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authorValentin Popov <valentin@popov.link>2024-01-08 00:21:28 +0300
committerValentin Popov <valentin@popov.link>2024-01-08 00:21:28 +0300
commit1b6a04ca5504955c571d1c97504fb45ea0befee4 (patch)
tree7579f518b23313e8a9748a88ab6173d5e030b227 /vendor/fastrand/src/lib.rs
parent5ecd8cf2cba827454317368b68571df0d13d7842 (diff)
downloadfparkan-1b6a04ca5504955c571d1c97504fb45ea0befee4.tar.xz
fparkan-1b6a04ca5504955c571d1c97504fb45ea0befee4.zip
Initial vendor packages
Signed-off-by: Valentin Popov <valentin@popov.link>
Diffstat (limited to 'vendor/fastrand/src/lib.rs')
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+//! A simple and fast random number generator.
+//!
+//! The implementation uses [Wyrand](https://github.com/wangyi-fudan/wyhash), a simple and fast
+//! generator but **not** cryptographically secure.
+//!
+//! # Examples
+//!
+//! Flip a coin:
+//!
+//! ```
+//! if fastrand::bool() {
+//! println!("heads");
+//! } else {
+//! println!("tails");
+//! }
+//! ```
+//!
+//! Generate a random `i32`:
+//!
+//! ```
+//! let num = fastrand::i32(..);
+//! ```
+//!
+//! Choose a random element in an array:
+//!
+//! ```
+//! let v = vec![1, 2, 3, 4, 5];
+//! let i = fastrand::usize(..v.len());
+//! 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:
+//!
+//! ```
+//! let mut v = vec![1, 2, 3, 4, 5];
+//! fastrand::shuffle(&mut v);
+//! ```
+//!
+//! Generate a random [`Vec`] or [`String`]:
+//!
+//! ```
+//! use std::iter::repeat_with;
+//!
+//! let v: Vec<i32> = repeat_with(|| fastrand::i32(..)).take(10).collect();
+//! let s: String = repeat_with(fastrand::alphanumeric).take(10).collect();
+//! ```
+//!
+//! To get reproducible results on every run, initialize the generator with a seed:
+//!
+//! ```
+//! // Pick an arbitrary number as seed.
+//! fastrand::seed(7);
+//!
+//! // Now this prints the same number on every run:
+//! println!("{}", fastrand::u32(..));
+//! ```
+//!
+//! To be more efficient, create a new [`Rng`] instance instead of using the thread-local
+//! generator:
+//!
+//! ```
+//! use std::iter::repeat_with;
+//!
+//! let mut 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;
+
+#[cfg(feature = "std")]
+#[cfg_attr(docsrs, doc(cfg(feature = "std")))]
+mod global_rng;
+
+#[cfg(feature = "std")]
+pub use global_rng::*;
+
+/// A random number generator.
+#[derive(Debug, PartialEq, Eq)]
+pub struct Rng(u64);
+
+impl Clone for Rng {
+ /// Clones the generator by creating a new generator with the same seed.
+ fn clone(&self) -> Rng {
+ Rng::with_seed(self.0)
+ }
+}
+
+impl Rng {
+ /// Generates a random `u32`.
+ #[inline]
+ fn gen_u32(&mut 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;
+ 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 {
+ (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 {
+ // 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);
+ let mut lo = r.wrapping_mul(n);
+ if lo < n {
+ let t = n.wrapping_neg() % n;
+ while lo < t {
+ r = self.gen_u32();
+ hi = mul_high_u32(r, n);
+ lo = r.wrapping_mul(n);
+ }
+ }
+ hi
+ }
+
+ /// Generates a random `u64` in `0..n`.
+ #[inline]
+ fn gen_mod_u64(&mut 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);
+ let mut lo = r.wrapping_mul(n);
+ if lo < n {
+ let t = n.wrapping_neg() % n;
+ while lo < t {
+ r = self.gen_u64();
+ hi = mul_high_u64(r, n);
+ lo = r.wrapping_mul(n);
+ }
+ }
+ hi
+ }
+
+ /// Generates a random `u128` in `0..n`.
+ #[inline]
+ fn gen_mod_u128(&mut 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);
+ let mut lo = r.wrapping_mul(n);
+ if lo < n {
+ let t = n.wrapping_neg() % n;
+ while lo < t {
+ r = self.gen_u128();
+ hi = mul_high_u128(r, n);
+ lo = r.wrapping_mul(n);
+ }
+ }
+ hi
+ }
+}
+
+/// Computes `(a * b) >> 32`.
+#[inline]
+fn mul_high_u32(a: u32, b: u32) -> u32 {
+ (((a as u64) * (b as u64)) >> 32) as u32
+}
+
+/// Computes `(a * b) >> 64`.
+#[inline]
+fn mul_high_u64(a: u64, b: u64) -> u64 {
+ (((a as u128) * (b as u128)) >> 64) as u64
+}
+
+/// Computes `(a * b) >> 128`.
+#[inline]
+fn mul_high_u128(a: u128, b: u128) -> u128 {
+ // Adapted from: https://stackoverflow.com/a/28904636
+ let a_lo = a as u64 as u128;
+ let a_hi = (a >> 64) as u64 as u128;
+ let b_lo = b as u64 as u128;
+ let b_hi = (b >> 64) as u64 as u128;
+ let carry = (a_lo * b_lo) >> 64;
+ let carry = ((a_hi * b_lo) as u64 as u128 + (a_lo * b_hi) as u64 as u128 + carry) >> 64;
+ a_hi * b_hi + ((a_hi * b_lo) >> 64) + ((a_lo * b_hi) >> 64) + carry
+}
+
+macro_rules! rng_integer {
+ ($t:tt, $unsigned_t:tt, $gen:tt, $mod:tt, $doc:tt) => {
+ #[doc = $doc]
+ ///
+ /// Panics if the range is empty.
+ #[inline]
+ pub fn $t(&mut self, range: impl RangeBounds<$t>) -> $t {
+ let panic_empty_range = || {
+ panic!(
+ "empty range: {:?}..{:?}",
+ range.start_bound(),
+ range.end_bound()
+ )
+ };
+
+ let low = match range.start_bound() {
+ Bound::Unbounded => core::$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::$t::MAX,
+ Bound::Included(&x) => x,
+ Bound::Excluded(&x) => x.checked_sub(1).unwrap_or_else(panic_empty_range),
+ };
+
+ if low > high {
+ panic_empty_range();
+ }
+
+ if low == core::$t::MIN && high == core::$t::MAX {
+ self.$gen() as $t
+ } else {
+ let len = high.wrapping_sub(low).wrapping_add(1);
+ low.wrapping_add(self.$mod(len as $unsigned_t as _) as $t)
+ }
+ }
+ };
+}
+
+impl Rng {
+ /// 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);
+
+ 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 {
+ const CHARS: &[u8] = b"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz";
+ *self.choice(CHARS).unwrap() as char
+ }
+
+ /// Generates a random `char` in ranges a-z, A-Z and 0-9.
+ #[inline]
+ pub fn alphanumeric(&mut self) -> char {
+ const CHARS: &[u8] = b"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789";
+ *self.choice(CHARS).unwrap() as char
+ }
+
+ /// Generates a random `bool`.
+ #[inline]
+ pub fn bool(&mut self) -> bool {
+ self.u8(..) % 2 == 0
+ }
+
+ /// 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(&mut self, base: u32) -> char {
+ if base == 0 {
+ panic!("base cannot be zero");
+ }
+ if base > 36 {
+ panic!("base cannot be larger than 36");
+ }
+ let num = self.u8(..base as u8);
+ if num < 10 {
+ (b'0' + num) as char
+ } else {
+ (b'a' + num - 10) as char
+ }
+ }
+
+ /// Generates a random `f32` in range `0..1`.
+ pub fn f32(&mut self) -> f32 {
+ let b = 32;
+ let f = core::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 {
+ let b = 64;
+ let f = core::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,
+ gen_u32,
+ gen_mod_u32,
+ "Generates a random `i8` in the given range."
+ );
+
+ rng_integer!(
+ i16,
+ u16,
+ gen_u32,
+ gen_mod_u32,
+ "Generates a random `i16` in the given range."
+ );
+
+ rng_integer!(
+ i32,
+ u32,
+ gen_u32,
+ gen_mod_u32,
+ "Generates a random `i32` in the given range."
+ );
+
+ rng_integer!(
+ i64,
+ u64,
+ gen_u64,
+ gen_mod_u64,
+ "Generates a random `i64` in the given range."
+ );
+
+ rng_integer!(
+ i128,
+ u128,
+ gen_u128,
+ gen_mod_u128,
+ "Generates a random `i128` in the given range."
+ );
+
+ #[cfg(target_pointer_width = "16")]
+ rng_integer!(
+ isize,
+ usize,
+ gen_u32,
+ gen_mod_u32,
+ "Generates a random `isize` in the given range."
+ );
+ #[cfg(target_pointer_width = "32")]
+ rng_integer!(
+ isize,
+ usize,
+ gen_u32,
+ gen_mod_u32,
+ "Generates a random `isize` in the given range."
+ );
+ #[cfg(target_pointer_width = "64")]
+ rng_integer!(
+ isize,
+ usize,
+ gen_u64,
+ gen_mod_u64,
+ "Generates a random `isize` in the given range."
+ );
+
+ /// Generates a random `char` in range a-z.
+ #[inline]
+ pub fn lowercase(&mut self) -> char {
+ const CHARS: &[u8] = b"abcdefghijklmnopqrstuvwxyz";
+ *self.choice(CHARS).unwrap() as char
+ }
+
+ /// Initializes this generator with the given seed.
+ #[inline]
+ pub fn seed(&mut self, seed: u64) {
+ self.0 = 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)
+ }
+
+ /// Shuffles a slice randomly.
+ #[inline]
+ pub fn shuffle<T>(&mut self, slice: &mut [T]) {
+ for i in 1..slice.len() {
+ slice.swap(i, self.usize(..=i));
+ }
+ }
+
+ /// Fill a byte slice with random data.
+ #[inline]
+ pub fn fill(&mut 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>());
+ for chunk in chunks.by_ref() {
+ let n = self.gen_u64().to_ne_bytes();
+ // Safe because the chunks are always 8 bytes exactly.
+ chunk.copy_from_slice(&n);
+ }
+
+ let remainder = chunks.into_remainder();
+
+ // Any remainder will always be less than 8 bytes.
+ if !remainder.is_empty() {
+ // Generate one last block of 8 bytes of entropy
+ let n = self.gen_u64().to_ne_bytes();
+
+ // Use the remaining length to copy from block
+ remainder.copy_from_slice(&n[..remainder.len()]);
+ }
+ }
+
+ rng_integer!(
+ u8,
+ u8,
+ gen_u32,
+ gen_mod_u32,
+ "Generates a random `u8` in the given range."
+ );
+
+ rng_integer!(
+ u16,
+ u16,
+ gen_u32,
+ gen_mod_u32,
+ "Generates a random `u16` in the given range."
+ );
+
+ rng_integer!(
+ u32,
+ u32,
+ gen_u32,
+ gen_mod_u32,
+ "Generates a random `u32` in the given range."
+ );
+
+ rng_integer!(
+ u64,
+ u64,
+ gen_u64,
+ gen_mod_u64,
+ "Generates a random `u64` in the given range."
+ );
+
+ rng_integer!(
+ u128,
+ u128,
+ gen_u128,
+ gen_mod_u128,
+ "Generates a random `u128` in the given range."
+ );
+
+ #[cfg(target_pointer_width = "16")]
+ rng_integer!(
+ usize,
+ usize,
+ gen_u32,
+ gen_mod_u32,
+ "Generates a random `usize` in the given range."
+ );
+ #[cfg(target_pointer_width = "32")]
+ rng_integer!(
+ usize,
+ usize,
+ gen_u32,
+ gen_mod_u32,
+ "Generates a random `usize` in the given range."
+ );
+ #[cfg(target_pointer_width = "64")]
+ rng_integer!(
+ usize,
+ usize,
+ gen_u64,
+ gen_mod_u64,
+ "Generates a random `usize` in the given range."
+ );
+ #[cfg(target_pointer_width = "128")]
+ rng_integer!(
+ usize,
+ usize,
+ gen_u128,
+ gen_mod_u128,
+ "Generates a random `usize` in the given range."
+ );
+
+ /// Generates a random `char` in range A-Z.
+ #[inline]
+ pub fn uppercase(&mut self) -> char {
+ const CHARS: &[u8] = b"ABCDEFGHIJKLMNOPQRSTUVWXYZ";
+ *self.choice(CHARS).unwrap() 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 {
+ let panic_empty_range = || {
+ panic!(
+ "empty range: {:?}..{:?}",
+ range.start_bound(),
+ range.end_bound()
+ )
+ };
+
+ let surrogate_start = 0xd800u32;
+ let surrogate_len = 0x800u32;
+
+ let low = match range.start_bound() {
+ Bound::Unbounded => 0u8 as char,
+ Bound::Included(&x) => x,
+ Bound::Excluded(&x) => {
+ let scalar = if x as u32 == surrogate_start - 1 {
+ surrogate_start + surrogate_len
+ } else {
+ x as u32 + 1
+ };
+ char::try_from(scalar).unwrap_or_else(|_| panic_empty_range())
+ }
+ };
+
+ let high = match range.end_bound() {
+ Bound::Unbounded => core::char::MAX,
+ Bound::Included(&x) => x,
+ Bound::Excluded(&x) => {
+ let scalar = if x as u32 == surrogate_start + surrogate_len {
+ surrogate_start - 1
+ } else {
+ (x as u32).wrapping_sub(1)
+ };
+ char::try_from(scalar).unwrap_or_else(|_| panic_empty_range())
+ }
+ };
+
+ if low > high {
+ panic_empty_range();
+ }
+
+ let gap = if (low as u32) < surrogate_start && (high as u32) >= surrogate_start {
+ surrogate_len
+ } else {
+ 0
+ };
+ let range = high as u32 - low as u32 - gap;
+ let mut val = self.u32(0..=range) + low as u32;
+ if val >= surrogate_start {
+ val += gap;
+ }
+ val.try_into().unwrap()
+ }
+}