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