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//! This crate provides a [`StaticTypeMap`] which allows you to store a single instance of any
//! `'static` value as long as it implements [`Any`].
//!
//! # Examples
//!
//! ```
//! # use static_type_map::StaticTypeMap;
//! let mut type_map = StaticTypeMap::new();
//! type_map.insert(10u8);
//! type_map.insert(20u16);
//! type_map.insert(true);
//! type_map.insert("a");
//!
//! assert!(type_map.contains::<bool>());
//!
//! assert_eq!(type_map.get::<&str>(), Some(&"a"));
//!
//! if let Some(previous_value) = type_map.insert(50u8) {
//! assert_eq!(previous_value, 10u8);
//! }
//!
//! type_map.remove::<u16>();
//!
//! assert_eq!(type_map.len(), 3);
//! ```
#![forbid(unsafe_code)]
#![cfg_attr(feature = "hashbrown", no_std)]
#[cfg(feature = "hashbrown")]
extern crate alloc;
#[cfg(feature = "hashbrown")]
extern crate core;
#[cfg(feature = "hashbrown")]
use alloc::boxed::Box;
#[cfg(feature = "hashbrown")]
use hashbrown::HashMap;
#[cfg(not(feature = "hashbrown"))]
use std::collections::HashMap;
use core::any::{Any, TypeId};
macro_rules! define_bounded_map {
(
$(#[$attr:meta])*
$vis:vis struct $name:ident: $bound:tt $(+ $others:tt)*;
) => {
$(#[$attr])*
$vis struct $name(HashMap<TypeId, Box<dyn $bound $(+ $others)*>>);
impl $name {
#[doc = concat!("Creates an empty [`", stringify!($name), "`].")]
///
/// The map is initially created with a capacity of 0, so it will not allocate
/// until it is first inserted into.
///
/// # Examples
///
/// ```
#[doc = concat!("# use static_type_map::", stringify!($name), ";")]
#[doc = concat!("let type_map = ", stringify!($name), "::new();")]
/// ```
#[must_use]
pub fn new() -> Self {
Self { ..Self::default() }
}
#[doc = concat!("Creates an empty [`", stringify!($name), "`] with the specified capacity.")]
///
/// The map will be able to hold at least `capacity` types without reallocating.
/// If `capacity` is 0, the static type map will not allocate.
///
/// # Examples
///
/// ```
#[doc = concat!("# use static_type_map::", stringify!($name), ";")]
#[doc = concat!("let type_map = ", stringify!($name), "::with_capacity(10);")]
/// ```
#[must_use]
pub fn with_capacity(capacity: usize) -> Self {
Self(HashMap::with_capacity(capacity))
}
/// Returns the number of types the map can hold without reallocating.
///
/// This number is a lower bound; the map might be able to hold more, but it is
/// guaranteed to be able to hold at least so many.
///
/// # Examples
///
/// ```
#[doc = concat!("# use static_type_map::", stringify!($name), ";")]
#[doc = concat!("let type_map = ", stringify!($name), "::with_capacity(100);")]
/// assert!(type_map.capacity() >= 100);
/// ```
#[must_use]
pub fn capacity(&self) -> usize {
self.0.capacity()
}
/// Returns `true` if the map contains no instances of any type.
///
/// # Examples
///
/// ```
#[doc = concat!("# use static_type_map::", stringify!($name), ";")]
#[doc = concat!("let type_map = ", stringify!($name), "::new();")]
/// assert!(type_map.is_empty());
/// ```
#[must_use]
pub fn is_empty(&self) -> bool {
self.0.is_empty()
}
/// Returns the number of types in the map.
///
/// # Examples
///
/// ```
#[doc = concat!("# use static_type_map::", stringify!($name), ";")]
#[doc = concat!("let mut type_map = ", stringify!($name), "::new();")]
/// assert_eq!(type_map.len(), 0);
/// type_map.insert("a");
/// assert_eq!(type_map.len(), 1);
/// ```
#[must_use]
pub fn len(&self) -> usize {
self.0.len()
}
/// Clears the map. Keep allocated memory for reuse.
///
/// # Examples
///
/// ```
#[doc = concat!("# use static_type_map::", stringify!($name), ";")]
#[doc = concat!("let mut type_map = ", stringify!($name), "::new();")]
/// type_map.insert("a");
/// type_map.clear();
/// assert!(type_map.is_empty());
/// ```
pub fn clear(&mut self) {
self.0.clear();
}
/// Reserves capacity for at least `additional` more types to be inserted in the map. The
/// collection may reserve more space to avoid frequent reallocations.
///
/// # Panics
///
/// Panics if the new allocation size overflows [`usize`].
///
/// # Examples
/// ```
#[doc = concat!("# use static_type_map::", stringify!($name), ";")]
#[doc = concat!("let mut type_map = ", stringify!($name), "::new();")]
/// assert_eq!(type_map.capacity(), 0);
/// type_map.reserve(10);
/// assert!(type_map.capacity() >= 10);
/// ```
pub fn reserve(&mut self, additional: usize) {
self.0.reserve(additional);
}
/// Shrinks the capacity of the map as much as possible. It will drop down as much as possible
/// while mainting the internal rules and possibly leaving some space in accordance with the
/// resize policy.
///
/// # Examples
///
/// ```
#[doc = concat!("# use static_type_map::", stringify!($name), ";")]
#[doc = concat!("let mut type_map = ", stringify!($name), "::with_capacity(100);")]
/// assert!(type_map.capacity() >= 0);
/// type_map.insert("a");
/// type_map.insert(true);
/// assert!(type_map.capacity() >= 2);
/// ```
pub fn shrink_to_fit(&mut self) {
self.0.shrink_to_fit();
}
/// Returns `true` if the map contains an instance of `T`.
///
/// # Examples
///
/// ```
#[doc = concat!("# use static_type_map::", stringify!($name), ";")]
#[doc = concat!("let mut type_map = ", stringify!($name), "::new();")]
/// type_map.insert("a");
/// assert!(type_map.contains::<&str>());
/// ```
#[must_use]
pub fn contains<T>(&self) -> bool
where
T: Any,
{
self.0.contains_key(&TypeId::of::<T>())
}
/// Returns a reference to an instance of `T`.
///
/// If the map does not have an instance of `T`, [`None`] is returned.
///
/// # Examples
///
/// ```
#[doc = concat!("# use static_type_map::", stringify!($name), ";")]
#[doc = concat!("let mut type_map = ", stringify!($name), "::new();")]
/// type_map.insert("a");
/// assert_eq!(type_map.get::<&str>(), Some(&"a"));
/// assert_eq!(type_map.get::<bool>(), None);
/// ```
#[must_use]
pub fn get<T>(&self) -> Option<&T>
where
T: $bound $(+ $others)*,
{
self.0
.get(&TypeId::of::<T>())
.and_then(|any| (&**any as &(dyn Any)).downcast_ref())
}
/// Returns a mutable reference to an instance of `T`.
///
/// If the map does not have an instance of `T`, [`None`] is returned.
///
/// # Examples
///
/// ```
#[doc = concat!("# use static_type_map::", stringify!($name), ";")]
#[doc = concat!("let mut type_map = ", stringify!($name), "::new();")]
/// type_map.insert("a");
/// if let Some(x) = type_map.get_mut::<&str>() {
/// *x = "b";
/// }
/// assert_eq!(type_map.get::<&str>(), Some(&"b"));
/// ```
#[must_use]
pub fn get_mut<T>(&mut self) -> Option<&mut T>
where
T: $bound $(+ $others)*,
{
self.0
.get_mut(&TypeId::of::<T>())
.and_then(|any| (&mut **any as &mut (dyn Any)).downcast_mut())
}
/// Insert an instance of type `T` into the map.
///
/// If the map did not have this type present, [`None`] is returned.
///
/// # Examples
///
/// ```
#[doc = concat!("# use static_type_map::", stringify!($name), ";")]
#[doc = concat!("let mut type_map = ", stringify!($name), "::new();")]
/// assert_eq!(type_map.insert("a"), None);
/// assert_eq!(type_map.insert("b"), Some("a"));
/// ```
pub fn insert<T>(&mut self, t: T) -> Option<T>
where
T: $bound $(+ $others)*,
{
self.0
.insert(TypeId::of::<T>(), Box::new(t))
.and_then(|any| (any as Box<dyn Any>).downcast().ok())
.map(|concrete_type| *concrete_type)
}
/// Remove and return an instance of type `T` from the map.
///
/// If the map did not have this type present, [`None`] is returned.
///
/// # Examples
///
/// ```
#[doc = concat!("# use static_type_map::", stringify!($name), ";")]
#[doc = concat!("let mut type_map = ", stringify!($name), "::new();")]
/// type_map.insert("a");
/// assert_eq!(type_map.remove::<&str>(), Some("a"));
/// ```
pub fn remove<T>(&mut self) -> Option<T>
where
T: $bound $(+ $others)*,
{
self.0
.remove(&TypeId::of::<T>())
.and_then(|any| (any as Box<dyn Any>).downcast().ok())
.map(|concrete_type| *concrete_type)
}
}
}
}
define_bounded_map! {
/// A map where the key is the type of the value.
#[derive(Debug, Default)]
pub struct StaticTypeMap: Any;
}
#[cfg(feature = "send")]
define_bounded_map! {
/// Like [`StaticTypeMap`] but with a [`Send`] bound.
#[derive(Debug, Default)]
pub struct SendStaticTypeMap: Any + Send;
}
#[cfg(feature = "sync")]
define_bounded_map! {
/// Like [`StaticTypeMap`] but with a [`Send`] + [`Sync`] bound.
#[derive(Debug, Default)]
pub struct SendSyncStaticTypeMap: Any + Send + Sync;
}