people are expected to use the safe
  54 /// `Map` interface instead, but there is the occasional use for this such as iteration over the
  55 /// contents of an `Map`. However, because you will then be dealing with `Any` trait objects, it
  56 /// doesn’t tend to be so very useful. Still, if you need it, it’s here.
  57 #[derive(Debug)]
  58 pub struct RawMap<A: ?Sized + UncheckedAnyExt = Any> {
  59     inner: HashMap<TypeId, Box<A>, BuildHasherDefault<TypeIdHasher>>,
  60 }
  61
  62 // #[derive(Clone)] would want A to implement Clone, but in reality it’s only Box<A> that can.
  63 impl<A: ?Sized + UncheckedAnyExt> Clone for RawMap<A> where Box<A>: Clone {
  64     #[inline]
  65     fn clone(&self) -> RawMap<A> {
  66         RawMap {
  67             inner: self.inner.clone(),
  68         }
  69     }
  70 }
  71
  72 impl<A: ?Sized + UncheckedAnyExt> Default for RawMap<A> {
  73     #[inline]
  74     fn default() -> RawMap<A> {
  75         RawMap::new()
  76     }
  77 }
  78
  79 impl_common_methods! {
  80     field: RawMap.inner;
  81     new() => HashMap::with_hasher(Default::default());
  82     with_capacity(capacity) => HashMap::with_capacity_and_hasher(capacity, Default::default());
  83 }
  84
  85 /// `RawMap` iterator.
  86 #[derive(Clone)]
  87 pub struct Iter<'a, A: ?Sized + UncheckedAnyExt> {
  88     inner: hash_map::Iter<'a, TypeId, Box<A>>,
  89 }
  90 impl<'a, A: ?Sized + UncheckedAnyExt> Iterator for Iter<'a, A> {
  91     type Item = &'a A;
  92     #[inline] fn next(&mut self) -> Option<&'a A> { self.inner.next().map(|x| &**x.1) }
  93     #[inline] fn size_hint(&self) -> (usize, Option<usize>) { self.inner.size_hint() }
  94 }
  95 impl<'a, A: ?Sized + UncheckedAnyExt> ExactSizeIterator for Iter<'a, A> {
  96     #[inline] fn len(&self) -> usize { self.inner.len() }
  97 }
  98
  99 /// `RawMap` mutable iterator.
 100 pub struct IterMut<'a, A: ?Sized + UncheckedAnyExt> {
 101     inner: hash_map::IterMut<'a, TypeId, Box<A>>,
 102 }
 103 impl<'a, A: ?Sized + UncheckedAnyExt> Iterator for IterMut<'a, A> {
 104     type Item = &'a mut A;
 105     #[inline] fn next(&mut self) -> Option<&'a mut A> { self.inner.next().map(|x| &mut **x.1) }
 106     #[inline] fn size_hint(&self) -> (usize, Option<usize>) { self.inner.size_hint() }
 107 }
 108 impl<'a, A: ?Sized + UncheckedAnyExt> ExactSizeIterator for IterMut<'a, A> {
 109     #[inline] fn len(&self) -> usize { self.inner.len() }
 110 }
 111
 112 /// `RawMap` move iterator.
 113 pub struct IntoIter<A: ?Sized + UncheckedAnyExt> {
 114     inner: hash_map::IntoIter<TypeId, Box<A>>,
 115 }
 116 impl<A: ?Sized + UncheckedAnyExt> Iterator for IntoIter<A> {
 117     type Item = Box<A>;
 118     #[inline] fn next(&mut self) -> Option<Box<A>> { self.inner.next().map(|x| x.1) }
 119     #[inline] fn size_hint(&self) -> (usize, Option<usize>) { self.inner.size_hint() }
 120 }
 121 impl<A: ?Sized + UncheckedAnyExt> ExactSizeIterator for IntoIter<A> {
 122     #[inline] fn len(&self) -> usize { self.inner.len() }
 123 }
 124
 125 /// `RawMap` drain iterator.
 126 pub struct Drain<'a, A: ?Sized + UncheckedAnyExt> {
 127     inner: hash_map::Drain<'a, TypeId, Box<A>>,
 128 }
 129 impl<'a, A: ?Sized + UncheckedAnyExt> Iterator for Drain<'a, A> {
 130     type Item = Box<A>;
 131     #[inline] fn next(&mut self) -> Option<Box<A>> { self.inner.next().map(|x| x.1) }
 132     #[inline] fn size_hint(&self) -> (usize, Option<usize>) { self.inner.size_hint() }
 133 }
 134 impl<'a, A: ?Sized + UncheckedAnyExt> ExactSizeIterator for Drain<'a, A> {
 135     #[inline] fn len(&self) -> usize { self.inner.len() }
 136 }
 137
 138 impl<A: ?Sized + UncheckedAnyExt> RawMap<A> {
 139     /// An iterator visiting all entries in arbitrary order.
 140     ///
 141     /// Iterator element type is `&Any`.
 142     #[inline]
 143     pub fn iter(&self) -> Iter<A> {
 144         Iter {
 145             inner: self.inner.iter(),
 146         }
 147     }
 148
 149     /// An iterator visiting all entries in arbitrary order.
 150     ///
 151     /// Iterator element type is `&mut Any`.
 152     #[inline]
 153     pub fn iter_mut(&mut self) -> IterMut<A> {
 154         IterMut {
 155             inner: self.inner.iter_mut(),
 156         }
 157     }
 158
 159     /// Clears the map, returning all items as an iterator.
 160     ///
 161     /// Iterator element type is `Box<Any>`.
 162     ///
 163     /// Keeps the allocated memory for reuse.
 164     #[inline]
 165     pub fn drain(&mut self) -> Drain<A> {
 166         Drain {
 167             inner: self.inner.drain(),
 168         }
 169     }
 170
 171     /// Gets the entry for the given type in the collection for in-place manipulation.
 172     #[inline]
 173     pub fn entry(&mut self, key: TypeId) -> Entry<A> {
 174         match self.inner.entry(key) {
 175             hash_map::Entry::Occupied(e) => Entry::Occupied(OccupiedEntry {
 176                 inner: e,
 177             }),
 178             hash_map::Entry::Vacant(e) => Entry::Vacant(VacantEntry {
 179                 inner: e,
 180             }),
 181         }
 182     }
 183
 184     /// Returns a reference to the value corresponding to the key.
 185     ///
 186     /// The key may be any borrowed form of the map's key type, but `Hash` and `Eq` on the borrowed
 187     /// form *must* match those for the key type.
 188     #[inline]
 189     pub fn get<Q: ?Sized>(&self, k: &Q) -> Option<&A>
 190     where TypeId: Borrow<Q>, Q: Hash + Eq {
 191         self.inner.get(k).map(|x| &**x)
 192     }
 193
 194     /// Returns true if the map contains a value for the specified key.
 195     ///
 196     /// The key may be any borrowed form of the map's key type, but `Hash` and `Eq` on the borrowed
 197     /// form *must* match those for the key type.
 198     #[inline]
 199     pub fn contains_key<Q: ?Sized>(&self, k: &Q) -> bool
 200     where TypeId: Borrow<Q>, Q: Hash + Eq {
 201         self.inner.contains_key(k)
 202     }
 203
 204     /// Returns a mutable reference to the value corresponding to the key.
 205     ///
 206     /// The key may be any borrowed form of the map's key type, but `Hash` and `Eq` on the borrowed
 207     /// form *must* match those for the key type.
 208     #[inline]
 209     pub fn get_mut<Q: ?Sized>(&mut self, k: &Q) -> Option<&mut A>
 210     where TypeId: Borrow<Q>, Q: Hash + Eq {
 211         self.inner.get_mut(k).map(|x| &mut **x)
 212     }
 213
 214     /// Inserts a key-value pair from the map. If the key already had a value present in the map,
 215     /// that value is returned. Otherwise, None is returned.
 216     ///
 217     /// It is the caller’s responsibility to ensure that the key corresponds with the type ID of
 218     /// the value. If they do not, memory safety may be violated.
 219     #[inline]
 220     pub unsafe fn insert(&mut self, key: TypeId, value: Box<A>) -> Option<Box<A>> {
 221         self.inner.insert(key, value)
 222     }
 223
 224     /// Removes a key from the map, returning the value at the key if the key was previously in the
 225     /// map.
 226     ///
 227     /// The key may be any borrowed form of the map's key type, but `Hash` and `Eq` on the borrowed
 228     /// form *must* match those for the key type.
 229     #[inline]
 230     pub fn remove<Q: ?Sized>(&mut self, k: &Q) -> Option<Box<A>>
 231     where TypeId: Borrow<Q>, Q: Hash + Eq {
 232         self.inner.remove(k)
 233     }
 234
 235 }
 236
 237 impl<A: ?Sized + UncheckedAnyExt, Q> Index<Q> for RawMap<A> where TypeId: Borrow<Q>, Q: Eq + Hash {
 238     type Output = A;
 239
 240     #[inline]
 241     fn index(&self, index: Q) -> &A {
 242         self.get(&index).expect("no entry found for key")
 243     }
 244 }
 245
 246 impl<A: ?Sized + UncheckedAnyExt, Q> IndexMut<Q> for RawMap<A> where TypeId: Borrow<Q>, Q: Eq + Hash {
 247     #[inline]
 248     fn index_mut(&mut self, index: Q) -> &mut A {
 249         self.get_mut(&index).expect("no entry found for key")
 250     }
 251 }
 252
 253 impl<A: ?Sized + UncheckedAnyExt> IntoIterator for RawMap<A> {
 254     type Item = Box<A>;
 255     type IntoIter = IntoIter<A>;
 256
 257     #[inline]
 258     fn into_iter(self) -> IntoIter<A> {
 259         IntoIter {
 260             inner: self.inner.into_iter(),
 261         }
 262     }
 263 }
 264
 265 /// A view into a single occupied location in a `RawMap`.
 266 pub struct OccupiedEntry<'a, A: ?Sized + UncheckedAnyExt> {
 267     inner: hash_map::OccupiedEntry<'a, TypeId, Box<A>>,
 268 }
 269
 270 /// A view into a single empty location in a `RawMap`.
 271 pub struct VacantEntry<'a, A: ?Sized + UncheckedAnyExt> {
 272     inner: hash_map::VacantEntry<'a, TypeId, Box<A>>,
 273 }
 274
 275 /// A view into a single location in a `RawMap`, which may be vacant or occupied.
 276 pub enum Entry<'a, A: ?Sized + UncheckedAnyExt> {
 277     /// An occupied Entry
 278     Occupied(OccupiedEntry<'a, A>),
 279     /// A vacant Entry
 280     Vacant(VacantEntry<'a, A>),
 281 }
 282
 283 impl<'a, A: ?Sized + UncheckedAnyExt> Entry<'a, A> {
 284     /// Ensures a value is in the entry by inserting the default if empty, and returns
 285     /// a mutable reference to the value in the entry.
 286     ///
 287     /// It is the caller’s responsibility to ensure that the key of the entry corresponds with
 288     /// the type ID of `value`. If they do not, memory safety may be violated.
 289     #[inline]
 290     pub unsafe fn or_insert(self, default: Box<A>) -> &'a mut A {
 291         match self {
 292             Entry::Occupied(inner) => inner.into_mut(),
 293             Entry::Vacant(inner) => inner.insert(default),
 294         }
 295     }
 296
 297     /// Ensures a value is in the entry by inserting the result of the default function if empty,
 298     /// and returns a mutable reference to the value in the entry.
 299     ///
 300     /// It is the caller’s responsibility to ensure that the key of the entry corresponds with
 301     /// the type ID of `value`. If they do not, memory safety may be violated.
 302     #[inline]
 303     pub unsafe fn or_insert_with<F: FnOnce() -> Box<A>>(self, default: F) -> &'a mut A {
 304         match self {
 305             Entry::Occupied(inner) => inner.into_mut(),
 306             Entry::Vacant(inner) => inner.insert(default()),
 307         }
 308     }
 309 }
 310
 311 impl<'a, A: ?Sized + UncheckedAnyExt> OccupiedEntry<'a, A> {
 312     /// Gets a reference to the value in the entry.
 313     #[inline]
 314     pub fn get(&self) -> &A {
 315         &**self.inner.get()
 316     }
 317
 318     /// Gets a mutable reference to the value in the entry.
 319     #[inline]
 320     pub fn get_mut(&mut self) -> &mut A {
 321         &mut **self.inner.get_mut()
 322     }
 323
 324     /// Converts the OccupiedEntry into a mutable reference to the value in the entry
 325     /// with a lifetime bound to the collection itself.
 326     #[inline]
 327     pub fn into_mut(self) -> &'a mut A {
 328         &mut **self.inner.into_mut()
 329     }
 330
 331     /// Sets the value of the entry, and returns the entry's old value.
 332     ///
 333     /// It is the caller’s responsibility to ensure that the key of the entry corresponds with
 334     /// the type ID of `value`. If they do not, memory safety may be violated.
 335     #[inline]
 336     pub unsafe fn insert(&mut self, value: Box<A>) -> Box<A> {
 337         self.inner.insert(value)
 338     }
 339
 340     /// Takes the value out of the entry, and returns it.
 341     #[inline]
 342     pub fn remove(self) -> Box<A> {
 343         self.inner.remove()
 344     }
 345 }
 346
 347 impl<'a, A: ?Sized + UncheckedAnyExt> VacantEntry<'a, A> {
 348     /// Sets the value of the entry with the VacantEntry's key,
 349     /// and returns a mutable reference to it
 350     ///
 351     /// It is the caller’s responsibility to ensure that the key of the entry corresponds with
 352     /// the type ID of `value`. If they do not, memory safety may be violated.
 353     #[inline]
 354     pub unsafe fn insert(self, value: Box<A>) -> &'a mut A {
 355         &mut **self.inner.insert(value)
 356     }
 357 }