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// SPDX-FileCopyrightText: 2017 - 2023 Kamila Borowska <kamila@borowska.pw>
// SPDX-FileCopyrightText: 2019 Riey <creeper844@gmail.com>
// SPDX-FileCopyrightText: 2021 Alex Sayers <alex@asayers.com>
// SPDX-FileCopyrightText: 2021 Bruno Corrêa Zimmermann <brunoczim@gmail.com>
// SPDX-FileCopyrightText: 2022 Cass Fridkin <cass@cloudflare.com>
// SPDX-FileCopyrightText: 2022 Mateusz Kowalczyk <fuuzetsu@fuuzetsu.co.uk>
//
// SPDX-License-Identifier: MIT OR Apache-2.0
//! An enum mapping type.
//!
//! It is implemented using an array type, so using it is as fast as using Rust
//! arrays.
//!
//! # Examples
//!
//! ```
//! use enum_map::{enum_map, Enum, EnumMap};
//!
//! #[derive(Debug, Enum)]
//! enum Example {
//! A(bool),
//! B,
//! C,
//! }
//!
//! let mut map = enum_map! {
//! Example::A(false) => 0,
//! Example::A(true) => 1,
//! Example::B => 2,
//! Example::C => 3,
//! };
//! map[Example::C] = 4;
//!
//! assert_eq!(map[Example::A(true)], 1);
//!
//! for (key, &value) in &map {
//! println!("{:?} has {} as value.", key, value);
//! }
//! ```
#![no_std]
#![deny(missing_docs)]
#![warn(clippy::pedantic)]
#[cfg(feature = "arbitrary")]
mod arbitrary;
mod enum_map_impls;
mod internal;
mod iter;
#[cfg(feature = "serde")]
mod serde;
#[doc(hidden)]
pub use core::mem::{self, ManuallyDrop, MaybeUninit};
#[doc(hidden)]
pub use core::primitive::usize;
use core::slice;
#[doc(hidden)]
// unreachable needs to be exported for compatibility with older versions of enum-map-derive
pub use core::{panic, ptr, unreachable};
pub use enum_map_derive::Enum;
#[doc(hidden)]
pub use internal::out_of_bounds;
use internal::Array;
pub use internal::{Enum, EnumArray};
pub use iter::{IntoIter, IntoValues, Iter, IterMut, Values, ValuesMut};
// SAFETY: initialized needs to represent number of initialized elements
#[doc(hidden)]
pub struct Guard<'a, K, V>
where
K: EnumArray<V>,
{
array_mut: &'a mut MaybeUninit<K::Array>,
initialized: usize,
}
impl<K, V> Drop for Guard<'_, K, V>
where
K: EnumArray<V>,
{
fn drop(&mut self) {
// This is safe as arr[..len] is initialized due to
// Guard's type invariant.
unsafe {
ptr::slice_from_raw_parts_mut(self.as_mut_ptr(), self.initialized).drop_in_place();
}
}
}
impl<'a, K, V> Guard<'a, K, V>
where
K: EnumArray<V>,
{
#[doc(hidden)]
pub fn as_mut_ptr(&mut self) -> *mut V {
self.array_mut.as_mut_ptr().cast::<V>()
}
#[doc(hidden)]
#[must_use]
pub fn new(array_mut: &'a mut MaybeUninit<K::Array>) -> Self {
Self {
array_mut,
initialized: 0,
}
}
#[doc(hidden)]
#[must_use]
#[allow(clippy::unused_self)]
pub fn storage_length(&self) -> usize {
// SAFETY: We need to use LENGTH from K::Array, as K::LENGTH is
// untrustworthy.
K::Array::LENGTH
}
#[doc(hidden)]
#[must_use]
pub fn get_key(&self) -> K {
K::from_usize(self.initialized)
}
#[doc(hidden)]
// Unsafe as it can write out of bounds.
pub unsafe fn push(&mut self, value: V) {
self.as_mut_ptr().add(self.initialized).write(value);
self.initialized += 1;
}
}
#[doc(hidden)]
pub struct TypeEqualizer<'a, K, V>
where
K: EnumArray<V>,
{
pub enum_map: [EnumMap<K, V>; 0],
pub guard: Guard<'a, K, V>,
}
/// Enum map constructor.
///
/// This macro allows to create a new enum map in a type safe way. It takes
/// a list of `,` separated pairs separated by `=>`. Left side is `|`
/// separated list of enum keys, or `_` to match all unmatched enum keys,
/// while right side is a value.
///
/// The iteration order when using this macro is not guaranteed to be
/// consistent. Future releases of this crate may change it, and this is not
/// considered to be a breaking change.
///
/// # Examples
///
/// ```
/// use enum_map::{enum_map, Enum};
///
/// #[derive(Enum)]
/// enum Example {
/// A,
/// B,
/// C,
/// D,
/// }
///
/// let enum_map = enum_map! {
/// Example::A | Example::B => 1,
/// Example::C => 2,
/// _ => 3,
/// };
/// assert_eq!(enum_map[Example::A], 1);
/// assert_eq!(enum_map[Example::B], 1);
/// assert_eq!(enum_map[Example::C], 2);
/// assert_eq!(enum_map[Example::D], 3);
/// ```
#[macro_export]
macro_rules! enum_map {
{$($t:tt)*} => {{
let mut uninit = $crate::MaybeUninit::uninit();
let mut eq = $crate::TypeEqualizer {
enum_map: [],
guard: $crate::Guard::new(&mut uninit),
};
if false {
// Safe because this code is unreachable
unsafe { (&mut eq.enum_map).as_mut_ptr().read() }
} else {
for _ in 0..(&eq.guard).storage_length() {
struct __PleaseDoNotUseBreakWithoutLabel;
let _please_do_not_use_continue_without_label;
let value;
#[allow(unreachable_code)]
loop {
_please_do_not_use_continue_without_label = ();
value = match (&eq.guard).get_key() { $($t)* };
break __PleaseDoNotUseBreakWithoutLabel;
};
unsafe { (&mut eq.guard).push(value); }
}
$crate::mem::forget(eq);
// Safe because the array was fully initialized.
$crate::EnumMap::from_array(unsafe { uninit.assume_init() })
}
}};
}
/// An enum mapping.
///
/// This internally uses an array which stores a value for each possible
/// enum value. To work, it requires implementation of internal (private,
/// although public due to macro limitations) trait which allows extracting
/// information about an enum, which can be automatically generated using
/// `#[derive(Enum)]` macro.
///
/// Additionally, `bool` and `u8` automatically derives from `Enum`. While
/// `u8` is not technically an enum, it's convenient to consider it like one.
/// In particular, [reverse-complement in benchmark game] could be using `u8`
/// as an enum.
///
/// # Examples
///
/// ```
/// use enum_map::{enum_map, Enum, EnumMap};
///
/// #[derive(Enum)]
/// enum Example {
/// A,
/// B,
/// C,
/// }
///
/// let mut map = EnumMap::default();
/// // new initializes map with default values
/// assert_eq!(map[Example::A], 0);
/// map[Example::A] = 3;
/// assert_eq!(map[Example::A], 3);
/// ```
///
/// [reverse-complement in benchmark game]:
pub struct EnumMap<K: EnumArray<V>, V> {
array: K::Array,
}
impl<K: EnumArray<V>, V: Default> EnumMap<K, V> {
/// Clear enum map with default values.
///
/// # Examples
///
/// ```
/// use enum_map::{Enum, EnumMap};
///
/// #[derive(Enum)]
/// enum Example {
/// A,
/// B,
/// }
///
/// let mut enum_map = EnumMap::<_, String>::default();
/// enum_map[Example::B] = "foo".into();
/// enum_map.clear();
/// assert_eq!(enum_map[Example::A], "");
/// assert_eq!(enum_map[Example::B], "");
/// ```
#[inline]
pub fn clear(&mut self) {
for v in self.as_mut_slice() {
*v = V::default();
}
}
}
#[allow(clippy::len_without_is_empty)]
impl<K: EnumArray<V>, V> EnumMap<K, V> {
/// Creates an enum map from array.
#[inline]
pub const fn from_array(array: K::Array) -> EnumMap<K, V> {
EnumMap { array }
}
/// Create an enum map, where each value is the returned value from `cb`
/// using provided enum key.
///
/// ```
/// # use enum_map_derive::*;
/// use enum_map::{enum_map, Enum, EnumMap};
///
/// #[derive(Enum, PartialEq, Debug)]
/// enum Example {
/// A,
/// B,
/// }
///
/// let map = EnumMap::from_fn(|k| k == Example::A);
/// assert_eq!(map, enum_map! { Example::A => true, Example::B => false })
/// ```
pub fn from_fn<F>(mut cb: F) -> Self
where
F: FnMut(K) -> V,
{
enum_map! { k => cb(k) }
}
/// Returns an iterator over enum map.
///
/// The iteration order is deterministic, and when using [macro@Enum] derive
/// it will be the order in which enum variants are declared.
///
/// # Examples
///
/// ```
/// use enum_map::{enum_map, Enum};
///
/// #[derive(Enum, PartialEq)]
/// enum E {
/// A,
/// B,
/// C,
/// }
///
/// let map = enum_map! { E::A => 1, E::B => 2, E::C => 3};
/// assert!(map.iter().eq([(E::A, &1), (E::B, &2), (E::C, &3)]));
/// ```
#[inline]
pub fn iter(&self) -> Iter<K, V> {
self.into_iter()
}
/// Returns a mutable iterator over enum map.
#[inline]
pub fn iter_mut(&mut self) -> IterMut<K, V> {
self.into_iter()
}
/// Returns number of elements in enum map.
#[inline]
#[allow(clippy::unused_self)]
pub const fn len(&self) -> usize {
K::Array::LENGTH
}
/// Swaps two indexes.
///
/// # Examples
///
/// ```
/// use enum_map::enum_map;
///
/// let mut map = enum_map! { false => 0, true => 1 };
/// map.swap(false, true);
/// assert_eq!(map[false], 1);
/// assert_eq!(map[true], 0);
/// ```
#[inline]
pub fn swap(&mut self, a: K, b: K) {
self.as_mut_slice().swap(a.into_usize(), b.into_usize());
}
/// Consumes an enum map and returns the underlying array.
///
/// The order of elements is deterministic, and when using [macro@Enum]
/// derive it will be the order in which enum variants are declared.
///
/// # Examples
///
/// ```
/// use enum_map::{enum_map, Enum};
///
/// #[derive(Enum, PartialEq)]
/// enum E {
/// A,
/// B,
/// C,
/// }
///
/// let map = enum_map! { E::A => 1, E::B => 2, E::C => 3};
/// assert_eq!(map.into_array(), [1, 2, 3]);
/// ```
pub fn into_array(self) -> K::Array {
self.array
}
/// Returns a reference to the underlying array.
///
/// The order of elements is deterministic, and when using [macro@Enum]
/// derive it will be the order in which enum variants are declared.
///
/// # Examples
///
/// ```
/// use enum_map::{enum_map, Enum};
///
/// #[derive(Enum, PartialEq)]
/// enum E {
/// A,
/// B,
/// C,
/// }
///
/// let map = enum_map! { E::A => 1, E::B => 2, E::C => 3};
/// assert_eq!(map.as_array(), &[1, 2, 3]);
/// ```
pub const fn as_array(&self) -> &K::Array {
&self.array
}
/// Returns a mutable reference to the underlying array.
///
/// The order of elements is deterministic, and when using [macro@Enum]
/// derive it will be the order in which enum variants are declared.
///
/// # Examples
///
/// ```
/// use enum_map::{enum_map, Enum};
///
/// #[derive(Enum, PartialEq)]
/// enum E {
/// A,
/// B,
/// C,
/// }
///
/// let mut map = enum_map! { E::A => 1, E::B => 2, E::C => 3};
/// map.as_mut_array()[1] = 42;
/// assert_eq!(map.as_array(), &[1, 42, 3]);
/// ```
pub fn as_mut_array(&mut self) -> &mut K::Array {
&mut self.array
}
/// Converts an enum map to a slice representing values.
///
/// The order of elements is deterministic, and when using [macro@Enum]
/// derive it will be the order in which enum variants are declared.
///
/// # Examples
///
/// ```
/// use enum_map::{enum_map, Enum};
///
/// #[derive(Enum, PartialEq)]
/// enum E {
/// A,
/// B,
/// C,
/// }
///
/// let map = enum_map! { E::A => 1, E::B => 2, E::C => 3};
/// assert_eq!(map.as_slice(), &[1, 2, 3]);
/// ```
#[inline]
pub fn as_slice(&self) -> &[V] {
unsafe { slice::from_raw_parts(ptr::addr_of!(self.array).cast(), K::Array::LENGTH) }
}
/// Converts a mutable enum map to a mutable slice representing values.
#[inline]
pub fn as_mut_slice(&mut self) -> &mut [V] {
unsafe { slice::from_raw_parts_mut(ptr::addr_of_mut!(self.array).cast(), K::Array::LENGTH) }
}
/// Returns an enum map with function `f` applied to each element in order.
///
/// # Examples
///
/// ```
/// use enum_map::enum_map;
///
/// let a = enum_map! { false => 0, true => 1 };
/// let b = a.map(|_, x| f64::from(x) + 0.5);
/// assert_eq!(b, enum_map! { false => 0.5, true => 1.5 });
/// ```
pub fn map<F, T>(self, mut f: F) -> EnumMap<K, T>
where
F: FnMut(K, V) -> T,
K: EnumArray<T>,
{
struct DropOnPanic<K, V>
where
K: EnumArray<V>,
{
position: usize,
map: ManuallyDrop<EnumMap<K, V>>,
}
impl<K, V> Drop for DropOnPanic<K, V>
where
K: EnumArray<V>,
{
fn drop(&mut self) {
unsafe {
ptr::drop_in_place(&mut self.map.as_mut_slice()[self.position..]);
}
}
}
let mut drop_protect = DropOnPanic {
position: 0,
map: ManuallyDrop::new(self),
};
enum_map! {
k => {
let value = unsafe { ptr::read(&drop_protect.map.as_slice()[drop_protect.position]) };
drop_protect.position += 1;
f(k, value)
}
}
}
}