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