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

   1 //! This crate provides a safe and convenient store for one value of each type.
   2 //!
   3 //! Your starting point is [`Map`]. It has an example.
   4
   5 #![warn(missing_docs, unused_results)]
   6
   7 #![cfg_attr(not(feature = "std"), no_std)]
   8
   9 use core::any::{Any, TypeId};
  10 use core::marker::PhantomData;
  11
  12 #[cfg(not(any(feature = "std", feature = "hashbrown")))]
  13 compile_error!("anymap: you must enable the 'std' feature or the 'hashbrown' feature");
  14
  15 #[cfg(not(feature = "std"))]
  16 extern crate alloc;
  17
  18 #[cfg(not(feature = "std"))]
  19 use alloc::boxed::Box;
  20
  21 use raw::RawMap;
  22 use any::{UncheckedAnyExt, IntoBox};
  23 pub use any::CloneAny;
  24
  25 macro_rules! impl_common_methods {
  26     (
  27         field: $t:ident.$field:ident;
  28         new() => $new:expr;
  29         with_capacity($with_capacity_arg:ident) => $with_capacity:expr;
  30     ) => {
  31         impl<A: ?Sized + UncheckedAnyExt> $t<A> {
  32             /// Create an empty collection.
  33             #[inline]
  34             pub fn new() -> $t<A> {
  35                 $t {
  36                     $field: $new,
  37                 }
  38             }
  39
  40             /// Creates an empty collection with the given initial capacity.
  41             #[inline]
  42             pub fn with_capacity($with_capacity_arg: usize) -> $t<A> {
  43                 $t {
  44                     $field: $with_capacity,
  45                 }
  46             }
  47
  48             /// Returns the number of elements the collection can hold without reallocating.
  49             #[inline]
  50             pub fn capacity(&self) -> usize {
  51                 self.$field.capacity()
  52             }
  53
  54             /// Reserves capacity for at least `additional` more elements to be inserted
  55             /// in the collection. The collection may reserve more space to avoid
  56             /// frequent reallocations.
  57             ///
  58             /// # Panics
  59             ///
  60             /// Panics if the new allocation size overflows `usize`.
  61             #[inline]
  62             pub fn reserve(&mut self, additional: usize) {
  63                 self.$field.reserve(additional)
  64             }
  65
  66             /// Shrinks the capacity of the collection as much as possible. It will drop
  67             /// down as much as possible while maintaining the internal rules
  68             /// and possibly leaving some space in accordance with the resize policy.
  69             #[inline]
  70             pub fn shrink_to_fit(&mut self) {
  71                 self.$field.shrink_to_fit()
  72             }
  73
  74             // Additional stable methods (as of 1.60.0-nightly) that could be added:
  75             // try_reserve(&mut self, additional: usize) -> Result<(), TryReserveError>    (1.57.0)
  76             // shrink_to(&mut self, min_capacity: usize)                                   (1.56.0)
  77
  78             /// Returns the number of items in the collection.
  79             #[inline]
  80             pub fn len(&self) -> usize {
  81                 self.$field.len()
  82             }
  83
  84             /// Returns true if there are no items in the collection.
  85             #[inline]
  86             pub fn is_empty(&self) -> bool {
  87                 self.$field.is_empty()
  88             }
  89
  90             /// Removes all items from the collection. Keeps the allocated memory for reuse.
  91             #[inline]
  92             pub fn clear(&mut self) {
  93                 self.$field.clear()
  94             }
  95         }
  96
  97         impl<A: ?Sized + UncheckedAnyExt> Default for $t<A> {
  98             #[inline]
  99             fn default() -> $t<A> {
 100                 $t::new()
 101             }
 102         }
 103     }
 104 }
 105
 106 mod any;
 107 pub mod raw;
 108
 109 /// A collection containing zero or one values for any given type and allowing convenient,
 110 /// type-safe access to those values.
 111 ///
 112 /// The type parameter `A` allows you to use a different value type; normally you will want it to
 113 /// be `core::any::Any` (also known as `std::any::Any`), but there are other choices:
 114 ///
 115 /// - If you want the entire map to be cloneable, use `CloneAny` instead of `Any`; with that, you
 116 ///   can only add types that implement `Clone` to the map.
 117 /// - You can add on `+ Send` or `+ Send + Sync` (e.g. `Map<dyn Any + Send>`) to add those auto
 118 ///   traits.
 119 ///
 120 /// Cumulatively, there are thus six forms of map:
 121 ///
 122 /// - <code>[Map]&lt;dyn [core::any::Any]&gt;</code>, also spelled [`AnyMap`] for convenience.
 123 /// - <code>[Map]&lt;dyn [core::any::Any] + Send&gt;</code>
 124 /// - <code>[Map]&lt;dyn [core::any::Any] + Send + Sync&gt;</code>
 125 /// - <code>[Map]&lt;dyn [CloneAny]&gt;</code>
 126 /// - <code>[Map]&lt;dyn [CloneAny] + Send&gt;</code>
 127 /// - <code>[Map]&lt;dyn [CloneAny] + Send + Sync&gt;</code>
 128 ///
 129 /// ## Example
 130 ///
 131 /// (Here using the [`AnyMap`] convenience alias; the first line could use
 132 /// <code>[anymap::Map][Map]::&lt;[core::any::Any]&gt;::new()</code> instead if desired.)
 133 ///
 134 /// ```rust
 135 /// let mut data = anymap::AnyMap::new();
 136 /// assert_eq!(data.get(), None::<&i32>);
 137 /// data.insert(42i32);
 138 /// assert_eq!(data.get(), Some(&42i32));
 139 /// data.remove::<i32>();
 140 /// assert_eq!(data.get::<i32>(), None);
 141 ///
 142 /// #[derive(Clone, PartialEq, Debug)]
 143 /// struct Foo {
 144 ///     str: String,
 145 /// }
 146 ///
 147 /// assert_eq!(data.get::<Foo>(), None);
 148 /// data.insert(Foo { str: format!("foo") });
 149 /// assert_eq!(data.get(), Some(&Foo { str: format!("foo") }));
 150 /// data.get_mut::<Foo>().map(|foo| foo.str.push('t'));
 151 /// assert_eq!(&*data.get::<Foo>().unwrap().str, "foot");
 152 /// ```
 153 ///
 154 /// Values containing non-static references are not permitted.
 155 #[derive(Debug)]
 156 pub struct Map<A: ?Sized + UncheckedAnyExt = dyn Any> {
 157     raw: RawMap<A>,
 158 }
 159
 160 // #[derive(Clone)] would want A to implement Clone, but in reality it’s only Box<A> that can.
 161 impl<A: ?Sized + UncheckedAnyExt> Clone for Map<A> where Box<A>: Clone {
 162     #[inline]
 163     fn clone(&self) -> Map<A> {
 164         Map {
 165             raw: self.raw.clone(),
 166         }
 167     }
 168 }
 169
 170 /// The most common type of `Map`: just using `Any`; <code>[Map]&lt;dyn [Any]&gt;</code>.
 171 ///
 172 /// Why is this a separate type alias rather than a default value for `Map<A>`? `Map::new()`
 173 /// doesn’t seem to be happy to infer that it should go with the default value.
 174 /// It’s a bit sad, really. Ah well, I guess this approach will do.
 175 pub type AnyMap = Map<dyn Any>;
 176
 177 impl_common_methods! {
 178     field: Map.raw;
 179     new() => RawMap::new();
 180     with_capacity(capacity) => RawMap::with_capacity(capacity);
 181 }
 182
 183 impl<A: ?Sized + UncheckedAnyExt> Map<A> {
 184     /// Returns a reference to the value stored in the collection for the type `T`, if it exists.
 185     #[inline]
 186     pub fn get<T: IntoBox<A>>(&self) -> Option<&T> {
 187         self.raw.get(&TypeId::of::<T>())
 188             .map(|any| unsafe { any.downcast_ref_unchecked::<T>() })
 189     }
 190
 191     /// Returns a mutable reference to the value stored in the collection for the type `T`,
 192     /// if it exists.
 193     #[inline]
 194     pub fn get_mut<T: IntoBox<A>>(&mut self) -> Option<&mut T> {
 195         self.raw.get_mut(&TypeId::of::<T>())
 196             .map(|any| unsafe { any.downcast_mut_unchecked::<T>() })
 197     }
 198
 199     /// Sets the value stored in the collection for the type `T`.
 200     /// If the collection already had a value of type `T`, that value is returned.
 201     /// Otherwise, `None` is returned.
 202     #[inline]
 203     pub fn insert<T: IntoBox<A>>(&mut self, value: T) -> Option<T> {
 204         unsafe {
 205             self.raw.insert(TypeId::of::<T>(), value.into_box())
 206                 .map(|any| *any.downcast_unchecked::<T>())
 207         }
 208     }
 209
 210     // rustc 1.60.0-nightly has another method try_insert that would be nice to add when stable.
 211
 212     /// Removes the `T` value from the collection,
 213     /// returning it if there was one or `None` if there was not.
 214     #[inline]
 215     pub fn remove<T: IntoBox<A>>(&mut self) -> Option<T> {
 216         self.raw.remove(&TypeId::of::<T>())
 217             .map(|any| *unsafe { any.downcast_unchecked::<T>() })
 218     }
 219
 220     /// Returns true if the collection contains a value of type `T`.
 221     #[inline]
 222     pub fn contains<T: IntoBox<A>>(&self) -> bool {
 223         self.raw.contains_key(&TypeId::of::<T>())
 224     }
 225
 226     /// Gets the entry for the given type in the collection for in-place manipulation
 227     #[inline]
 228     pub fn entry<T: IntoBox<A>>(&mut self) -> Entry<A, T> {
 229         match self.raw.entry(TypeId::of::<T>()) {
 230             raw::Entry::Occupied(e) => Entry::Occupied(OccupiedEntry {
 231                 inner: e,
 232                 type_: PhantomData,
 233             }),
 234             raw::Entry::Vacant(e) => Entry::Vacant(VacantEntry {
 235                 inner: e,
 236                 type_: PhantomData,
 237             }),
 238         }
 239     }
 240 }
 241
 242 impl<A: ?Sized + UncheckedAnyExt> Extend<Box<A>> for Map<A> {
 243     #[inline]
 244     fn extend<T: IntoIterator<Item = Box<A>>>(&mut self, iter: T) {
 245         for item in iter {
 246             let _ = unsafe { self.raw.insert(item.type_id(), item) };
 247         }
 248     }
 249 }
 250
 251 impl<A: ?Sized + UncheckedAnyExt> AsRef<RawMap<A>> for Map<A> {
 252     #[inline]
 253     fn as_ref(&self) -> &RawMap<A> {
 254         &self.raw
 255     }
 256 }
 257
 258 impl<A: ?Sized + UncheckedAnyExt> AsMut<RawMap<A>> for Map<A> {
 259     #[inline]
 260     fn as_mut(&mut self) -> &mut RawMap<A> {
 261         &mut self.raw
 262     }
 263 }
 264
 265 impl<A: ?Sized + UncheckedAnyExt> From<Map<A>> for RawMap<A> {
 266     #[inline]
 267     fn from(map: Map<A>) -> RawMap<A> {
 268         map.raw
 269     }
 270 }
 271
 272 /// A view into a single occupied location in an `Map`.
 273 pub struct OccupiedEntry<'a, A: ?Sized + UncheckedAnyExt, V: 'a> {
 274     inner: raw::OccupiedEntry<'a, A>,
 275     type_: PhantomData<V>,
 276 }
 277
 278 /// A view into a single empty location in an `Map`.
 279 pub struct VacantEntry<'a, A: ?Sized + UncheckedAnyExt, V: 'a> {
 280     inner: raw::VacantEntry<'a, A>,
 281     type_: PhantomData<V>,
 282 }
 283
 284 /// A view into a single location in an `Map`, which may be vacant or occupied.
 285 pub enum Entry<'a, A: ?Sized + UncheckedAnyExt, V: 'a> {
 286     /// An occupied Entry
 287     Occupied(OccupiedEntry<'a, A, V>),
 288     /// A vacant Entry
 289     Vacant(VacantEntry<'a, A, V>),
 290 }
 291
 292 impl<'a, A: ?Sized + UncheckedAnyExt, V: IntoBox<A>> Entry<'a, A, V> {
 293     /// Ensures a value is in the entry by inserting the default if empty, and returns
 294     /// a mutable reference to the value in the entry.
 295     #[inline]
 296     pub fn or_insert(self, default: V) -> &'a mut V {
 297         match self {
 298             Entry::Occupied(inner) => inner.into_mut(),
 299             Entry::Vacant(inner) => inner.insert(default),
 300         }
 301     }
 302
 303     /// Ensures a value is in the entry by inserting the result of the default function if empty,
 304     /// and returns a mutable reference to the value in the entry.
 305     #[inline]
 306     pub fn or_insert_with<F: FnOnce() -> V>(self, default: F) -> &'a mut V {
 307         match self {
 308             Entry::Occupied(inner) => inner.into_mut(),
 309             Entry::Vacant(inner) => inner.insert(default()),
 310         }
 311     }
 312 }
 313
 314 impl<'a, A: ?Sized + UncheckedAnyExt, V: IntoBox<A>> OccupiedEntry<'a, A, V> {
 315     /// Gets a reference to the value in the entry
 316     #[inline]
 317     pub fn get(&self) -> &V {
 318         unsafe { self.inner.get().downcast_ref_unchecked() }
 319     }
 320
 321     /// Gets a mutable reference to the value in the entry
 322     #[inline]
 323     pub fn get_mut(&mut self) -> &mut V {
 324         unsafe { self.inner.get_mut().downcast_mut_unchecked() }
 325     }
 326
 327     /// Converts the OccupiedEntry into a mutable reference to the value in the entry
 328     /// with a lifetime bound to the collection itself
 329     #[inline]
 330     pub fn into_mut(self) -> &'a mut V {
 331         unsafe { self.inner.into_mut().downcast_mut_unchecked() }
 332     }
 333
 334     /// Sets the value of the entry, and returns the entry's old value
 335     #[inline]
 336     pub fn insert(&mut self, value: V) -> V {
 337         unsafe { *self.inner.insert(value.into_box()).downcast_unchecked() }
 338     }
 339
 340     /// Takes the value out of the entry, and returns it
 341     #[inline]
 342     pub fn remove(self) -> V {
 343         unsafe { *self.inner.remove().downcast_unchecked() }
 344     }
 345 }
 346
 347 impl<'a, A: ?Sized + UncheckedAnyExt, V: IntoBox<A>> VacantEntry<'a, A, V> {
 348     /// Sets the value of the entry with the VacantEntry's key,
 349     /// and returns a mutable reference to it
 350     #[inline]
 351     pub fn insert(self, value: V) -> &'a mut V {
 352         unsafe { self.inner.insert(value.into_box()).downcast_mut_unchecked() }
 353     }
 354 }
 355
 356 #[cfg(test)]
 357 mod tests {
 358     use super::*;
 359
 360     #[derive(Clone, Debug, PartialEq)] struct A(i32);
 361     #[derive(Clone, Debug, PartialEq)] struct B(i32);
 362     #[derive(Clone, Debug, PartialEq)] struct C(i32);
 363     #[derive(Clone, Debug, PartialEq)] struct D(i32);
 364     #[derive(Clone, Debug, PartialEq)] struct E(i32);
 365     #[derive(Clone, Debug, PartialEq)] struct F(i32);
 366     #[derive(Clone, Debug, PartialEq)] struct J(i32);
 367
 368     macro_rules! test_entry {
 369         ($name:ident, $init:ty) => {
 370             #[test]
 371             fn $name() {
 372                 let mut map = <$init>::new();
 373                 assert_eq!(map.insert(A(10)), None);
 374                 assert_eq!(map.insert(B(20)), None);
 375                 assert_eq!(map.insert(C(30)), None);
 376                 assert_eq!(map.insert(D(40)), None);
 377                 assert_eq!(map.insert(E(50)), None);
 378                 assert_eq!(map.insert(F(60)), None);
 379
 380                 // Existing key (insert)
 381                 match map.entry::<A>() {
 382                     Entry::Vacant(_) => unreachable!(),
 383                     Entry::Occupied(mut view) => {
 384                         assert_eq!(view.get(), &A(10));
 385                         assert_eq!(view.insert(A(100)), A(10));
 386                     }
 387                 }
 388                 assert_eq!(map.get::<A>().unwrap(), &A(100));
 389                 assert_eq!(map.len(), 6);
 390
 391
 392                 // Existing key (update)
 393                 match map.entry::<B>() {
 394                     Entry::Vacant(_) => unreachable!(),
 395                     Entry::Occupied(mut view) => {
 396                         let v = view.get_mut();
 397                         let new_v = B(v.0 * 10);
 398                         *v = new_v;
 399                     }
 400                 }
 401                 assert_eq!(map.get::<B>().unwrap(), &B(200));
 402                 assert_eq!(map.len(), 6);
 403
 404
 405                 // Existing key (remove)
 406                 match map.entry::<C>() {
 407                     Entry::Vacant(_) => unreachable!(),
 408                     Entry::Occupied(view) => {
 409                         assert_eq!(view.remove(), C(30));
 410                     }
 411                 }
 412                 assert_eq!(map.get::<C>(), None);
 413                 assert_eq!(map.len(), 5);
 414
 415
 416                 // Inexistent key (insert)
 417                 match map.entry::<J>() {
 418                     Entry::Occupied(_) => unreachable!(),
 419                     Entry::Vacant(view) => {
 420                         assert_eq!(*view.insert(J(1000)), J(1000));
 421                     }
 422                 }
 423                 assert_eq!(map.get::<J>().unwrap(), &J(1000));
 424                 assert_eq!(map.len(), 6);
 425
 426                 // Entry.or_insert on existing key
 427                 map.entry::<B>().or_insert(B(71)).0 += 1;
 428                 assert_eq!(map.get::<B>().unwrap(), &B(201));
 429                 assert_eq!(map.len(), 6);
 430
 431                 // Entry.or_insert on nonexisting key
 432                 map.entry::<C>().or_insert(C(300)).0 += 1;
 433                 assert_eq!(map.get::<C>().unwrap(), &C(301));
 434                 assert_eq!(map.len(), 7);
 435             }
 436         }
 437     }
 438
 439     test_entry!(test_entry_any, AnyMap);
 440     test_entry!(test_entry_cloneany, Map<dyn CloneAny>);
 441
 442     #[test]
 443     fn test_default() {
 444         let map: AnyMap = Default::default();
 445         assert_eq!(map.len(), 0);
 446     }
 447
 448     #[test]
 449     fn test_clone() {
 450         let mut map: Map<dyn CloneAny> = Map::new();
 451         let _ = map.insert(A(1));
 452         let _ = map.insert(B(2));
 453         let _ = map.insert(D(3));
 454         let _ = map.insert(E(4));
 455         let _ = map.insert(F(5));
 456         let _ = map.insert(J(6));
 457         let map2 = map.clone();
 458         assert_eq!(map2.len(), 6);
 459         assert_eq!(map2.get::<A>(), Some(&A(1)));
 460         assert_eq!(map2.get::<B>(), Some(&B(2)));
 461         assert_eq!(map2.get::<C>(), None);
 462         assert_eq!(map2.get::<D>(), Some(&D(3)));
 463         assert_eq!(map2.get::<E>(), Some(&E(4)));
 464         assert_eq!(map2.get::<F>(), Some(&F(5)));
 465         assert_eq!(map2.get::<J>(), Some(&J(6)));
 466     }
 467
 468     #[test]
 469     fn test_varieties() {
 470         fn assert_send<T: Send>() { }
 471         fn assert_sync<T: Sync>() { }
 472         fn assert_clone<T: Clone>() { }
 473         fn assert_debug<T: ::core::fmt::Debug>() { }
 474         assert_send::<Map<dyn Any + Send>>();
 475         assert_send::<Map<dyn Any + Send + Sync>>();
 476         assert_sync::<Map<dyn Any + Send + Sync>>();
 477         assert_debug::<Map<dyn Any>>();
 478         assert_debug::<Map<dyn Any + Send>>();
 479         assert_debug::<Map<dyn Any + Send + Sync>>();
 480         assert_send::<Map<dyn CloneAny + Send>>();
 481         assert_send::<Map<dyn CloneAny + Send + Sync>>();
 482         assert_sync::<Map<dyn CloneAny + Send + Sync>>();
 483         assert_clone::<Map<dyn CloneAny + Send>>();
 484         assert_clone::<Map<dyn CloneAny + Send + Sync>>();
 485         assert_clone::<Map<dyn CloneAny + Send + Sync>>();
 486         assert_debug::<Map<dyn CloneAny>>();
 487         assert_debug::<Map<dyn CloneAny + Send>>();
 488         assert_debug::<Map<dyn CloneAny + Send + Sync>>();
 489     }
 490 }