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 #[cfg(feature = "unstable")]
   9 use std::collections::hash_state::HashState;
  10 use std::hash::Hash;
  11 #[cfg(feature = "unstable")]
  12 use std::hash::Hasher;
  13 #[cfg(feature = "unstable")]
  14 use std::mem;
  15 use std::ops::{Index, IndexMut};
  16 #[cfg(feature = "unstable")]
  17 use std::ptr;
  18
  19 use any::{Any, UncheckedAnyExt};
  20
  21 #[cfg(feature = "unstable")]
  22 struct TypeIdHasher {
  23     value: u64,
  24 }
  25
  26 #[derive(Clone)]
  27 #[cfg(feature = "unstable")]
  28 struct TypeIdState;
  29
  30 #[cfg(feature = "unstable")]
  31 impl HashState for TypeIdState {
  32     type Hasher = TypeIdHasher;
  33
  34     fn hasher(&self) -> TypeIdHasher {
  35         TypeIdHasher { value: 0 }
  36     }
  37 }
  38
  39 #[cfg(feature = "unstable")]
  40 impl Hasher for TypeIdHasher {
  41     #[inline(always)]
  42     fn write(&mut self, bytes: &[u8]) {
  43         // This expects to receive one and exactly one 64-bit value
  44         debug_assert!(bytes.len() == 8);
  45         unsafe {
  46             ptr::copy_nonoverlapping(&mut self.value, mem::transmute(&bytes[0]), 1)
  47         }
  48     }
  49
  50     #[inline(always)]
  51     fn finish(&self) -> u64 { self.value }
  52 }
  53
  54
  55 /// The raw, underlying form of a `Map`.
  56 ///
  57 /// At its essence, this is a wrapper around `HashMap<TypeId, Box<Any>>`, with the portions that
  58 /// would be memory-unsafe removed or marked unsafe. Normal people are expected to use the safe
  59 /// `Map` interface instead, but there is the occasional use for this such as iteration over the
  60 /// contents of an `Map`. However, because you will then be dealing with `Any` trait objects, it
  61 /// doesn’t tend to be so very useful. Still, if you need it, it’s here.
  62 #[derive(Debug)]
  63 pub struct RawMap<A: ?Sized + UncheckedAnyExt = Any> {
  64     #[cfg(feature = "unstable")]
  65     inner: HashMap<TypeId, Box<A>, TypeIdState>,
  66
  67     #[cfg(not(feature = "unstable"))]
  68     inner: HashMap<TypeId, Box<A>>,
  69 }
  70
  71 // #[derive(Clone)] would want A to implement Clone, but in reality it’s only Box<A> that can.
  72 impl<A: ?Sized + UncheckedAnyExt> Clone for RawMap<A> where Box<A>: Clone {
  73     fn clone(&self) -> RawMap<A> {
  74         RawMap {
  75             inner: self.inner.clone(),
  76         }
  77     }
  78 }
  79
  80 impl<A: ?Sized + UncheckedAnyExt> Default for RawMap<A> {
  81     fn default() -> RawMap<A> {
  82         RawMap::new()
  83     }
  84 }
  85
  86 #[cfg(feature = "unstable")]
  87 impl_common_methods! {
  88     field: RawMap.inner;
  89     new() => HashMap::with_hash_state(TypeIdState);
  90     with_capacity(capacity) => HashMap::with_capacity_and_hash_state(capacity, TypeIdState);
  91 }
  92
  93 #[cfg(not(feature = "unstable"))]
  94 impl_common_methods! {
  95     field: RawMap.inner;
  96     new() => HashMap::new();
  97     with_capacity(capacity) => HashMap::with_capacity(capacity);
  98 }
  99
 100 /// RawMap iterator.
 101 #[derive(Clone)]
 102 pub struct Iter<'a, A: ?Sized + UncheckedAnyExt> {
 103     inner: hash_map::Iter<'a, TypeId, Box<A>>,
 104 }
 105 impl<'a, A: ?Sized + UncheckedAnyExt> Iterator for Iter<'a, A> {
 106     type Item = &'a A;
 107     #[inline] fn next(&mut self) -> Option<&'a A> { self.inner.next().map(|x| &**x.1) }
 108     #[inline] fn size_hint(&self) -> (usize, Option<usize>) { self.inner.size_hint() }
 109 }
 110 impl<'a, A: ?Sized + UncheckedAnyExt> ExactSizeIterator for Iter<'a, A> {
 111     #[inline] fn len(&self) -> usize { self.inner.len() }
 112 }
 113
 114 /// RawMap mutable iterator.
 115 pub struct IterMut<'a, A: ?Sized + UncheckedAnyExt> {
 116     inner: hash_map::IterMut<'a, TypeId, Box<A>>,
 117 }
 118 impl<'a, A: ?Sized + UncheckedAnyExt> Iterator for IterMut<'a, A> {
 119     type Item = &'a mut A;
 120     #[inline] fn next(&mut self) -> Option<&'a mut A> { self.inner.next().map(|x| &mut **x.1) }
 121     #[inline] fn size_hint(&self) -> (usize, Option<usize>) { self.inner.size_hint() }
 122 }
 123 impl<'a, A: ?Sized + UncheckedAnyExt> ExactSizeIterator for IterMut<'a, A> {
 124     #[inline] fn len(&self) -> usize { self.inner.len() }
 125 }
 126
 127 /// RawMap move iterator.
 128 pub struct IntoIter<A: ?Sized + UncheckedAnyExt> {
 129     inner: hash_map::IntoIter<TypeId, Box<A>>,
 130 }
 131 impl<A: ?Sized + UncheckedAnyExt> Iterator for IntoIter<A> {
 132     type Item = Box<A>;
 133     #[inline] fn next(&mut self) -> Option<Box<A>> { self.inner.next().map(|x| x.1) }
 134     #[inline] fn size_hint(&self) -> (usize, Option<usize>) { self.inner.size_hint() }
 135 }
 136 impl<A: ?Sized + UncheckedAnyExt> ExactSizeIterator for IntoIter<A> {
 137     #[inline] fn len(&self) -> usize { self.inner.len() }
 138 }
 139
 140 /// RawMap drain iterator.
 141 #[cfg(feature = "unstable")]
 142 pub struct Drain<'a, A: ?Sized + UncheckedAnyExt> {
 143     inner: hash_map::Drain<'a, TypeId, Box<A>>,
 144 }
 145 #[cfg(feature = "unstable")]
 146 impl<'a, A: ?Sized + UncheckedAnyExt> Iterator for Drain<'a, A> {
 147     type Item = Box<A>;
 148     #[inline] fn next(&mut self) -> Option<Box<A>> { self.inner.next().map(|x| x.1) }
 149     #[inline] fn size_hint(&self) -> (usize, Option<usize>) { self.inner.size_hint() }
 150 }
 151 #[cfg(feature = "unstable")]
 152 impl<'a, A: ?Sized + UncheckedAnyExt> ExactSizeIterator for Drain<'a, A> {
 153     #[inline] fn len(&self) -> usize { self.inner.len() }
 154 }
 155
 156 impl<A: ?Sized + UncheckedAnyExt> RawMap<A> {
 157     /// An iterator visiting all entries in arbitrary order.
 158     ///
 159     /// Iterator element type is `&Any`.
 160     #[inline]
 161     pub fn iter(&self) -> Iter<A> {
 162         Iter {
 163             inner: self.inner.iter(),
 164         }
 165     }
 166
 167     /// An iterator visiting all entries in arbitrary order.
 168     ///
 169     /// Iterator element type is `&mut Any`.
 170     #[inline]
 171     pub fn iter_mut(&mut self) -> IterMut<A> {
 172         IterMut {
 173             inner: self.inner.iter_mut(),
 174         }
 175     }
 176
 177     /// Clears the map, returning all items as an iterator.
 178     ///
 179     /// Iterator element type is `Box<Any>`.
 180     ///
 181     /// Keeps the allocated memory for reuse.
 182     #[inline]
 183     #[cfg(feature = "unstable")]
 184     pub fn drain(&mut self) -> Drain<A> {
 185         Drain {
 186             inner: self.inner.drain(),
 187         }
 188     }
 189
 190     /// Gets the entry for the given type in the collection for in-place manipulation.
 191     pub fn entry(&mut self, key: TypeId) -> Entry<A> {
 192         match self.inner.entry(key) {
 193             hash_map::Entry::Occupied(e) => Entry::Occupied(OccupiedEntry {
 194                 inner: e,
 195             }),
 196             hash_map::Entry::Vacant(e) => Entry::Vacant(VacantEntry {
 197                 inner: e,
 198             }),
 199         }
 200     }
 201
 202     /// Returns a reference to the value corresponding to the key.
 203     ///
 204     /// The key may be any borrowed form of the map's key type, but `Hash` and `Eq` on the borrowed
 205     /// form *must* match those for the key type.
 206     pub fn get<Q: ?Sized>(&self, k: &Q) -> Option<&A>
 207     where TypeId: Borrow<Q>, Q: Hash + Eq {
 208         self.inner.get(k).map(|x| &**x)
 209     }
 210
 211     /// Returns true if the map contains a value for the specified key.
 212     ///
 213     /// The key may be any borrowed form of the map's key type, but `Hash` and `Eq` on the borrowed
 214     /// form *must* match those for the key type.
 215     pub fn contains_key<Q: ?Sized>(&self, k: &Q) -> bool
 216     where TypeId: Borrow<Q>, Q: Hash + Eq {
 217         self.inner.contains_key(k)
 218     }
 219
 220     /// Returns a mutable reference to the value corresponding to the key.
 221     ///
 222     /// The key may be any borrowed form of the map's key type, but `Hash` and `Eq` on the borrowed
 223     /// form *must* match those for the key type.
 224     pub fn get_mut<Q: ?Sized>(&mut self, k: &Q) -> Option<&mut A>
 225     where TypeId: Borrow<Q>, Q: Hash + Eq {
 226         self.inner.get_mut(k).map(|x| &mut **x)
 227     }
 228
 229     /// Inserts a key-value pair from the map. If the key already had a value present in the map,
 230     /// that value is returned. Otherwise, None is returned.
 231     ///
 232     /// It is the caller’s responsibility to ensure that the key corresponds with the type ID of
 233     /// the value. If they do not, memory safety may be violated.
 234     pub unsafe fn insert(&mut self, key: TypeId, value: Box<A>) -> Option<Box<A>> {
 235         self.inner.insert(key, value)
 236     }
 237
 238     /// Removes a key from the map, returning the value at the key if the key was previously in the
 239     /// map.
 240     ///
 241     /// The key may be any borrowed form of the map's key type, but `Hash` and `Eq` on the borrowed
 242     /// form *must* match those for the key type.
 243     pub fn remove<Q: ?Sized>(&mut self, k: &Q) -> Option<Box<A>>
 244     where TypeId: Borrow<Q>, Q: Hash + Eq {
 245         self.inner.remove(k)
 246     }
 247
 248 }
 249
 250 impl<A: ?Sized + UncheckedAnyExt, Q> Index<Q> for RawMap<A> where TypeId: Borrow<Q>, Q: Eq + Hash {
 251     type Output = A;
 252
 253     fn index<'a>(&'a self, index: Q) -> &'a A {
 254         self.get(&index).expect("no entry found for key")
 255     }
 256 }
 257
 258 impl<A: ?Sized + UncheckedAnyExt, Q> IndexMut<Q> for RawMap<A> where TypeId: Borrow<Q>, Q: Eq + Hash {
 259     fn index_mut<'a>(&'a mut self, index: Q) -> &'a mut A {
 260         self.get_mut(&index).expect("no entry found for key")
 261     }
 262 }
 263
 264 impl<A: ?Sized + UncheckedAnyExt> IntoIterator for RawMap<A> {
 265     type Item = Box<A>;
 266     type IntoIter = IntoIter<A>;
 267
 268     fn into_iter(self) -> IntoIter<A> {
 269         IntoIter {
 270             inner: self.inner.into_iter(),
 271         }
 272     }
 273 }
 274
 275 /// A view into a single occupied location in a `RawMap`.
 276 pub struct OccupiedEntry<'a, A: ?Sized + UncheckedAnyExt> {
 277     inner: hash_map::OccupiedEntry<'a, TypeId, Box<A>>,
 278 }
 279
 280 /// A view into a single empty location in a `RawMap`.
 281 pub struct VacantEntry<'a, A: ?Sized + UncheckedAnyExt> {
 282     inner: hash_map::VacantEntry<'a, TypeId, Box<A>>,
 283 }
 284
 285 /// A view into a single location in a `RawMap`, which may be vacant or occupied.
 286 pub enum Entry<'a, A: ?Sized + UncheckedAnyExt> {
 287     /// An occupied Entry
 288     Occupied(OccupiedEntry<'a, A>),
 289     /// A vacant Entry
 290     Vacant(VacantEntry<'a, A>),
 291 }
 292
 293 impl<'a, A: ?Sized + UncheckedAnyExt> Entry<'a, A> {
 294     /// Ensures a value is in the entry by inserting the default if empty, and returns
 295     /// a mutable reference to the value in the entry.
 296     ///
 297     /// It is the caller’s responsibility to ensure that the key of the entry corresponds with
 298     /// the type ID of `value`. If they do not, memory safety may be violated.
 299     pub unsafe fn or_insert(self, default: Box<A>) -> &'a mut A {
 300         match self {
 301             Entry::Occupied(inner) => inner.into_mut(),
 302             Entry::Vacant(inner) => inner.insert(default),
 303         }
 304     }
 305
 306     /// Ensures a value is in the entry by inserting the result of the default function if empty,
 307     /// and returns a mutable reference to the value in the entry.
 308     ///
 309     /// It is the caller’s responsibility to ensure that the key of the entry corresponds with
 310     /// the type ID of `value`. If they do not, memory safety may be violated.
 311     pub unsafe fn or_insert_with<F: FnOnce() -> Box<A>>(self, default: F) -> &'a mut A {
 312         match self {
 313             Entry::Occupied(inner) => inner.into_mut(),
 314             Entry::Vacant(inner) => inner.insert(default()),
 315         }
 316     }
 317 }
 318
 319 impl<'a, A: ?Sized + UncheckedAnyExt> OccupiedEntry<'a, A> {
 320     /// Gets a reference to the value in the entry.
 321     pub fn get(&self) -> &A {
 322         &**self.inner.get()
 323     }
 324
 325     /// Gets a mutable reference to the value in the entry.
 326     pub fn get_mut(&mut self) -> &mut A {
 327         &mut **self.inner.get_mut()
 328     }
 329
 330     /// Converts the OccupiedEntry into a mutable reference to the value in the entry
 331     /// with a lifetime bound to the collection itself.
 332     pub fn into_mut(self) -> &'a mut A {
 333         &mut **self.inner.into_mut()
 334     }
 335
 336     /// Sets the value of the entry, and returns the entry's old value.
 337     ///
 338     /// It is the caller’s responsibility to ensure that the key of the entry corresponds with
 339     /// the type ID of `value`. If they do not, memory safety may be violated.
 340     pub unsafe fn insert(&mut self, value: Box<A>) -> Box<A> {
 341         self.inner.insert(value)
 342     }
 343
 344     /// Takes the value out of the entry, and returns it.
 345     pub fn remove(self) -> Box<A> {
 346         self.inner.remove()
 347     }
 348 }
 349
 350 impl<'a, A: ?Sized + UncheckedAnyExt> VacantEntry<'a, A> {
 351     /// Sets the value of the entry with the VacantEntry's key,
 352     /// and returns a mutable reference to it
 353     ///
 354     /// It is the caller’s responsibility to ensure that the key of the entry corresponds with
 355     /// the type ID of `value`. If they do not, memory safety may be violated.
 356     pub unsafe fn insert(self, value: Box<A>) -> &'a mut A {
 357         &mut **self.inner.insert(value)
 358     }
 359 }