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authorDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-17 12:02:58 +0000
committerDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-17 12:02:58 +0000
commit698f8c2f01ea549d77d7dc3338a12e04c11057b9 (patch)
tree173a775858bd501c378080a10dca74132f05bc50 /vendor/rand-0.7.3/src/distributions/other.rs
parentInitial commit. (diff)
downloadrustc-698f8c2f01ea549d77d7dc3338a12e04c11057b9.tar.xz
rustc-698f8c2f01ea549d77d7dc3338a12e04c11057b9.zip
Adding upstream version 1.64.0+dfsg1.upstream/1.64.0+dfsg1
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
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+// Copyright 2018 Developers of the Rand project.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// https://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or https://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+//! The implementations of the `Standard` distribution for other built-in types.
+
+use core::char;
+use core::num::Wrapping;
+
+use crate::distributions::{Distribution, Standard, Uniform};
+use crate::Rng;
+
+// ----- Sampling distributions -----
+
+/// Sample a `char`, uniformly distributed over ASCII letters and numbers:
+/// a-z, A-Z and 0-9.
+///
+/// # Example
+///
+/// ```
+/// use std::iter;
+/// use rand::{Rng, thread_rng};
+/// use rand::distributions::Alphanumeric;
+///
+/// let mut rng = thread_rng();
+/// let chars: String = iter::repeat(())
+/// .map(|()| rng.sample(Alphanumeric))
+/// .take(7)
+/// .collect();
+/// println!("Random chars: {}", chars);
+/// ```
+#[derive(Debug)]
+pub struct Alphanumeric;
+
+
+// ----- Implementations of distributions -----
+
+impl Distribution<char> for Standard {
+ #[inline]
+ fn sample<R: Rng + ?Sized>(&self, rng: &mut R) -> char {
+ // A valid `char` is either in the interval `[0, 0xD800)` or
+ // `(0xDFFF, 0x11_0000)`. All `char`s must therefore be in
+ // `[0, 0x11_0000)` but not in the "gap" `[0xD800, 0xDFFF]` which is
+ // reserved for surrogates. This is the size of that gap.
+ const GAP_SIZE: u32 = 0xDFFF - 0xD800 + 1;
+
+ // Uniform::new(0, 0x11_0000 - GAP_SIZE) can also be used but it
+ // seemed slower.
+ let range = Uniform::new(GAP_SIZE, 0x11_0000);
+
+ let mut n = range.sample(rng);
+ if n <= 0xDFFF {
+ n -= GAP_SIZE;
+ }
+ unsafe { char::from_u32_unchecked(n) }
+ }
+}
+
+impl Distribution<char> for Alphanumeric {
+ fn sample<R: Rng + ?Sized>(&self, rng: &mut R) -> char {
+ const RANGE: u32 = 26 + 26 + 10;
+ const GEN_ASCII_STR_CHARSET: &[u8] = b"ABCDEFGHIJKLMNOPQRSTUVWXYZ\
+ abcdefghijklmnopqrstuvwxyz\
+ 0123456789";
+ // We can pick from 62 characters. This is so close to a power of 2, 64,
+ // that we can do better than `Uniform`. Use a simple bitshift and
+ // rejection sampling. We do not use a bitmask, because for small RNGs
+ // the most significant bits are usually of higher quality.
+ loop {
+ let var = rng.next_u32() >> (32 - 6);
+ if var < RANGE {
+ return GEN_ASCII_STR_CHARSET[var as usize] as char;
+ }
+ }
+ }
+}
+
+impl Distribution<bool> for Standard {
+ #[inline]
+ fn sample<R: Rng + ?Sized>(&self, rng: &mut R) -> bool {
+ // We can compare against an arbitrary bit of an u32 to get a bool.
+ // Because the least significant bits of a lower quality RNG can have
+ // simple patterns, we compare against the most significant bit. This is
+ // easiest done using a sign test.
+ (rng.next_u32() as i32) < 0
+ }
+}
+
+macro_rules! tuple_impl {
+ // use variables to indicate the arity of the tuple
+ ($($tyvar:ident),* ) => {
+ // the trailing commas are for the 1 tuple
+ impl< $( $tyvar ),* >
+ Distribution<( $( $tyvar ),* , )>
+ for Standard
+ where $( Standard: Distribution<$tyvar> ),*
+ {
+ #[inline]
+ fn sample<R: Rng + ?Sized>(&self, _rng: &mut R) -> ( $( $tyvar ),* , ) {
+ (
+ // use the $tyvar's to get the appropriate number of
+ // repeats (they're not actually needed)
+ $(
+ _rng.gen::<$tyvar>()
+ ),*
+ ,
+ )
+ }
+ }
+ }
+}
+
+impl Distribution<()> for Standard {
+ #[allow(clippy::unused_unit)]
+ #[inline]
+ fn sample<R: Rng + ?Sized>(&self, _: &mut R) -> () {
+ ()
+ }
+}
+tuple_impl! {A}
+tuple_impl! {A, B}
+tuple_impl! {A, B, C}
+tuple_impl! {A, B, C, D}
+tuple_impl! {A, B, C, D, E}
+tuple_impl! {A, B, C, D, E, F}
+tuple_impl! {A, B, C, D, E, F, G}
+tuple_impl! {A, B, C, D, E, F, G, H}
+tuple_impl! {A, B, C, D, E, F, G, H, I}
+tuple_impl! {A, B, C, D, E, F, G, H, I, J}
+tuple_impl! {A, B, C, D, E, F, G, H, I, J, K}
+tuple_impl! {A, B, C, D, E, F, G, H, I, J, K, L}
+
+macro_rules! array_impl {
+ // recursive, given at least one type parameter:
+ {$n:expr, $t:ident, $($ts:ident,)*} => {
+ array_impl!{($n - 1), $($ts,)*}
+
+ impl<T> Distribution<[T; $n]> for Standard where Standard: Distribution<T> {
+ #[inline]
+ fn sample<R: Rng + ?Sized>(&self, _rng: &mut R) -> [T; $n] {
+ [_rng.gen::<$t>(), $(_rng.gen::<$ts>()),*]
+ }
+ }
+ };
+ // empty case:
+ {$n:expr,} => {
+ impl<T> Distribution<[T; $n]> for Standard {
+ fn sample<R: Rng + ?Sized>(&self, _rng: &mut R) -> [T; $n] { [] }
+ }
+ };
+}
+
+array_impl! {32, T, T, T, T, T, T, T, T, T, T, T, T, T, T, T, T, T, T, T, T, T, T, T, T, T, T, T, T, T, T, T, T,}
+
+impl<T> Distribution<Option<T>> for Standard
+where Standard: Distribution<T>
+{
+ #[inline]
+ fn sample<R: Rng + ?Sized>(&self, rng: &mut R) -> Option<T> {
+ // UFCS is needed here: https://github.com/rust-lang/rust/issues/24066
+ if rng.gen::<bool>() {
+ Some(rng.gen())
+ } else {
+ None
+ }
+ }
+}
+
+impl<T> Distribution<Wrapping<T>> for Standard
+where Standard: Distribution<T>
+{
+ #[inline]
+ fn sample<R: Rng + ?Sized>(&self, rng: &mut R) -> Wrapping<T> {
+ Wrapping(rng.gen())
+ }
+}
+
+
+#[cfg(test)]
+mod tests {
+ use super::*;
+ use crate::RngCore;
+ #[cfg(all(not(feature = "std"), feature = "alloc"))] use alloc::string::String;
+
+ #[test]
+ fn test_misc() {
+ let rng: &mut dyn RngCore = &mut crate::test::rng(820);
+
+ rng.sample::<char, _>(Standard);
+ rng.sample::<bool, _>(Standard);
+ }
+
+ #[cfg(feature = "alloc")]
+ #[test]
+ fn test_chars() {
+ use core::iter;
+ let mut rng = crate::test::rng(805);
+
+ // Test by generating a relatively large number of chars, so we also
+ // take the rejection sampling path.
+ let word: String = iter::repeat(())
+ .map(|()| rng.gen::<char>())
+ .take(1000)
+ .collect();
+ assert!(word.len() != 0);
+ }
+
+ #[test]
+ fn test_alphanumeric() {
+ let mut rng = crate::test::rng(806);
+
+ // Test by generating a relatively large number of chars, so we also
+ // take the rejection sampling path.
+ let mut incorrect = false;
+ for _ in 0..100 {
+ let c = rng.sample(Alphanumeric);
+ incorrect |= !((c >= '0' && c <= '9') ||
+ (c >= 'A' && c <= 'Z') ||
+ (c >= 'a' && c <= 'z') );
+ }
+ assert!(incorrect == false);
+ }
+
+ #[test]
+ fn value_stability() {
+ fn test_samples<T: Copy + core::fmt::Debug + PartialEq, D: Distribution<T>>(
+ distr: &D, zero: T, expected: &[T],
+ ) {
+ let mut rng = crate::test::rng(807);
+ let mut buf = [zero; 5];
+ for x in &mut buf {
+ *x = rng.sample(&distr);
+ }
+ assert_eq!(&buf, expected);
+ }
+
+ test_samples(&Standard, 'a', &[
+ '\u{8cdac}',
+ '\u{a346a}',
+ '\u{80120}',
+ '\u{ed692}',
+ '\u{35888}',
+ ]);
+ test_samples(&Alphanumeric, 'a', &['h', 'm', 'e', '3', 'M']);
+ test_samples(&Standard, false, &[true, true, false, true, false]);
+ test_samples(&Standard, None as Option<bool>, &[
+ Some(true),
+ None,
+ Some(false),
+ None,
+ Some(false),
+ ]);
+ test_samples(&Standard, Wrapping(0i32), &[
+ Wrapping(-2074640887),
+ Wrapping(-1719949321),
+ Wrapping(2018088303),
+ Wrapping(-547181756),
+ Wrapping(838957336),
+ ]);
+
+ // We test only sub-sets of tuple and array impls
+ test_samples(&Standard, (), &[(), (), (), (), ()]);
+ test_samples(&Standard, (false,), &[
+ (true,),
+ (true,),
+ (false,),
+ (true,),
+ (false,),
+ ]);
+ test_samples(&Standard, (false, false), &[
+ (true, true),
+ (false, true),
+ (false, false),
+ (true, false),
+ (false, false),
+ ]);
+
+ test_samples(&Standard, [0u8; 0], &[[], [], [], [], []]);
+ test_samples(&Standard, [0u8; 3], &[
+ [9, 247, 111],
+ [68, 24, 13],
+ [174, 19, 194],
+ [172, 69, 213],
+ [149, 207, 29],
+ ]);
+ }
+}