f1710353a0
A minor [breaking-change] as downstream users will have to import the variants themselves, or prefix the variant with the Entry enum's namespace.
359 lines
11 KiB
Rust
359 lines
11 KiB
Rust
//! This crate provides the `AnyMap` type, a safe and convenient store for one value of each type.
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#![feature(default_type_params)]
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#![warn(unused_qualifications, non_upper_case_globals,
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variant_size_differences, unused_typecasts,
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missing_docs, unused_results)]
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#[cfg(test)]
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extern crate test;
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use std::any::Any;
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use std::intrinsics::{forget, TypeId};
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use std::collections::HashMap;
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use std::collections::hash_map;
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use std::hash::{Hash, Hasher, Writer};
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use std::mem::transmute;
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use std::raw::TraitObject;
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struct TypeIdHasher;
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struct TypeIdState {
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value: u64,
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}
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impl Writer for TypeIdState {
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#[inline(always)]
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fn write(&mut self, bytes: &[u8]) {
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// This expects to receive one and exactly one 64-bit value
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debug_assert!(bytes.len() == 8);
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unsafe {
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std::ptr::copy_nonoverlapping_memory(&mut self.value,
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transmute(&bytes[0]),
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1)
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}
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}
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}
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impl Hasher<TypeIdState> for TypeIdHasher {
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fn hash<Sized? T: Hash<TypeIdState>>(&self, value: &T) -> u64 {
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let mut state = TypeIdState {
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value: 0,
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};
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value.hash(&mut state);
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state.value
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}
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}
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/// An extension of `AnyRefExt` allowing unchecked downcasting of trait objects to `&T`.
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trait UncheckedAnyRefExt<'a> {
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/// Returns a reference to the boxed value, assuming that it is of type `T`. This should only be
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/// called if you are ABSOLUTELY CERTAIN of `T` as you will get really wacky output if it’s not.
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unsafe fn downcast_ref_unchecked<T: 'static>(self) -> &'a T;
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}
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impl<'a> UncheckedAnyRefExt<'a> for &'a Any {
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#[inline]
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unsafe fn downcast_ref_unchecked<T: 'static>(self) -> &'a T {
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// Get the raw representation of the trait object
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let to: TraitObject = transmute(self);
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// Extract the data pointer
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transmute(to.data)
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}
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}
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/// An extension of `AnyMutRefExt` allowing unchecked downcasting of trait objects to `&mut T`.
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trait UncheckedAnyMutRefExt<'a> {
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/// Returns a reference to the boxed value, assuming that it is of type `T`. This should only be
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/// called if you are ABSOLUTELY CERTAIN of `T` as you will get really wacky output if it’s not.
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unsafe fn downcast_mut_unchecked<T: 'static>(self) -> &'a mut T;
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}
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impl<'a> UncheckedAnyMutRefExt<'a> for &'a mut Any {
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#[inline]
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unsafe fn downcast_mut_unchecked<T: 'static>(self) -> &'a mut T {
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// Get the raw representation of the trait object
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let to: TraitObject = transmute(self);
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// Extract the data pointer
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transmute(to.data)
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}
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}
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/// An extension of `BoxAny` allowing unchecked downcasting of trait objects to `Box<T>`.
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trait UncheckedBoxAny {
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/// Returns the boxed value, assuming that it is of type `T`. This should only be called if you
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/// are ABSOLUTELY CERTAIN of `T` as you will get really wacky output if it’s not.
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unsafe fn downcast_unchecked<T: 'static>(self) -> Box<T>;
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}
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impl UncheckedBoxAny for Box<Any + 'static> {
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#[inline]
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unsafe fn downcast_unchecked<T: 'static>(self) -> Box<T> {
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// Get the raw representation of the trait object
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let to: TraitObject = *transmute::<&Box<Any>, &TraitObject>(&self);
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// Prevent destructor on self being run
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forget(self);
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// Extract the data pointer
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transmute(to.data)
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}
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}
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/// A map containing zero or one values for any given type and allowing convenient,
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/// type-safe access to those values.
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///
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/// ```rust
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/// # use anymap::AnyMap;
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/// let mut data = AnyMap::new();
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/// assert_eq!(data.get(), None::<&int>);
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/// data.insert(42i);
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/// assert_eq!(data.get(), Some(&42i));
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/// data.remove::<int>();
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/// assert_eq!(data.get::<int>(), None);
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///
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/// #[deriving(PartialEq, Show)]
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/// struct Foo {
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/// str: String,
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/// }
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///
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/// assert_eq!(data.get::<Foo>(), None);
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/// data.insert(Foo { str: "foo".to_string() });
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/// assert_eq!(data.get(), Some(&Foo { str: "foo".to_string() }));
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/// data.get_mut::<Foo>().map(|foo| foo.str.push('t'));
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/// assert_eq!(data.get::<Foo>().unwrap().str.as_slice(), "foot");
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/// ```
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///
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/// Values containing non-static references are not permitted.
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pub struct AnyMap {
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data: HashMap<TypeId, Box<Any + 'static>, TypeIdHasher>,
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}
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impl AnyMap {
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/// Construct a new `AnyMap`.
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pub fn new() -> AnyMap {
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AnyMap {
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data: HashMap::with_hasher(TypeIdHasher),
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}
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}
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}
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impl AnyMap {
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/// Deprecated: Renamed to `get`.
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#[deprecated = "Renamed to `get`"]
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pub fn find<T: Any + 'static>(&self) -> Option<&T> {
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self.get::<T>()
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}
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/// Deprecated: Renamed to `get_mut`.
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#[deprecated = "Renamed to `get_mut`"]
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pub fn find_mut<T: Any + 'static>(&mut self) -> Option<&mut T> {
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self.get_mut::<T>()
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}
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/// Retrieve the value stored in the map for the type `T`, if it exists.
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pub fn get<T: Any + 'static>(&self) -> Option<&T> {
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self.data.get(&TypeId::of::<T>())
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.map(|any| unsafe { any.downcast_ref_unchecked::<T>() })
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}
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/// Retrieve a mutable reference to the value stored in the map for the type `T`, if it exists.
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pub fn get_mut<T: Any + 'static>(&mut self) -> Option<&mut T> {
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self.data.get_mut(&TypeId::of::<T>())
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.map(|any| unsafe { any.downcast_mut_unchecked::<T>() })
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}
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/// Set the value contained in the map for the type `T`.
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/// If there is a previous value stored, it will be returned.
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pub fn insert<T: Any + 'static>(&mut self, value: T) -> Option<T> {
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self.data.insert(TypeId::of::<T>(), box value as Box<Any>)
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.map(|any| *unsafe { any.downcast_unchecked::<T>() })
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}
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/// Remove and return the value for the type `T` if it existed.
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pub fn remove<T: Any + 'static>(&mut self) -> Option<T> {
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self.data.remove(&TypeId::of::<T>())
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.map(|any| *unsafe { any.downcast_unchecked::<T>() })
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}
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/// Does a value of type `T` exist?
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pub fn contains<T: Any + 'static>(&self) -> bool {
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self.data.contains_key(&TypeId::of::<T>())
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}
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/// Gets the given key's corresponding entry in the map for in-place manipulation
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pub fn entry<T: Any + 'static>(&mut self) -> Entry<T> {
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match self.data.entry(TypeId::of::<T>()) {
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hash_map::Entry::Occupied(e) => Entry::Occupied(OccupiedEntry { entry: e }),
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hash_map::Entry::Vacant(e) => Entry::Vacant(VacantEntry { entry: e }),
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}
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}
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/// Returns the number of items in the collection.
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pub fn len(&self) -> uint {
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self.data.len()
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}
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/// Returns true if there are no items in the collection.
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pub fn is_empty(&self) -> bool {
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self.data.is_empty()
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}
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/// Removes all items from the collection.
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pub fn clear(&mut self) {
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self.data.clear();
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}
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}
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/// A view into a single occupied location in an AnyMap
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pub struct OccupiedEntry<'a, V: 'a> {
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entry: hash_map::OccupiedEntry<'a, TypeId, Box<Any + 'static>>,
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}
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/// A view into a single empty location in an AnyMap
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pub struct VacantEntry<'a, V: 'a> {
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entry: hash_map::VacantEntry<'a, TypeId, Box<Any + 'static>>,
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}
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/// A view into a single location in a map, which may be vacant or occupied
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pub enum Entry<'a, V: 'a> {
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/// An occupied Entry
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Occupied(OccupiedEntry<'a, V>),
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/// A vacant Entry
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Vacant(VacantEntry<'a, V>),
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}
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impl<'a, V: 'static> OccupiedEntry<'a, V> {
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/// Gets a reference to the value in the entry
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pub fn get(&self) -> &V {
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unsafe { self.entry.get().downcast_ref_unchecked() }
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}
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/// Gets a mutable reference to the value in the entry
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pub fn get_mut(&mut self) -> &mut V {
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unsafe { self.entry.get_mut().downcast_mut_unchecked() }
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}
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/// Converts the OccupiedEntry into a mutable reference to the value in the entry
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/// with a lifetime bound to the map itself
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pub fn into_mut(self) -> &'a mut V {
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unsafe { self.entry.into_mut().downcast_mut_unchecked() }
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}
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/// Sets the value of the entry, and returns the entry's old value
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pub fn set(&mut self, value: V) -> V {
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unsafe { *self.entry.set(box value as Box<Any + 'static>).downcast_unchecked() }
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}
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/// Takes the value out of the entry, and returns it
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pub fn take(self) -> V {
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unsafe { *self.entry.take().downcast_unchecked() }
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}
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}
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impl<'a, V: 'static> VacantEntry<'a, V> {
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/// Sets the value of the entry with the VacantEntry's key,
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/// and returns a mutable reference to it
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pub fn set(self, value: V) -> &'a mut V {
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unsafe { self.entry.set(box value as Box<Any + 'static>).downcast_mut_unchecked() }
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}
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}
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#[bench]
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fn bench_insertion(b: &mut ::test::Bencher) {
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b.iter(|| {
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let mut data = AnyMap::new();
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for _ in range(0u, 100) {
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let _ = data.insert(42i);
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}
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})
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}
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#[bench]
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fn bench_get_missing(b: &mut ::test::Bencher) {
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b.iter(|| {
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let data = AnyMap::new();
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for _ in range(0u, 100) {
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assert_eq!(data.get(), None::<&int>);
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}
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})
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}
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#[bench]
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fn bench_get_present(b: &mut ::test::Bencher) {
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b.iter(|| {
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let mut data = AnyMap::new();
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let _ = data.insert(42i);
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// These inner loops are a feeble attempt to drown the other factors.
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for _ in range(0u, 100) {
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assert_eq!(data.get(), Some(&42i));
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}
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})
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}
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#[test]
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fn test_entry() {
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#[deriving(Show, PartialEq)] struct A(int);
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#[deriving(Show, PartialEq)] struct B(int);
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#[deriving(Show, PartialEq)] struct C(int);
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#[deriving(Show, PartialEq)] struct D(int);
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#[deriving(Show, PartialEq)] struct E(int);
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#[deriving(Show, PartialEq)] struct F(int);
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#[deriving(Show, PartialEq)] struct J(int);
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let mut map: AnyMap = AnyMap::new();
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assert_eq!(map.insert(A(10)), None);
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assert_eq!(map.insert(B(20)), None);
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assert_eq!(map.insert(C(30)), None);
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assert_eq!(map.insert(D(40)), None);
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assert_eq!(map.insert(E(50)), None);
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assert_eq!(map.insert(F(60)), None);
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// Existing key (insert)
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match map.entry::<A>() {
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Entry::Vacant(_) => unreachable!(),
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Entry::Occupied(mut view) => {
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assert_eq!(view.get(), &A(10));
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assert_eq!(view.set(A(100)), A(10));
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}
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}
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assert_eq!(map.get::<A>().unwrap(), &A(100));
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assert_eq!(map.len(), 6);
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// Existing key (update)
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match map.entry::<B>() {
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Entry::Vacant(_) => unreachable!(),
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Entry::Occupied(mut view) => {
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let v = view.get_mut();
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let new_v = B(v.0 * 10);
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*v = new_v;
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}
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}
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assert_eq!(map.get().unwrap(), &B(200));
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assert_eq!(map.len(), 6);
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// Existing key (take)
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match map.entry::<C>() {
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Entry::Vacant(_) => unreachable!(),
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Entry::Occupied(view) => {
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assert_eq!(view.take(), C(30));
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}
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}
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assert_eq!(map.get::<C>(), None);
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assert_eq!(map.len(), 5);
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// Inexistent key (insert)
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match map.entry::<J>() {
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Entry::Occupied(_) => unreachable!(),
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Entry::Vacant(view) => {
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assert_eq!(*view.set(J(1000)), J(1000));
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}
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}
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assert_eq!(map.get::<J>().unwrap(), &J(1000));
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assert_eq!(map.len(), 6);
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}
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