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 #![warn(unused_qualifications, non_upper_case_globals,
   4         variant_size_differences, unused_typecasts,
   5         missing_docs, unused_results)]
   6 #![allow(unstable)]
   7
   8 #[cfg(test)]
   9 extern crate test;
  10
  11 use std::any::{Any, TypeId};
  12 use std::mem::forget;
  13 use std::collections::HashMap;
  14 use std::collections::hash_map;
  15 use std::hash::{Hasher, Writer};
  16 use std::collections::hash_state::HashState;
  17 use std::mem::transmute;
  18 use std::raw::TraitObject;
  19
  20 struct TypeIdHasher {
  21     value: u64,
  22 }
  23
  24 struct TypeIdState;
  25
  26 impl HashState for TypeIdState {
  27     type Hasher = TypeIdHasher;
  28
  29     fn hasher(&self) -> TypeIdHasher {
  30         TypeIdHasher { value: 0 }
  31     }
  32 }
  33
  34 impl Writer for TypeIdHasher {
  35     #[inline(always)]
  36     fn write(&mut self, bytes: &[u8]) {
  37         // This expects to receive one and exactly one 64-bit value
  38         debug_assert!(bytes.len() == 8);
  39         unsafe {
  40             std::ptr::copy_nonoverlapping_memory(&mut self.value,
  41                                                  transmute(&bytes[0]),
  42                                                  1)
  43         }
  44     }
  45 }
  46
  47 impl Hasher for TypeIdHasher {
  48     type Output = u64;
  49
  50     fn reset(&mut self) { }
  51
  52     fn finish(&self) -> u64 { self.value }
  53 }
  54
  55 /// An extension of `AnyRefExt` allowing unchecked downcasting of trait objects to `&T`.
  56 trait UncheckedAnyRefExt<'a> {
  57     /// Returns a reference to the boxed value, assuming that it is of type `T`. This should only be
  58     /// called if you are ABSOLUTELY CERTAIN of `T` as you will get really wacky output if it’s not.
  59     unsafe fn downcast_ref_unchecked<T: 'static>(self) -> &'a T;
  60 }
  61
  62 impl<'a> UncheckedAnyRefExt<'a> for &'a Any {
  63     #[inline]
  64     unsafe fn downcast_ref_unchecked<T: 'static>(self) -> &'a T {
  65         // Get the raw representation of the trait object
  66         let to: TraitObject = transmute(self);
  67
  68         // Extract the data pointer
  69         transmute(to.data)
  70     }
  71 }
  72
  73 /// An extension of `AnyMutRefExt` allowing unchecked downcasting of trait objects to `&mut T`.
  74 trait UncheckedAnyMutRefExt<'a> {
  75     /// Returns a reference to the boxed value, assuming that it is of type `T`. This should only be
  76     /// called if you are ABSOLUTELY CERTAIN of `T` as you will get really wacky output if it’s not.
  77     unsafe fn downcast_mut_unchecked<T: 'static>(self) -> &'a mut T;
  78 }
  79
  80 impl<'a> UncheckedAnyMutRefExt<'a> for &'a mut Any {
  81     #[inline]
  82     unsafe fn downcast_mut_unchecked<T: 'static>(self) -> &'a mut T {
  83         // Get the raw representation of the trait object
  84         let to: TraitObject = transmute(self);
  85
  86         // Extract the data pointer
  87         transmute(to.data)
  88     }
  89 }
  90
  91 /// An extension of `BoxAny` allowing unchecked downcasting of trait objects to `Box<T>`.
  92 trait UncheckedBoxAny {
  93     /// Returns the boxed value, assuming that it is of type `T`. This should only be called if you
  94     /// are ABSOLUTELY CERTAIN of `T` as you will get really wacky output if it’s not.
  95     unsafe fn downcast_unchecked<T: 'static>(self) -> Box<T>;
  96 }
  97
  98 impl UncheckedBoxAny for Box<Any + 'static> {
  99     #[inline]
 100     unsafe fn downcast_unchecked<T: 'static>(self) -> Box<T> {
 101         // Get the raw representation of the trait object
 102         let to: TraitObject = *transmute::<&Box<Any>, &TraitObject>(&self);
 103
 104         // Prevent destructor on self being run
 105         forget(self);
 106
 107         // Extract the data pointer
 108         transmute(to.data)
 109     }
 110 }
 111
 112 /// A collection containing zero or one values for any given type and allowing convenient,
 113 /// type-safe access to those values.
 114 ///
 115 /// ```rust
 116 /// # use anymap::AnyMap;
 117 /// let mut data = AnyMap::new();
 118 /// assert_eq!(data.get(), None::<&i32>);
 119 /// data.insert(42i32);
 120 /// assert_eq!(data.get(), Some(&42i32));
 121 /// data.remove::<i32>();
 122 /// assert_eq!(data.get::<i32>(), None);
 123 ///
 124 /// #[derive(PartialEq, Show)]
 125 /// struct Foo {
 126 ///     str: String,
 127 /// }
 128 ///
 129 /// assert_eq!(data.get::<Foo>(), None);
 130 /// data.insert(Foo { str: format!("foo") });
 131 /// assert_eq!(data.get(), Some(&Foo { str: format!("foo") }));
 132 /// data.get_mut::<Foo>().map(|foo| foo.str.push('t'));
 133 /// assert_eq!(&*data.get::<Foo>().unwrap().str, "foot");
 134 /// ```
 135 ///
 136 /// Values containing non-static references are not permitted.
 137 #[stable]
 138 pub struct AnyMap {
 139     data: HashMap<TypeId, Box<Any + 'static>, TypeIdState>,
 140 }
 141
 142 impl AnyMap {
 143     /// Construct a new `AnyMap`.
 144     #[inline]
 145     #[stable]
 146     pub fn new() -> AnyMap {
 147         AnyMap {
 148             data: HashMap::with_hash_state(TypeIdState),
 149         }
 150     }
 151
 152     /// Creates an empty AnyMap with the given initial capacity.
 153     #[inline]
 154     #[stable]
 155     pub fn with_capcity(capacity: usize) -> AnyMap {
 156         AnyMap {
 157             data: HashMap::with_capacity_and_hash_state(capacity, TypeIdState),
 158         }
 159     }
 160
 161     /// Returns the number of elements the collection can hold without reallocating.
 162     #[inline]
 163     #[stable]
 164     pub fn capacity(&self) -> usize {
 165         self.data.capacity()
 166     }
 167
 168     /// Reserves capacity for at least `additional` more elements to be inserted
 169     /// in the `AnyMap`. The collection may reserve more space to avoid
 170     /// frequent reallocations.
 171     ///
 172     /// # Panics
 173     ///
 174     /// Panics if the new allocation size overflows `usize`.
 175     #[inline]
 176     #[stable]
 177     pub fn reserve(&mut self, additional: usize) {
 178         self.data.reserve(additional)
 179     }
 180
 181     /// Shrinks the capacity of the collection as much as possible. It will drop
 182     /// down as much as possible while maintaining the internal rules
 183     /// and possibly leaving some space in accordance with the resize policy.
 184     #[inline]
 185     #[stable]
 186     pub fn shrink_to_fit(&mut self) {
 187         self.data.shrink_to_fit()
 188     }
 189
 190     /// An iterator visiting all items in the collection in arbitrary order.
 191     /// Iterator element type is `&Any`.
 192     ///
 193     /// This is probably not a great deal of use.
 194     #[inline]
 195     #[stable]
 196     pub fn iter(&self) -> Iter {
 197         Iter {
 198             inner: self.data.iter(),
 199         }
 200     }
 201
 202     /// An iterator visiting all items in the collection in arbitrary order.
 203     /// Iterator element type is `&mut Any`.
 204     ///
 205     /// This is probably not a great deal of use.
 206     #[inline]
 207     #[stable]
 208     pub fn iter_mut(&mut self) -> IterMut {
 209         IterMut {
 210             inner: self.data.iter_mut(),
 211         }
 212     }
 213
 214     /// An iterator visiting all items in the collection in arbitrary order.
 215     /// Creates a consuming iterator, that is, one that moves each item
 216     /// out of the map in arbitrary order. The map cannot be used after
 217     /// calling this.
 218     ///
 219     /// Iterator element type is `Box<Any>`.
 220     #[inline]
 221     #[stable]
 222     pub fn into_iter(self) -> IntoIter {
 223         IntoIter {
 224             inner: self.data.into_iter(),
 225         }
 226     }
 227
 228     /// Returns a reference to the value stored in the collection for the type `T`, if it exists.
 229     #[stable]
 230     pub fn get<T: Any + 'static>(&self) -> Option<&T> {
 231         self.data.get(&TypeId::of::<T>())
 232             .map(|any| unsafe { any.downcast_ref_unchecked::<T>() })
 233     }
 234
 235     /// Returns a mutable reference to the value stored in the collection for the type `T`,
 236     /// if it exists.
 237     #[stable]
 238     pub fn get_mut<T: Any + 'static>(&mut self) -> Option<&mut T> {
 239         self.data.get_mut(&TypeId::of::<T>())
 240             .map(|any| unsafe { any.downcast_mut_unchecked::<T>() })
 241     }
 242
 243     /// Sets the value stored in the collection for the type `T`.
 244     /// If the collection already had a value of type `T`, that value is returned.
 245     /// Otherwise, `None` is returned.
 246     #[stable]
 247     pub fn insert<T: Any + 'static>(&mut self, value: T) -> Option<T> {
 248         self.data.insert(TypeId::of::<T>(), Box::new(value) as Box<Any>)
 249             .map(|any| *unsafe { any.downcast_unchecked::<T>() })
 250     }
 251
 252     /// Removes the `T` value from the collection,
 253     /// returning it if there was one or `None` if there was not.
 254     #[stable]
 255     pub fn remove<T: Any + 'static>(&mut self) -> Option<T> {
 256         self.data.remove(&TypeId::of::<T>())
 257             .map(|any| *unsafe { any.downcast_unchecked::<T>() })
 258     }
 259
 260     /// Returns true if the collection contains a value of type `T`.
 261     #[stable]
 262     pub fn contains<T: Any + 'static>(&self) -> bool {
 263         self.data.contains_key(&TypeId::of::<T>())
 264     }
 265
 266     /// Gets the entry for the given type in the collection for in-place manipulation
 267     #[stable]
 268     pub fn entry<T: Any + 'static>(&mut self) -> Entry<T> {
 269         match self.data.entry(TypeId::of::<T>()) {
 270             hash_map::Entry::Occupied(e) => Entry::Occupied(OccupiedEntry { entry: e }),
 271             hash_map::Entry::Vacant(e) => Entry::Vacant(VacantEntry { entry: e }),
 272         }
 273     }
 274
 275     /// Returns the number of items in the collection.
 276     #[inline]
 277     #[stable]
 278     pub fn len(&self) -> usize {
 279         self.data.len()
 280     }
 281
 282     /// Returns true if there are no items in the collection.
 283     #[inline]
 284     #[stable]
 285     pub fn is_empty(&self) -> bool {
 286         self.data.is_empty()
 287     }
 288
 289     /// Clears the map, returning all items as an iterator.
 290     ///
 291     /// Iterator element type is `Box<Any>`.
 292     ///
 293     /// Keeps the allocated memory for reuse.
 294     #[inline]
 295     #[unstable = "matches collection reform specification, waiting for dust to settle"]
 296     pub fn drain(&mut self) -> Drain {
 297         Drain {
 298             inner: self.data.drain(),
 299         }
 300     }
 301
 302     /// Removes all items from the collection. Keeps the allocated memory for reuse.
 303     #[inline]
 304     #[stable]
 305     pub fn clear(&mut self) {
 306         self.data.clear();
 307     }
 308 }
 309
 310 /// A view into a single occupied location in an AnyMap
 311 #[stable]
 312 pub struct OccupiedEntry<'a, V: 'a> {
 313     entry: hash_map::OccupiedEntry<'a, TypeId, Box<Any + 'static>>,
 314 }
 315
 316 /// A view into a single empty location in an AnyMap
 317 #[stable]
 318 pub struct VacantEntry<'a, V: 'a> {
 319     entry: hash_map::VacantEntry<'a, TypeId, Box<Any + 'static>>,
 320 }
 321
 322 /// A view into a single location in an AnyMap, which may be vacant or occupied
 323 #[stable]
 324 pub enum Entry<'a, V: 'a> {
 325     /// An occupied Entry
 326     Occupied(OccupiedEntry<'a, V>),
 327     /// A vacant Entry
 328     Vacant(VacantEntry<'a, V>),
 329 }
 330
 331 impl<'a, V: 'static + Clone> Entry<'a, V> {
 332     #[unstable = "matches collection reform v2 specification, waiting for dust to settle"]
 333     /// Returns a mutable reference to the entry if occupied, or the VacantEntry if vacant
 334     pub fn get(self) -> Result<&'a mut V, VacantEntry<'a, V>> {
 335         match self {
 336             Entry::Occupied(entry) => Ok(entry.into_mut()),
 337             Entry::Vacant(entry) => Err(entry),
 338         }
 339     }
 340 }
 341
 342 impl<'a, V: 'static> OccupiedEntry<'a, V> {
 343     #[stable]
 344     /// Gets a reference to the value in the entry
 345     pub fn get(&self) -> &V {
 346         unsafe { self.entry.get().downcast_ref_unchecked() }
 347     }
 348
 349     #[stable]
 350     /// Gets a mutable reference to the value in the entry
 351     pub fn get_mut(&mut self) -> &mut V {
 352         unsafe { self.entry.get_mut().downcast_mut_unchecked() }
 353     }
 354
 355     #[stable]
 356     /// Converts the OccupiedEntry into a mutable reference to the value in the entry
 357     /// with a lifetime bound to the collection itself
 358     pub fn into_mut(self) -> &'a mut V {
 359         unsafe { self.entry.into_mut().downcast_mut_unchecked() }
 360     }
 361
 362     #[stable]
 363     /// Sets the value of the entry, and returns the entry's old value
 364     pub fn insert(&mut self, value: V) -> V {
 365         unsafe { *self.entry.insert(Box::new(value) as Box<Any + 'static>).downcast_unchecked() }
 366     }
 367
 368     #[stable]
 369     /// Takes the value out of the entry, and returns it
 370     pub fn remove(self) -> V {
 371         unsafe { *self.entry.remove().downcast_unchecked() }
 372     }
 373 }
 374
 375 impl<'a, V: 'static> VacantEntry<'a, V> {
 376     #[stable]
 377     /// Sets the value of the entry with the VacantEntry's key,
 378     /// and returns a mutable reference to it
 379     pub fn insert(self, value: V) -> &'a mut V {
 380         unsafe { self.entry.insert(Box::new(value) as Box<Any + 'static>).downcast_mut_unchecked() }
 381     }
 382 }
 383
 384 /// `AnyMap` iterator.
 385 #[stable]
 386 #[derive(Clone)]
 387 pub struct Iter<'a> {
 388     inner: hash_map::Iter<'a, TypeId, Box<Any + 'static>>,
 389 }
 390
 391 /// `AnyMap` mutable references iterator.
 392 #[stable]
 393 pub struct IterMut<'a> {
 394     inner: hash_map::IterMut<'a, TypeId, Box<Any + 'static>>,
 395 }
 396
 397 /// `AnyMap` draining iterator.
 398 #[unstable = "matches collection reform specification, waiting for dust to settle"]
 399 pub struct Drain<'a> {
 400     inner: hash_map::Drain<'a, TypeId, Box<Any + 'static>>,
 401 }
 402
 403 /// `AnyMap` move iterator.
 404 #[stable]
 405 pub struct IntoIter {
 406     inner: hash_map::IntoIter<TypeId, Box<Any + 'static>>,
 407 }
 408
 409 #[stable]
 410 impl<'a> Iterator for Iter<'a> {
 411     type Item = &'a Any;
 412
 413     #[inline]
 414     fn next(&mut self) -> Option<&'a Any> {
 415         self.inner.next().map(|item| &**item.1)
 416     }
 417
 418     #[inline]
 419     fn size_hint(&self) -> (usize, Option<usize>) { self.inner.size_hint() }
 420 }
 421
 422 #[stable]
 423 impl<'a> Iterator for IterMut<'a> {
 424     type Item = &'a mut Any;
 425
 426     #[inline]
 427     fn next(&mut self) -> Option<&'a mut Any> {
 428         self.inner.next().map(|item| &mut **item.1)
 429     }
 430
 431     #[inline]
 432     fn size_hint(&self) -> (usize, Option<usize>) { self.inner.size_hint() }
 433 }
 434
 435 #[stable]
 436 impl<'a> Iterator for Drain<'a> {
 437     type Item = Box<Any + 'static>;
 438
 439     #[inline]
 440     fn next(&mut self) -> Option<Box<Any + 'static>> {
 441         self.inner.next().map(|item| item.1)
 442     }
 443
 444     #[inline]
 445     fn size_hint(&self) -> (usize, Option<usize>) { self.inner.size_hint() }
 446 }
 447
 448 #[stable]
 449 impl Iterator for IntoIter {
 450     type Item = Box<Any + 'static>;
 451
 452     #[inline]
 453     fn next(&mut self) -> Option<Box<Any + 'static>> {
 454         self.inner.next().map(|item| item.1)
 455     }
 456
 457     #[inline]
 458     fn size_hint(&self) -> (usize, Option<usize>) { self.inner.size_hint() }
 459 }
 460
 461 #[bench]
 462 fn bench_insertion(b: &mut ::test::Bencher) {
 463     b.iter(|| {
 464         let mut data = AnyMap::new();
 465         for _ in range(0, 100) {
 466             let _ = data.insert(42i32);
 467         }
 468     })
 469 }
 470
 471 #[bench]
 472 fn bench_get_missing(b: &mut ::test::Bencher) {
 473     b.iter(|| {
 474         let data = AnyMap::new();
 475         for _ in range(0, 100) {
 476             assert_eq!(data.get(), None::<&i32>);
 477         }
 478     })
 479 }
 480
 481 #[bench]
 482 fn bench_get_present(b: &mut ::test::Bencher) {
 483     b.iter(|| {
 484         let mut data = AnyMap::new();
 485         let _ = data.insert(42i32);
 486         // These inner loops are a feeble attempt to drown the other factors.
 487         for _ in range(0, 100) {
 488             assert_eq!(data.get(), Some(&42i32));
 489         }
 490     })
 491 }
 492
 493 #[test]
 494 fn test_entry() {
 495     #[derive(Show, PartialEq)] struct A(i32);
 496     #[derive(Show, PartialEq)] struct B(i32);
 497     #[derive(Show, PartialEq)] struct C(i32);
 498     #[derive(Show, PartialEq)] struct D(i32);
 499     #[derive(Show, PartialEq)] struct E(i32);
 500     #[derive(Show, PartialEq)] struct F(i32);
 501     #[derive(Show, PartialEq)] struct J(i32);
 502
 503     let mut map: AnyMap = AnyMap::new();
 504     assert_eq!(map.insert(A(10)), None);
 505     assert_eq!(map.insert(B(20)), None);
 506     assert_eq!(map.insert(C(30)), None);
 507     assert_eq!(map.insert(D(40)), None);
 508     assert_eq!(map.insert(E(50)), None);
 509     assert_eq!(map.insert(F(60)), None);
 510
 511     // Existing key (insert)
 512     match map.entry::<A>() {
 513         Entry::Vacant(_) => unreachable!(),
 514         Entry::Occupied(mut view) => {
 515             assert_eq!(view.get(), &A(10));
 516             assert_eq!(view.insert(A(100)), A(10));
 517         }
 518     }
 519     assert_eq!(map.get::<A>().unwrap(), &A(100));
 520     assert_eq!(map.len(), 6);
 521
 522
 523     // Existing key (update)
 524     match map.entry::<B>() {
 525         Entry::Vacant(_) => unreachable!(),
 526         Entry::Occupied(mut view) => {
 527             let v = view.get_mut();
 528             let new_v = B(v.0 * 10);
 529             *v = new_v;
 530         }
 531     }
 532     assert_eq!(map.get().unwrap(), &B(200));
 533     assert_eq!(map.len(), 6);
 534
 535
 536     // Existing key (remove)
 537     match map.entry::<C>() {
 538         Entry::Vacant(_) => unreachable!(),
 539         Entry::Occupied(view) => {
 540             assert_eq!(view.remove(), C(30));
 541         }
 542     }
 543     assert_eq!(map.get::<C>(), None);
 544     assert_eq!(map.len(), 5);
 545
 546
 547     // Inexistent key (insert)
 548     match map.entry::<J>() {
 549         Entry::Occupied(_) => unreachable!(),
 550         Entry::Vacant(view) => {
 551             assert_eq!(*view.insert(J(1000)), J(1000));
 552         }
 553     }
 554     assert_eq!(map.get::<J>().unwrap(), &J(1000));
 555     assert_eq!(map.len(), 6);
 556 }