diff options
Diffstat (limited to 'src/lib.rs')
| -rw-r--r-- | src/lib.rs | 380 |
1 files changed, 197 insertions, 183 deletions
@@ -29,14 +29,6 @@ //! let elem = v[i]; //! ``` //! -//! Sample values from an array with `O(n)` complexity (`n` is the length of array): -//! -//! ``` -//! fastrand::choose_multiple(vec![1, 4, 5].iter(), 2); -//! fastrand::choose_multiple(0..20, 12); -//! ``` -//! -//! //! Shuffle an array: //! //! ``` @@ -69,98 +61,87 @@ //! ``` //! use std::iter::repeat_with; //! -//! let mut rng = fastrand::Rng::new(); +//! let rng = fastrand::Rng::new(); //! let mut bytes: Vec<u8> = repeat_with(|| rng.u8(..)).take(10_000).collect(); //! ``` -//! -//! This crate aims to expose a core set of useful randomness primitives. For more niche algorithms, -//! consider using the [`fastrand-contrib`] crate alongside this one. -//! -//! # Features -//! -//! - `std` (enabled by default): Enables the `std` library. This is required for the global -//! generator and global entropy. Without this feature, [`Rng`] can only be instantiated using -//! the [`with_seed`](Rng::with_seed) method. -//! - `js`: Assumes that WebAssembly targets are being run in a JavaScript environment. See the -//! [WebAssembly Notes](#webassembly-notes) section for more information. -//! -//! # WebAssembly Notes -//! -//! For non-WASI WASM targets, there is additional sublety to consider when utilizing the global RNG. -//! By default, `std` targets will use entropy sources in the standard library to seed the global RNG. -//! However, these sources are not available by default on WASM targets outside of WASI. -//! -//! If the `js` feature is enabled, this crate will assume that it is running in a JavaScript -//! environment. At this point, the [`getrandom`] crate will be used in order to access the available -//! entropy sources and seed the global RNG. If the `js` feature is not enabled, the global RNG will -//! use a predefined seed. -//! -//! [`fastrand-contrib`]: https://crates.io/crates/fastrand-contrib -//! [`getrandom`]: https://crates.io/crates/getrandom -#![cfg_attr(not(feature = "std"), no_std)] -#![cfg_attr(docsrs, feature(doc_cfg))] #![forbid(unsafe_code)] #![warn(missing_docs, missing_debug_implementations, rust_2018_idioms)] -#![doc( - html_favicon_url = "https://raw.githubusercontent.com/smol-rs/smol/master/assets/images/logo_fullsize_transparent.png" -)] -#![doc( - html_logo_url = "https://raw.githubusercontent.com/smol-rs/smol/master/assets/images/logo_fullsize_transparent.png" -)] - -#[cfg(feature = "alloc")] -extern crate alloc; - -use core::convert::{TryFrom, TryInto}; -use core::ops::{Bound, RangeBounds}; -#[cfg(feature = "alloc")] -use alloc::vec::Vec; +use std::cell::Cell; +use std::collections::hash_map::DefaultHasher; +use std::convert::TryInto; +use std::hash::{Hash, Hasher}; +use std::ops::{Bound, RangeBounds}; +use std::thread; -#[cfg(feature = "std")] -#[cfg_attr(docsrs, doc(cfg(feature = "std")))] -mod global_rng; - -#[cfg(feature = "std")] -pub use global_rng::*; +#[cfg(all(target_arch = "wasm32", not(target_os = "wasi")))] +use instant::Instant; +#[cfg(not(all(target_arch = "wasm32", not(target_os = "wasi"))))] +use std::time::Instant; /// A random number generator. #[derive(Debug, PartialEq, Eq)] -pub struct Rng(u64); +pub struct Rng(Cell<u64>); + +impl Default for Rng { + #[inline] + fn default() -> Rng { + Rng::new() + } +} impl Clone for Rng { - /// Clones the generator by creating a new generator with the same seed. + /// Clones the generator by deterministically deriving a new generator based on the initial + /// seed. + /// + /// # Example + /// + /// ``` + /// // Seed two generators equally, and clone both of them. + /// let base1 = fastrand::Rng::new(); + /// base1.seed(0x4d595df4d0f33173); + /// base1.bool(); // Use the generator once. + /// + /// let base2 = fastrand::Rng::new(); + /// base2.seed(0x4d595df4d0f33173); + /// base2.bool(); // Use the generator once. + /// + /// let rng1 = base1.clone(); + /// let rng2 = base2.clone(); + /// + /// assert_eq!(rng1.u64(..), rng2.u64(..), "the cloned generators are identical"); + /// ``` fn clone(&self) -> Rng { - Rng::with_seed(self.0) + Rng::with_seed(self.gen_u64()) } } impl Rng { /// Generates a random `u32`. #[inline] - fn gen_u32(&mut self) -> u32 { + fn gen_u32(&self) -> u32 { self.gen_u64() as u32 } /// Generates a random `u64`. #[inline] - fn gen_u64(&mut self) -> u64 { - let s = self.0.wrapping_add(0xA0761D6478BD642F); - self.0 = s; + fn gen_u64(&self) -> u64 { + let s = self.0.get().wrapping_add(0xA0761D6478BD642F); + self.0.set(s); let t = u128::from(s) * u128::from(s ^ 0xE7037ED1A0B428DB); (t as u64) ^ (t >> 64) as u64 } /// Generates a random `u128`. #[inline] - fn gen_u128(&mut self) -> u128 { + fn gen_u128(&self) -> u128 { (u128::from(self.gen_u64()) << 64) | u128::from(self.gen_u64()) } /// Generates a random `u32` in `0..n`. #[inline] - fn gen_mod_u32(&mut self, n: u32) -> u32 { + fn gen_mod_u32(&self, n: u32) -> u32 { // Adapted from: https://lemire.me/blog/2016/06/30/fast-random-shuffling/ let mut r = self.gen_u32(); let mut hi = mul_high_u32(r, n); @@ -178,7 +159,7 @@ impl Rng { /// Generates a random `u64` in `0..n`. #[inline] - fn gen_mod_u64(&mut self, n: u64) -> u64 { + fn gen_mod_u64(&self, n: u64) -> u64 { // Adapted from: https://lemire.me/blog/2016/06/30/fast-random-shuffling/ let mut r = self.gen_u64(); let mut hi = mul_high_u64(r, n); @@ -196,7 +177,7 @@ impl Rng { /// Generates a random `u128` in `0..n`. #[inline] - fn gen_mod_u128(&mut self, n: u128) -> u128 { + fn gen_mod_u128(&self, n: u128) -> u128 { // Adapted from: https://lemire.me/blog/2016/06/30/fast-random-shuffling/ let mut r = self.gen_u128(); let mut hi = mul_high_u128(r, n); @@ -213,6 +194,16 @@ impl Rng { } } +thread_local! { + static RNG: Rng = Rng(Cell::new({ + let mut hasher = DefaultHasher::new(); + Instant::now().hash(&mut hasher); + thread::current().id().hash(&mut hasher); + let hash = hasher.finish(); + (hash << 1) | 1 + })); +} + /// Computes `(a * b) >> 32`. #[inline] fn mul_high_u32(a: u32, b: u32) -> u32 { @@ -244,7 +235,7 @@ macro_rules! rng_integer { /// /// Panics if the range is empty. #[inline] - pub fn $t(&mut self, range: impl RangeBounds<$t>) -> $t { + pub fn $t(&self, range: impl RangeBounds<$t>) -> $t { let panic_empty_range = || { panic!( "empty range: {:?}..{:?}", @@ -254,13 +245,13 @@ macro_rules! rng_integer { }; let low = match range.start_bound() { - Bound::Unbounded => core::$t::MIN, + Bound::Unbounded => std::$t::MIN, Bound::Included(&x) => x, Bound::Excluded(&x) => x.checked_add(1).unwrap_or_else(panic_empty_range), }; let high = match range.end_bound() { - Bound::Unbounded => core::$t::MAX, + Bound::Unbounded => std::$t::MAX, Bound::Included(&x) => x, Bound::Excluded(&x) => x.checked_sub(1).unwrap_or_else(panic_empty_range), }; @@ -269,7 +260,7 @@ macro_rules! rng_integer { panic_empty_range(); } - if low == core::$t::MIN && high == core::$t::MAX { + if low == std::$t::MIN && high == std::$t::MAX { self.$gen() as $t } else { let len = high.wrapping_sub(low).wrapping_add(1); @@ -280,62 +271,46 @@ macro_rules! rng_integer { } impl Rng { + /// Creates a new random number generator. + #[inline] + pub fn new() -> Rng { + Rng::with_seed( + RNG.try_with(|rng| rng.u64(..)) + .unwrap_or(0x4d595df4d0f33173), + ) + } + /// Creates a new random number generator with the initial seed. #[inline] #[must_use = "this creates a new instance of `Rng`; if you want to initialize the thread-local generator, use `fastrand::seed()` instead"] pub fn with_seed(seed: u64) -> Self { - let mut rng = Rng(0); + let rng = Rng(Cell::new(0)); rng.seed(seed); rng } - /// Clones the generator by deterministically deriving a new generator based on the initial - /// seed. - /// - /// This function can be used to create a new generator that is a "spinoff" of the old - /// generator. The new generator will not produce the same sequence of values as the - /// old generator. - /// - /// # Example - /// - /// ``` - /// // Seed two generators equally, and clone both of them. - /// let mut base1 = fastrand::Rng::with_seed(0x4d595df4d0f33173); - /// base1.bool(); // Use the generator once. - /// - /// let mut base2 = fastrand::Rng::with_seed(0x4d595df4d0f33173); - /// base2.bool(); // Use the generator once. - /// - /// let mut rng1 = base1.fork(); - /// let mut rng2 = base2.fork(); - /// - /// println!("rng1 returns {}", rng1.u32(..)); - /// println!("rng2 returns {}", rng2.u32(..)); - /// ``` - #[inline] - #[must_use = "this creates a new instance of `Rng`"] - pub fn fork(&mut self) -> Self { - Rng::with_seed(self.gen_u64()) - } - /// Generates a random `char` in ranges a-z and A-Z. #[inline] - pub fn alphabetic(&mut self) -> char { + pub fn alphabetic(&self) -> char { const CHARS: &[u8] = b"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz"; - *self.choice(CHARS).unwrap() as char + let len = CHARS.len() as u8; + let i = self.u8(..len); + CHARS[i as usize] as char } /// Generates a random `char` in ranges a-z, A-Z and 0-9. #[inline] - pub fn alphanumeric(&mut self) -> char { + pub fn alphanumeric(&self) -> char { const CHARS: &[u8] = b"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789"; - *self.choice(CHARS).unwrap() as char + let len = CHARS.len() as u8; + let i = self.u8(..len); + CHARS[i as usize] as char } /// Generates a random `bool`. #[inline] - pub fn bool(&mut self) -> bool { + pub fn bool(&self) -> bool { self.u8(..) % 2 == 0 } @@ -345,7 +320,7 @@ impl Rng { /// /// Panics if the base is zero or greater than 36. #[inline] - pub fn digit(&mut self, base: u32) -> char { + pub fn digit(&self, base: u32) -> char { if base == 0 { panic!("base cannot be zero"); } @@ -361,57 +336,19 @@ impl Rng { } /// Generates a random `f32` in range `0..1`. - pub fn f32(&mut self) -> f32 { + pub fn f32(&self) -> f32 { let b = 32; - let f = core::f32::MANTISSA_DIGITS - 1; + let f = std::f32::MANTISSA_DIGITS - 1; f32::from_bits((1 << (b - 2)) - (1 << f) + (self.u32(..) >> (b - f))) - 1.0 } /// Generates a random `f64` in range `0..1`. - pub fn f64(&mut self) -> f64 { + pub fn f64(&self) -> f64 { let b = 64; - let f = core::f64::MANTISSA_DIGITS - 1; + let f = std::f64::MANTISSA_DIGITS - 1; f64::from_bits((1 << (b - 2)) - (1 << f) + (self.u64(..) >> (b - f))) - 1.0 } - /// Collects `amount` values at random from the iterator into a vector. - /// - /// The length of the returned vector equals `amount` unless the iterator - /// contains insufficient elements, in which case it equals the number of - /// elements available. - /// - /// Complexity is `O(n)` where `n` is the length of the iterator. - #[cfg(feature = "alloc")] - #[cfg_attr(docsrs, doc(cfg(feature = "alloc")))] - pub fn choose_multiple<T: Iterator>(&mut self, mut source: T, amount: usize) -> Vec<T::Item> { - // Adapted from: https://docs.rs/rand/latest/rand/seq/trait.IteratorRandom.html#method.choose_multiple - let mut reservoir = Vec::with_capacity(amount); - - reservoir.extend(source.by_ref().take(amount)); - - // Continue unless the iterator was exhausted - // - // note: this prevents iterators that "restart" from causing problems. - // If the iterator stops once, then so do we. - if reservoir.len() == amount { - for (i, elem) in source.enumerate() { - let end = i + 1 + amount; - let k = self.usize(0..end); - if let Some(slot) = reservoir.get_mut(k) { - *slot = elem; - } - } - } else { - // If less than one third of the `Vec` was used, reallocate - // so that the unused space is not wasted. There is a corner - // case where `amount` was much less than `self.len()`. - if reservoir.capacity() > 3 * reservoir.len() { - reservoir.shrink_to_fit(); - } - } - reservoir - } - rng_integer!( i8, u8, @@ -479,49 +416,28 @@ impl Rng { /// Generates a random `char` in range a-z. #[inline] - pub fn lowercase(&mut self) -> char { + pub fn lowercase(&self) -> char { const CHARS: &[u8] = b"abcdefghijklmnopqrstuvwxyz"; - *self.choice(CHARS).unwrap() as char + let len = CHARS.len() as u8; + let i = self.u8(..len); + CHARS[i as usize] as char } /// Initializes this generator with the given seed. #[inline] - pub fn seed(&mut self, seed: u64) { - self.0 = seed; + pub fn seed(&self, seed: u64) { + self.0.set(seed); } /// Gives back **current** seed that is being held by this generator. #[inline] pub fn get_seed(&self) -> u64 { - self.0 - } - - /// Choose an item from an iterator at random. - /// - /// This function may have an unexpected result if the `len()` property of the - /// iterator does not match the actual number of items in the iterator. If - /// the iterator is empty, this returns `None`. - #[inline] - pub fn choice<I>(&mut self, iter: I) -> Option<I::Item> - where - I: IntoIterator, - I::IntoIter: ExactSizeIterator, - { - let mut iter = iter.into_iter(); - - // Get the item at a random index. - let len = iter.len(); - if len == 0 { - return None; - } - let index = self.usize(0..len); - - iter.nth(index) + self.0.get() } /// Shuffles a slice randomly. #[inline] - pub fn shuffle<T>(&mut self, slice: &mut [T]) { + pub fn shuffle<T>(&self, slice: &mut [T]) { for i in 1..slice.len() { slice.swap(i, self.usize(..=i)); } @@ -529,7 +445,7 @@ impl Rng { /// Fill a byte slice with random data. #[inline] - pub fn fill(&mut self, slice: &mut [u8]) { + pub fn fill(&self, slice: &mut [u8]) { // We fill the slice by chunks of 8 bytes, or one block of // WyRand output per new state. let mut chunks = slice.chunks_exact_mut(core::mem::size_of::<u64>()); @@ -626,16 +542,20 @@ impl Rng { /// Generates a random `char` in range A-Z. #[inline] - pub fn uppercase(&mut self) -> char { + pub fn uppercase(&self) -> char { const CHARS: &[u8] = b"ABCDEFGHIJKLMNOPQRSTUVWXYZ"; - *self.choice(CHARS).unwrap() as char + let len = CHARS.len() as u8; + let i = self.u8(..len); + CHARS[i as usize] as char } /// Generates a random `char` in the given range. /// /// Panics if the range is empty. #[inline] - pub fn char(&mut self, range: impl RangeBounds<char>) -> char { + pub fn char(&self, range: impl RangeBounds<char>) -> char { + use std::convert::TryFrom; + let panic_empty_range = || { panic!( "empty range: {:?}..{:?}", @@ -661,7 +581,7 @@ impl Rng { }; let high = match range.end_bound() { - Bound::Unbounded => core::char::MAX, + Bound::Unbounded => std::char::MAX, Bound::Included(&x) => x, Bound::Excluded(&x) => { let scalar = if x as u32 == surrogate_start + surrogate_len { @@ -690,3 +610,97 @@ impl Rng { val.try_into().unwrap() } } + +/// Initializes the thread-local generator with the given seed. +#[inline] +pub fn seed(seed: u64) { + RNG.with(|rng| rng.seed(seed)) +} + +/// Gives back **current** seed that is being held by the thread-local generator. +#[inline] +pub fn get_seed() -> u64 { + RNG.with(|rng| rng.get_seed()) +} + +/// Generates a random `bool`. +#[inline] +pub fn bool() -> bool { + RNG.with(|rng| rng.bool()) +} + +/// Generates a random `char` in ranges a-z and A-Z. +#[inline] +pub fn alphabetic() -> char { + RNG.with(|rng| rng.alphabetic()) +} + +/// Generates a random `char` in ranges a-z, A-Z and 0-9. +#[inline] +pub fn alphanumeric() -> char { + RNG.with(|rng| rng.alphanumeric()) +} + +/// Generates a random `char` in range a-z. +#[inline] +pub fn lowercase() -> char { + RNG.with(|rng| rng.lowercase()) +} + +/// Generates a random `char` in range A-Z. +#[inline] +pub fn uppercase() -> char { + RNG.with(|rng| rng.uppercase()) +} + +/// Generates a random digit in the given `base`. +/// +/// Digits are represented by `char`s in ranges 0-9 and a-z. +/// +/// Panics if the base is zero or greater than 36. +#[inline] +pub fn digit(base: u32) -> char { + RNG.with(|rng| rng.digit(base)) +} + +/// Shuffles a slice randomly. +#[inline] +pub fn shuffle<T>(slice: &mut [T]) { + RNG.with(|rng| rng.shuffle(slice)) +} + +macro_rules! integer { + ($t:tt, $doc:tt) => { + #[doc = $doc] + /// + /// Panics if the range is empty. + #[inline] + pub fn $t(range: impl RangeBounds<$t>) -> $t { + RNG.with(|rng| rng.$t(range)) + } + }; +} + +integer!(u8, "Generates a random `u8` in the given range."); +integer!(i8, "Generates a random `i8` in the given range."); +integer!(u16, "Generates a random `u16` in the given range."); +integer!(i16, "Generates a random `i16` in the given range."); +integer!(u32, "Generates a random `u32` in the given range."); +integer!(i32, "Generates a random `i32` in the given range."); +integer!(u64, "Generates a random `u64` in the given range."); +integer!(i64, "Generates a random `i64` in the given range."); +integer!(u128, "Generates a random `u128` in the given range."); +integer!(i128, "Generates a random `i128` in the given range."); +integer!(usize, "Generates a random `usize` in the given range."); +integer!(isize, "Generates a random `isize` in the given range."); +integer!(char, "Generates a random `char` in the given range."); + +/// Generates a random `f32` in range `0..1`. +pub fn f32() -> f32 { + RNG.with(|rng| rng.f32()) +} + +/// Generates a random `f64` in range `0..1`. +pub fn f64() -> f64 { + RNG.with(|rng| rng.f64()) +} |