//! This crate provides the `AnyMap` type, a safe and convenient store for one value of each type.
-#![crate_id = "anymap#0.9"]
-#![crate_type = "rlib"]
-#![crate_type = "dylib"]
-#![warn(unnecessary_qualification, non_uppercase_statics, unsafe_block,
- variant_size_difference, managed_heap_memory, unnecessary_typecast,
- missing_doc, unused_result, deprecated_owned_vector)]
-
-use std::any::{Any, AnyRefExt, AnyMutRefExt};
+#![crate_name = "anymap"]
+#![crate_type = "lib"]
+#![feature(default_type_params)]
+#![warn(unused_qualifications, non_upper_case_globals,
+ variant_size_differences, unused_typecasts,
+ missing_docs, unused_results)]
+
+#[cfg(test)]
+extern crate test;
+
+use std::any::Any;
use std::intrinsics::TypeId;
use std::collections::HashMap;
+use std::hash::{Hash, Hasher, Writer};
+use std::mem::{transmute, transmute_copy};
+use std::raw::TraitObject;
+
+struct TypeIdHasher;
+
+struct TypeIdState {
+ value: u64,
+}
+
+impl Writer for TypeIdState {
+ #[inline(always)]
+ fn write(&mut self, bytes: &[u8]) {
+ // This expects to receive one and exactly one 64-bit value
+ debug_assert!(bytes.len() == 8);
+ unsafe {
+ std::ptr::copy_nonoverlapping_memory(&mut self.value,
+ transmute(&bytes[0]),
+ 1)
+ }
+ }
+}
+
+impl Hasher<TypeIdState> for TypeIdHasher {
+ fn hash<Sized? T: Hash<TypeIdState>>(&self, value: &T) -> u64 {
+ let mut state = TypeIdState {
+ value: 0,
+ };
+ value.hash(&mut state);
+ state.value
+ }
+}
+
+/// An extension of `AnyRefExt` allowing unchecked downcasting of trait objects to `&T`.
+trait UncheckedAnyRefExt<'a> {
+ /// Returns a reference to the boxed value, assuming that it is of type `T`. This should only be
+ /// called if you are ABSOLUTELY CERTAIN of `T` as you will get really wacky output if it’s not.
+ unsafe fn as_ref_unchecked<T: 'static>(self) -> &'a T;
+}
+
+impl<'a> UncheckedAnyRefExt<'a> for &'a Any + 'a {
+ #[inline]
+ unsafe fn as_ref_unchecked<T: 'static>(self) -> &'a T {
+ // Get the raw representation of the trait object
+ let to: TraitObject = transmute_copy(&self);
+
+ // Extract the data pointer
+ transmute(to.data)
+ }
+}
+
+/// An extension of `AnyMutRefExt` allowing unchecked downcasting of trait objects to `&mut T`.
+trait UncheckedAnyMutRefExt<'a> {
+ /// Returns a reference to the boxed value, assuming that it is of type `T`. This should only be
+ /// called if you are ABSOLUTELY CERTAIN of `T` as you will get really wacky output if it’s not.
+ unsafe fn as_mut_unchecked<T: 'static>(self) -> &'a mut T;
+}
+
+impl<'a> UncheckedAnyMutRefExt<'a> for &'a mut Any + 'a {
+ #[inline]
+ unsafe fn as_mut_unchecked<T: 'static>(self) -> &'a mut T {
+ // Get the raw representation of the trait object
+ let to: TraitObject = transmute_copy(&self);
+
+ // Extract the data pointer
+ transmute(to.data)
+ }
+}
/// A map containing zero or one values for any given type and allowing convenient,
/// type-safe access to those values.
/// assert_eq!(data.find::<Foo>(), None);
/// data.insert(Foo { str: "foo".to_string() });
/// assert_eq!(data.find(), Some(&Foo { str: "foo".to_string() }));
-/// data.find_mut::<Foo>().map(|foo| foo.str.push_char('t'));
+/// data.find_mut::<Foo>().map(|foo| foo.str.push('t'));
/// assert_eq!(data.find::<Foo>().unwrap().str.as_slice(), "foot");
/// ```
///
/// Values containing non-static references are not permitted.
pub struct AnyMap {
- data: HashMap<TypeId, Box<Any>:'static>,
+ data: HashMap<TypeId, Box<Any + 'static>, TypeIdHasher>,
}
impl AnyMap {
/// Construct a new `AnyMap`.
pub fn new() -> AnyMap {
AnyMap {
- data: HashMap::new(),
+ data: HashMap::with_hasher(TypeIdHasher),
}
}
}
impl AnyMap {
/// Retrieve the value stored in the map for the type `T`, if it exists.
- pub fn find<'a, T: 'static>(&'a self) -> Option<&'a T> {
- self.data.find(&TypeId::of::<T>()).and_then(|any| any.as_ref::<T>())
+ pub fn find<T: 'static>(&self) -> Option<&T> {
+ self.data.find(&TypeId::of::<T>()).map(|any| unsafe { any.as_ref_unchecked::<T>() })
}
/// Retrieve a mutable reference to the value stored in the map for the type `T`, if it exists.
- pub fn find_mut<'a, T: 'static>(&'a mut self) -> Option<&'a mut T> {
- self.data.find_mut(&TypeId::of::<T>()).and_then(|any| any.as_mut::<T>())
+ pub fn find_mut<T: 'static>(&mut self) -> Option<&mut T> {
+ self.data.find_mut(&TypeId::of::<T>()).map(|any| unsafe { any.as_mut_unchecked::<T>() })
}
/// Set the value contained in the map for the type `T`.
/// This will override any previous value stored.
pub fn insert<T: 'static>(&mut self, value: T) {
- self.data.insert(TypeId::of::<T>(), box value as Box<Any>:'static);
+ self.data.insert(TypeId::of::<T>(), box value as Box<Any>);
}
/// Remove the value for the type `T` if it existed.
pub fn remove<T: 'static>(&mut self) {
self.data.remove(&TypeId::of::<T>());
}
+
+ /// Does a value of type `T` exist?
+ pub fn contains<T: 'static>(&self) -> bool {
+ self.data.contains_key(&TypeId::of::<T>())
+ }
+
+ /// Returns the number of items in the collection.
+ pub fn len(&self) -> uint {
+ self.data.len()
+ }
+
+ /// Returns true if there are no items in the collection.
+ pub fn is_empty(&self) -> bool {
+ self.data.is_empty()
+ }
+
+ /// Removes all items from the collection.
+ pub fn clear(&mut self) {
+ self.data.clear();
+ }
+}
+
+#[bench]
+fn bench_insertion(b: &mut ::test::Bencher) {
+ b.iter(|| {
+ let mut data = AnyMap::new();
+ for _ in range(0u, 100) {
+ data.insert(42i);
+ }
+ })
+}
+
+#[bench]
+fn bench_find_missing(b: &mut ::test::Bencher) {
+ b.iter(|| {
+ let data = AnyMap::new();
+ for _ in range(0u, 100) {
+ assert_eq!(data.find(), None::<&int>);
+ }
+ })
+}
+
+#[bench]
+fn bench_find_present(b: &mut ::test::Bencher) {
+ b.iter(|| {
+ let mut data = AnyMap::new();
+ data.insert(42i);
+ // These inner loops are a feeble attempt to drown the other factors.
+ for _ in range(0u, 100) {
+ assert_eq!(data.find(), Some(&42i));
+ }
+ })
}