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

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