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<span id="1017">1017</span>
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<span id="1020">1020</span>
<span id="1021">1021</span>
<span id="1022">1022</span>
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<span id="1024">1024</span>
<span id="1025">1025</span>
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<span id="1038">1038</span>
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<span id="1096">1096</span>
<span id="1097">1097</span>
<span id="1098">1098</span>
<span id="1099">1099</span>
<span id="1100">1100</span>
<span id="1101">1101</span>
<span id="1102">1102</span>
<span id="1103">1103</span>
<span id="1104">1104</span>
<span id="1105">1105</span>
<span id="1106">1106</span>
<span id="1107">1107</span>
<span id="1108">1108</span>
<span id="1109">1109</span>
<span id="1110">1110</span>
<span id="1111">1111</span>
<span id="1112">1112</span>
<span id="1113">1113</span>
<span id="1114">1114</span>
<span id="1115">1115</span>
<span id="1116">1116</span>
<span id="1117">1117</span>
<span id="1118">1118</span>
<span id="1119">1119</span>
<span id="1120">1120</span>
<span id="1121">1121</span>
<span id="1122">1122</span>
<span id="1123">1123</span>
<span id="1124">1124</span>
<span id="1125">1125</span>
<span id="1126">1126</span>
<span id="1127">1127</span>
<span id="1128">1128</span>
<span id="1129">1129</span>
<span id="1130">1130</span>
<span id="1131">1131</span>
<span id="1132">1132</span>
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<span id="1195">1195</span>
<span id="1196">1196</span>
<span id="1197">1197</span>
<span id="1198">1198</span>
<span id="1199">1199</span>
<span id="1200">1200</span>
<span id="1201">1201</span>
<span id="1202">1202</span>
<span id="1203">1203</span>
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<span id="1211">1211</span>
<span id="1212">1212</span>
<span id="1213">1213</span>
<span id="1214">1214</span>
</pre><pre class="rust ">
<span class="comment">// Copyright 2013-2017 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 = "0.4"</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::seq::sample_slice(rng, &choices, 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="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://docs.rs/rand/0.3"</span>)]</span>
<span class="attribute">#![<span class="ident">deny</span>(<span class="ident">missing_debug_implementations</span>)]</span>
<span class="attribute">#![<span class="ident">cfg_attr</span>(<span class="ident">not</span>(<span class="ident">feature</span><span class="op">=</span><span class="string">"std"</span>), <span class="ident">no_std</span>)]</span>
<span class="attribute">#![<span class="ident">cfg_attr</span>(<span class="ident">all</span>(<span class="ident">feature</span><span class="op">=</span><span class="string">"alloc"</span>, <span class="ident">not</span>(<span class="ident">feature</span><span class="op">=</span><span class="string">"std"</span>)), <span class="ident">feature</span>(<span class="ident">alloc</span>))]</span>
<span class="attribute">#![<span class="ident">cfg_attr</span>(<span class="ident">feature</span> <span class="op">=</span> <span class="string">"i128_support"</span>, <span class="ident">feature</span>(<span class="ident">i128_type</span>, <span class="ident">i128</span>))]</span>
<span class="attribute">#[<span class="ident">cfg</span>(<span class="ident">feature</span><span class="op">=</span><span class="string">"std"</span>)]</span> <span class="kw">extern</span> <span class="kw">crate</span> <span class="ident">std</span> <span class="kw">as</span> <span class="ident">core</span>;
<span class="attribute">#[<span class="ident">cfg</span>(<span class="ident">all</span>(<span class="ident">feature</span> <span class="op">=</span> <span class="string">"alloc"</span>, <span class="ident">not</span>(<span class="ident">feature</span><span class="op">=</span><span class="string">"std"</span>)))]</span> <span class="kw">extern</span> <span class="kw">crate</span> <span class="ident">alloc</span>;
<span class="kw">use</span> <span class="ident">core</span>::<span class="ident">marker</span>;
<span class="kw">use</span> <span class="ident">core</span>::<span class="ident">mem</span>;
<span class="attribute">#[<span class="ident">cfg</span>(<span class="ident">feature</span><span class="op">=</span><span class="string">"std"</span>)]</span> <span class="kw">use</span> <span class="ident">std</span>::<span class="ident">cell</span>::<span class="ident">RefCell</span>;
<span class="attribute">#[<span class="ident">cfg</span>(<span class="ident">feature</span><span class="op">=</span><span class="string">"std"</span>)]</span> <span class="kw">use</span> <span class="ident">std</span>::<span class="ident">io</span>;
<span class="attribute">#[<span class="ident">cfg</span>(<span class="ident">feature</span><span class="op">=</span><span class="string">"std"</span>)]</span> <span class="kw">use</span> <span class="ident">std</span>::<span class="ident">rc</span>::<span class="ident">Rc</span>;
<span class="comment">// external rngs</span>
<span class="kw">pub</span> <span class="kw">use</span> <span class="ident">jitter</span>::<span class="ident">JitterRng</span>;
<span class="attribute">#[<span class="ident">cfg</span>(<span class="ident">feature</span><span class="op">=</span><span class="string">"std"</span>)]</span> <span class="kw">pub</span> <span class="kw">use</span> <span class="ident">os</span>::<span class="ident">OsRng</span>;
<span class="comment">// pseudo rngs</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="kw">pub</span> <span class="kw">use</span> <span class="ident">prng</span>::<span class="ident">XorShiftRng</span>;
<span class="comment">// local use declarations</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">prng</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">prng</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="comment">// public modules</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">jitter</span>;
<span class="attribute">#[<span class="ident">cfg</span>(<span class="ident">feature</span><span class="op">=</span><span class="string">"std"</span>)]</span> <span class="kw">pub</span> <span class="kw">mod</span> <span class="ident">os</span>;
<span class="attribute">#[<span class="ident">cfg</span>(<span class="ident">feature</span><span class="op">=</span><span class="string">"std"</span>)]</span> <span class="kw">pub</span> <span class="kw">mod</span> <span class="ident">read</span>;
<span class="kw">pub</span> <span class="kw">mod</span> <span class="ident">reseeding</span>;
<span class="attribute">#[<span class="ident">cfg</span>(<span class="ident">any</span>(<span class="ident">feature</span><span class="op">=</span><span class="string">"std"</span>, <span class="ident">feature</span> <span class="op">=</span> <span class="string">"alloc"</span>))]</span> <span class="kw">pub</span> <span class="kw">mod</span> <span class="ident">seq</span>;
<span class="comment">// These tiny modules are here to avoid API breakage, probably only temporarily</span>
<span class="kw">pub</span> <span class="kw">mod</span> <span class="ident">chacha</span> {
<span class="doccomment">//! The ChaCha random number generator.</span>
<span class="kw">pub</span> <span class="kw">use</span> <span class="ident">prng</span>::<span class="ident">ChaChaRng</span>;
}
<span class="kw">pub</span> <span class="kw">mod</span> <span class="ident">isaac</span> {
<span class="doccomment">//! The ISAAC random number generator.</span>
<span class="kw">pub</span> <span class="kw">use</span> <span class="ident">prng</span>::{<span class="ident">IsaacRng</span>, <span class="ident">Isaac64Rng</span>};
}
<span class="comment">// private modules</span>
<span class="kw">mod</span> <span class="ident">rand_impls</span>;
<span class="kw">mod</span> <span class="ident">prng</span>;
<span class="doccomment">/// A type that can be randomly generated using an `Rng`.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// ## Built-in Implementations</span>
<span class="doccomment">///</span>
<span class="doccomment">/// This crate implements `Rand` for various primitive types. Assuming the</span>
<span class="doccomment">/// provided `Rng` is well-behaved, these implementations generate values with</span>
<span class="doccomment">/// the following ranges and distributions:</span>
<span class="doccomment">///</span>
<span class="doccomment">/// * Integers (`i32`, `u32`, `isize`, `usize`, etc.): Uniformly distributed</span>
<span class="doccomment">/// over all values of the type.</span>
<span class="doccomment">/// * `char`: Uniformly distributed over all Unicode scalar values, i.e. all</span>
<span class="doccomment">/// code points in the range `0...0x10_FFFF`, except for the range</span>
<span class="doccomment">/// `0xD800...0xDFFF` (the surrogate code points). This includes</span>
<span class="doccomment">/// unassigned/reserved code points.</span>
<span class="doccomment">/// * `bool`: Generates `false` or `true`, each with probability 0.5.</span>
<span class="doccomment">/// * Floating point types (`f32` and `f64`): Uniformly distributed in the</span>
<span class="doccomment">/// half-open range `[0, 1)`. (The [`Open01`], [`Closed01`], [`Exp1`], and</span>
<span class="doccomment">/// [`StandardNormal`] wrapper types produce floating point numbers with</span>
<span class="doccomment">/// alternative ranges or distributions.)</span>
<span class="doccomment">///</span>
<span class="doccomment">/// [`Open01`]: struct.Open01.html</span>
<span class="doccomment">/// [`Closed01`]: struct.Closed01.html</span>
<span class="doccomment">/// [`Exp1`]: distributions/exponential/struct.Exp1.html</span>
<span class="doccomment">/// [`StandardNormal`]: distributions/normal/struct.StandardNormal.html</span>
<span class="doccomment">///</span>
<span class="doccomment">/// The following aggregate types also implement `Rand` as long as their</span>
<span class="doccomment">/// component types implement it:</span>
<span class="doccomment">///</span>
<span class="doccomment">/// * Tuples and arrays: Each element of the tuple or array is generated</span>
<span class="doccomment">/// independently, using its own `Rand` implementation.</span>
<span class="doccomment">/// * `Option<T>`: Returns `None` with probability 0.5; otherwise generates a</span>
<span class="doccomment">/// random `T` and returns `Some(T)`.</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 #rust-lang/rfcs#628: 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">///</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">/// This applies Durstenfeld's algorithm for the [Fisher–Yates shuffle](https://en.wikipedia.org/wiki/Fisher%E2%80%93Yates_shuffle#The_modern_algorithm)</span>
<span class="doccomment">/// which produces an unbiased permutation.</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="attribute">#[<span class="ident">cfg</span>(<span class="ident">feature</span><span class="op">=</span><span class="string">"std"</span>)]</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="attribute">#[<span class="ident">derive</span>(<span class="ident">Debug</span>)]</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="attribute">#[<span class="ident">derive</span>(<span class="ident">Debug</span>)]</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">/// 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="attribute">#[<span class="ident">derive</span>(<span class="ident">Debug</span>)]</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="attribute">#[<span class="ident">derive</span>(<span class="ident">Debug</span>)]</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 class="ident">Debug</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="attribute">#[<span class="ident">cfg</span>(<span class="ident">feature</span><span class="op">=</span><span class="string">"std"</span>)]</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="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="prelude-val">Ok</span>(<span class="ident">StdRng</span> { <span class="ident">rng</span>: <span class="ident">r</span>.<span class="ident">gen</span>() }),
<span class="prelude-val">Err</span>(<span class="ident">e1</span>) <span class="op">=></span> {
<span class="kw">match</span> <span class="ident">JitterRng</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="prelude-val">Ok</span>(<span class="ident">StdRng</span> { <span class="ident">rng</span>: <span class="ident">r</span>.<span class="ident">gen</span>() }),
<span class="prelude-val">Err</span>(_) <span class="op">=></span> {
<span class="prelude-val">Err</span>(<span class="ident">e1</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 seed the generator with randomness from thread_rng.</span>
<span class="attribute">#[<span class="ident">cfg</span>(<span class="ident">feature</span><span class="op">=</span><span class="string">"std"</span>)]</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="ident">thread_rng</span>().<span class="ident">gen</span>()
}
<span class="doccomment">/// Controls how the thread-local RNG is reseeded.</span>
<span class="attribute">#[<span class="ident">cfg</span>(<span class="ident">feature</span><span class="op">=</span><span class="string">"std"</span>)]</span>
<span class="attribute">#[<span class="ident">derive</span>(<span class="ident">Debug</span>)]</span>
<span class="kw">struct</span> <span class="ident">ThreadRngReseeder</span>;
<span class="attribute">#[<span class="ident">cfg</span>(<span class="ident">feature</span><span class="op">=</span><span class="string">"std"</span>)]</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">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="kw-2">*</span><span class="ident">rng</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">"No entropy available: {}"</span>, <span class="ident">e</span>),
}
}
}
<span class="attribute">#[<span class="ident">cfg</span>(<span class="ident">feature</span><span class="op">=</span><span class="string">"std"</span>)]</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="attribute">#[<span class="ident">cfg</span>(<span class="ident">feature</span><span class="op">=</span><span class="string">"std"</span>)]</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">cfg</span>(<span class="ident">feature</span><span class="op">=</span><span class="string">"std"</span>)]</span>
<span class="attribute">#[<span class="ident">derive</span>(<span class="ident">Clone</span>, <span class="ident">Debug</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">/// After generating a certain amount of randomness, the RNG will reseed itself</span>
<span class="doccomment">/// from the operating system or, if the operating system RNG returns an error,</span>
<span class="doccomment">/// a seed based on the current system time.</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="attribute">#[<span class="ident">cfg</span>(<span class="ident">feature</span><span class="op">=</span><span class="string">"std"</span>)]</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">"No entropy available: {}"</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="attribute">#[<span class="ident">cfg</span>(<span class="ident">feature</span><span class="op">=</span><span class="string">"std"</span>)]</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">/// // can be made faster by caching thread_rng</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">cfg</span>(<span class="ident">feature</span><span class="op">=</span><span class="string">"std"</span>)]</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">/// DEPRECATED: use `seq::sample_iter` instead.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// Randomly sample up to `amount` elements from a finite iterator.</span>
<span class="doccomment">/// The order of elements in the sample is not random.</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="attribute">#[<span class="ident">cfg</span>(<span class="ident">feature</span><span class="op">=</span><span class="string">"std"</span>)]</span>
<span class="attribute">#[<span class="ident">inline</span>(<span class="ident">always</span>)]</span>
<span class="attribute">#[<span class="ident">deprecated</span>(<span class="ident">since</span><span class="op">=</span><span class="string">"0.4.0"</span>, <span class="ident">note</span><span class="op">=</span><span class="string">"renamed to seq::sample_iter"</span>)]</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="comment">// the legacy sample didn't care whether amount was met</span>
<span class="ident">seq</span>::<span class="ident">sample_iter</span>(<span class="ident">rng</span>, <span class="ident">iterable</span>, <span class="ident">amount</span>)
.<span class="ident">unwrap_or_else</span>(<span class="op">|</span><span class="ident">e</span><span class="op">|</span> <span class="ident">e</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">weak_rng</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_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_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>);
}
<span class="attribute">#[<span class="ident">test</span>]</span>
<span class="kw">fn</span> <span class="ident">test_weak_rng</span>() {
<span class="kw">let</span> <span class="ident">s</span> <span class="op">=</span> <span class="ident">weak_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>)));
}
}
</pre>
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