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