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 pub struct Drain<'a, A: ?Sized + UncheckedAnyExt> {
 110     inner: hash_map::Drain<'a, TypeId, Box<A>>,
 111 }
 112 impl<'a, A: ?Sized + UncheckedAnyExt> Iterator for Drain<'a, A> {
 113     type Item = Box<A>;
 114     #[inline] fn next(&mut self) -> Option<Box<A>> { self.inner.next().map(|x| x.1) }
 115     #[inline] fn size_hint(&self) -> (usize, Option<usize>) { self.inner.size_hint() }
 116 }
 117 impl<'a, A: ?Sized + UncheckedAnyExt> ExactSizeIterator for Drain<'a, A> {
 118     #[inline] fn len(&self) -> usize { self.inner.len() }
 119 }
 120
 121 impl<A: ?Sized + UncheckedAnyExt> RawMap<A> {
 122     /// An iterator visiting all entries in arbitrary order.
 123     ///
 124     /// Iterator element type is `&Any`.
 125     #[inline]
 126     pub fn iter(&self) -> Iter<A> {
 127         Iter {
 128             inner: self.inner.iter(),
 129         }
 130     }
 131
 132     /// An iterator visiting all entries in arbitrary order.
 133     ///
 134     /// Iterator element type is `&mut Any`.
 135     #[inline]
 136     pub fn iter_mut(&mut self) -> IterMut<A> {
 137         IterMut {
 138             inner: self.inner.iter_mut(),
 139         }
 140     }
 141
 142     /// Clears the map, returning all items as an iterator.
 143     ///
 144     /// Iterator element type is `Box<Any>`.
 145     ///
 146     /// Keeps the allocated memory for reuse.
 147     #[inline]
 148     pub fn drain(&mut self) -> Drain<A> {
 149         Drain {
 150             inner: self.inner.drain(),
 151         }
 152     }
 153
 154     /// Gets the entry for the given type in the collection for in-place manipulation.
 155     pub fn entry(&mut self, key: TypeId) -> Entry<A> {
 156         match self.inner.entry(key) {
 157             hash_map::Entry::Occupied(e) => Entry::Occupied(OccupiedEntry {
 158                 inner: e,
 159             }),
 160             hash_map::Entry::Vacant(e) => Entry::Vacant(VacantEntry {
 161                 inner: e,
 162             }),
 163         }
 164     }
 165
 166     /// Returns a reference to the value corresponding to the key.
 167     ///
 168     /// The key may be any borrowed form of the map's key type, but `Hash` and `Eq` on the borrowed
 169     /// form *must* match those for the key type.
 170     pub fn get<Q: ?Sized>(&self, k: &Q) -> Option<&A>
 171     where TypeId: Borrow<Q>, Q: Hash + Eq {
 172         self.inner.get(k).map(|x| &**x)
 173     }
 174
 175     /// Returns true if the map contains a value for the specified key.
 176     ///
 177     /// The key may be any borrowed form of the map's key type, but `Hash` and `Eq` on the borrowed
 178     /// form *must* match those for the key type.
 179     pub fn contains_key<Q: ?Sized>(&self, k: &Q) -> bool
 180     where TypeId: Borrow<Q>, Q: Hash + Eq {
 181         self.inner.contains_key(k)
 182     }
 183
 184     /// Returns a mutable 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     pub fn get_mut<Q: ?Sized>(&mut self, k: &Q) -> Option<&mut A>
 189     where TypeId: Borrow<Q>, Q: Hash + Eq {
 190         self.inner.get_mut(k).map(|x| &mut **x)
 191     }
 192
 193     /// Inserts a key-value pair from the map. If the key already had a value present in the map,
 194     /// that value is returned. Otherwise, None is returned.
 195     ///
 196     /// It is the caller’s responsibility to ensure that the key corresponds with the type ID of
 197     /// the value. If they do not, memory safety may be violated.
 198     pub unsafe fn insert(&mut self, key: TypeId, value: Box<A>) -> Option<Box<A>> {
 199         self.inner.insert(key, value)
 200     }
 201
 202     /// Removes a key from the map, returning the value at the key if the key was previously in the
 203     /// map.
 204     ///
 205     /// The key may be any borrowed form of the map's key type, but `Hash` and `Eq` on the borrowed
 206     /// form *must* match those for the key type.
 207     pub fn remove<Q: ?Sized>(&mut self, k: &Q) -> Option<Box<A>>
 208     where TypeId: Borrow<Q>, Q: Hash + Eq {
 209         self.inner.remove(k)
 210     }
 211
 212 }
 213
 214 impl<A: ?Sized + UncheckedAnyExt, Q> Index<Q> for RawMap<A> where TypeId: Borrow<Q>, Q: Eq + Hash {
 215     type Output = A;
 216
 217     fn index<'a>(&'a self, index: Q) -> &'a A {
 218         self.get(&index).expect("no entry found for key")
 219     }
 220 }
 221
 222 impl<A: ?Sized + UncheckedAnyExt, Q> IndexMut<Q> for RawMap<A> where TypeId: Borrow<Q>, Q: Eq + Hash {
 223     fn index_mut<'a>(&'a mut self, index: Q) -> &'a mut A {
 224         self.get_mut(&index).expect("no entry found for key")
 225     }
 226 }
 227
 228 impl<A: ?Sized + UncheckedAnyExt> IntoIterator for RawMap<A> {
 229     type Item = Box<A>;
 230     type IntoIter = IntoIter<A>;
 231
 232     fn into_iter(self) -> IntoIter<A> {
 233         IntoIter {
 234             inner: self.inner.into_iter(),
 235         }
 236     }
 237 }
 238
 239 /// A view into a single occupied location in a `RawMap`.
 240 pub struct OccupiedEntry<'a, A: ?Sized + UncheckedAnyExt> {
 241     inner: hash_map::OccupiedEntry<'a, TypeId, Box<A>>,
 242 }
 243
 244 /// A view into a single empty location in a `RawMap`.
 245 pub struct VacantEntry<'a, A: ?Sized + UncheckedAnyExt> {
 246     inner: hash_map::VacantEntry<'a, TypeId, Box<A>>,
 247 }
 248
 249 /// A view into a single location in a `RawMap`, which may be vacant or occupied.
 250 pub enum Entry<'a, A: ?Sized + UncheckedAnyExt> {
 251     /// An occupied Entry
 252     Occupied(OccupiedEntry<'a, A>),
 253     /// A vacant Entry
 254     Vacant(VacantEntry<'a, A>),
 255 }
 256
 257 impl<'a, A: ?Sized + UncheckedAnyExt> Entry<'a, A> {
 258     /// Ensures a value is in the entry by inserting the default if empty, and returns
 259     /// a mutable reference to the value in the entry.
 260     ///
 261     /// It is the caller’s responsibility to ensure that the key of the entry corresponds with
 262     /// the type ID of `value`. If they do not, memory safety may be violated.
 263     pub unsafe fn or_insert(self, default: Box<A>) -> &'a mut A {
 264         match self {
 265             Entry::Occupied(inner) => inner.into_mut(),
 266             Entry::Vacant(inner) => inner.insert(default),
 267         }
 268     }
 269
 270     /// Ensures a value is in the entry by inserting the result of the default function if empty,
 271     /// and returns a mutable reference to the value in the entry.
 272     ///
 273     /// It is the caller’s responsibility to ensure that the key of the entry corresponds with
 274     /// the type ID of `value`. If they do not, memory safety may be violated.
 275     pub unsafe fn or_insert_with<F: FnOnce() -> Box<A>>(self, default: F) -> &'a mut A {
 276         match self {
 277             Entry::Occupied(inner) => inner.into_mut(),
 278             Entry::Vacant(inner) => inner.insert(default()),
 279         }
 280     }
 281 }
 282
 283 impl<'a, A: ?Sized + UncheckedAnyExt> OccupiedEntry<'a, A> {
 284     /// Gets a reference to the value in the entry.
 285     pub fn get(&self) -> &A {
 286         &**self.inner.get()
 287     }
 288
 289     /// Gets a mutable reference to the value in the entry.
 290     pub fn get_mut(&mut self) -> &mut A {
 291         &mut **self.inner.get_mut()
 292     }
 293
 294     /// Converts the OccupiedEntry into a mutable reference to the value in the entry
 295     /// with a lifetime bound to the collection itself.
 296     pub fn into_mut(self) -> &'a mut A {
 297         &mut **self.inner.into_mut()
 298     }
 299
 300     /// Sets the value of the entry, and returns the entry's old value.
 301     ///
 302     /// It is the caller’s responsibility to ensure that the key of the entry corresponds with
 303     /// the type ID of `value`. If they do not, memory safety may be violated.
 304     pub unsafe fn insert(&mut self, value: Box<A>) -> Box<A> {
 305         self.inner.insert(value)
 306     }
 307
 308     /// Takes the value out of the entry, and returns it.
 309     pub fn remove(self) -> Box<A> {
 310         self.inner.remove()
 311     }
 312 }
 313
 314 impl<'a, A: ?Sized + UncheckedAnyExt> VacantEntry<'a, A> {
 315     /// Sets the value of the entry with the VacantEntry's key,
 316     /// and returns a mutable reference to it
 317     ///
 318     /// It is the caller’s responsibility to ensure that the key of the entry corresponds with
 319     /// the type ID of `value`. If they do not, memory safety may be violated.
 320     pub unsafe fn insert(self, value: Box<A>) -> &'a mut A {
 321         &mut **self.inner.insert(value)
 322     }
 323 }