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<span id="1242">1242</span>
</pre><pre class='rust '>
<span class='comment'>// Copyright 2013-2014 The Rust Project Developers. See the COPYRIGHT</span>
<span class='comment'>// file at the top-level directory of this distribution and at</span>
<span class='comment'>// http://rust-lang.org/COPYRIGHT.</span>
<span class='comment'>//</span>
<span class='comment'>// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or</span>
<span class='comment'>// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license</span>
<span class='comment'>// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your</span>
<span class='comment'>// option. This file may not be copied, modified, or distributed</span>
<span class='comment'>// except according to those terms.</span>
<span class='doccomment'>//! Utilities for random number generation</span>
<span class='doccomment'>//!</span>
<span class='doccomment'>//! The key functions are `random()` and `Rng::gen()`. These are polymorphic and</span>
<span class='doccomment'>//! so can be used to generate any type that implements `Rand`. Type inference</span>
<span class='doccomment'>//! means that often a simple call to `rand::random()` or `rng.gen()` will</span>
<span class='doccomment'>//! suffice, but sometimes an annotation is required, e.g.</span>
<span class='doccomment'>//! `rand::random::<f64>()`.</span>
<span class='doccomment'>//!</span>
<span class='doccomment'>//! See the `distributions` submodule for sampling random numbers from</span>
<span class='doccomment'>//! distributions like normal and exponential.</span>
<span class='doccomment'>//!</span>
<span class='doccomment'>//! # Usage</span>
<span class='doccomment'>//!</span>
<span class='doccomment'>//! This crate is [on crates.io](https://crates.io/crates/rand) and can be</span>
<span class='doccomment'>//! used by adding `rand` to the dependencies in your project's `Cargo.toml`.</span>
<span class='doccomment'>//!</span>
<span class='doccomment'>//! ```toml</span>
<span class='doccomment'>//! [dependencies]</span>
<span class='doccomment'>//! rand = "0.3"</span>
<span class='doccomment'>//! ```</span>
<span class='doccomment'>//!</span>
<span class='doccomment'>//! and this to your crate root:</span>
<span class='doccomment'>//!</span>
<span class='doccomment'>//! ```rust</span>
<span class='doccomment'>//! extern crate rand;</span>
<span class='doccomment'>//! ```</span>
<span class='doccomment'>//!</span>
<span class='doccomment'>//! # Thread-local RNG</span>
<span class='doccomment'>//!</span>
<span class='doccomment'>//! There is built-in support for a RNG associated with each thread stored</span>
<span class='doccomment'>//! in thread-local storage. This RNG can be accessed via `thread_rng`, or</span>
<span class='doccomment'>//! used implicitly via `random`. This RNG is normally randomly seeded</span>
<span class='doccomment'>//! from an operating-system source of randomness, e.g. `/dev/urandom` on</span>
<span class='doccomment'>//! Unix systems, and will automatically reseed itself from this source</span>
<span class='doccomment'>//! after generating 32 KiB of random data.</span>
<span class='doccomment'>//!</span>
<span class='doccomment'>//! # Cryptographic security</span>
<span class='doccomment'>//!</span>
<span class='doccomment'>//! An application that requires an entropy source for cryptographic purposes</span>
<span class='doccomment'>//! must use `OsRng`, which reads randomness from the source that the operating</span>
<span class='doccomment'>//! system provides (e.g. `/dev/urandom` on Unixes or `CryptGenRandom()` on</span>
<span class='doccomment'>//! Windows).</span>
<span class='doccomment'>//! The other random number generators provided by this module are not suitable</span>
<span class='doccomment'>//! for such purposes.</span>
<span class='doccomment'>//!</span>
<span class='doccomment'>//! *Note*: many Unix systems provide `/dev/random` as well as `/dev/urandom`.</span>
<span class='doccomment'>//! This module uses `/dev/urandom` for the following reasons:</span>
<span class='doccomment'>//!</span>
<span class='doccomment'>//! - On Linux, `/dev/random` may block if entropy pool is empty;</span>
<span class='doccomment'>//! `/dev/urandom` will not block. This does not mean that `/dev/random`</span>
<span class='doccomment'>//! provides better output than `/dev/urandom`; the kernel internally runs a</span>
<span class='doccomment'>//! cryptographically secure pseudorandom number generator (CSPRNG) based on</span>
<span class='doccomment'>//! entropy pool for random number generation, so the "quality" of</span>
<span class='doccomment'>//! `/dev/random` is not better than `/dev/urandom` in most cases. However,</span>
<span class='doccomment'>//! this means that `/dev/urandom` can yield somewhat predictable randomness</span>
<span class='doccomment'>//! if the entropy pool is very small, such as immediately after first</span>
<span class='doccomment'>//! booting. Linux 3.17 added the `getrandom(2)` system call which solves</span>
<span class='doccomment'>//! the issue: it blocks if entropy pool is not initialized yet, but it does</span>
<span class='doccomment'>//! not block once initialized. `OsRng` tries to use `getrandom(2)` if</span>
<span class='doccomment'>//! available, and use `/dev/urandom` fallback if not. If an application</span>
<span class='doccomment'>//! does not have `getrandom` and likely to be run soon after first booting,</span>
<span class='doccomment'>//! or on a system with very few entropy sources, one should consider using</span>
<span class='doccomment'>//! `/dev/random` via `ReadRng`.</span>
<span class='doccomment'>//! - On some systems (e.g. FreeBSD, OpenBSD and Mac OS X) there is no</span>
<span class='doccomment'>//! difference between the two sources. (Also note that, on some systems</span>
<span class='doccomment'>//! e.g. FreeBSD, both `/dev/random` and `/dev/urandom` may block once if</span>
<span class='doccomment'>//! the CSPRNG has not seeded yet.)</span>
<span class='doccomment'>//!</span>
<span class='doccomment'>//! # Examples</span>
<span class='doccomment'>//!</span>
<span class='doccomment'>//! ```rust</span>
<span class='doccomment'>//! use rand::Rng;</span>
<span class='doccomment'>//!</span>
<span class='doccomment'>//! let mut rng = rand::thread_rng();</span>
<span class='doccomment'>//! if rng.gen() { // random bool</span>
<span class='doccomment'>//! println!("i32: {}, u32: {}", rng.gen::<i32>(), rng.gen::<u32>())</span>
<span class='doccomment'>//! }</span>
<span class='doccomment'>//! ```</span>
<span class='doccomment'>//!</span>
<span class='doccomment'>//! ```rust</span>
<span class='doccomment'>//! let tuple = rand::random::<(f64, char)>();</span>
<span class='doccomment'>//! println!("{:?}", tuple)</span>
<span class='doccomment'>//! ```</span>
<span class='doccomment'>//!</span>
<span class='doccomment'>//! ## Monte Carlo estimation of π</span>
<span class='doccomment'>//!</span>
<span class='doccomment'>//! For this example, imagine we have a square with sides of length 2 and a unit</span>
<span class='doccomment'>//! circle, both centered at the origin. Since the area of a unit circle is π,</span>
<span class='doccomment'>//! we have:</span>
<span class='doccomment'>//!</span>
<span class='doccomment'>//! ```text</span>
<span class='doccomment'>//! (area of unit circle) / (area of square) = π / 4</span>
<span class='doccomment'>//! ```</span>
<span class='doccomment'>//!</span>
<span class='doccomment'>//! So if we sample many points randomly from the square, roughly π / 4 of them</span>
<span class='doccomment'>//! should be inside the circle.</span>
<span class='doccomment'>//!</span>
<span class='doccomment'>//! We can use the above fact to estimate the value of π: pick many points in</span>
<span class='doccomment'>//! the square at random, calculate the fraction that fall within the circle,</span>
<span class='doccomment'>//! and multiply this fraction by 4.</span>
<span class='doccomment'>//!</span>
<span class='doccomment'>//! ```</span>
<span class='doccomment'>//! use rand::distributions::{IndependentSample, Range};</span>
<span class='doccomment'>//!</span>
<span class='doccomment'>//! fn main() {</span>
<span class='doccomment'>//! let between = Range::new(-1f64, 1.);</span>
<span class='doccomment'>//! let mut rng = rand::thread_rng();</span>
<span class='doccomment'>//!</span>
<span class='doccomment'>//! let total = 1_000_000;</span>
<span class='doccomment'>//! let mut in_circle = 0;</span>
<span class='doccomment'>//!</span>
<span class='doccomment'>//! for _ in 0..total {</span>
<span class='doccomment'>//! let a = between.ind_sample(&mut rng);</span>
<span class='doccomment'>//! let b = between.ind_sample(&mut rng);</span>
<span class='doccomment'>//! if a*a + b*b <= 1. {</span>
<span class='doccomment'>//! in_circle += 1;</span>
<span class='doccomment'>//! }</span>
<span class='doccomment'>//! }</span>
<span class='doccomment'>//!</span>
<span class='doccomment'>//! // prints something close to 3.14159...</span>
<span class='doccomment'>//! println!("{}", 4. * (in_circle as f64) / (total as f64));</span>
<span class='doccomment'>//! }</span>
<span class='doccomment'>//! ```</span>
<span class='doccomment'>//!</span>
<span class='doccomment'>//! ## Monty Hall Problem</span>
<span class='doccomment'>//!</span>
<span class='doccomment'>//! This is a simulation of the [Monty Hall Problem][]:</span>
<span class='doccomment'>//!</span>
<span class='doccomment'>//! > Suppose you're on a game show, and you're given the choice of three doors:</span>
<span class='doccomment'>//! > Behind one door is a car; behind the others, goats. You pick a door, say</span>
<span class='doccomment'>//! > No. 1, and the host, who knows what's behind the doors, opens another</span>
<span class='doccomment'>//! > door, say No. 3, which has a goat. He then says to you, "Do you want to</span>
<span class='doccomment'>//! > pick door No. 2?" Is it to your advantage to switch your choice?</span>
<span class='doccomment'>//!</span>
<span class='doccomment'>//! The rather unintuitive answer is that you will have a 2/3 chance of winning</span>
<span class='doccomment'>//! if you switch and a 1/3 chance of winning if you don't, so it's better to</span>
<span class='doccomment'>//! switch.</span>
<span class='doccomment'>//!</span>
<span class='doccomment'>//! This program will simulate the game show and with large enough simulation</span>
<span class='doccomment'>//! steps it will indeed confirm that it is better to switch.</span>
<span class='doccomment'>//!</span>
<span class='doccomment'>//! [Monty Hall Problem]: http://en.wikipedia.org/wiki/Monty_Hall_problem</span>
<span class='doccomment'>//!</span>
<span class='doccomment'>//! ```</span>
<span class='doccomment'>//! use rand::Rng;</span>
<span class='doccomment'>//! use rand::distributions::{IndependentSample, Range};</span>
<span class='doccomment'>//!</span>
<span class='doccomment'>//! struct SimulationResult {</span>
<span class='doccomment'>//! win: bool,</span>
<span class='doccomment'>//! switch: bool,</span>
<span class='doccomment'>//! }</span>
<span class='doccomment'>//!</span>
<span class='doccomment'>//! // Run a single simulation of the Monty Hall problem.</span>
<span class='doccomment'>//! fn simulate<R: Rng>(random_door: &Range<u32>, rng: &mut R)</span>
<span class='doccomment'>//! -> SimulationResult {</span>
<span class='doccomment'>//! let car = random_door.ind_sample(rng);</span>
<span class='doccomment'>//!</span>
<span class='doccomment'>//! // This is our initial choice</span>
<span class='doccomment'>//! let mut choice = random_door.ind_sample(rng);</span>
<span class='doccomment'>//!</span>
<span class='doccomment'>//! // The game host opens a door</span>
<span class='doccomment'>//! let open = game_host_open(car, choice, rng);</span>
<span class='doccomment'>//!</span>
<span class='doccomment'>//! // Shall we switch?</span>
<span class='doccomment'>//! let switch = rng.gen();</span>
<span class='doccomment'>//! if switch {</span>
<span class='doccomment'>//! choice = switch_door(choice, open);</span>
<span class='doccomment'>//! }</span>
<span class='doccomment'>//!</span>
<span class='doccomment'>//! SimulationResult { win: choice == car, switch: switch }</span>
<span class='doccomment'>//! }</span>
<span class='doccomment'>//!</span>
<span class='doccomment'>//! // Returns the door the game host opens given our choice and knowledge of</span>
<span class='doccomment'>//! // where the car is. The game host will never open the door with the car.</span>
<span class='doccomment'>//! fn game_host_open<R: Rng>(car: u32, choice: u32, rng: &mut R) -> u32 {</span>
<span class='doccomment'>//! let choices = free_doors(&[car, choice]);</span>
<span class='doccomment'>//! rand::sample(rng, choices.into_iter(), 1)[0]</span>
<span class='doccomment'>//! }</span>
<span class='doccomment'>//!</span>
<span class='doccomment'>//! // Returns the door we switch to, given our current choice and</span>
<span class='doccomment'>//! // the open door. There will only be one valid door.</span>
<span class='doccomment'>//! fn switch_door(choice: u32, open: u32) -> u32 {</span>
<span class='doccomment'>//! free_doors(&[choice, open])[0]</span>
<span class='doccomment'>//! }</span>
<span class='doccomment'>//!</span>
<span class='doccomment'>//! fn free_doors(blocked: &[u32]) -> Vec<u32> {</span>
<span class='doccomment'>//! (0..3).filter(|x| !blocked.contains(x)).collect()</span>
<span class='doccomment'>//! }</span>
<span class='doccomment'>//!</span>
<span class='doccomment'>//! fn main() {</span>
<span class='doccomment'>//! // The estimation will be more accurate with more simulations</span>
<span class='doccomment'>//! let num_simulations = 10000;</span>
<span class='doccomment'>//!</span>
<span class='doccomment'>//! let mut rng = rand::thread_rng();</span>
<span class='doccomment'>//! let random_door = Range::new(0, 3);</span>
<span class='doccomment'>//!</span>
<span class='doccomment'>//! let (mut switch_wins, mut switch_losses) = (0, 0);</span>
<span class='doccomment'>//! let (mut keep_wins, mut keep_losses) = (0, 0);</span>
<span class='doccomment'>//!</span>
<span class='doccomment'>//! println!("Running {} simulations...", num_simulations);</span>
<span class='doccomment'>//! for _ in 0..num_simulations {</span>
<span class='doccomment'>//! let result = simulate(&random_door, &mut rng);</span>
<span class='doccomment'>//!</span>
<span class='doccomment'>//! match (result.win, result.switch) {</span>
<span class='doccomment'>//! (true, true) => switch_wins += 1,</span>
<span class='doccomment'>//! (true, false) => keep_wins += 1,</span>
<span class='doccomment'>//! (false, true) => switch_losses += 1,</span>
<span class='doccomment'>//! (false, false) => keep_losses += 1,</span>
<span class='doccomment'>//! }</span>
<span class='doccomment'>//! }</span>
<span class='doccomment'>//!</span>
<span class='doccomment'>//! let total_switches = switch_wins + switch_losses;</span>
<span class='doccomment'>//! let total_keeps = keep_wins + keep_losses;</span>
<span class='doccomment'>//!</span>
<span class='doccomment'>//! println!("Switched door {} times with {} wins and {} losses",</span>
<span class='doccomment'>//! total_switches, switch_wins, switch_losses);</span>
<span class='doccomment'>//!</span>
<span class='doccomment'>//! println!("Kept our choice {} times with {} wins and {} losses",</span>
<span class='doccomment'>//! total_keeps, keep_wins, keep_losses);</span>
<span class='doccomment'>//!</span>
<span class='doccomment'>//! // With a large number of simulations, the values should converge to</span>
<span class='doccomment'>//! // 0.667 and 0.333 respectively.</span>
<span class='doccomment'>//! println!("Estimated chance to win if we switch: {}",</span>
<span class='doccomment'>//! switch_wins as f32 / total_switches as f32);</span>
<span class='doccomment'>//! println!("Estimated chance to win if we don't: {}",</span>
<span class='doccomment'>//! keep_wins as f32 / total_keeps as f32);</span>
<span class='doccomment'>//! }</span>
<span class='doccomment'>//! ```</span>
<span class='attribute'>#<span class='op'>!</span>[<span class='ident'>doc</span>(<span class='ident'>html_logo_url</span> <span class='op'>=</span> <span class='string'>"https://www.rust-lang.org/logos/rust-logo-128x128-blk.png"</span>,
<span class='ident'>html_favicon_url</span> <span class='op'>=</span> <span class='string'>"https://www.rust-lang.org/favicon.ico"</span>,
<span class='ident'>html_root_url</span> <span class='op'>=</span> <span class='string'>"https://doc.rust-lang.org/rand/"</span>)]</span>
<span class='attribute'>#[<span class='ident'>cfg</span>(<span class='ident'>test</span>)]</span> <span class='attribute'>#[<span class='ident'>macro_use</span>]</span> <span class='kw'>extern</span> <span class='kw'>crate</span> <span class='ident'>log</span>;
<span class='kw'>use</span> <span class='ident'>std</span>::<span class='ident'>cell</span>::<span class='ident'>RefCell</span>;
<span class='kw'>use</span> <span class='ident'>std</span>::<span class='ident'>marker</span>;
<span class='kw'>use</span> <span class='ident'>std</span>::<span class='ident'>mem</span>;
<span class='kw'>use</span> <span class='ident'>std</span>::<span class='ident'>io</span>;
<span class='kw'>use</span> <span class='ident'>std</span>::<span class='ident'>rc</span>::<span class='ident'>Rc</span>;
<span class='kw'>use</span> <span class='ident'>std</span>::<span class='ident'>num</span>::<span class='ident'>Wrapping</span> <span class='kw'>as</span> <span class='ident'>w</span>;
<span class='kw'>pub</span> <span class='kw'>use</span> <span class='ident'>os</span>::<span class='ident'>OsRng</span>;
<span class='kw'>pub</span> <span class='kw'>use</span> <span class='ident'>isaac</span>::{<span class='ident'>IsaacRng</span>, <span class='ident'>Isaac64Rng</span>};
<span class='kw'>pub</span> <span class='kw'>use</span> <span class='ident'>chacha</span>::<span class='ident'>ChaChaRng</span>;
<span class='attribute'>#[<span class='ident'>cfg</span>(<span class='ident'>target_pointer_width</span> <span class='op'>=</span> <span class='string'>"32"</span>)]</span>
<span class='kw'>use</span> <span class='ident'>IsaacRng</span> <span class='kw'>as</span> <span class='ident'>IsaacWordRng</span>;
<span class='attribute'>#[<span class='ident'>cfg</span>(<span class='ident'>target_pointer_width</span> <span class='op'>=</span> <span class='string'>"64"</span>)]</span>
<span class='kw'>use</span> <span class='ident'>Isaac64Rng</span> <span class='kw'>as</span> <span class='ident'>IsaacWordRng</span>;
<span class='kw'>use</span> <span class='ident'>distributions</span>::{<span class='ident'>Range</span>, <span class='ident'>IndependentSample</span>};
<span class='kw'>use</span> <span class='ident'>distributions</span>::<span class='ident'>range</span>::<span class='ident'>SampleRange</span>;
<span class='kw'>pub</span> <span class='kw'>mod</span> <span class='ident'>distributions</span>;
<span class='kw'>pub</span> <span class='kw'>mod</span> <span class='ident'>isaac</span>;
<span class='kw'>pub</span> <span class='kw'>mod</span> <span class='ident'>chacha</span>;
<span class='kw'>pub</span> <span class='kw'>mod</span> <span class='ident'>reseeding</span>;
<span class='kw'>mod</span> <span class='ident'>rand_impls</span>;
<span class='kw'>pub</span> <span class='kw'>mod</span> <span class='ident'>os</span>;
<span class='kw'>pub</span> <span class='kw'>mod</span> <span class='ident'>read</span>;
<span class='attribute'>#[<span class='ident'>allow</span>(<span class='ident'>bad_style</span>)]</span>
<span class='kw'>type</span> <span class='ident'>w64</span> <span class='op'>=</span> <span class='ident'>w</span><span class='op'><</span><span class='ident'>u64</span><span class='op'>></span>;
<span class='attribute'>#[<span class='ident'>allow</span>(<span class='ident'>bad_style</span>)]</span>
<span class='kw'>type</span> <span class='ident'>w32</span> <span class='op'>=</span> <span class='ident'>w</span><span class='op'><</span><span class='ident'>u32</span><span class='op'>></span>;
<span class='doccomment'>/// A type that can be randomly generated using an `Rng`.</span>
<span class='kw'>pub</span> <span class='kw'>trait</span> <span class='ident'>Rand</span> : <span class='ident'>Sized</span> {
<span class='doccomment'>/// Generates a random instance of this type using the specified source of</span>
<span class='doccomment'>/// randomness.</span>
<span class='kw'>fn</span> <span class='ident'>rand</span><span class='op'><</span><span class='ident'>R</span>: <span class='ident'>Rng</span><span class='op'>></span>(<span class='ident'>rng</span>: <span class='kw-2'>&</span><span class='kw-2'>mut</span> <span class='ident'>R</span>) <span class='op'>-></span> <span class='self'>Self</span>;
}
<span class='doccomment'>/// A random number generator.</span>
<span class='kw'>pub</span> <span class='kw'>trait</span> <span class='ident'>Rng</span> {
<span class='doccomment'>/// Return the next random u32.</span>
<span class='doccomment'>///</span>
<span class='doccomment'>/// This rarely needs to be called directly, prefer `r.gen()` to</span>
<span class='doccomment'>/// `r.next_u32()`.</span>
<span class='comment'>// FIXME #7771: Should be implemented in terms of next_u64</span>
<span class='kw'>fn</span> <span class='ident'>next_u32</span>(<span class='kw-2'>&</span><span class='kw-2'>mut</span> <span class='self'>self</span>) <span class='op'>-></span> <span class='ident'>u32</span>;
<span class='doccomment'>/// Return the next random u64.</span>
<span class='doccomment'>///</span>
<span class='doccomment'>/// By default this is implemented in terms of `next_u32`. An</span>
<span class='doccomment'>/// implementation of this trait must provide at least one of</span>
<span class='doccomment'>/// these two methods. Similarly to `next_u32`, this rarely needs</span>
<span class='doccomment'>/// to be called directly, prefer `r.gen()` to `r.next_u64()`.</span>
<span class='kw'>fn</span> <span class='ident'>next_u64</span>(<span class='kw-2'>&</span><span class='kw-2'>mut</span> <span class='self'>self</span>) <span class='op'>-></span> <span class='ident'>u64</span> {
((<span class='self'>self</span>.<span class='ident'>next_u32</span>() <span class='kw'>as</span> <span class='ident'>u64</span>) <span class='op'><<</span> <span class='number'>32</span>) <span class='op'>|</span> (<span class='self'>self</span>.<span class='ident'>next_u32</span>() <span class='kw'>as</span> <span class='ident'>u64</span>)
}
<span class='doccomment'>/// Return the next random f32 selected from the half-open</span>
<span class='doccomment'>/// interval `[0, 1)`.</span>
<span class='doccomment'>///</span>
<span class='doccomment'>/// This uses a technique described by Saito and Matsumoto at</span>
<span class='doccomment'>/// MCQMC'08. Given that the IEEE floating point numbers are</span>
<span class='doccomment'>/// uniformly distributed over [1,2), we generate a number in</span>
<span class='doccomment'>/// this range and then offset it onto the range [0,1). Our</span>
<span class='doccomment'>/// choice of bits (masking v. shifting) is arbitrary and</span>
<span class='doccomment'>/// should be immaterial for high quality generators. For low</span>
<span class='doccomment'>/// quality generators (ex. LCG), prefer bitshifting due to</span>
<span class='doccomment'>/// correlation between sequential low order bits.</span>
<span class='doccomment'>///</span>
<span class='doccomment'>/// See:</span>
<span class='doccomment'>/// A PRNG specialized in double precision floating point numbers using</span>
<span class='doccomment'>/// an affine transition</span>
<span class='doccomment'>/// http://www.math.sci.hiroshima-u.ac.jp/~m-mat/MT/ARTICLES/dSFMT.pdf</span>
<span class='doccomment'>/// http://www.math.sci.hiroshima-u.ac.jp/~m-mat/MT/SFMT/dSFMT-slide-e.pdf</span>
<span class='doccomment'>///</span>
<span class='doccomment'>/// By default this is implemented in terms of `next_u32`, but a</span>
<span class='doccomment'>/// random number generator which can generate numbers satisfying</span>
<span class='doccomment'>/// the requirements directly can overload this for performance.</span>
<span class='doccomment'>/// It is required that the return value lies in `[0, 1)`.</span>
<span class='doccomment'>///</span>
<span class='doccomment'>/// See `Closed01` for the closed interval `[0,1]`, and</span>
<span class='doccomment'>/// `Open01` for the open interval `(0,1)`.</span>
<span class='kw'>fn</span> <span class='ident'>next_f32</span>(<span class='kw-2'>&</span><span class='kw-2'>mut</span> <span class='self'>self</span>) <span class='op'>-></span> <span class='ident'>f32</span> {
<span class='kw'>const</span> <span class='ident'>UPPER_MASK</span>: <span class='ident'>u32</span> <span class='op'>=</span> <span class='number'>0x3F800000</span>;
<span class='kw'>const</span> <span class='ident'>LOWER_MASK</span>: <span class='ident'>u32</span> <span class='op'>=</span> <span class='number'>0x7FFFFF</span>;
<span class='kw'>let</span> <span class='ident'>tmp</span> <span class='op'>=</span> <span class='ident'>UPPER_MASK</span> <span class='op'>|</span> (<span class='self'>self</span>.<span class='ident'>next_u32</span>() <span class='op'>&</span> <span class='ident'>LOWER_MASK</span>);
<span class='kw'>let</span> <span class='ident'>result</span>: <span class='ident'>f32</span> <span class='op'>=</span> <span class='kw'>unsafe</span> { <span class='ident'>mem</span>::<span class='ident'>transmute</span>(<span class='ident'>tmp</span>) };
<span class='ident'>result</span> <span class='op'>-</span> <span class='number'>1.0</span>
}
<span class='doccomment'>/// Return the next random f64 selected from the half-open</span>
<span class='doccomment'>/// interval `[0, 1)`.</span>
<span class='doccomment'>///</span>
<span class='doccomment'>/// By default this is implemented in terms of `next_u64`, but a</span>
<span class='doccomment'>/// random number generator which can generate numbers satisfying</span>
<span class='doccomment'>/// the requirements directly can overload this for performance.</span>
<span class='doccomment'>/// It is required that the return value lies in `[0, 1)`.</span>
<span class='doccomment'>///</span>
<span class='doccomment'>/// See `Closed01` for the closed interval `[0,1]`, and</span>
<span class='doccomment'>/// `Open01` for the open interval `(0,1)`.</span>
<span class='kw'>fn</span> <span class='ident'>next_f64</span>(<span class='kw-2'>&</span><span class='kw-2'>mut</span> <span class='self'>self</span>) <span class='op'>-></span> <span class='ident'>f64</span> {
<span class='kw'>const</span> <span class='ident'>UPPER_MASK</span>: <span class='ident'>u64</span> <span class='op'>=</span> <span class='number'>0x3FF0000000000000</span>;
<span class='kw'>const</span> <span class='ident'>LOWER_MASK</span>: <span class='ident'>u64</span> <span class='op'>=</span> <span class='number'>0xFFFFFFFFFFFFF</span>;
<span class='kw'>let</span> <span class='ident'>tmp</span> <span class='op'>=</span> <span class='ident'>UPPER_MASK</span> <span class='op'>|</span> (<span class='self'>self</span>.<span class='ident'>next_u64</span>() <span class='op'>&</span> <span class='ident'>LOWER_MASK</span>);
<span class='kw'>let</span> <span class='ident'>result</span>: <span class='ident'>f64</span> <span class='op'>=</span> <span class='kw'>unsafe</span> { <span class='ident'>mem</span>::<span class='ident'>transmute</span>(<span class='ident'>tmp</span>) };
<span class='ident'>result</span> <span class='op'>-</span> <span class='number'>1.0</span>
}
<span class='doccomment'>/// Fill `dest` with random data.</span>
<span class='doccomment'>///</span>
<span class='doccomment'>/// This has a default implementation in terms of `next_u64` and</span>
<span class='doccomment'>/// `next_u32`, but should be overridden by implementations that</span>
<span class='doccomment'>/// offer a more efficient solution than just calling those</span>
<span class='doccomment'>/// methods repeatedly.</span>
<span class='doccomment'>///</span>
<span class='doccomment'>/// This method does *not* have a requirement to bear any fixed</span>
<span class='doccomment'>/// relationship to the other methods, for example, it does *not*</span>
<span class='doccomment'>/// have to result in the same output as progressively filling</span>
<span class='doccomment'>/// `dest` with `self.gen::<u8>()`, and any such behaviour should</span>
<span class='doccomment'>/// not be relied upon.</span>
<span class='doccomment'>///</span>
<span class='doccomment'>/// This method should guarantee that `dest` is entirely filled</span>
<span class='doccomment'>/// with new data, and may panic if this is impossible</span>
<span class='doccomment'>/// (e.g. reading past the end of a file that is being used as the</span>
<span class='doccomment'>/// source of randomness).</span>
<span class='doccomment'>///</span>
<span class='doccomment'>/// # Example</span>
<span class='doccomment'>///</span>
<span class='doccomment'>/// ```rust</span>
<span class='doccomment'>/// use rand::{thread_rng, Rng};</span>
<span class='doccomment'>///</span>
<span class='doccomment'>/// let mut v = [0u8; 13579];</span>
<span class='doccomment'>/// thread_rng().fill_bytes(&mut v);</span>
<span class='doccomment'>/// println!("{:?}", &v[..]);</span>
<span class='doccomment'>/// ```</span>
<span class='kw'>fn</span> <span class='ident'>fill_bytes</span>(<span class='kw-2'>&</span><span class='kw-2'>mut</span> <span class='self'>self</span>, <span class='ident'>dest</span>: <span class='kw-2'>&</span><span class='kw-2'>mut</span> [<span class='ident'>u8</span>]) {
<span class='comment'>// this could, in theory, be done by transmuting dest to a</span>
<span class='comment'>// [u64], but this is (1) likely to be undefined behaviour for</span>
<span class='comment'>// LLVM, (2) has to be very careful about alignment concerns,</span>
<span class='comment'>// (3) adds more `unsafe` that needs to be checked, (4)</span>
<span class='comment'>// probably doesn't give much performance gain if</span>
<span class='comment'>// optimisations are on.</span>
<span class='kw'>let</span> <span class='kw-2'>mut</span> <span class='ident'>count</span> <span class='op'>=</span> <span class='number'>0</span>;
<span class='kw'>let</span> <span class='kw-2'>mut</span> <span class='ident'>num</span> <span class='op'>=</span> <span class='number'>0</span>;
<span class='kw'>for</span> <span class='ident'>byte</span> <span class='kw'>in</span> <span class='ident'>dest</span>.<span class='ident'>iter_mut</span>() {
<span class='kw'>if</span> <span class='ident'>count</span> <span class='op'>==</span> <span class='number'>0</span> {
<span class='comment'>// we could micro-optimise here by generating a u32 if</span>
<span class='comment'>// we only need a few more bytes to fill the vector</span>
<span class='comment'>// (i.e. at most 4).</span>
<span class='ident'>num</span> <span class='op'>=</span> <span class='self'>self</span>.<span class='ident'>next_u64</span>();
<span class='ident'>count</span> <span class='op'>=</span> <span class='number'>8</span>;
}
<span class='kw-2'>*</span><span class='ident'>byte</span> <span class='op'>=</span> (<span class='ident'>num</span> <span class='op'>&</span> <span class='number'>0xff</span>) <span class='kw'>as</span> <span class='ident'>u8</span>;
<span class='ident'>num</span> <span class='op'>>>=</span> <span class='number'>8</span>;
<span class='ident'>count</span> <span class='op'>-=</span> <span class='number'>1</span>;
}
}
<span class='doccomment'>/// Return a random value of a `Rand` type.</span>
<span class='doccomment'>///</span>
<span class='doccomment'>/// # Example</span>
<span class='doccomment'>///</span>
<span class='doccomment'>/// ```rust</span>
<span class='doccomment'>/// use rand::{thread_rng, Rng};</span>
<span class='doccomment'>///</span>
<span class='doccomment'>/// let mut rng = thread_rng();</span>
<span class='doccomment'>/// let x: u32 = rng.gen();</span>
<span class='doccomment'>/// println!("{}", x);</span>
<span class='doccomment'>/// println!("{:?}", rng.gen::<(f64, bool)>());</span>
<span class='doccomment'>/// ```</span>
<span class='attribute'>#[<span class='ident'>inline</span>(<span class='ident'>always</span>)]</span>
<span class='kw'>fn</span> <span class='ident'>gen</span><span class='op'><</span><span class='ident'>T</span>: <span class='ident'>Rand</span><span class='op'>></span>(<span class='kw-2'>&</span><span class='kw-2'>mut</span> <span class='self'>self</span>) <span class='op'>-></span> <span class='ident'>T</span> <span class='kw'>where</span> <span class='self'>Self</span>: <span class='ident'>Sized</span> {
<span class='ident'>Rand</span>::<span class='ident'>rand</span>(<span class='self'>self</span>)
}
<span class='doccomment'>/// Return an iterator that will yield an infinite number of randomly</span>
<span class='doccomment'>/// generated items.</span>
<span class='doccomment'>///</span>
<span class='doccomment'>/// # Example</span>
<span class='doccomment'>///</span>
<span class='doccomment'>/// ```</span>
<span class='doccomment'>/// use rand::{thread_rng, Rng};</span>
<span class='doccomment'>///</span>
<span class='doccomment'>/// let mut rng = thread_rng();</span>
<span class='doccomment'>/// let x = rng.gen_iter::<u32>().take(10).collect::<Vec<u32>>();</span>
<span class='doccomment'>/// println!("{:?}", x);</span>
<span class='doccomment'>/// println!("{:?}", rng.gen_iter::<(f64, bool)>().take(5)</span>
<span class='doccomment'>/// .collect::<Vec<(f64, bool)>>());</span>
<span class='doccomment'>/// ```</span>
<span class='kw'>fn</span> <span class='ident'>gen_iter</span><span class='op'><</span><span class='lifetime'>'a</span>, <span class='ident'>T</span>: <span class='ident'>Rand</span><span class='op'>></span>(<span class='kw-2'>&</span><span class='lifetime'>'a</span> <span class='kw-2'>mut</span> <span class='self'>self</span>) <span class='op'>-></span> <span class='ident'>Generator</span><span class='op'><</span><span class='lifetime'>'a</span>, <span class='ident'>T</span>, <span class='self'>Self</span><span class='op'>></span> <span class='kw'>where</span> <span class='self'>Self</span>: <span class='ident'>Sized</span> {
<span class='ident'>Generator</span> { <span class='ident'>rng</span>: <span class='self'>self</span>, <span class='ident'>_marker</span>: <span class='ident'>marker</span>::<span class='ident'>PhantomData</span> }
}
<span class='doccomment'>/// Generate a random value in the range [`low`, `high`).</span>
<span class='doccomment'>///</span>
<span class='doccomment'>/// This is a convenience wrapper around</span>
<span class='doccomment'>/// `distributions::Range`. If this function will be called</span>
<span class='doccomment'>/// repeatedly with the same arguments, one should use `Range`, as</span>
<span class='doccomment'>/// that will amortize the computations that allow for perfect</span>
<span class='doccomment'>/// uniformity, as they only happen on initialization.</span>
<span class='doccomment'>///</span>
<span class='doccomment'>/// # Panics</span>
<span class='doccomment'>///</span>
<span class='doccomment'>/// Panics if `low >= high`.</span>
<span class='doccomment'>///</span>
<span class='doccomment'>/// # Example</span>
<span class='doccomment'>///</span>
<span class='doccomment'>/// ```rust</span>
<span class='doccomment'>/// use rand::{thread_rng, Rng};</span>
<span class='doccomment'>///</span>
<span class='doccomment'>/// let mut rng = thread_rng();</span>
<span class='doccomment'>/// let n: u32 = rng.gen_range(0, 10);</span>
<span class='doccomment'>/// println!("{}", n);</span>
<span class='doccomment'>/// let m: f64 = rng.gen_range(-40.0f64, 1.3e5f64);</span>
<span class='doccomment'>/// println!("{}", m);</span>
<span class='doccomment'>/// ```</span>
<span class='kw'>fn</span> <span class='ident'>gen_range</span><span class='op'><</span><span class='ident'>T</span>: <span class='ident'>PartialOrd</span> <span class='op'>+</span> <span class='ident'>SampleRange</span><span class='op'>></span>(<span class='kw-2'>&</span><span class='kw-2'>mut</span> <span class='self'>self</span>, <span class='ident'>low</span>: <span class='ident'>T</span>, <span class='ident'>high</span>: <span class='ident'>T</span>) <span class='op'>-></span> <span class='ident'>T</span> <span class='kw'>where</span> <span class='self'>Self</span>: <span class='ident'>Sized</span> {
<span class='macro'>assert</span><span class='macro'>!</span>(<span class='ident'>low</span> <span class='op'><</span> <span class='ident'>high</span>, <span class='string'>"Rng.gen_range called with low >= high"</span>);
<span class='ident'>Range</span>::<span class='ident'>new</span>(<span class='ident'>low</span>, <span class='ident'>high</span>).<span class='ident'>ind_sample</span>(<span class='self'>self</span>)
}
<span class='doccomment'>/// Return a bool with a 1 in n chance of true</span>
<span class='doccomment'>///</span>
<span class='doccomment'>/// # Example</span>
<span class='doccomment'>///</span>
<span class='doccomment'>/// ```rust</span>
<span class='doccomment'>/// use rand::{thread_rng, Rng};</span>
<span class='doccomment'>///</span>
<span class='doccomment'>/// let mut rng = thread_rng();</span>
<span class='doccomment'>/// println!("{}", rng.gen_weighted_bool(3));</span>
<span class='doccomment'>/// ```</span>
<span class='kw'>fn</span> <span class='ident'>gen_weighted_bool</span>(<span class='kw-2'>&</span><span class='kw-2'>mut</span> <span class='self'>self</span>, <span class='ident'>n</span>: <span class='ident'>u32</span>) <span class='op'>-></span> <span class='ident'>bool</span> <span class='kw'>where</span> <span class='self'>Self</span>: <span class='ident'>Sized</span> {
<span class='ident'>n</span> <span class='op'><=</span> <span class='number'>1</span> <span class='op'>||</span> <span class='self'>self</span>.<span class='ident'>gen_range</span>(<span class='number'>0</span>, <span class='ident'>n</span>) <span class='op'>==</span> <span class='number'>0</span>
}
<span class='doccomment'>/// Return an iterator of random characters from the set A-Z,a-z,0-9.</span>
<span class='doccomment'>///</span>
<span class='doccomment'>/// # Example</span>
<span class='doccomment'>///</span>
<span class='doccomment'>/// ```rust</span>
<span class='doccomment'>/// use rand::{thread_rng, Rng};</span>
<span class='doccomment'>///</span>
<span class='doccomment'>/// let s: String = thread_rng().gen_ascii_chars().take(10).collect();</span>
<span class='doccomment'>/// println!("{}", s);</span>
<span class='doccomment'>/// ```</span>
<span class='kw'>fn</span> <span class='ident'>gen_ascii_chars</span><span class='op'><</span><span class='lifetime'>'a</span><span class='op'>></span>(<span class='kw-2'>&</span><span class='lifetime'>'a</span> <span class='kw-2'>mut</span> <span class='self'>self</span>) <span class='op'>-></span> <span class='ident'>AsciiGenerator</span><span class='op'><</span><span class='lifetime'>'a</span>, <span class='self'>Self</span><span class='op'>></span> <span class='kw'>where</span> <span class='self'>Self</span>: <span class='ident'>Sized</span> {
<span class='ident'>AsciiGenerator</span> { <span class='ident'>rng</span>: <span class='self'>self</span> }
}
<span class='doccomment'>/// Return a random element from `values`.</span>
<span class='doccomment'>///</span>
<span class='doccomment'>/// Return `None` if `values` is empty.</span>
<span class='doccomment'>///</span>
<span class='doccomment'>/// # Example</span>
<span class='doccomment'>///</span>
<span class='doccomment'>/// ```</span>
<span class='doccomment'>/// use rand::{thread_rng, Rng};</span>
<span class='doccomment'>///</span>
<span class='doccomment'>/// let choices = [1, 2, 4, 8, 16, 32];</span>
<span class='doccomment'>/// let mut rng = thread_rng();</span>
<span class='doccomment'>/// println!("{:?}", rng.choose(&choices));</span>
<span class='doccomment'>/// assert_eq!(rng.choose(&choices[..0]), None);</span>
<span class='doccomment'>/// ```</span>
<span class='kw'>fn</span> <span class='ident'>choose</span><span class='op'><</span><span class='lifetime'>'a</span>, <span class='ident'>T</span><span class='op'>></span>(<span class='kw-2'>&</span><span class='kw-2'>mut</span> <span class='self'>self</span>, <span class='ident'>values</span>: <span class='kw-2'>&</span><span class='lifetime'>'a</span> [<span class='ident'>T</span>]) <span class='op'>-></span> <span class='prelude-ty'>Option</span><span class='op'><</span><span class='kw-2'>&</span><span class='lifetime'>'a</span> <span class='ident'>T</span><span class='op'>></span> <span class='kw'>where</span> <span class='self'>Self</span>: <span class='ident'>Sized</span> {
<span class='kw'>if</span> <span class='ident'>values</span>.<span class='ident'>is_empty</span>() {
<span class='prelude-val'>None</span>
} <span class='kw'>else</span> {
<span class='prelude-val'>Some</span>(<span class='kw-2'>&</span><span class='ident'>values</span>[<span class='self'>self</span>.<span class='ident'>gen_range</span>(<span class='number'>0</span>, <span class='ident'>values</span>.<span class='ident'>len</span>())])
}
}
<span class='doccomment'>/// Return a mutable pointer to a random element from `values`.</span>
<span class='doccomment'>///</span>
<span class='doccomment'>/// Return `None` if `values` is empty.</span>
<span class='kw'>fn</span> <span class='ident'>choose_mut</span><span class='op'><</span><span class='lifetime'>'a</span>, <span class='ident'>T</span><span class='op'>></span>(<span class='kw-2'>&</span><span class='kw-2'>mut</span> <span class='self'>self</span>, <span class='ident'>values</span>: <span class='kw-2'>&</span><span class='lifetime'>'a</span> <span class='kw-2'>mut</span> [<span class='ident'>T</span>]) <span class='op'>-></span> <span class='prelude-ty'>Option</span><span class='op'><</span><span class='kw-2'>&</span><span class='lifetime'>'a</span> <span class='kw-2'>mut</span> <span class='ident'>T</span><span class='op'>></span> <span class='kw'>where</span> <span class='self'>Self</span>: <span class='ident'>Sized</span> {
<span class='kw'>if</span> <span class='ident'>values</span>.<span class='ident'>is_empty</span>() {
<span class='prelude-val'>None</span>
} <span class='kw'>else</span> {
<span class='kw'>let</span> <span class='ident'>len</span> <span class='op'>=</span> <span class='ident'>values</span>.<span class='ident'>len</span>();
<span class='prelude-val'>Some</span>(<span class='kw-2'>&</span><span class='kw-2'>mut</span> <span class='ident'>values</span>[<span class='self'>self</span>.<span class='ident'>gen_range</span>(<span class='number'>0</span>, <span class='ident'>len</span>)])
}
}
<span class='doccomment'>/// Shuffle a mutable slice in place.</span>
<span class='doccomment'>///</span>
<span class='doccomment'>/// # Example</span>
<span class='doccomment'>///</span>
<span class='doccomment'>/// ```rust</span>
<span class='doccomment'>/// use rand::{thread_rng, Rng};</span>
<span class='doccomment'>///</span>
<span class='doccomment'>/// let mut rng = thread_rng();</span>
<span class='doccomment'>/// let mut y = [1, 2, 3];</span>
<span class='doccomment'>/// rng.shuffle(&mut y);</span>
<span class='doccomment'>/// println!("{:?}", y);</span>
<span class='doccomment'>/// rng.shuffle(&mut y);</span>
<span class='doccomment'>/// println!("{:?}", y);</span>
<span class='doccomment'>/// ```</span>
<span class='kw'>fn</span> <span class='ident'>shuffle</span><span class='op'><</span><span class='ident'>T</span><span class='op'>></span>(<span class='kw-2'>&</span><span class='kw-2'>mut</span> <span class='self'>self</span>, <span class='ident'>values</span>: <span class='kw-2'>&</span><span class='kw-2'>mut</span> [<span class='ident'>T</span>]) <span class='kw'>where</span> <span class='self'>Self</span>: <span class='ident'>Sized</span> {
<span class='kw'>let</span> <span class='kw-2'>mut</span> <span class='ident'>i</span> <span class='op'>=</span> <span class='ident'>values</span>.<span class='ident'>len</span>();
<span class='kw'>while</span> <span class='ident'>i</span> <span class='op'>>=</span> <span class='number'>2</span> {
<span class='comment'>// invariant: elements with index >= i have been locked in place.</span>
<span class='ident'>i</span> <span class='op'>-=</span> <span class='number'>1</span>;
<span class='comment'>// lock element i in place.</span>
<span class='ident'>values</span>.<span class='ident'>swap</span>(<span class='ident'>i</span>, <span class='self'>self</span>.<span class='ident'>gen_range</span>(<span class='number'>0</span>, <span class='ident'>i</span> <span class='op'>+</span> <span class='number'>1</span>));
}
}
}
<span class='kw'>impl</span><span class='op'><</span><span class='lifetime'>'a</span>, <span class='ident'>R</span>: <span class='question-mark'>?</span><span class='ident'>Sized</span><span class='op'>></span> <span class='ident'>Rng</span> <span class='kw'>for</span> <span class='kw-2'>&</span><span class='lifetime'>'a</span> <span class='kw-2'>mut</span> <span class='ident'>R</span> <span class='kw'>where</span> <span class='ident'>R</span>: <span class='ident'>Rng</span> {
<span class='kw'>fn</span> <span class='ident'>next_u32</span>(<span class='kw-2'>&</span><span class='kw-2'>mut</span> <span class='self'>self</span>) <span class='op'>-></span> <span class='ident'>u32</span> {
(<span class='kw-2'>*</span><span class='kw-2'>*</span><span class='self'>self</span>).<span class='ident'>next_u32</span>()
}
<span class='kw'>fn</span> <span class='ident'>next_u64</span>(<span class='kw-2'>&</span><span class='kw-2'>mut</span> <span class='self'>self</span>) <span class='op'>-></span> <span class='ident'>u64</span> {
(<span class='kw-2'>*</span><span class='kw-2'>*</span><span class='self'>self</span>).<span class='ident'>next_u64</span>()
}
<span class='kw'>fn</span> <span class='ident'>next_f32</span>(<span class='kw-2'>&</span><span class='kw-2'>mut</span> <span class='self'>self</span>) <span class='op'>-></span> <span class='ident'>f32</span> {
(<span class='kw-2'>*</span><span class='kw-2'>*</span><span class='self'>self</span>).<span class='ident'>next_f32</span>()
}
<span class='kw'>fn</span> <span class='ident'>next_f64</span>(<span class='kw-2'>&</span><span class='kw-2'>mut</span> <span class='self'>self</span>) <span class='op'>-></span> <span class='ident'>f64</span> {
(<span class='kw-2'>*</span><span class='kw-2'>*</span><span class='self'>self</span>).<span class='ident'>next_f64</span>()
}
<span class='kw'>fn</span> <span class='ident'>fill_bytes</span>(<span class='kw-2'>&</span><span class='kw-2'>mut</span> <span class='self'>self</span>, <span class='ident'>dest</span>: <span class='kw-2'>&</span><span class='kw-2'>mut</span> [<span class='ident'>u8</span>]) {
(<span class='kw-2'>*</span><span class='kw-2'>*</span><span class='self'>self</span>).<span class='ident'>fill_bytes</span>(<span class='ident'>dest</span>)
}
}
<span class='kw'>impl</span><span class='op'><</span><span class='ident'>R</span>: <span class='question-mark'>?</span><span class='ident'>Sized</span><span class='op'>></span> <span class='ident'>Rng</span> <span class='kw'>for</span> <span class='ident'>Box</span><span class='op'><</span><span class='ident'>R</span><span class='op'>></span> <span class='kw'>where</span> <span class='ident'>R</span>: <span class='ident'>Rng</span> {
<span class='kw'>fn</span> <span class='ident'>next_u32</span>(<span class='kw-2'>&</span><span class='kw-2'>mut</span> <span class='self'>self</span>) <span class='op'>-></span> <span class='ident'>u32</span> {
(<span class='kw-2'>*</span><span class='kw-2'>*</span><span class='self'>self</span>).<span class='ident'>next_u32</span>()
}
<span class='kw'>fn</span> <span class='ident'>next_u64</span>(<span class='kw-2'>&</span><span class='kw-2'>mut</span> <span class='self'>self</span>) <span class='op'>-></span> <span class='ident'>u64</span> {
(<span class='kw-2'>*</span><span class='kw-2'>*</span><span class='self'>self</span>).<span class='ident'>next_u64</span>()
}
<span class='kw'>fn</span> <span class='ident'>next_f32</span>(<span class='kw-2'>&</span><span class='kw-2'>mut</span> <span class='self'>self</span>) <span class='op'>-></span> <span class='ident'>f32</span> {
(<span class='kw-2'>*</span><span class='kw-2'>*</span><span class='self'>self</span>).<span class='ident'>next_f32</span>()
}
<span class='kw'>fn</span> <span class='ident'>next_f64</span>(<span class='kw-2'>&</span><span class='kw-2'>mut</span> <span class='self'>self</span>) <span class='op'>-></span> <span class='ident'>f64</span> {
(<span class='kw-2'>*</span><span class='kw-2'>*</span><span class='self'>self</span>).<span class='ident'>next_f64</span>()
}
<span class='kw'>fn</span> <span class='ident'>fill_bytes</span>(<span class='kw-2'>&</span><span class='kw-2'>mut</span> <span class='self'>self</span>, <span class='ident'>dest</span>: <span class='kw-2'>&</span><span class='kw-2'>mut</span> [<span class='ident'>u8</span>]) {
(<span class='kw-2'>*</span><span class='kw-2'>*</span><span class='self'>self</span>).<span class='ident'>fill_bytes</span>(<span class='ident'>dest</span>)
}
}
<span class='doccomment'>/// Iterator which will generate a stream of random items.</span>
<span class='doccomment'>///</span>
<span class='doccomment'>/// This iterator is created via the [`gen_iter`] method on [`Rng`].</span>
<span class='doccomment'>///</span>
<span class='doccomment'>/// [`gen_iter`]: trait.Rng.html#method.gen_iter</span>
<span class='doccomment'>/// [`Rng`]: trait.Rng.html</span>
<span class='kw'>pub</span> <span class='kw'>struct</span> <span class='ident'>Generator</span><span class='op'><</span><span class='lifetime'>'a</span>, <span class='ident'>T</span>, <span class='ident'>R</span>:<span class='lifetime'>'a</span><span class='op'>></span> {
<span class='ident'>rng</span>: <span class='kw-2'>&</span><span class='lifetime'>'a</span> <span class='kw-2'>mut</span> <span class='ident'>R</span>,
<span class='ident'>_marker</span>: <span class='ident'>marker</span>::<span class='ident'>PhantomData</span><span class='op'><</span><span class='kw'>fn</span>() <span class='op'>-></span> <span class='ident'>T</span><span class='op'>></span>,
}
<span class='kw'>impl</span><span class='op'><</span><span class='lifetime'>'a</span>, <span class='ident'>T</span>: <span class='ident'>Rand</span>, <span class='ident'>R</span>: <span class='ident'>Rng</span><span class='op'>></span> <span class='ident'>Iterator</span> <span class='kw'>for</span> <span class='ident'>Generator</span><span class='op'><</span><span class='lifetime'>'a</span>, <span class='ident'>T</span>, <span class='ident'>R</span><span class='op'>></span> {
<span class='kw'>type</span> <span class='ident'>Item</span> <span class='op'>=</span> <span class='ident'>T</span>;
<span class='kw'>fn</span> <span class='ident'>next</span>(<span class='kw-2'>&</span><span class='kw-2'>mut</span> <span class='self'>self</span>) <span class='op'>-></span> <span class='prelude-ty'>Option</span><span class='op'><</span><span class='ident'>T</span><span class='op'>></span> {
<span class='prelude-val'>Some</span>(<span class='self'>self</span>.<span class='ident'>rng</span>.<span class='ident'>gen</span>())
}
}
<span class='doccomment'>/// Iterator which will continuously generate random ascii characters.</span>
<span class='doccomment'>///</span>
<span class='doccomment'>/// This iterator is created via the [`gen_ascii_chars`] method on [`Rng`].</span>
<span class='doccomment'>///</span>
<span class='doccomment'>/// [`gen_ascii_chars`]: trait.Rng.html#method.gen_ascii_chars</span>
<span class='doccomment'>/// [`Rng`]: trait.Rng.html</span>
<span class='kw'>pub</span> <span class='kw'>struct</span> <span class='ident'>AsciiGenerator</span><span class='op'><</span><span class='lifetime'>'a</span>, <span class='ident'>R</span>:<span class='lifetime'>'a</span><span class='op'>></span> {
<span class='ident'>rng</span>: <span class='kw-2'>&</span><span class='lifetime'>'a</span> <span class='kw-2'>mut</span> <span class='ident'>R</span>,
}
<span class='kw'>impl</span><span class='op'><</span><span class='lifetime'>'a</span>, <span class='ident'>R</span>: <span class='ident'>Rng</span><span class='op'>></span> <span class='ident'>Iterator</span> <span class='kw'>for</span> <span class='ident'>AsciiGenerator</span><span class='op'><</span><span class='lifetime'>'a</span>, <span class='ident'>R</span><span class='op'>></span> {
<span class='kw'>type</span> <span class='ident'>Item</span> <span class='op'>=</span> <span class='ident'>char</span>;
<span class='kw'>fn</span> <span class='ident'>next</span>(<span class='kw-2'>&</span><span class='kw-2'>mut</span> <span class='self'>self</span>) <span class='op'>-></span> <span class='prelude-ty'>Option</span><span class='op'><</span><span class='ident'>char</span><span class='op'>></span> {
<span class='kw'>const</span> <span class='ident'>GEN_ASCII_STR_CHARSET</span>: <span class='kw-2'>&</span><span class='lifetime'>'static</span> [<span class='ident'>u8</span>] <span class='op'>=</span>
<span class='string'>b"ABCDEFGHIJKLMNOPQRSTUVWXYZ\
abcdefghijklmnopqrstuvwxyz\
0123456789"</span>;
<span class='prelude-val'>Some</span>(<span class='kw-2'>*</span><span class='self'>self</span>.<span class='ident'>rng</span>.<span class='ident'>choose</span>(<span class='ident'>GEN_ASCII_STR_CHARSET</span>).<span class='ident'>unwrap</span>() <span class='kw'>as</span> <span class='ident'>char</span>)
}
}
<span class='doccomment'>/// A random number generator that can be explicitly seeded to produce</span>
<span class='doccomment'>/// the same stream of randomness multiple times.</span>
<span class='kw'>pub</span> <span class='kw'>trait</span> <span class='ident'>SeedableRng</span><span class='op'><</span><span class='ident'>Seed</span><span class='op'>></span>: <span class='ident'>Rng</span> {
<span class='doccomment'>/// Reseed an RNG with the given seed.</span>
<span class='doccomment'>///</span>
<span class='doccomment'>/// # Example</span>
<span class='doccomment'>///</span>
<span class='doccomment'>/// ```rust</span>
<span class='doccomment'>/// use rand::{Rng, SeedableRng, StdRng};</span>
<span class='doccomment'>///</span>
<span class='doccomment'>/// let seed: &[_] = &[1, 2, 3, 4];</span>
<span class='doccomment'>/// let mut rng: StdRng = SeedableRng::from_seed(seed);</span>
<span class='doccomment'>/// println!("{}", rng.gen::<f64>());</span>
<span class='doccomment'>/// rng.reseed(&[5, 6, 7, 8]);</span>
<span class='doccomment'>/// println!("{}", rng.gen::<f64>());</span>
<span class='doccomment'>/// ```</span>
<span class='kw'>fn</span> <span class='ident'>reseed</span>(<span class='kw-2'>&</span><span class='kw-2'>mut</span> <span class='self'>self</span>, <span class='ident'>Seed</span>);
<span class='doccomment'>/// Create a new RNG with the given seed.</span>
<span class='doccomment'>///</span>
<span class='doccomment'>/// # Example</span>
<span class='doccomment'>///</span>
<span class='doccomment'>/// ```rust</span>
<span class='doccomment'>/// use rand::{Rng, SeedableRng, StdRng};</span>
<span class='doccomment'>///</span>
<span class='doccomment'>/// let seed: &[_] = &[1, 2, 3, 4];</span>
<span class='doccomment'>/// let mut rng: StdRng = SeedableRng::from_seed(seed);</span>
<span class='doccomment'>/// println!("{}", rng.gen::<f64>());</span>
<span class='doccomment'>/// ```</span>
<span class='kw'>fn</span> <span class='ident'>from_seed</span>(<span class='ident'>seed</span>: <span class='ident'>Seed</span>) <span class='op'>-></span> <span class='self'>Self</span>;
}
<span class='doccomment'>/// An Xorshift[1] random number</span>
<span class='doccomment'>/// generator.</span>
<span class='doccomment'>///</span>
<span class='doccomment'>/// The Xorshift algorithm is not suitable for cryptographic purposes</span>
<span class='doccomment'>/// but is very fast. If you do not know for sure that it fits your</span>
<span class='doccomment'>/// requirements, use a more secure one such as `IsaacRng` or `OsRng`.</span>
<span class='doccomment'>///</span>
<span class='doccomment'>/// [1]: Marsaglia, George (July 2003). ["Xorshift</span>
<span class='doccomment'>/// RNGs"](http://www.jstatsoft.org/v08/i14/paper). *Journal of</span>
<span class='doccomment'>/// Statistical Software*. Vol. 8 (Issue 14).</span>
<span class='attribute'>#[<span class='ident'>allow</span>(<span class='ident'>missing_copy_implementations</span>)]</span>
<span class='attribute'>#[<span class='ident'>derive</span>(<span class='ident'>Clone</span>)]</span>
<span class='kw'>pub</span> <span class='kw'>struct</span> <span class='ident'>XorShiftRng</span> {
<span class='ident'>x</span>: <span class='ident'>w32</span>,
<span class='ident'>y</span>: <span class='ident'>w32</span>,
<span class='ident'>z</span>: <span class='ident'>w32</span>,
<span class='ident'>w</span>: <span class='ident'>w32</span>,
}
<span class='kw'>impl</span> <span class='ident'>XorShiftRng</span> {
<span class='doccomment'>/// Creates a new XorShiftRng instance which is not seeded.</span>
<span class='doccomment'>///</span>
<span class='doccomment'>/// The initial values of this RNG are constants, so all generators created</span>
<span class='doccomment'>/// by this function will yield the same stream of random numbers. It is</span>
<span class='doccomment'>/// highly recommended that this is created through `SeedableRng` instead of</span>
<span class='doccomment'>/// this function</span>
<span class='kw'>pub</span> <span class='kw'>fn</span> <span class='ident'>new_unseeded</span>() <span class='op'>-></span> <span class='ident'>XorShiftRng</span> {
<span class='ident'>XorShiftRng</span> {
<span class='ident'>x</span>: <span class='ident'>w</span>(<span class='number'>0x193a6754</span>),
<span class='ident'>y</span>: <span class='ident'>w</span>(<span class='number'>0xa8a7d469</span>),
<span class='ident'>z</span>: <span class='ident'>w</span>(<span class='number'>0x97830e05</span>),
<span class='ident'>w</span>: <span class='ident'>w</span>(<span class='number'>0x113ba7bb</span>),
}
}
}
<span class='kw'>impl</span> <span class='ident'>Rng</span> <span class='kw'>for</span> <span class='ident'>XorShiftRng</span> {
<span class='attribute'>#[<span class='ident'>inline</span>]</span>
<span class='kw'>fn</span> <span class='ident'>next_u32</span>(<span class='kw-2'>&</span><span class='kw-2'>mut</span> <span class='self'>self</span>) <span class='op'>-></span> <span class='ident'>u32</span> {
<span class='kw'>let</span> <span class='ident'>x</span> <span class='op'>=</span> <span class='self'>self</span>.<span class='ident'>x</span>;
<span class='kw'>let</span> <span class='ident'>t</span> <span class='op'>=</span> <span class='ident'>x</span> <span class='op'>^</span> (<span class='ident'>x</span> <span class='op'><<</span> <span class='number'>11</span>);
<span class='self'>self</span>.<span class='ident'>x</span> <span class='op'>=</span> <span class='self'>self</span>.<span class='ident'>y</span>;
<span class='self'>self</span>.<span class='ident'>y</span> <span class='op'>=</span> <span class='self'>self</span>.<span class='ident'>z</span>;
<span class='self'>self</span>.<span class='ident'>z</span> <span class='op'>=</span> <span class='self'>self</span>.<span class='ident'>w</span>;
<span class='kw'>let</span> <span class='ident'>w_</span> <span class='op'>=</span> <span class='self'>self</span>.<span class='ident'>w</span>;
<span class='self'>self</span>.<span class='ident'>w</span> <span class='op'>=</span> <span class='ident'>w_</span> <span class='op'>^</span> (<span class='ident'>w_</span> <span class='op'>>></span> <span class='number'>19</span>) <span class='op'>^</span> (<span class='ident'>t</span> <span class='op'>^</span> (<span class='ident'>t</span> <span class='op'>>></span> <span class='number'>8</span>));
<span class='self'>self</span>.<span class='ident'>w</span>.<span class='number'>0</span>
}
}
<span class='kw'>impl</span> <span class='ident'>SeedableRng</span><span class='op'><</span>[<span class='ident'>u32</span>; <span class='number'>4</span>]<span class='op'>></span> <span class='kw'>for</span> <span class='ident'>XorShiftRng</span> {
<span class='doccomment'>/// Reseed an XorShiftRng. This will panic if `seed` is entirely 0.</span>
<span class='kw'>fn</span> <span class='ident'>reseed</span>(<span class='kw-2'>&</span><span class='kw-2'>mut</span> <span class='self'>self</span>, <span class='ident'>seed</span>: [<span class='ident'>u32</span>; <span class='number'>4</span>]) {
<span class='macro'>assert</span><span class='macro'>!</span>(<span class='op'>!</span><span class='ident'>seed</span>.<span class='ident'>iter</span>().<span class='ident'>all</span>(<span class='op'>|</span><span class='kw-2'>&</span><span class='ident'>x</span><span class='op'>|</span> <span class='ident'>x</span> <span class='op'>==</span> <span class='number'>0</span>),
<span class='string'>"XorShiftRng.reseed called with an all zero seed."</span>);
<span class='self'>self</span>.<span class='ident'>x</span> <span class='op'>=</span> <span class='ident'>w</span>(<span class='ident'>seed</span>[<span class='number'>0</span>]);
<span class='self'>self</span>.<span class='ident'>y</span> <span class='op'>=</span> <span class='ident'>w</span>(<span class='ident'>seed</span>[<span class='number'>1</span>]);
<span class='self'>self</span>.<span class='ident'>z</span> <span class='op'>=</span> <span class='ident'>w</span>(<span class='ident'>seed</span>[<span class='number'>2</span>]);
<span class='self'>self</span>.<span class='ident'>w</span> <span class='op'>=</span> <span class='ident'>w</span>(<span class='ident'>seed</span>[<span class='number'>3</span>]);
}
<span class='doccomment'>/// Create a new XorShiftRng. This will panic if `seed` is entirely 0.</span>
<span class='kw'>fn</span> <span class='ident'>from_seed</span>(<span class='ident'>seed</span>: [<span class='ident'>u32</span>; <span class='number'>4</span>]) <span class='op'>-></span> <span class='ident'>XorShiftRng</span> {
<span class='macro'>assert</span><span class='macro'>!</span>(<span class='op'>!</span><span class='ident'>seed</span>.<span class='ident'>iter</span>().<span class='ident'>all</span>(<span class='op'>|</span><span class='kw-2'>&</span><span class='ident'>x</span><span class='op'>|</span> <span class='ident'>x</span> <span class='op'>==</span> <span class='number'>0</span>),
<span class='string'>"XorShiftRng::from_seed called with an all zero seed."</span>);
<span class='ident'>XorShiftRng</span> {
<span class='ident'>x</span>: <span class='ident'>w</span>(<span class='ident'>seed</span>[<span class='number'>0</span>]),
<span class='ident'>y</span>: <span class='ident'>w</span>(<span class='ident'>seed</span>[<span class='number'>1</span>]),
<span class='ident'>z</span>: <span class='ident'>w</span>(<span class='ident'>seed</span>[<span class='number'>2</span>]),
<span class='ident'>w</span>: <span class='ident'>w</span>(<span class='ident'>seed</span>[<span class='number'>3</span>]),
}
}
}
<span class='kw'>impl</span> <span class='ident'>Rand</span> <span class='kw'>for</span> <span class='ident'>XorShiftRng</span> {
<span class='kw'>fn</span> <span class='ident'>rand</span><span class='op'><</span><span class='ident'>R</span>: <span class='ident'>Rng</span><span class='op'>></span>(<span class='ident'>rng</span>: <span class='kw-2'>&</span><span class='kw-2'>mut</span> <span class='ident'>R</span>) <span class='op'>-></span> <span class='ident'>XorShiftRng</span> {
<span class='kw'>let</span> <span class='kw-2'>mut</span> <span class='ident'>tuple</span>: (<span class='ident'>u32</span>, <span class='ident'>u32</span>, <span class='ident'>u32</span>, <span class='ident'>u32</span>) <span class='op'>=</span> <span class='ident'>rng</span>.<span class='ident'>gen</span>();
<span class='kw'>while</span> <span class='ident'>tuple</span> <span class='op'>==</span> (<span class='number'>0</span>, <span class='number'>0</span>, <span class='number'>0</span>, <span class='number'>0</span>) {
<span class='ident'>tuple</span> <span class='op'>=</span> <span class='ident'>rng</span>.<span class='ident'>gen</span>();
}
<span class='kw'>let</span> (<span class='ident'>x</span>, <span class='ident'>y</span>, <span class='ident'>z</span>, <span class='ident'>w_</span>) <span class='op'>=</span> <span class='ident'>tuple</span>;
<span class='ident'>XorShiftRng</span> { <span class='ident'>x</span>: <span class='ident'>w</span>(<span class='ident'>x</span>), <span class='ident'>y</span>: <span class='ident'>w</span>(<span class='ident'>y</span>), <span class='ident'>z</span>: <span class='ident'>w</span>(<span class='ident'>z</span>), <span class='ident'>w</span>: <span class='ident'>w</span>(<span class='ident'>w_</span>) }
}
}
<span class='doccomment'>/// A wrapper for generating floating point numbers uniformly in the</span>
<span class='doccomment'>/// open interval `(0,1)` (not including either endpoint).</span>
<span class='doccomment'>///</span>
<span class='doccomment'>/// Use `Closed01` for the closed interval `[0,1]`, and the default</span>
<span class='doccomment'>/// `Rand` implementation for `f32` and `f64` for the half-open</span>
<span class='doccomment'>/// `[0,1)`.</span>
<span class='doccomment'>///</span>
<span class='doccomment'>/// # Example</span>
<span class='doccomment'>/// ```rust</span>
<span class='doccomment'>/// use rand::{random, Open01};</span>
<span class='doccomment'>///</span>
<span class='doccomment'>/// let Open01(val) = random::<Open01<f32>>();</span>
<span class='doccomment'>/// println!("f32 from (0,1): {}", val);</span>
<span class='doccomment'>/// ```</span>
<span class='kw'>pub</span> <span class='kw'>struct</span> <span class='ident'>Open01</span><span class='op'><</span><span class='ident'>F</span><span class='op'>></span>(<span class='kw'>pub</span> <span class='ident'>F</span>);
<span class='doccomment'>/// A wrapper for generating floating point numbers uniformly in the</span>
<span class='doccomment'>/// closed interval `[0,1]` (including both endpoints).</span>
<span class='doccomment'>///</span>
<span class='doccomment'>/// Use `Open01` for the closed interval `(0,1)`, and the default</span>
<span class='doccomment'>/// `Rand` implementation of `f32` and `f64` for the half-open</span>
<span class='doccomment'>/// `[0,1)`.</span>
<span class='doccomment'>///</span>
<span class='doccomment'>/// # Example</span>
<span class='doccomment'>///</span>
<span class='doccomment'>/// ```rust</span>
<span class='doccomment'>/// use rand::{random, Closed01};</span>
<span class='doccomment'>///</span>
<span class='doccomment'>/// let Closed01(val) = random::<Closed01<f32>>();</span>
<span class='doccomment'>/// println!("f32 from [0,1]: {}", val);</span>
<span class='doccomment'>/// ```</span>
<span class='kw'>pub</span> <span class='kw'>struct</span> <span class='ident'>Closed01</span><span class='op'><</span><span class='ident'>F</span><span class='op'>></span>(<span class='kw'>pub</span> <span class='ident'>F</span>);
<span class='doccomment'>/// The standard RNG. This is designed to be efficient on the current</span>
<span class='doccomment'>/// platform.</span>
<span class='attribute'>#[<span class='ident'>derive</span>(<span class='ident'>Copy</span>, <span class='ident'>Clone</span>)]</span>
<span class='kw'>pub</span> <span class='kw'>struct</span> <span class='ident'>StdRng</span> {
<span class='ident'>rng</span>: <span class='ident'>IsaacWordRng</span>,
}
<span class='kw'>impl</span> <span class='ident'>StdRng</span> {
<span class='doccomment'>/// Create a randomly seeded instance of `StdRng`.</span>
<span class='doccomment'>///</span>
<span class='doccomment'>/// This is a very expensive operation as it has to read</span>
<span class='doccomment'>/// randomness from the operating system and use this in an</span>
<span class='doccomment'>/// expensive seeding operation. If one is only generating a small</span>
<span class='doccomment'>/// number of random numbers, or doesn't need the utmost speed for</span>
<span class='doccomment'>/// generating each number, `thread_rng` and/or `random` may be more</span>
<span class='doccomment'>/// appropriate.</span>
<span class='doccomment'>///</span>
<span class='doccomment'>/// Reading the randomness from the OS may fail, and any error is</span>
<span class='doccomment'>/// propagated via the `io::Result` return value.</span>
<span class='kw'>pub</span> <span class='kw'>fn</span> <span class='ident'>new</span>() <span class='op'>-></span> <span class='ident'>io</span>::<span class='prelude-ty'>Result</span><span class='op'><</span><span class='ident'>StdRng</span><span class='op'>></span> {
<span class='ident'>OsRng</span>::<span class='ident'>new</span>().<span class='ident'>map</span>(<span class='op'>|</span><span class='kw-2'>mut</span> <span class='ident'>r</span><span class='op'>|</span> <span class='ident'>StdRng</span> { <span class='ident'>rng</span>: <span class='ident'>r</span>.<span class='ident'>gen</span>() })
}
}
<span class='kw'>impl</span> <span class='ident'>Rng</span> <span class='kw'>for</span> <span class='ident'>StdRng</span> {
<span class='attribute'>#[<span class='ident'>inline</span>]</span>
<span class='kw'>fn</span> <span class='ident'>next_u32</span>(<span class='kw-2'>&</span><span class='kw-2'>mut</span> <span class='self'>self</span>) <span class='op'>-></span> <span class='ident'>u32</span> {
<span class='self'>self</span>.<span class='ident'>rng</span>.<span class='ident'>next_u32</span>()
}
<span class='attribute'>#[<span class='ident'>inline</span>]</span>
<span class='kw'>fn</span> <span class='ident'>next_u64</span>(<span class='kw-2'>&</span><span class='kw-2'>mut</span> <span class='self'>self</span>) <span class='op'>-></span> <span class='ident'>u64</span> {
<span class='self'>self</span>.<span class='ident'>rng</span>.<span class='ident'>next_u64</span>()
}
}
<span class='kw'>impl</span><span class='op'><</span><span class='lifetime'>'a</span><span class='op'>></span> <span class='ident'>SeedableRng</span><span class='op'><</span><span class='kw-2'>&</span><span class='lifetime'>'a</span> [<span class='ident'>usize</span>]<span class='op'>></span> <span class='kw'>for</span> <span class='ident'>StdRng</span> {
<span class='kw'>fn</span> <span class='ident'>reseed</span>(<span class='kw-2'>&</span><span class='kw-2'>mut</span> <span class='self'>self</span>, <span class='ident'>seed</span>: <span class='kw-2'>&</span><span class='lifetime'>'a</span> [<span class='ident'>usize</span>]) {
<span class='comment'>// the internal RNG can just be seeded from the above</span>
<span class='comment'>// randomness.</span>
<span class='self'>self</span>.<span class='ident'>rng</span>.<span class='ident'>reseed</span>(<span class='kw'>unsafe</span> {<span class='ident'>mem</span>::<span class='ident'>transmute</span>(<span class='ident'>seed</span>)})
}
<span class='kw'>fn</span> <span class='ident'>from_seed</span>(<span class='ident'>seed</span>: <span class='kw-2'>&</span><span class='lifetime'>'a</span> [<span class='ident'>usize</span>]) <span class='op'>-></span> <span class='ident'>StdRng</span> {
<span class='ident'>StdRng</span> { <span class='ident'>rng</span>: <span class='ident'>SeedableRng</span>::<span class='ident'>from_seed</span>(<span class='kw'>unsafe</span> {<span class='ident'>mem</span>::<span class='ident'>transmute</span>(<span class='ident'>seed</span>)}) }
}
}
<span class='doccomment'>/// Create a weak random number generator with a default algorithm and seed.</span>
<span class='doccomment'>///</span>
<span class='doccomment'>/// It returns the fastest `Rng` algorithm currently available in Rust without</span>
<span class='doccomment'>/// consideration for cryptography or security. If you require a specifically</span>
<span class='doccomment'>/// seeded `Rng` for consistency over time you should pick one algorithm and</span>
<span class='doccomment'>/// create the `Rng` yourself.</span>
<span class='doccomment'>///</span>
<span class='doccomment'>/// This will read randomness from the operating system to seed the</span>
<span class='doccomment'>/// generator.</span>
<span class='kw'>pub</span> <span class='kw'>fn</span> <span class='ident'>weak_rng</span>() <span class='op'>-></span> <span class='ident'>XorShiftRng</span> {
<span class='kw'>match</span> <span class='ident'>OsRng</span>::<span class='ident'>new</span>() {
<span class='prelude-val'>Ok</span>(<span class='kw-2'>mut</span> <span class='ident'>r</span>) <span class='op'>=></span> <span class='ident'>r</span>.<span class='ident'>gen</span>(),
<span class='prelude-val'>Err</span>(<span class='ident'>e</span>) <span class='op'>=></span> <span class='macro'>panic</span><span class='macro'>!</span>(<span class='string'>"weak_rng: failed to create seeded RNG: {:?}"</span>, <span class='ident'>e</span>)
}
}
<span class='doccomment'>/// Controls how the thread-local RNG is reseeded.</span>
<span class='kw'>struct</span> <span class='ident'>ThreadRngReseeder</span>;
<span class='kw'>impl</span> <span class='ident'>reseeding</span>::<span class='ident'>Reseeder</span><span class='op'><</span><span class='ident'>StdRng</span><span class='op'>></span> <span class='kw'>for</span> <span class='ident'>ThreadRngReseeder</span> {
<span class='kw'>fn</span> <span class='ident'>reseed</span>(<span class='kw-2'>&</span><span class='kw-2'>mut</span> <span class='self'>self</span>, <span class='ident'>rng</span>: <span class='kw-2'>&</span><span class='kw-2'>mut</span> <span class='ident'>StdRng</span>) {
<span class='kw-2'>*</span><span class='ident'>rng</span> <span class='op'>=</span> <span class='kw'>match</span> <span class='ident'>StdRng</span>::<span class='ident'>new</span>() {
<span class='prelude-val'>Ok</span>(<span class='ident'>r</span>) <span class='op'>=></span> <span class='ident'>r</span>,
<span class='prelude-val'>Err</span>(<span class='ident'>e</span>) <span class='op'>=></span> <span class='macro'>panic</span><span class='macro'>!</span>(<span class='string'>"could not reseed thread_rng: {}"</span>, <span class='ident'>e</span>)
}
}
}
<span class='kw'>const</span> <span class='ident'>THREAD_RNG_RESEED_THRESHOLD</span>: <span class='ident'>u64</span> <span class='op'>=</span> <span class='number'>32_768</span>;
<span class='kw'>type</span> <span class='ident'>ThreadRngInner</span> <span class='op'>=</span> <span class='ident'>reseeding</span>::<span class='ident'>ReseedingRng</span><span class='op'><</span><span class='ident'>StdRng</span>, <span class='ident'>ThreadRngReseeder</span><span class='op'>></span>;
<span class='doccomment'>/// The thread-local RNG.</span>
<span class='attribute'>#[<span class='ident'>derive</span>(<span class='ident'>Clone</span>)]</span>
<span class='kw'>pub</span> <span class='kw'>struct</span> <span class='ident'>ThreadRng</span> {
<span class='ident'>rng</span>: <span class='ident'>Rc</span><span class='op'><</span><span class='ident'>RefCell</span><span class='op'><</span><span class='ident'>ThreadRngInner</span><span class='op'>>></span>,
}
<span class='doccomment'>/// Retrieve the lazily-initialized thread-local random number</span>
<span class='doccomment'>/// generator, seeded by the system. Intended to be used in method</span>
<span class='doccomment'>/// chaining style, e.g. `thread_rng().gen::<i32>()`.</span>
<span class='doccomment'>///</span>
<span class='doccomment'>/// The RNG provided will reseed itself from the operating system</span>
<span class='doccomment'>/// after generating a certain amount of randomness.</span>
<span class='doccomment'>///</span>
<span class='doccomment'>/// The internal RNG used is platform and architecture dependent, even</span>
<span class='doccomment'>/// if the operating system random number generator is rigged to give</span>
<span class='doccomment'>/// the same sequence always. If absolute consistency is required,</span>
<span class='doccomment'>/// explicitly select an RNG, e.g. `IsaacRng` or `Isaac64Rng`.</span>
<span class='kw'>pub</span> <span class='kw'>fn</span> <span class='ident'>thread_rng</span>() <span class='op'>-></span> <span class='ident'>ThreadRng</span> {
<span class='comment'>// used to make space in TLS for a random number generator</span>
<span class='macro'>thread_local</span><span class='macro'>!</span>(<span class='kw'>static</span> <span class='ident'>THREAD_RNG_KEY</span>: <span class='ident'>Rc</span><span class='op'><</span><span class='ident'>RefCell</span><span class='op'><</span><span class='ident'>ThreadRngInner</span><span class='op'>>></span> <span class='op'>=</span> {
<span class='kw'>let</span> <span class='ident'>r</span> <span class='op'>=</span> <span class='kw'>match</span> <span class='ident'>StdRng</span>::<span class='ident'>new</span>() {
<span class='prelude-val'>Ok</span>(<span class='ident'>r</span>) <span class='op'>=></span> <span class='ident'>r</span>,
<span class='prelude-val'>Err</span>(<span class='ident'>e</span>) <span class='op'>=></span> <span class='macro'>panic</span><span class='macro'>!</span>(<span class='string'>"could not initialize thread_rng: {}"</span>, <span class='ident'>e</span>)
};
<span class='kw'>let</span> <span class='ident'>rng</span> <span class='op'>=</span> <span class='ident'>reseeding</span>::<span class='ident'>ReseedingRng</span>::<span class='ident'>new</span>(<span class='ident'>r</span>,
<span class='ident'>THREAD_RNG_RESEED_THRESHOLD</span>,
<span class='ident'>ThreadRngReseeder</span>);
<span class='ident'>Rc</span>::<span class='ident'>new</span>(<span class='ident'>RefCell</span>::<span class='ident'>new</span>(<span class='ident'>rng</span>))
});
<span class='ident'>ThreadRng</span> { <span class='ident'>rng</span>: <span class='ident'>THREAD_RNG_KEY</span>.<span class='ident'>with</span>(<span class='op'>|</span><span class='ident'>t</span><span class='op'>|</span> <span class='ident'>t</span>.<span class='ident'>clone</span>()) }
}
<span class='kw'>impl</span> <span class='ident'>Rng</span> <span class='kw'>for</span> <span class='ident'>ThreadRng</span> {
<span class='kw'>fn</span> <span class='ident'>next_u32</span>(<span class='kw-2'>&</span><span class='kw-2'>mut</span> <span class='self'>self</span>) <span class='op'>-></span> <span class='ident'>u32</span> {
<span class='self'>self</span>.<span class='ident'>rng</span>.<span class='ident'>borrow_mut</span>().<span class='ident'>next_u32</span>()
}
<span class='kw'>fn</span> <span class='ident'>next_u64</span>(<span class='kw-2'>&</span><span class='kw-2'>mut</span> <span class='self'>self</span>) <span class='op'>-></span> <span class='ident'>u64</span> {
<span class='self'>self</span>.<span class='ident'>rng</span>.<span class='ident'>borrow_mut</span>().<span class='ident'>next_u64</span>()
}
<span class='attribute'>#[<span class='ident'>inline</span>]</span>
<span class='kw'>fn</span> <span class='ident'>fill_bytes</span>(<span class='kw-2'>&</span><span class='kw-2'>mut</span> <span class='self'>self</span>, <span class='ident'>bytes</span>: <span class='kw-2'>&</span><span class='kw-2'>mut</span> [<span class='ident'>u8</span>]) {
<span class='self'>self</span>.<span class='ident'>rng</span>.<span class='ident'>borrow_mut</span>().<span class='ident'>fill_bytes</span>(<span class='ident'>bytes</span>)
}
}
<span class='doccomment'>/// Generates a random value using the thread-local random number generator.</span>
<span class='doccomment'>///</span>
<span class='doccomment'>/// `random()` can generate various types of random things, and so may require</span>
<span class='doccomment'>/// type hinting to generate the specific type you want.</span>
<span class='doccomment'>///</span>
<span class='doccomment'>/// This function uses the thread local random number generator. This means</span>
<span class='doccomment'>/// that if you're calling `random()` in a loop, caching the generator can</span>
<span class='doccomment'>/// increase performance. An example is shown below.</span>
<span class='doccomment'>///</span>
<span class='doccomment'>/// # Examples</span>
<span class='doccomment'>///</span>
<span class='doccomment'>/// ```</span>
<span class='doccomment'>/// let x = rand::random::<u8>();</span>
<span class='doccomment'>/// println!("{}", x);</span>
<span class='doccomment'>///</span>
<span class='doccomment'>/// let y = rand::random::<f64>();</span>
<span class='doccomment'>/// println!("{}", y);</span>
<span class='doccomment'>///</span>
<span class='doccomment'>/// if rand::random() { // generates a boolean</span>
<span class='doccomment'>/// println!("Better lucky than good!");</span>
<span class='doccomment'>/// }</span>
<span class='doccomment'>/// ```</span>
<span class='doccomment'>///</span>
<span class='doccomment'>/// Caching the thread local random number generator:</span>
<span class='doccomment'>///</span>
<span class='doccomment'>/// ```</span>
<span class='doccomment'>/// use rand::Rng;</span>
<span class='doccomment'>///</span>
<span class='doccomment'>/// let mut v = vec![1, 2, 3];</span>
<span class='doccomment'>///</span>
<span class='doccomment'>/// for x in v.iter_mut() {</span>
<span class='doccomment'>/// *x = rand::random()</span>
<span class='doccomment'>/// }</span>
<span class='doccomment'>///</span>
<span class='doccomment'>/// // would be faster as</span>
<span class='doccomment'>///</span>
<span class='doccomment'>/// let mut rng = rand::thread_rng();</span>
<span class='doccomment'>///</span>
<span class='doccomment'>/// for x in v.iter_mut() {</span>
<span class='doccomment'>/// *x = rng.gen();</span>
<span class='doccomment'>/// }</span>
<span class='doccomment'>/// ```</span>
<span class='attribute'>#[<span class='ident'>inline</span>]</span>
<span class='kw'>pub</span> <span class='kw'>fn</span> <span class='ident'>random</span><span class='op'><</span><span class='ident'>T</span>: <span class='ident'>Rand</span><span class='op'>></span>() <span class='op'>-></span> <span class='ident'>T</span> {
<span class='ident'>thread_rng</span>().<span class='ident'>gen</span>()
}
<span class='doccomment'>/// Randomly sample up to `amount` elements from an iterator.</span>
<span class='doccomment'>///</span>
<span class='doccomment'>/// # Example</span>
<span class='doccomment'>///</span>
<span class='doccomment'>/// ```rust</span>
<span class='doccomment'>/// use rand::{thread_rng, sample};</span>
<span class='doccomment'>///</span>
<span class='doccomment'>/// let mut rng = thread_rng();</span>
<span class='doccomment'>/// let sample = sample(&mut rng, 1..100, 5);</span>
<span class='doccomment'>/// println!("{:?}", sample);</span>
<span class='doccomment'>/// ```</span>
<span class='kw'>pub</span> <span class='kw'>fn</span> <span class='ident'>sample</span><span class='op'><</span><span class='ident'>T</span>, <span class='ident'>I</span>, <span class='ident'>R</span><span class='op'>></span>(<span class='ident'>rng</span>: <span class='kw-2'>&</span><span class='kw-2'>mut</span> <span class='ident'>R</span>, <span class='ident'>iterable</span>: <span class='ident'>I</span>, <span class='ident'>amount</span>: <span class='ident'>usize</span>) <span class='op'>-></span> <span class='ident'>Vec</span><span class='op'><</span><span class='ident'>T</span><span class='op'>></span>
<span class='kw'>where</span> <span class='ident'>I</span>: <span class='ident'>IntoIterator</span><span class='op'><</span><span class='ident'>Item</span><span class='op'>=</span><span class='ident'>T</span><span class='op'>></span>,
<span class='ident'>R</span>: <span class='ident'>Rng</span>,
{
<span class='kw'>let</span> <span class='kw-2'>mut</span> <span class='ident'>iter</span> <span class='op'>=</span> <span class='ident'>iterable</span>.<span class='ident'>into_iter</span>();
<span class='kw'>let</span> <span class='kw-2'>mut</span> <span class='ident'>reservoir</span>: <span class='ident'>Vec</span><span class='op'><</span><span class='ident'>T</span><span class='op'>></span> <span class='op'>=</span> <span class='ident'>iter</span>.<span class='ident'>by_ref</span>().<span class='ident'>take</span>(<span class='ident'>amount</span>).<span class='ident'>collect</span>();
<span class='comment'>// continue unless the iterator was exhausted</span>
<span class='kw'>if</span> <span class='ident'>reservoir</span>.<span class='ident'>len</span>() <span class='op'>==</span> <span class='ident'>amount</span> {
<span class='kw'>for</span> (<span class='ident'>i</span>, <span class='ident'>elem</span>) <span class='kw'>in</span> <span class='ident'>iter</span>.<span class='ident'>enumerate</span>() {
<span class='kw'>let</span> <span class='ident'>k</span> <span class='op'>=</span> <span class='ident'>rng</span>.<span class='ident'>gen_range</span>(<span class='number'>0</span>, <span class='ident'>i</span> <span class='op'>+</span> <span class='number'>1</span> <span class='op'>+</span> <span class='ident'>amount</span>);
<span class='kw'>if</span> <span class='kw'>let</span> <span class='prelude-val'>Some</span>(<span class='ident'>spot</span>) <span class='op'>=</span> <span class='ident'>reservoir</span>.<span class='ident'>get_mut</span>(<span class='ident'>k</span>) {
<span class='kw-2'>*</span><span class='ident'>spot</span> <span class='op'>=</span> <span class='ident'>elem</span>;
}
}
}
<span class='ident'>reservoir</span>
}
<span class='attribute'>#[<span class='ident'>cfg</span>(<span class='ident'>test</span>)]</span>
<span class='kw'>mod</span> <span class='ident'>test</span> {
<span class='kw'>use</span> <span class='kw'>super</span>::{<span class='ident'>Rng</span>, <span class='ident'>thread_rng</span>, <span class='ident'>random</span>, <span class='ident'>SeedableRng</span>, <span class='ident'>StdRng</span>, <span class='ident'>sample</span>};
<span class='kw'>use</span> <span class='ident'>std</span>::<span class='ident'>iter</span>::<span class='ident'>repeat</span>;
<span class='kw'>pub</span> <span class='kw'>struct</span> <span class='ident'>MyRng</span><span class='op'><</span><span class='ident'>R</span><span class='op'>></span> { <span class='ident'>inner</span>: <span class='ident'>R</span> }
<span class='kw'>impl</span><span class='op'><</span><span class='ident'>R</span>: <span class='ident'>Rng</span><span class='op'>></span> <span class='ident'>Rng</span> <span class='kw'>for</span> <span class='ident'>MyRng</span><span class='op'><</span><span class='ident'>R</span><span class='op'>></span> {
<span class='kw'>fn</span> <span class='ident'>next_u32</span>(<span class='kw-2'>&</span><span class='kw-2'>mut</span> <span class='self'>self</span>) <span class='op'>-></span> <span class='ident'>u32</span> {
<span class='kw'>fn</span> <span class='ident'>next</span><span class='op'><</span><span class='ident'>T</span>: <span class='ident'>Rng</span><span class='op'>></span>(<span class='ident'>t</span>: <span class='kw-2'>&</span><span class='kw-2'>mut</span> <span class='ident'>T</span>) <span class='op'>-></span> <span class='ident'>u32</span> {
<span class='ident'>t</span>.<span class='ident'>next_u32</span>()
}
<span class='ident'>next</span>(<span class='kw-2'>&</span><span class='kw-2'>mut</span> <span class='self'>self</span>.<span class='ident'>inner</span>)
}
}
<span class='kw'>pub</span> <span class='kw'>fn</span> <span class='ident'>rng</span>() <span class='op'>-></span> <span class='ident'>MyRng</span><span class='op'><</span>::<span class='ident'>ThreadRng</span><span class='op'>></span> {
<span class='ident'>MyRng</span> { <span class='ident'>inner</span>: ::<span class='ident'>thread_rng</span>() }
}
<span class='kw'>struct</span> <span class='ident'>ConstRng</span> { <span class='ident'>i</span>: <span class='ident'>u64</span> }
<span class='kw'>impl</span> <span class='ident'>Rng</span> <span class='kw'>for</span> <span class='ident'>ConstRng</span> {
<span class='kw'>fn</span> <span class='ident'>next_u32</span>(<span class='kw-2'>&</span><span class='kw-2'>mut</span> <span class='self'>self</span>) <span class='op'>-></span> <span class='ident'>u32</span> { <span class='self'>self</span>.<span class='ident'>i</span> <span class='kw'>as</span> <span class='ident'>u32</span> }
<span class='kw'>fn</span> <span class='ident'>next_u64</span>(<span class='kw-2'>&</span><span class='kw-2'>mut</span> <span class='self'>self</span>) <span class='op'>-></span> <span class='ident'>u64</span> { <span class='self'>self</span>.<span class='ident'>i</span> }
<span class='comment'>// no fill_bytes on purpose</span>
}
<span class='kw'>pub</span> <span class='kw'>fn</span> <span class='ident'>iter_eq</span><span class='op'><</span><span class='ident'>I</span>, <span class='ident'>J</span><span class='op'>></span>(<span class='ident'>i</span>: <span class='ident'>I</span>, <span class='ident'>j</span>: <span class='ident'>J</span>) <span class='op'>-></span> <span class='ident'>bool</span>
<span class='kw'>where</span> <span class='ident'>I</span>: <span class='ident'>IntoIterator</span>,
<span class='ident'>J</span>: <span class='ident'>IntoIterator</span><span class='op'><</span><span class='ident'>Item</span><span class='op'>=</span><span class='ident'>I</span>::<span class='ident'>Item</span><span class='op'>></span>,
<span class='ident'>I</span>::<span class='ident'>Item</span>: <span class='ident'>Eq</span>
{
<span class='comment'>// make sure the iterators have equal length</span>
<span class='kw'>let</span> <span class='kw-2'>mut</span> <span class='ident'>i</span> <span class='op'>=</span> <span class='ident'>i</span>.<span class='ident'>into_iter</span>();
<span class='kw'>let</span> <span class='kw-2'>mut</span> <span class='ident'>j</span> <span class='op'>=</span> <span class='ident'>j</span>.<span class='ident'>into_iter</span>();
<span class='kw'>loop</span> {
<span class='kw'>match</span> (<span class='ident'>i</span>.<span class='ident'>next</span>(), <span class='ident'>j</span>.<span class='ident'>next</span>()) {
(<span class='prelude-val'>Some</span>(<span class='kw-2'>ref</span> <span class='ident'>ei</span>), <span class='prelude-val'>Some</span>(<span class='kw-2'>ref</span> <span class='ident'>ej</span>)) <span class='kw'>if</span> <span class='ident'>ei</span> <span class='op'>==</span> <span class='ident'>ej</span> <span class='op'>=></span> { }
(<span class='prelude-val'>None</span>, <span class='prelude-val'>None</span>) <span class='op'>=></span> <span class='kw'>return</span> <span class='bool-val'>true</span>,
_ <span class='op'>=></span> <span class='kw'>return</span> <span class='bool-val'>false</span>,
}
}
}
<span class='attribute'>#[<span class='ident'>test</span>]</span>
<span class='kw'>fn</span> <span class='ident'>test_fill_bytes_default</span>() {
<span class='kw'>let</span> <span class='kw-2'>mut</span> <span class='ident'>r</span> <span class='op'>=</span> <span class='ident'>ConstRng</span> { <span class='ident'>i</span>: <span class='number'>0x11_22_33_44_55_66_77_88</span> };
<span class='comment'>// check every remainder mod 8, both in small and big vectors.</span>
<span class='kw'>let</span> <span class='ident'>lengths</span> <span class='op'>=</span> [<span class='number'>0</span>, <span class='number'>1</span>, <span class='number'>2</span>, <span class='number'>3</span>, <span class='number'>4</span>, <span class='number'>5</span>, <span class='number'>6</span>, <span class='number'>7</span>,
<span class='number'>80</span>, <span class='number'>81</span>, <span class='number'>82</span>, <span class='number'>83</span>, <span class='number'>84</span>, <span class='number'>85</span>, <span class='number'>86</span>, <span class='number'>87</span>];
<span class='kw'>for</span> <span class='kw-2'>&</span><span class='ident'>n</span> <span class='kw'>in</span> <span class='ident'>lengths</span>.<span class='ident'>iter</span>() {
<span class='kw'>let</span> <span class='kw-2'>mut</span> <span class='ident'>v</span> <span class='op'>=</span> <span class='ident'>repeat</span>(<span class='number'>0u8</span>).<span class='ident'>take</span>(<span class='ident'>n</span>).<span class='ident'>collect</span>::<span class='op'><</span><span class='ident'>Vec</span><span class='op'><</span>_<span class='op'>>></span>();
<span class='ident'>r</span>.<span class='ident'>fill_bytes</span>(<span class='kw-2'>&</span><span class='kw-2'>mut</span> <span class='ident'>v</span>);
<span class='comment'>// use this to get nicer error messages.</span>
<span class='kw'>for</span> (<span class='ident'>i</span>, <span class='kw-2'>&</span><span class='ident'>byte</span>) <span class='kw'>in</span> <span class='ident'>v</span>.<span class='ident'>iter</span>().<span class='ident'>enumerate</span>() {
<span class='kw'>if</span> <span class='ident'>byte</span> <span class='op'>==</span> <span class='number'>0</span> {
<span class='macro'>panic</span><span class='macro'>!</span>(<span class='string'>"byte {} of {} is zero"</span>, <span class='ident'>i</span>, <span class='ident'>n</span>)
}
}
}
}
<span class='attribute'>#[<span class='ident'>test</span>]</span>
<span class='kw'>fn</span> <span class='ident'>test_gen_range</span>() {
<span class='kw'>let</span> <span class='kw-2'>mut</span> <span class='ident'>r</span> <span class='op'>=</span> <span class='ident'>thread_rng</span>();
<span class='kw'>for</span> _ <span class='kw'>in</span> <span class='number'>0</span>..<span class='number'>1000</span> {
<span class='kw'>let</span> <span class='ident'>a</span> <span class='op'>=</span> <span class='ident'>r</span>.<span class='ident'>gen_range</span>(<span class='op'>-</span><span class='number'>3</span>, <span class='number'>42</span>);
<span class='macro'>assert</span><span class='macro'>!</span>(<span class='ident'>a</span> <span class='op'>>=</span> <span class='op'>-</span><span class='number'>3</span> <span class='op'>&&</span> <span class='ident'>a</span> <span class='op'><</span> <span class='number'>42</span>);
<span class='macro'>assert_eq</span><span class='macro'>!</span>(<span class='ident'>r</span>.<span class='ident'>gen_range</span>(<span class='number'>0</span>, <span class='number'>1</span>), <span class='number'>0</span>);
<span class='macro'>assert_eq</span><span class='macro'>!</span>(<span class='ident'>r</span>.<span class='ident'>gen_range</span>(<span class='op'>-</span><span class='number'>12</span>, <span class='op'>-</span><span class='number'>11</span>), <span class='op'>-</span><span class='number'>12</span>);
}
<span class='kw'>for</span> _ <span class='kw'>in</span> <span class='number'>0</span>..<span class='number'>1000</span> {
<span class='kw'>let</span> <span class='ident'>a</span> <span class='op'>=</span> <span class='ident'>r</span>.<span class='ident'>gen_range</span>(<span class='number'>10</span>, <span class='number'>42</span>);
<span class='macro'>assert</span><span class='macro'>!</span>(<span class='ident'>a</span> <span class='op'>>=</span> <span class='number'>10</span> <span class='op'>&&</span> <span class='ident'>a</span> <span class='op'><</span> <span class='number'>42</span>);
<span class='macro'>assert_eq</span><span class='macro'>!</span>(<span class='ident'>r</span>.<span class='ident'>gen_range</span>(<span class='number'>0</span>, <span class='number'>1</span>), <span class='number'>0</span>);
<span class='macro'>assert_eq</span><span class='macro'>!</span>(<span class='ident'>r</span>.<span class='ident'>gen_range</span>(<span class='number'>3_000_000</span>, <span class='number'>3_000_001</span>), <span class='number'>3_000_000</span>);
}
}
<span class='attribute'>#[<span class='ident'>test</span>]</span>
<span class='attribute'>#[<span class='ident'>should_panic</span>]</span>
<span class='kw'>fn</span> <span class='ident'>test_gen_range_panic_int</span>() {
<span class='kw'>let</span> <span class='kw-2'>mut</span> <span class='ident'>r</span> <span class='op'>=</span> <span class='ident'>thread_rng</span>();
<span class='ident'>r</span>.<span class='ident'>gen_range</span>(<span class='number'>5</span>, <span class='op'>-</span><span class='number'>2</span>);
}
<span class='attribute'>#[<span class='ident'>test</span>]</span>
<span class='attribute'>#[<span class='ident'>should_panic</span>]</span>
<span class='kw'>fn</span> <span class='ident'>test_gen_range_panic_usize</span>() {
<span class='kw'>let</span> <span class='kw-2'>mut</span> <span class='ident'>r</span> <span class='op'>=</span> <span class='ident'>thread_rng</span>();
<span class='ident'>r</span>.<span class='ident'>gen_range</span>(<span class='number'>5</span>, <span class='number'>2</span>);
}
<span class='attribute'>#[<span class='ident'>test</span>]</span>
<span class='kw'>fn</span> <span class='ident'>test_gen_f64</span>() {
<span class='kw'>let</span> <span class='kw-2'>mut</span> <span class='ident'>r</span> <span class='op'>=</span> <span class='ident'>thread_rng</span>();
<span class='kw'>let</span> <span class='ident'>a</span> <span class='op'>=</span> <span class='ident'>r</span>.<span class='ident'>gen</span>::<span class='op'><</span><span class='ident'>f64</span><span class='op'>></span>();
<span class='kw'>let</span> <span class='ident'>b</span> <span class='op'>=</span> <span class='ident'>r</span>.<span class='ident'>gen</span>::<span class='op'><</span><span class='ident'>f64</span><span class='op'>></span>();
<span class='macro'>debug</span><span class='macro'>!</span>(<span class='string'>"{:?}"</span>, (<span class='ident'>a</span>, <span class='ident'>b</span>));
}
<span class='attribute'>#[<span class='ident'>test</span>]</span>
<span class='kw'>fn</span> <span class='ident'>test_gen_weighted_bool</span>() {
<span class='kw'>let</span> <span class='kw-2'>mut</span> <span class='ident'>r</span> <span class='op'>=</span> <span class='ident'>thread_rng</span>();
<span class='macro'>assert_eq</span><span class='macro'>!</span>(<span class='ident'>r</span>.<span class='ident'>gen_weighted_bool</span>(<span class='number'>0</span>), <span class='bool-val'>true</span>);
<span class='macro'>assert_eq</span><span class='macro'>!</span>(<span class='ident'>r</span>.<span class='ident'>gen_weighted_bool</span>(<span class='number'>1</span>), <span class='bool-val'>true</span>);
}
<span class='attribute'>#[<span class='ident'>test</span>]</span>
<span class='kw'>fn</span> <span class='ident'>test_gen_ascii_str</span>() {
<span class='kw'>let</span> <span class='kw-2'>mut</span> <span class='ident'>r</span> <span class='op'>=</span> <span class='ident'>thread_rng</span>();
<span class='macro'>assert_eq</span><span class='macro'>!</span>(<span class='ident'>r</span>.<span class='ident'>gen_ascii_chars</span>().<span class='ident'>take</span>(<span class='number'>0</span>).<span class='ident'>count</span>(), <span class='number'>0</span>);
<span class='macro'>assert_eq</span><span class='macro'>!</span>(<span class='ident'>r</span>.<span class='ident'>gen_ascii_chars</span>().<span class='ident'>take</span>(<span class='number'>10</span>).<span class='ident'>count</span>(), <span class='number'>10</span>);
<span class='macro'>assert_eq</span><span class='macro'>!</span>(<span class='ident'>r</span>.<span class='ident'>gen_ascii_chars</span>().<span class='ident'>take</span>(<span class='number'>16</span>).<span class='ident'>count</span>(), <span class='number'>16</span>);
}
<span class='attribute'>#[<span class='ident'>test</span>]</span>
<span class='kw'>fn</span> <span class='ident'>test_gen_vec</span>() {
<span class='kw'>let</span> <span class='kw-2'>mut</span> <span class='ident'>r</span> <span class='op'>=</span> <span class='ident'>thread_rng</span>();
<span class='macro'>assert_eq</span><span class='macro'>!</span>(<span class='ident'>r</span>.<span class='ident'>gen_iter</span>::<span class='op'><</span><span class='ident'>u8</span><span class='op'>></span>().<span class='ident'>take</span>(<span class='number'>0</span>).<span class='ident'>count</span>(), <span class='number'>0</span>);
<span class='macro'>assert_eq</span><span class='macro'>!</span>(<span class='ident'>r</span>.<span class='ident'>gen_iter</span>::<span class='op'><</span><span class='ident'>u8</span><span class='op'>></span>().<span class='ident'>take</span>(<span class='number'>10</span>).<span class='ident'>count</span>(), <span class='number'>10</span>);
<span class='macro'>assert_eq</span><span class='macro'>!</span>(<span class='ident'>r</span>.<span class='ident'>gen_iter</span>::<span class='op'><</span><span class='ident'>f64</span><span class='op'>></span>().<span class='ident'>take</span>(<span class='number'>16</span>).<span class='ident'>count</span>(), <span class='number'>16</span>);
}
<span class='attribute'>#[<span class='ident'>test</span>]</span>
<span class='kw'>fn</span> <span class='ident'>test_choose</span>() {
<span class='kw'>let</span> <span class='kw-2'>mut</span> <span class='ident'>r</span> <span class='op'>=</span> <span class='ident'>thread_rng</span>();
<span class='macro'>assert_eq</span><span class='macro'>!</span>(<span class='ident'>r</span>.<span class='ident'>choose</span>(<span class='kw-2'>&</span>[<span class='number'>1</span>, <span class='number'>1</span>, <span class='number'>1</span>]).<span class='ident'>map</span>(<span class='op'>|</span><span class='kw-2'>&</span><span class='ident'>x</span><span class='op'>|</span><span class='ident'>x</span>), <span class='prelude-val'>Some</span>(<span class='number'>1</span>));
<span class='kw'>let</span> <span class='ident'>v</span>: <span class='kw-2'>&</span>[<span class='ident'>isize</span>] <span class='op'>=</span> <span class='kw-2'>&</span>[];
<span class='macro'>assert_eq</span><span class='macro'>!</span>(<span class='ident'>r</span>.<span class='ident'>choose</span>(<span class='ident'>v</span>), <span class='prelude-val'>None</span>);
}
<span class='attribute'>#[<span class='ident'>test</span>]</span>
<span class='kw'>fn</span> <span class='ident'>test_shuffle</span>() {
<span class='kw'>let</span> <span class='kw-2'>mut</span> <span class='ident'>r</span> <span class='op'>=</span> <span class='ident'>thread_rng</span>();
<span class='kw'>let</span> <span class='ident'>empty</span>: <span class='kw-2'>&</span><span class='kw-2'>mut</span> [<span class='ident'>isize</span>] <span class='op'>=</span> <span class='kw-2'>&</span><span class='kw-2'>mut</span> [];
<span class='ident'>r</span>.<span class='ident'>shuffle</span>(<span class='ident'>empty</span>);
<span class='kw'>let</span> <span class='kw-2'>mut</span> <span class='ident'>one</span> <span class='op'>=</span> [<span class='number'>1</span>];
<span class='ident'>r</span>.<span class='ident'>shuffle</span>(<span class='kw-2'>&</span><span class='kw-2'>mut</span> <span class='ident'>one</span>);
<span class='kw'>let</span> <span class='ident'>b</span>: <span class='kw-2'>&</span>[_] <span class='op'>=</span> <span class='kw-2'>&</span>[<span class='number'>1</span>];
<span class='macro'>assert_eq</span><span class='macro'>!</span>(<span class='ident'>one</span>, <span class='ident'>b</span>);
<span class='kw'>let</span> <span class='kw-2'>mut</span> <span class='ident'>two</span> <span class='op'>=</span> [<span class='number'>1</span>, <span class='number'>2</span>];
<span class='ident'>r</span>.<span class='ident'>shuffle</span>(<span class='kw-2'>&</span><span class='kw-2'>mut</span> <span class='ident'>two</span>);
<span class='macro'>assert</span><span class='macro'>!</span>(<span class='ident'>two</span> <span class='op'>==</span> [<span class='number'>1</span>, <span class='number'>2</span>] <span class='op'>||</span> <span class='ident'>two</span> <span class='op'>==</span> [<span class='number'>2</span>, <span class='number'>1</span>]);
<span class='kw'>let</span> <span class='kw-2'>mut</span> <span class='ident'>x</span> <span class='op'>=</span> [<span class='number'>1</span>, <span class='number'>1</span>, <span class='number'>1</span>];
<span class='ident'>r</span>.<span class='ident'>shuffle</span>(<span class='kw-2'>&</span><span class='kw-2'>mut</span> <span class='ident'>x</span>);
<span class='kw'>let</span> <span class='ident'>b</span>: <span class='kw-2'>&</span>[_] <span class='op'>=</span> <span class='kw-2'>&</span>[<span class='number'>1</span>, <span class='number'>1</span>, <span class='number'>1</span>];
<span class='macro'>assert_eq</span><span class='macro'>!</span>(<span class='ident'>x</span>, <span class='ident'>b</span>);
}
<span class='attribute'>#[<span class='ident'>test</span>]</span>
<span class='kw'>fn</span> <span class='ident'>test_thread_rng</span>() {
<span class='kw'>let</span> <span class='kw-2'>mut</span> <span class='ident'>r</span> <span class='op'>=</span> <span class='ident'>thread_rng</span>();
<span class='ident'>r</span>.<span class='ident'>gen</span>::<span class='op'><</span><span class='ident'>i32</span><span class='op'>></span>();
<span class='kw'>let</span> <span class='kw-2'>mut</span> <span class='ident'>v</span> <span class='op'>=</span> [<span class='number'>1</span>, <span class='number'>1</span>, <span class='number'>1</span>];
<span class='ident'>r</span>.<span class='ident'>shuffle</span>(<span class='kw-2'>&</span><span class='kw-2'>mut</span> <span class='ident'>v</span>);
<span class='kw'>let</span> <span class='ident'>b</span>: <span class='kw-2'>&</span>[_] <span class='op'>=</span> <span class='kw-2'>&</span>[<span class='number'>1</span>, <span class='number'>1</span>, <span class='number'>1</span>];
<span class='macro'>assert_eq</span><span class='macro'>!</span>(<span class='ident'>v</span>, <span class='ident'>b</span>);
<span class='macro'>assert_eq</span><span class='macro'>!</span>(<span class='ident'>r</span>.<span class='ident'>gen_range</span>(<span class='number'>0</span>, <span class='number'>1</span>), <span class='number'>0</span>);
}
<span class='attribute'>#[<span class='ident'>test</span>]</span>
<span class='kw'>fn</span> <span class='ident'>test_rng_trait_object</span>() {
<span class='kw'>let</span> <span class='kw-2'>mut</span> <span class='ident'>rng</span> <span class='op'>=</span> <span class='ident'>thread_rng</span>();
{
<span class='kw'>let</span> <span class='kw-2'>mut</span> <span class='ident'>r</span> <span class='op'>=</span> <span class='kw-2'>&</span><span class='kw-2'>mut</span> <span class='ident'>rng</span> <span class='kw'>as</span> <span class='kw-2'>&</span><span class='kw-2'>mut</span> <span class='ident'>Rng</span>;
<span class='ident'>r</span>.<span class='ident'>next_u32</span>();
(<span class='kw-2'>&</span><span class='kw-2'>mut</span> <span class='ident'>r</span>).<span class='ident'>gen</span>::<span class='op'><</span><span class='ident'>i32</span><span class='op'>></span>();
<span class='kw'>let</span> <span class='kw-2'>mut</span> <span class='ident'>v</span> <span class='op'>=</span> [<span class='number'>1</span>, <span class='number'>1</span>, <span class='number'>1</span>];
(<span class='kw-2'>&</span><span class='kw-2'>mut</span> <span class='ident'>r</span>).<span class='ident'>shuffle</span>(<span class='kw-2'>&</span><span class='kw-2'>mut</span> <span class='ident'>v</span>);
<span class='kw'>let</span> <span class='ident'>b</span>: <span class='kw-2'>&</span>[_] <span class='op'>=</span> <span class='kw-2'>&</span>[<span class='number'>1</span>, <span class='number'>1</span>, <span class='number'>1</span>];
<span class='macro'>assert_eq</span><span class='macro'>!</span>(<span class='ident'>v</span>, <span class='ident'>b</span>);
<span class='macro'>assert_eq</span><span class='macro'>!</span>((<span class='kw-2'>&</span><span class='kw-2'>mut</span> <span class='ident'>r</span>).<span class='ident'>gen_range</span>(<span class='number'>0</span>, <span class='number'>1</span>), <span class='number'>0</span>);
}
{
<span class='kw'>let</span> <span class='kw-2'>mut</span> <span class='ident'>r</span> <span class='op'>=</span> <span class='ident'>Box</span>::<span class='ident'>new</span>(<span class='ident'>rng</span>) <span class='kw'>as</span> <span class='ident'>Box</span><span class='op'><</span><span class='ident'>Rng</span><span class='op'>></span>;
<span class='ident'>r</span>.<span class='ident'>next_u32</span>();
<span class='ident'>r</span>.<span class='ident'>gen</span>::<span class='op'><</span><span class='ident'>i32</span><span class='op'>></span>();
<span class='kw'>let</span> <span class='kw-2'>mut</span> <span class='ident'>v</span> <span class='op'>=</span> [<span class='number'>1</span>, <span class='number'>1</span>, <span class='number'>1</span>];
<span class='ident'>r</span>.<span class='ident'>shuffle</span>(<span class='kw-2'>&</span><span class='kw-2'>mut</span> <span class='ident'>v</span>);
<span class='kw'>let</span> <span class='ident'>b</span>: <span class='kw-2'>&</span>[_] <span class='op'>=</span> <span class='kw-2'>&</span>[<span class='number'>1</span>, <span class='number'>1</span>, <span class='number'>1</span>];
<span class='macro'>assert_eq</span><span class='macro'>!</span>(<span class='ident'>v</span>, <span class='ident'>b</span>);
<span class='macro'>assert_eq</span><span class='macro'>!</span>(<span class='ident'>r</span>.<span class='ident'>gen_range</span>(<span class='number'>0</span>, <span class='number'>1</span>), <span class='number'>0</span>);
}
}
<span class='attribute'>#[<span class='ident'>test</span>]</span>
<span class='kw'>fn</span> <span class='ident'>test_random</span>() {
<span class='comment'>// not sure how to test this aside from just getting some values</span>
<span class='kw'>let</span> <span class='ident'>_n</span> : <span class='ident'>usize</span> <span class='op'>=</span> <span class='ident'>random</span>();
<span class='kw'>let</span> <span class='ident'>_f</span> : <span class='ident'>f32</span> <span class='op'>=</span> <span class='ident'>random</span>();
<span class='kw'>let</span> <span class='ident'>_o</span> : <span class='prelude-ty'>Option</span><span class='op'><</span><span class='prelude-ty'>Option</span><span class='op'><</span><span class='ident'>i8</span><span class='op'>>></span> <span class='op'>=</span> <span class='ident'>random</span>();
<span class='kw'>let</span> <span class='ident'>_many</span> : ((),
(<span class='ident'>usize</span>,
<span class='ident'>isize</span>,
<span class='prelude-ty'>Option</span><span class='op'><</span>(<span class='ident'>u32</span>, (<span class='ident'>bool</span>,))<span class='op'>></span>),
(<span class='ident'>u8</span>, <span class='ident'>i8</span>, <span class='ident'>u16</span>, <span class='ident'>i16</span>, <span class='ident'>u32</span>, <span class='ident'>i32</span>, <span class='ident'>u64</span>, <span class='ident'>i64</span>),
(<span class='ident'>f32</span>, (<span class='ident'>f64</span>, (<span class='ident'>f64</span>,)))) <span class='op'>=</span> <span class='ident'>random</span>();
}
<span class='attribute'>#[<span class='ident'>test</span>]</span>
<span class='kw'>fn</span> <span class='ident'>test_sample</span>() {
<span class='kw'>let</span> <span class='ident'>min_val</span> <span class='op'>=</span> <span class='number'>1</span>;
<span class='kw'>let</span> <span class='ident'>max_val</span> <span class='op'>=</span> <span class='number'>100</span>;
<span class='kw'>let</span> <span class='kw-2'>mut</span> <span class='ident'>r</span> <span class='op'>=</span> <span class='ident'>thread_rng</span>();
<span class='kw'>let</span> <span class='ident'>vals</span> <span class='op'>=</span> (<span class='ident'>min_val</span>..<span class='ident'>max_val</span>).<span class='ident'>collect</span>::<span class='op'><</span><span class='ident'>Vec</span><span class='op'><</span><span class='ident'>i32</span><span class='op'>>></span>();
<span class='kw'>let</span> <span class='ident'>small_sample</span> <span class='op'>=</span> <span class='ident'>sample</span>(<span class='kw-2'>&</span><span class='kw-2'>mut</span> <span class='ident'>r</span>, <span class='ident'>vals</span>.<span class='ident'>iter</span>(), <span class='number'>5</span>);
<span class='kw'>let</span> <span class='ident'>large_sample</span> <span class='op'>=</span> <span class='ident'>sample</span>(<span class='kw-2'>&</span><span class='kw-2'>mut</span> <span class='ident'>r</span>, <span class='ident'>vals</span>.<span class='ident'>iter</span>(), <span class='ident'>vals</span>.<span class='ident'>len</span>() <span class='op'>+</span> <span class='number'>5</span>);
<span class='macro'>assert_eq</span><span class='macro'>!</span>(<span class='ident'>small_sample</span>.<span class='ident'>len</span>(), <span class='number'>5</span>);
<span class='macro'>assert_eq</span><span class='macro'>!</span>(<span class='ident'>large_sample</span>.<span class='ident'>len</span>(), <span class='ident'>vals</span>.<span class='ident'>len</span>());
<span class='macro'>assert</span><span class='macro'>!</span>(<span class='ident'>small_sample</span>.<span class='ident'>iter</span>().<span class='ident'>all</span>(<span class='op'>|</span><span class='ident'>e</span><span class='op'>|</span> {
<span class='kw-2'>*</span><span class='kw-2'>*</span><span class='ident'>e</span> <span class='op'>>=</span> <span class='ident'>min_val</span> <span class='op'>&&</span> <span class='kw-2'>*</span><span class='kw-2'>*</span><span class='ident'>e</span> <span class='op'><=</span> <span class='ident'>max_val</span>
}));
}
<span class='attribute'>#[<span class='ident'>test</span>]</span>
<span class='kw'>fn</span> <span class='ident'>test_std_rng_seeded</span>() {
<span class='kw'>let</span> <span class='ident'>s</span> <span class='op'>=</span> <span class='ident'>thread_rng</span>().<span class='ident'>gen_iter</span>::<span class='op'><</span><span class='ident'>usize</span><span class='op'>></span>().<span class='ident'>take</span>(<span class='number'>256</span>).<span class='ident'>collect</span>::<span class='op'><</span><span class='ident'>Vec</span><span class='op'><</span><span class='ident'>usize</span><span class='op'>>></span>();
<span class='kw'>let</span> <span class='kw-2'>mut</span> <span class='ident'>ra</span>: <span class='ident'>StdRng</span> <span class='op'>=</span> <span class='ident'>SeedableRng</span>::<span class='ident'>from_seed</span>(<span class='kw-2'>&</span><span class='ident'>s</span>[..]);
<span class='kw'>let</span> <span class='kw-2'>mut</span> <span class='ident'>rb</span>: <span class='ident'>StdRng</span> <span class='op'>=</span> <span class='ident'>SeedableRng</span>::<span class='ident'>from_seed</span>(<span class='kw-2'>&</span><span class='ident'>s</span>[..]);
<span class='macro'>assert</span><span class='macro'>!</span>(<span class='ident'>iter_eq</span>(<span class='ident'>ra</span>.<span class='ident'>gen_ascii_chars</span>().<span class='ident'>take</span>(<span class='number'>100</span>),
<span class='ident'>rb</span>.<span class='ident'>gen_ascii_chars</span>().<span class='ident'>take</span>(<span class='number'>100</span>)));
}
<span class='attribute'>#[<span class='ident'>test</span>]</span>
<span class='kw'>fn</span> <span class='ident'>test_std_rng_reseed</span>() {
<span class='kw'>let</span> <span class='ident'>s</span> <span class='op'>=</span> <span class='ident'>thread_rng</span>().<span class='ident'>gen_iter</span>::<span class='op'><</span><span class='ident'>usize</span><span class='op'>></span>().<span class='ident'>take</span>(<span class='number'>256</span>).<span class='ident'>collect</span>::<span class='op'><</span><span class='ident'>Vec</span><span class='op'><</span><span class='ident'>usize</span><span class='op'>>></span>();
<span class='kw'>let</span> <span class='kw-2'>mut</span> <span class='ident'>r</span>: <span class='ident'>StdRng</span> <span class='op'>=</span> <span class='ident'>SeedableRng</span>::<span class='ident'>from_seed</span>(<span class='kw-2'>&</span><span class='ident'>s</span>[..]);
<span class='kw'>let</span> <span class='ident'>string1</span> <span class='op'>=</span> <span class='ident'>r</span>.<span class='ident'>gen_ascii_chars</span>().<span class='ident'>take</span>(<span class='number'>100</span>).<span class='ident'>collect</span>::<span class='op'><</span><span class='ident'>String</span><span class='op'>></span>();
<span class='ident'>r</span>.<span class='ident'>reseed</span>(<span class='kw-2'>&</span><span class='ident'>s</span>);
<span class='kw'>let</span> <span class='ident'>string2</span> <span class='op'>=</span> <span class='ident'>r</span>.<span class='ident'>gen_ascii_chars</span>().<span class='ident'>take</span>(<span class='number'>100</span>).<span class='ident'>collect</span>::<span class='op'><</span><span class='ident'>String</span><span class='op'>></span>();
<span class='macro'>assert_eq</span><span class='macro'>!</span>(<span class='ident'>string1</span>, <span class='ident'>string2</span>);
}
}
</pre>
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