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::default::Default;
  11 use std::hash::Hash;
  12 #[cfg(feature = "unstable")]
  13 use std::hash::Hasher;
  14 use std::iter::IntoIterator;
  15 #[cfg(feature = "unstable")]
  16 use std::mem;
  17 use std::ops::{Index, IndexMut};
  18 #[cfg(feature = "unstable")]
  19 use std::ptr;
  20
  21 use any::{Any, UncheckedAnyExt};
  22
  23 #[cfg(feature = "unstable")]
  24 struct TypeIdHasher {
  25     value: u64,
  26 }
  27
  28 #[derive(Clone)]
  29 #[cfg(feature = "unstable")]
  30 struct TypeIdState;
  31
  32 #[cfg(feature = "unstable")]
  33 impl HashState for TypeIdState {
  34     type Hasher = TypeIdHasher;
  35
  36     fn hasher(&self) -> TypeIdHasher {
  37         TypeIdHasher { value: 0 }
  38     }
  39 }
  40
  41 #[cfg(feature = "unstable")]
  42 impl Hasher for TypeIdHasher {
  43     #[inline(always)]
  44     fn write(&mut self, bytes: &[u8]) {
  45         // This expects to receive one and exactly one 64-bit value
  46         debug_assert!(bytes.len() == 8);
  47         unsafe {
  48             ptr::copy_nonoverlapping(&mut self.value, mem::transmute(&bytes[0]), 1)
  49         }
  50     }
  51
  52     #[inline(always)]
  53     fn finish(&self) -> u64 { self.value }
  54 }
  55
  56
  57 /// The raw, underlying form of a `Map`.
  58 ///
  59 /// At its essence, this is a wrapper around `HashMap<TypeId, Box<Any>>`, with the portions that
  60 /// would be memory-unsafe removed or marked unsafe. Normal people are expected to use the safe
  61 /// `Map` interface instead, but there is the occasional use for this such as iteration over the
  62 /// contents of an `Map`. However, because you will then be dealing with `Any` trait objects, it
  63 /// doesn’t tend to be so very useful. Still, if you need it, it’s here.
  64 #[derive(Debug)]
  65 pub struct RawMap<A: ?Sized + UncheckedAnyExt = Any> {
  66     #[cfg(feature = "unstable")]
  67     inner: HashMap<TypeId, Box<A>, TypeIdState>,
  68
  69     #[cfg(not(feature = "unstable"))]
  70     inner: HashMap<TypeId, Box<A>>,
  71 }
  72
  73 // #[derive(Clone)] would want A to implement Clone, but in reality it’s only Box<A> that can.
  74 impl<A: ?Sized + UncheckedAnyExt> Clone for RawMap<A> where Box<A>: Clone {
  75     fn clone(&self) -> RawMap<A> {
  76         RawMap {
  77             inner: self.inner.clone(),
  78         }
  79     }
  80 }
  81
  82 impl<A: ?Sized + UncheckedAnyExt> Default for RawMap<A> {
  83     fn default() -> RawMap<A> {
  84         RawMap::new()
  85     }
  86 }
  87
  88 #[cfg(feature = "unstable")]
  89 impl_common_methods! {
  90     field: RawMap.inner;
  91     new() => HashMap::with_hash_state(TypeIdState);
  92     with_capacity(capacity) => HashMap::with_capacity_and_hash_state(capacity, TypeIdState);
  93 }
  94
  95 #[cfg(not(feature = "unstable"))]
  96 impl_common_methods! {
  97     field: RawMap.inner;
  98     new() => HashMap::new();
  99     with_capacity(capacity) => HashMap::with_capacity(capacity);
 100 }
 101
 102 /// RawMap iterator.
 103 #[derive(Clone)]
 104 pub struct Iter<'a, A: ?Sized + UncheckedAnyExt> {
 105     inner: hash_map::Iter<'a, TypeId, Box<A>>,
 106 }
 107 impl<'a, A: ?Sized + UncheckedAnyExt> Iterator for Iter<'a, A> {
 108     type Item = &'a A;
 109     #[inline] fn next(&mut self) -> Option<&'a A> { self.inner.next().map(|x| &**x.1) }
 110     #[inline] fn size_hint(&self) -> (usize, Option<usize>) { self.inner.size_hint() }
 111 }
 112 impl<'a, A: ?Sized + UncheckedAnyExt> ExactSizeIterator for Iter<'a, A> {
 113     #[inline] fn len(&self) -> usize { self.inner.len() }
 114 }
 115
 116 /// RawMap mutable iterator.
 117 pub struct IterMut<'a, A: ?Sized + UncheckedAnyExt> {
 118     inner: hash_map::IterMut<'a, TypeId, Box<A>>,
 119 }
 120 impl<'a, A: ?Sized + UncheckedAnyExt> Iterator for IterMut<'a, A> {
 121     type Item = &'a mut A;
 122     #[inline] fn next(&mut self) -> Option<&'a mut A> { self.inner.next().map(|x| &mut **x.1) }
 123     #[inline] fn size_hint(&self) -> (usize, Option<usize>) { self.inner.size_hint() }
 124 }
 125 impl<'a, A: ?Sized + UncheckedAnyExt> ExactSizeIterator for IterMut<'a, A> {
 126     #[inline] fn len(&self) -> usize { self.inner.len() }
 127 }
 128
 129 /// RawMap move iterator.
 130 pub struct IntoIter<A: ?Sized + UncheckedAnyExt> {
 131     inner: hash_map::IntoIter<TypeId, Box<A>>,
 132 }
 133 impl<A: ?Sized + UncheckedAnyExt> Iterator for IntoIter<A> {
 134     type Item = Box<A>;
 135     #[inline] fn next(&mut self) -> Option<Box<A>> { self.inner.next().map(|x| x.1) }
 136     #[inline] fn size_hint(&self) -> (usize, Option<usize>) { self.inner.size_hint() }
 137 }
 138 impl<A: ?Sized + UncheckedAnyExt> ExactSizeIterator for IntoIter<A> {
 139     #[inline] fn len(&self) -> usize { self.inner.len() }
 140 }
 141
 142 /// RawMap drain iterator.
 143 #[cfg(feature = "unstable")]
 144 pub struct Drain<'a, A: ?Sized + UncheckedAnyExt> {
 145     inner: hash_map::Drain<'a, TypeId, Box<A>>,
 146 }
 147 #[cfg(feature = "unstable")]
 148 impl<'a, A: ?Sized + UncheckedAnyExt> Iterator for Drain<'a, A> {
 149     type Item = Box<A>;
 150     #[inline] fn next(&mut self) -> Option<Box<A>> { self.inner.next().map(|x| x.1) }
 151     #[inline] fn size_hint(&self) -> (usize, Option<usize>) { self.inner.size_hint() }
 152 }
 153 #[cfg(feature = "unstable")]
 154 impl<'a, A: ?Sized + UncheckedAnyExt> ExactSizeIterator for Drain<'a, A> {
 155     #[inline] fn len(&self) -> usize { self.inner.len() }
 156 }
 157
 158 impl<A: ?Sized + UncheckedAnyExt> RawMap<A> {
 159     /// An iterator visiting all entries in arbitrary order.
 160     ///
 161     /// Iterator element type is `&Any`.
 162     #[inline]
 163     pub fn iter(&self) -> Iter<A> {
 164         Iter {
 165             inner: self.inner.iter(),
 166         }
 167     }
 168
 169     /// An iterator visiting all entries in arbitrary order.
 170     ///
 171     /// Iterator element type is `&mut Any`.
 172     #[inline]
 173     pub fn iter_mut(&mut self) -> IterMut<A> {
 174         IterMut {
 175             inner: self.inner.iter_mut(),
 176         }
 177     }
 178
 179     /// Clears the map, returning all items as an iterator.
 180     ///
 181     /// Iterator element type is `Box<Any>`.
 182     ///
 183     /// Keeps the allocated memory for reuse.
 184     #[inline]
 185     #[cfg(feature = "unstable")]
 186     pub fn drain(&mut self) -> Drain<A> {
 187         Drain {
 188             inner: self.inner.drain(),
 189         }
 190     }
 191
 192     /// Gets the entry for the given type in the collection for in-place manipulation.
 193     pub fn entry(&mut self, key: TypeId) -> Entry<A> {
 194         match self.inner.entry(key) {
 195             hash_map::Entry::Occupied(e) => Entry::Occupied(OccupiedEntry {
 196                 inner: e,
 197             }),
 198             hash_map::Entry::Vacant(e) => Entry::Vacant(VacantEntry {
 199                 inner: e,
 200             }),
 201         }
 202     }
 203
 204     /// Returns a 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     pub fn get<Q: ?Sized>(&self, k: &Q) -> Option<&A>
 209     where TypeId: Borrow<Q>, Q: Hash + Eq {
 210         self.inner.get(k).map(|x| &**x)
 211     }
 212
 213     /// Returns true if the map contains a value for the specified key.
 214     ///
 215     /// The key may be any borrowed form of the map's key type, but `Hash` and `Eq` on the borrowed
 216     /// form *must* match those for the key type.
 217     pub fn contains_key<Q: ?Sized>(&self, k: &Q) -> bool
 218     where TypeId: Borrow<Q>, Q: Hash + Eq {
 219         self.inner.contains_key(k)
 220     }
 221
 222     /// Returns a mutable reference to the value corresponding to the key.
 223     ///
 224     /// The key may be any borrowed form of the map's key type, but `Hash` and `Eq` on the borrowed
 225     /// form *must* match those for the key type.
 226     pub fn get_mut<Q: ?Sized>(&mut self, k: &Q) -> Option<&mut A>
 227     where TypeId: Borrow<Q>, Q: Hash + Eq {
 228         self.inner.get_mut(k).map(|x| &mut **x)
 229     }
 230
 231     /// Inserts a key-value pair from the map. If the key already had a value present in the map,
 232     /// that value is returned. Otherwise, None is returned.
 233     ///
 234     /// It is the caller’s responsibility to ensure that the key corresponds with the type ID of
 235     /// the value. If they do not, memory safety may be violated.
 236     pub unsafe fn insert(&mut self, key: TypeId, value: Box<A>) -> Option<Box<A>> {
 237         self.inner.insert(key, value)
 238     }
 239
 240     /// Removes a key from the map, returning the value at the key if the key was previously in the
 241     /// map.
 242     ///
 243     /// The key may be any borrowed form of the map's key type, but `Hash` and `Eq` on the borrowed
 244     /// form *must* match those for the key type.
 245     pub fn remove<Q: ?Sized>(&mut self, k: &Q) -> Option<Box<A>>
 246     where TypeId: Borrow<Q>, Q: Hash + Eq {
 247         self.inner.remove(k)
 248     }
 249
 250 }
 251
 252 impl<A: ?Sized + UncheckedAnyExt, Q> Index<Q> for RawMap<A> where TypeId: Borrow<Q>, Q: Eq + Hash {
 253     type Output = A;
 254
 255     fn index<'a>(&'a self, index: Q) -> &'a A {
 256         self.get(&index).expect("no entry found for key")
 257     }
 258 }
 259
 260 impl<A: ?Sized + UncheckedAnyExt, Q> IndexMut<Q> for RawMap<A> where TypeId: Borrow<Q>, Q: Eq + Hash {
 261     fn index_mut<'a>(&'a mut self, index: Q) -> &'a mut A {
 262         self.get_mut(&index).expect("no entry found for key")
 263     }
 264 }
 265
 266 impl<A: ?Sized + UncheckedAnyExt> IntoIterator for RawMap<A> {
 267     type Item = Box<A>;
 268     type IntoIter = IntoIter<A>;
 269
 270     fn into_iter(self) -> IntoIter<A> {
 271         IntoIter {
 272             inner: self.inner.into_iter(),
 273         }
 274     }
 275 }
 276
 277 /// A view into a single occupied location in a `RawMap`.
 278 pub struct OccupiedEntry<'a, A: ?Sized + UncheckedAnyExt> {
 279     inner: hash_map::OccupiedEntry<'a, TypeId, Box<A>>,
 280 }
 281
 282 /// A view into a single empty location in a `RawMap`.
 283 pub struct VacantEntry<'a, A: ?Sized + UncheckedAnyExt> {
 284     inner: hash_map::VacantEntry<'a, TypeId, Box<A>>,
 285 }
 286
 287 /// A view into a single location in a `RawMap`, which may be vacant or occupied.
 288 pub enum Entry<'a, A: ?Sized + UncheckedAnyExt> {
 289     /// An occupied Entry
 290     Occupied(OccupiedEntry<'a, A>),
 291     /// A vacant Entry
 292     Vacant(VacantEntry<'a, A>),
 293 }
 294
 295 impl<'a, A: ?Sized + UncheckedAnyExt> Entry<'a, A> {
 296     /// Ensures a value is in the entry by inserting the default if empty, and returns
 297     /// a mutable reference to the value in the entry.
 298     ///
 299     /// It is the caller’s responsibility to ensure that the key of the entry corresponds with
 300     /// the type ID of `value`. If they do not, memory safety may be violated.
 301     pub unsafe fn or_insert(self, default: Box<A>) -> &'a mut A {
 302         match self {
 303             Entry::Occupied(inner) => inner.into_mut(),
 304             Entry::Vacant(inner) => inner.insert(default),
 305         }
 306     }
 307
 308     /// Ensures a value is in the entry by inserting the result of the default function if empty,
 309     /// and returns a mutable reference to the value in the entry.
 310     ///
 311     /// It is the caller’s responsibility to ensure that the key of the entry corresponds with
 312     /// the type ID of `value`. If they do not, memory safety may be violated.
 313     pub unsafe fn or_insert_with<F: FnOnce() -> Box<A>>(self, default: F) -> &'a mut A {
 314         match self {
 315             Entry::Occupied(inner) => inner.into_mut(),
 316             Entry::Vacant(inner) => inner.insert(default()),
 317         }
 318     }
 319 }
 320
 321 impl<'a, A: ?Sized + UncheckedAnyExt> OccupiedEntry<'a, A> {
 322     /// Gets a reference to the value in the entry.
 323     pub fn get(&self) -> &A {
 324         &**self.inner.get()
 325     }
 326
 327     /// Gets a mutable reference to the value in the entry.
 328     pub fn get_mut(&mut self) -> &mut A {
 329         &mut **self.inner.get_mut()
 330     }
 331
 332     /// Converts the OccupiedEntry into a mutable reference to the value in the entry
 333     /// with a lifetime bound to the collection itself.
 334     pub fn into_mut(self) -> &'a mut A {
 335         &mut **self.inner.into_mut()
 336     }
 337
 338     /// Sets the value of the entry, and returns the entry's old value.
 339     ///
 340     /// It is the caller’s responsibility to ensure that the key of the entry corresponds with
 341     /// the type ID of `value`. If they do not, memory safety may be violated.
 342     pub unsafe fn insert(&mut self, value: Box<A>) -> Box<A> {
 343         self.inner.insert(value)
 344     }
 345
 346     /// Takes the value out of the entry, and returns it.
 347     pub fn remove(self) -> Box<A> {
 348         self.inner.remove()
 349     }
 350 }
 351
 352 impl<'a, A: ?Sized + UncheckedAnyExt> VacantEntry<'a, A> {
 353     /// Sets the value of the entry with the VacantEntry's key,
 354     /// and returns a mutable reference to it
 355     ///
 356     /// It is the caller’s responsibility to ensure that the key of the entry corresponds with
 357     /// the type ID of `value`. If they do not, memory safety may be violated.
 358     pub unsafe fn insert(self, value: Box<A>) -> &'a mut A {
 359         &mut **self.inner.insert(value)
 360     }
 361 }