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

   1 //! This crate provides the `AnyMap` type, a safe and convenient store for one value of each type.
   2
   3 #![feature(core, std_misc, convert)]
   4 #![cfg_attr(test, feature(test))]
   5 #![warn(missing_docs, unused_results)]
   6
   7 #[cfg(test)]
   8 extern crate test;
   9
  10 use std::any::{Any, TypeId};
  11 use std::marker::PhantomData;
  12
  13 use raw::RawAnyMap;
  14 use unchecked_any::UncheckedAnyExt;
  15
  16 macro_rules! impl_common_methods {
  17     (
  18         field: $t:ident.$field:ident;
  19         new() => $new:expr;
  20         with_capacity($with_capacity_arg:ident) => $with_capacity:expr;
  21     ) => {
  22         impl $t {
  23             /// Create an empty collection.
  24             #[inline]
  25             pub fn new() -> $t {
  26                 $t {
  27                     $field: $new,
  28                 }
  29             }
  30
  31             /// Creates an empty collection with the given initial capacity.
  32             #[inline]
  33             pub fn with_capacity($with_capacity_arg: usize) -> $t {
  34                 $t {
  35                     $field: $with_capacity,
  36                 }
  37             }
  38
  39             /// Returns the number of elements the collection can hold without reallocating.
  40             #[inline]
  41             pub fn capacity(&self) -> usize {
  42                 self.$field.capacity()
  43             }
  44
  45             /// Reserves capacity for at least `additional` more elements to be inserted
  46             /// in the collection. The collection may reserve more space to avoid
  47             /// frequent reallocations.
  48             ///
  49             /// # Panics
  50             ///
  51             /// Panics if the new allocation size overflows `usize`.
  52             #[inline]
  53             pub fn reserve(&mut self, additional: usize) {
  54                 self.$field.reserve(additional)
  55             }
  56
  57             /// Shrinks the capacity of the collection as much as possible. It will drop
  58             /// down as much as possible while maintaining the internal rules
  59             /// and possibly leaving some space in accordance with the resize policy.
  60             #[inline]
  61             pub fn shrink_to_fit(&mut self) {
  62                 self.$field.shrink_to_fit()
  63             }
  64
  65             /// Returns the number of items in the collection.
  66             #[inline]
  67             pub fn len(&self) -> usize {
  68                 self.$field.len()
  69             }
  70
  71             /// Returns true if there are no items in the collection.
  72             #[inline]
  73             pub fn is_empty(&self) -> bool {
  74                 self.$field.is_empty()
  75             }
  76
  77             /// Removes all items from the collection. Keeps the allocated memory for reuse.
  78             #[inline]
  79             pub fn clear(&mut self) {
  80                 self.$field.clear()
  81             }
  82         }
  83     }
  84 }
  85
  86 mod unchecked_any;
  87 pub mod raw;
  88
  89 /// A collection containing zero or one values for any given type and allowing convenient,
  90 /// type-safe access to those values.
  91 ///
  92 /// ```rust
  93 /// # use anymap::AnyMap;
  94 /// let mut data = AnyMap::new();
  95 /// assert_eq!(data.get(), None::<&i32>);
  96 /// data.insert(42i32);
  97 /// assert_eq!(data.get(), Some(&42i32));
  98 /// data.remove::<i32>();
  99 /// assert_eq!(data.get::<i32>(), None);
 100 ///
 101 /// #[derive(PartialEq, Debug)]
 102 /// struct Foo {
 103 ///     str: String,
 104 /// }
 105 ///
 106 /// assert_eq!(data.get::<Foo>(), None);
 107 /// data.insert(Foo { str: format!("foo") });
 108 /// assert_eq!(data.get(), Some(&Foo { str: format!("foo") }));
 109 /// data.get_mut::<Foo>().map(|foo| foo.str.push('t'));
 110 /// assert_eq!(&*data.get::<Foo>().unwrap().str, "foot");
 111 /// ```
 112 ///
 113 /// Values containing non-static references are not permitted.
 114 #[derive(Debug)]
 115 pub struct AnyMap {
 116     raw: RawAnyMap,
 117 }
 118
 119 impl_common_methods! {
 120     field: AnyMap.raw;
 121     new() => RawAnyMap::new();
 122     with_capacity(capacity) => RawAnyMap::with_capacity(capacity);
 123 }
 124
 125 impl AnyMap {
 126     /// Returns a reference to the value stored in the collection for the type `T`, if it exists.
 127     pub fn get<T: Any>(&self) -> Option<&T> {
 128         self.raw.get(&TypeId::of::<T>())
 129             .map(|any| unsafe { any.downcast_ref_unchecked::<T>() })
 130     }
 131
 132     /// Returns a mutable reference to the value stored in the collection for the type `T`,
 133     /// if it exists.
 134     pub fn get_mut<T: Any>(&mut self) -> Option<&mut T> {
 135         self.raw.get_mut(&TypeId::of::<T>())
 136             .map(|any| unsafe { any.downcast_mut_unchecked::<T>() })
 137     }
 138
 139     /// Sets the value stored in the collection for the type `T`.
 140     /// If the collection already had a value of type `T`, that value is returned.
 141     /// Otherwise, `None` is returned.
 142     pub fn insert<T: Any>(&mut self, value: T) -> Option<T> {
 143         unsafe {
 144             self.raw.insert(TypeId::of::<T>(), Box::new(value))
 145                 .map(|any| *any.downcast_unchecked::<T>())
 146         }
 147     }
 148
 149     /// Removes the `T` value from the collection,
 150     /// returning it if there was one or `None` if there was not.
 151     pub fn remove<T: Any>(&mut self) -> Option<T> {
 152         self.raw.remove(&TypeId::of::<T>())
 153             .map(|any| *unsafe { any.downcast_unchecked::<T>() })
 154     }
 155
 156     /// Returns true if the collection contains a value of type `T`.
 157     #[inline]
 158     pub fn contains<T: Any>(&self) -> bool {
 159         self.raw.contains_key(&TypeId::of::<T>())
 160     }
 161
 162     /// Gets the entry for the given type in the collection for in-place manipulation
 163     pub fn entry<T: Any>(&mut self) -> Entry<T> {
 164         match self.raw.entry(TypeId::of::<T>()) {
 165             raw::Entry::Occupied(e) => Entry::Occupied(OccupiedEntry {
 166                 inner: e,
 167                 type_: PhantomData,
 168             }),
 169             raw::Entry::Vacant(e) => Entry::Vacant(VacantEntry {
 170                 inner: e,
 171                 type_: PhantomData,
 172             }),
 173         }
 174     }
 175 }
 176
 177 impl AsRef<RawAnyMap> for AnyMap {
 178     fn as_ref(&self) -> &RawAnyMap {
 179         &self.raw
 180     }
 181 }
 182
 183 impl AsMut<RawAnyMap> for AnyMap {
 184     fn as_mut(&mut self) -> &mut RawAnyMap {
 185         &mut self.raw
 186     }
 187 }
 188
 189 impl Into<RawAnyMap> for AnyMap {
 190     fn into(self) -> RawAnyMap {
 191         self.raw
 192     }
 193 }
 194
 195 /// A view into a single occupied location in an `AnyMap`.
 196 pub struct OccupiedEntry<'a, V: 'a> {
 197     inner: raw::OccupiedEntry<'a>,
 198     type_: PhantomData<V>,
 199 }
 200
 201 /// A view into a single empty location in an `AnyMap`.
 202 pub struct VacantEntry<'a, V: 'a> {
 203     inner: raw::VacantEntry<'a>,
 204     type_: PhantomData<V>,
 205 }
 206
 207 /// A view into a single location in an `AnyMap`, which may be vacant or occupied.
 208 pub enum Entry<'a, V: 'a> {
 209     /// An occupied Entry
 210     Occupied(OccupiedEntry<'a, V>),
 211     /// A vacant Entry
 212     Vacant(VacantEntry<'a, V>),
 213 }
 214
 215 impl<'a, V: Any + Clone> Entry<'a, V> {
 216     /// Ensures a value is in the entry by inserting the default if empty, and returns
 217     /// a mutable reference to the value in the entry.
 218     pub fn or_insert(self, default: V) -> &'a mut V {
 219         match self {
 220             Entry::Occupied(inner) => inner.into_mut(),
 221             Entry::Vacant(inner) => inner.insert(default),
 222         }
 223     }
 224
 225     /// Ensures a value is in the entry by inserting the result of the default function if empty,
 226     /// and returns a mutable reference to the value in the entry.
 227     pub fn or_insert_with<F: FnOnce() -> V>(self, default: F) -> &'a mut V {
 228         match self {
 229             Entry::Occupied(inner) => inner.into_mut(),
 230             Entry::Vacant(inner) => inner.insert(default()),
 231         }
 232     }
 233 }
 234
 235 impl<'a, V: Any> OccupiedEntry<'a, V> {
 236     /// Gets a reference to the value in the entry
 237     pub fn get(&self) -> &V {
 238         unsafe { self.inner.get().downcast_ref_unchecked() }
 239     }
 240
 241     /// Gets a mutable reference to the value in the entry
 242     pub fn get_mut(&mut self) -> &mut V {
 243         unsafe { self.inner.get_mut().downcast_mut_unchecked() }
 244     }
 245
 246     /// Converts the OccupiedEntry into a mutable reference to the value in the entry
 247     /// with a lifetime bound to the collection itself
 248     pub fn into_mut(self) -> &'a mut V {
 249         unsafe { self.inner.into_mut().downcast_mut_unchecked() }
 250     }
 251
 252     /// Sets the value of the entry, and returns the entry's old value
 253     pub fn insert(&mut self, value: V) -> V {
 254         unsafe { *self.inner.insert(Box::new(value)).downcast_unchecked() }
 255     }
 256
 257     /// Takes the value out of the entry, and returns it
 258     pub fn remove(self) -> V {
 259         unsafe { *self.inner.remove().downcast_unchecked() }
 260     }
 261 }
 262
 263 impl<'a, V: Any> VacantEntry<'a, V> {
 264     /// Sets the value of the entry with the VacantEntry's key,
 265     /// and returns a mutable reference to it
 266     pub fn insert(self, value: V) -> &'a mut V {
 267         unsafe { self.inner.insert(Box::new(value)).downcast_mut_unchecked() }
 268     }
 269 }
 270
 271 #[bench]
 272 fn bench_insertion(b: &mut ::test::Bencher) {
 273     b.iter(|| {
 274         let mut data = AnyMap::new();
 275         for _ in 0..100 {
 276             let _ = data.insert(42);
 277         }
 278     })
 279 }
 280
 281 #[bench]
 282 fn bench_get_missing(b: &mut ::test::Bencher) {
 283     b.iter(|| {
 284         let data = AnyMap::new();
 285         for _ in 0..100 {
 286             assert_eq!(data.get(), None::<&i32>);
 287         }
 288     })
 289 }
 290
 291 #[bench]
 292 fn bench_get_present(b: &mut ::test::Bencher) {
 293     b.iter(|| {
 294         let mut data = AnyMap::new();
 295         let _ = data.insert(42);
 296         // These inner loops are a feeble attempt to drown the other factors.
 297         for _ in 0..100 {
 298             assert_eq!(data.get(), Some(&42));
 299         }
 300     })
 301 }
 302
 303 #[test]
 304 fn test_entry() {
 305     #[derive(Debug, PartialEq)] struct A(i32);
 306     #[derive(Debug, PartialEq)] struct B(i32);
 307     #[derive(Debug, PartialEq)] struct C(i32);
 308     #[derive(Debug, PartialEq)] struct D(i32);
 309     #[derive(Debug, PartialEq)] struct E(i32);
 310     #[derive(Debug, PartialEq)] struct F(i32);
 311     #[derive(Debug, PartialEq)] struct J(i32);
 312
 313     let mut map: AnyMap = AnyMap::new();
 314     assert_eq!(map.insert(A(10)), None);
 315     assert_eq!(map.insert(B(20)), None);
 316     assert_eq!(map.insert(C(30)), None);
 317     assert_eq!(map.insert(D(40)), None);
 318     assert_eq!(map.insert(E(50)), None);
 319     assert_eq!(map.insert(F(60)), None);
 320
 321     // Existing key (insert)
 322     match map.entry::<A>() {
 323         Entry::Vacant(_) => unreachable!(),
 324         Entry::Occupied(mut view) => {
 325             assert_eq!(view.get(), &A(10));
 326             assert_eq!(view.insert(A(100)), A(10));
 327         }
 328     }
 329     assert_eq!(map.get::<A>().unwrap(), &A(100));
 330     assert_eq!(map.len(), 6);
 331
 332
 333     // Existing key (update)
 334     match map.entry::<B>() {
 335         Entry::Vacant(_) => unreachable!(),
 336         Entry::Occupied(mut view) => {
 337             let v = view.get_mut();
 338             let new_v = B(v.0 * 10);
 339             *v = new_v;
 340         }
 341     }
 342     assert_eq!(map.get().unwrap(), &B(200));
 343     assert_eq!(map.len(), 6);
 344
 345
 346     // Existing key (remove)
 347     match map.entry::<C>() {
 348         Entry::Vacant(_) => unreachable!(),
 349         Entry::Occupied(view) => {
 350             assert_eq!(view.remove(), C(30));
 351         }
 352     }
 353     assert_eq!(map.get::<C>(), None);
 354     assert_eq!(map.len(), 5);
 355
 356
 357     // Inexistent key (insert)
 358     match map.entry::<J>() {
 359         Entry::Occupied(_) => unreachable!(),
 360         Entry::Vacant(view) => {
 361             assert_eq!(*view.insert(J(1000)), J(1000));
 362         }
 363     }
 364     assert_eq!(map.get::<J>().unwrap(), &J(1000));
 365     assert_eq!(map.len(), 6);
 366 }