| <!DOCTYPE html><html lang="en"><head><meta charset="utf-8"><meta name="viewport" content="width=device-width, initial-scale=1.0"><meta name="generator" content="rustdoc"><meta name="description" content="The core of a random number generator."><meta name="keywords" content="rust, rustlang, rust-lang, RngCore"><title>RngCore in rand_core - Rust</title><link rel="preload" as="font" type="font/woff2" crossorigin href="../SourceSerif4-Regular.ttf.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../FiraSans-Regular.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../FiraSans-Medium.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../SourceCodePro-Regular.ttf.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../SourceSerif4-Bold.ttf.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../SourceCodePro-Semibold.ttf.woff2"><link rel="stylesheet" type="text/css" href="../normalize.css"><link rel="stylesheet" type="text/css" href="../rustdoc.css" id="mainThemeStyle"><link rel="stylesheet" type="text/css" href="../ayu.css" disabled><link rel="stylesheet" type="text/css" href="../dark.css" disabled><link rel="stylesheet" type="text/css" href="../light.css" id="themeStyle"><script id="default-settings" ></script><script src="../storage.js"></script><script src="../crates.js"></script><script defer src="../main.js"></script> |
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| </a><h2 class="location">Trait RngCore</h2><div class="sidebar-elems"><div class="block items"><h3 class="sidebar-title"><a href="#required-methods">Required Methods</a></h3><div class="sidebar-links"><a href="#tymethod.fill_bytes">fill_bytes</a><a href="#tymethod.next_u32">next_u32</a><a href="#tymethod.next_u64">next_u64</a><a href="#tymethod.try_fill_bytes">try_fill_bytes</a></div><h3 class="sidebar-title"><a href="#foreign-impls">Implementations on Foreign Types</a></h3><div class="sidebar-links"><a href="#impl-RngCore-for-%26%27a%20mut%20R">&'a mut R</a><a href="#impl-RngCore-for-Box%3CR%3E">Box<R></a></div><h3 class="sidebar-title"><a href="#trait-implementations">Trait Implementations</a></h3><div class="sidebar-links"><a href="#impl-Read">Read</a></div><h3 class="sidebar-title"><a href="#implementors">Implementors</a></h3></div><h2 class="location">Other items in<br><a href="index.html">rand_core</a></h2><div id="sidebar-vars" data-name="RngCore" data-ty="trait" data-relpath=""></div><script defer src="sidebar-items.js"></script></div></nav><main><div class="width-limiter"><div class="sub-container"><a class="sub-logo-container" href="../rand_core/index.html"><img src="https://www.rust-lang.org/logos/rust-logo-128x128-blk.png" alt="logo"></a><nav class="sub"><div class="theme-picker"><button id="theme-picker" aria-label="Pick another theme!" aria-haspopup="menu" title="themes"><img width="18" height="18" alt="Pick another theme!" src="../brush.svg"></button><div id="theme-choices" role="menu"></div></div><form class="search-form"><div class="search-container"><div> |
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| <h1 class="fqn"><span class="in-band">Trait <a href="index.html">rand_core</a>::<wbr><a class="trait" href="#">RngCore</a><button id="copy-path" onclick="copy_path(this)" title="Copy item path to clipboard"><img src="../clipboard.svg" width="19" height="18" alt="Copy item path"></button></span></h1><span class="out-of-band"> |
| <a class="srclink" href="../src/rand_core/lib.rs.html#142-185" title="goto source code">source</a> · |
| <a id="toggle-all-docs" href="javascript:void(0)" title="collapse all docs">[<span class="inner">−</span>]</a></span></div> |
| <div class="docblock item-decl"><pre class="rust trait"><code>pub trait RngCore { |
| fn <a href="#tymethod.next_u32" class="fnname">next_u32</a>(&mut self) -> <a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.u32.html">u32</a>; |
| <div class="item-spacer"></div> fn <a href="#tymethod.next_u64" class="fnname">next_u64</a>(&mut self) -> <a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.u64.html">u64</a>; |
| <div class="item-spacer"></div> fn <a href="#tymethod.fill_bytes" class="fnname">fill_bytes</a>(&mut self, dest: <a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.slice.html">&mut [</a><a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.u8.html">u8</a><a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.slice.html">]</a>); |
| <div class="item-spacer"></div> fn <a href="#tymethod.try_fill_bytes" class="fnname">try_fill_bytes</a>(&mut self, dest: <a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.slice.html">&mut [</a><a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.u8.html">u8</a><a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.slice.html">]</a>) -> <a class="enum" href="https://doc.rust-lang.org/nightly/core/result/enum.Result.html" title="enum core::result::Result">Result</a><<a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.unit.html">()</a>, <a class="struct" href="struct.Error.html" title="struct rand_core::Error">Error</a>>; |
| }</code></pre></div><details class="rustdoc-toggle top-doc" open><summary class="hideme"><span>Expand description</span></summary><div class="docblock"><p>The core of a random number generator.</p> |
| <p>This trait encapsulates the low-level functionality common to all |
| generators, and is the “back end”, to be implemented by generators. |
| End users should normally use the <code>Rng</code> trait from the <a href="https://docs.rs/rand"><code>rand</code></a> crate, |
| which is automatically implemented for every type implementing <code>RngCore</code>.</p> |
| <p>Three different methods for generating random data are provided since the |
| optimal implementation of each is dependent on the type of generator. There |
| is no required relationship between the output of each; e.g. many |
| implementations of <a href="trait.RngCore.html#tymethod.fill_bytes"><code>fill_bytes</code></a> consume a whole number of <code>u32</code> or <code>u64</code> |
| values and drop any remaining unused bytes. The same can happen with the |
| <a href="trait.RngCore.html#tymethod.next_u32"><code>next_u32</code></a> and <a href="trait.RngCore.html#tymethod.next_u64"><code>next_u64</code></a> methods, implementations may discard some |
| random bits for efficiency.</p> |
| <p>The <a href="trait.RngCore.html#tymethod.try_fill_bytes"><code>try_fill_bytes</code></a> method is a variant of <a href="trait.RngCore.html#tymethod.fill_bytes"><code>fill_bytes</code></a> allowing error |
| handling; it is not deemed sufficiently useful to add equivalents for |
| <a href="trait.RngCore.html#tymethod.next_u32"><code>next_u32</code></a> or <a href="trait.RngCore.html#tymethod.next_u64"><code>next_u64</code></a> since the latter methods are almost always used |
| with algorithmic generators (PRNGs), which are normally infallible.</p> |
| <p>Implementers should produce bits uniformly. Pathological RNGs (e.g. always |
| returning the same value, or never setting certain bits) can break rejection |
| sampling used by random distributions, and also break other RNGs when |
| seeding them via <a href="trait.SeedableRng.html#method.from_rng" title="SeedableRng::from_rng"><code>SeedableRng::from_rng</code></a>.</p> |
| <p>Algorithmic generators implementing <a href="trait.SeedableRng.html" title="SeedableRng"><code>SeedableRng</code></a> should normally have |
| <em>portable, reproducible</em> output, i.e. fix Endianness when converting values |
| to avoid platform differences, and avoid making any changes which affect |
| output (except by communicating that the release has breaking changes).</p> |
| <p>Typically an RNG will implement only one of the methods available |
| in this trait directly, then use the helper functions from the |
| <a href="impls/index.html" title="impls"><code>impls</code></a> module to implement the other methods.</p> |
| <p>It is recommended that implementations also implement:</p> |
| <ul> |
| <li><code>Debug</code> with a custom implementation which <em>does not</em> print any internal |
| state (at least, <a href="trait.CryptoRng.html" title="CryptoRng"><code>CryptoRng</code></a>s should not risk leaking state through |
| <code>Debug</code>).</li> |
| <li><code>Serialize</code> and <code>Deserialize</code> (from Serde), preferably making Serde |
| support optional at the crate level in PRNG libs.</li> |
| <li><code>Clone</code>, if possible.</li> |
| <li><em>never</em> implement <code>Copy</code> (accidental copies may cause repeated values).</li> |
| <li><em>do not</em> implement <code>Default</code> for pseudorandom generators, but instead |
| implement <a href="trait.SeedableRng.html" title="SeedableRng"><code>SeedableRng</code></a>, to guide users towards proper seeding. |
| External / hardware RNGs can choose to implement <code>Default</code>.</li> |
| <li><code>Eq</code> and <code>PartialEq</code> could be implemented, but are probably not useful.</li> |
| </ul> |
| <h2 id="example" class="section-header"><a href="#example">Example</a></h2> |
| <p>A simple example, obviously not generating very <em>random</em> output:</p> |
| |
| <div class="example-wrap"><pre class="rust rust-example-rendered"><code><span class="attribute">#![<span class="ident">allow</span>(<span class="ident">dead_code</span>)]</span> |
| <span class="kw">use</span> <span class="ident">rand_core</span>::{<span class="ident">RngCore</span>, <span class="ident">Error</span>, <span class="ident">impls</span>}; |
| |
| <span class="kw">struct</span> <span class="ident">CountingRng</span>(<span class="ident">u64</span>); |
| |
| <span class="kw">impl</span> <span class="ident">RngCore</span> <span class="kw">for</span> <span class="ident">CountingRng</span> { |
| <span class="kw">fn</span> <span class="ident">next_u32</span>(<span class="kw-2">&mut</span> <span class="self">self</span>) -> <span class="ident">u32</span> { |
| <span class="self">self</span>.<span class="ident">next_u64</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">&mut</span> <span class="self">self</span>) -> <span class="ident">u64</span> { |
| <span class="self">self</span>.<span class="number">0</span> <span class="op">+</span><span class="op">=</span> <span class="number">1</span>; |
| <span class="self">self</span>.<span class="number">0</span> |
| } |
| |
| <span class="kw">fn</span> <span class="ident">fill_bytes</span>(<span class="kw-2">&mut</span> <span class="self">self</span>, <span class="ident">dest</span>: <span class="kw-2">&mut</span> [<span class="ident">u8</span>]) { |
| <span class="ident">impls::fill_bytes_via_next</span>(<span class="self">self</span>, <span class="ident">dest</span>) |
| } |
| |
| <span class="kw">fn</span> <span class="ident">try_fill_bytes</span>(<span class="kw-2">&mut</span> <span class="self">self</span>, <span class="ident">dest</span>: <span class="kw-2">&mut</span> [<span class="ident">u8</span>]) -> <span class="prelude-ty">Result</span><span class="op"><</span>(), <span class="ident">Error</span><span class="op">></span> { |
| <span class="prelude-val">Ok</span>(<span class="self">self</span>.<span class="ident">fill_bytes</span>(<span class="ident">dest</span>)) |
| } |
| }</code></pre></div> |
| </div></details><h2 id="required-methods" class="small-section-header">Required methods<a href="#required-methods" class="anchor"></a></h2><div class="methods"><details class="rustdoc-toggle" open><summary><div id="tymethod.next_u32" class="method has-srclink"><div class="rightside"><a class="srclink" href="../src/rand_core/lib.rs.html#148" title="goto source code">source</a></div><h4 class="code-header">fn <a href="#tymethod.next_u32" class="fnname">next_u32</a>(&mut self) -> <a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.u32.html">u32</a></h4></div></summary><div class="docblock"><p>Return the next random <code>u32</code>.</p> |
| <p>RNGs must implement at least one method from this trait directly. In |
| the case this method is not implemented directly, it can be implemented |
| using <code>self.next_u64() as u32</code> or via <a href="impls/fn.next_u32_via_fill.html" title="impls::next_u32_via_fill"><code>impls::next_u32_via_fill</code></a>.</p> |
| </div></details><details class="rustdoc-toggle" open><summary><div id="tymethod.next_u64" class="method has-srclink"><div class="rightside"><a class="srclink" href="../src/rand_core/lib.rs.html#155" title="goto source code">source</a></div><h4 class="code-header">fn <a href="#tymethod.next_u64" class="fnname">next_u64</a>(&mut self) -> <a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.u64.html">u64</a></h4></div></summary><div class="docblock"><p>Return the next random <code>u64</code>.</p> |
| <p>RNGs must implement at least one method from this trait directly. In |
| the case this method is not implemented directly, it can be implemented |
| via <a href="impls/fn.next_u64_via_u32.html" title="impls::next_u64_via_u32"><code>impls::next_u64_via_u32</code></a> or via <a href="impls/fn.next_u64_via_fill.html" title="impls::next_u64_via_fill"><code>impls::next_u64_via_fill</code></a>.</p> |
| </div></details><details class="rustdoc-toggle" open><summary><div id="tymethod.fill_bytes" class="method has-srclink"><div class="rightside"><a class="srclink" href="../src/rand_core/lib.rs.html#171" title="goto source code">source</a></div><h4 class="code-header">fn <a href="#tymethod.fill_bytes" class="fnname">fill_bytes</a>(&mut self, dest: <a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.slice.html">&mut [</a><a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.u8.html">u8</a><a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.slice.html">]</a>)</h4></div></summary><div class="docblock"><p>Fill <code>dest</code> with random data.</p> |
| <p>RNGs must implement at least one method from this trait directly. In |
| the case this method is not implemented directly, it can be implemented |
| via <a href="impls/fn.fill_bytes_via_next.html" title="impls::fill_bytes_via_next"><code>impls::fill_bytes_via_next</code></a> or |
| via <a href="trait.RngCore.html#tymethod.try_fill_bytes" title="RngCore::try_fill_bytes"><code>RngCore::try_fill_bytes</code></a>; if this generator can |
| fail the implementation must choose how best to handle errors here |
| (e.g. panic with a descriptive message or log a warning and retry a few |
| times).</p> |
| <p>This method should guarantee that <code>dest</code> is entirely filled |
| with new data, and may panic if this is impossible |
| (e.g. reading past the end of a file that is being used as the |
| source of randomness).</p> |
| </div></details><details class="rustdoc-toggle" open><summary><div id="tymethod.try_fill_bytes" class="method has-srclink"><div class="rightside"><a class="srclink" href="../src/rand_core/lib.rs.html#184" title="goto source code">source</a></div><h4 class="code-header">fn <a href="#tymethod.try_fill_bytes" class="fnname">try_fill_bytes</a>(&mut self, dest: <a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.slice.html">&mut [</a><a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.u8.html">u8</a><a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.slice.html">]</a>) -> <a class="enum" href="https://doc.rust-lang.org/nightly/core/result/enum.Result.html" title="enum core::result::Result">Result</a><<a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.unit.html">()</a>, <a class="struct" href="struct.Error.html" title="struct rand_core::Error">Error</a>></h4></div></summary><div class="docblock"><p>Fill <code>dest</code> entirely with random data.</p> |
| <p>This is the only method which allows an RNG to report errors while |
| generating random data thus making this the primary method implemented |
| by external (true) RNGs (e.g. <code>OsRng</code>) which can fail. It may be used |
| directly to generate keys and to seed (infallible) PRNGs.</p> |
| <p>Other than error handling, this method is identical to <a href="trait.RngCore.html#tymethod.fill_bytes" title="RngCore::fill_bytes"><code>RngCore::fill_bytes</code></a>; |
| thus this may be implemented using <code>Ok(self.fill_bytes(dest))</code> or |
| <code>fill_bytes</code> may be implemented with |
| <code>self.try_fill_bytes(dest).unwrap()</code> or more specific error handling.</p> |
| </div></details></div><h2 id="trait-implementations" class="small-section-header">Trait Implementations<a href="#trait-implementations" class="anchor"></a></h2><div id="trait-implementations-list"><details class="rustdoc-toggle implementors-toggle" open><summary><div id="impl-Read" class="impl has-srclink"><div class="rightside"><a class="srclink" href="../src/rand_core/lib.rs.html#473-478" title="goto source code">source</a></div><a href="#impl-Read" class="anchor"></a><h3 class="code-header in-band">impl <a class="trait" href="https://doc.rust-lang.org/nightly/std/io/trait.Read.html" title="trait std::io::Read">Read</a> for dyn <a class="trait" href="trait.RngCore.html" title="trait rand_core::RngCore">RngCore</a></h3></div></summary><div class="impl-items"><details class="rustdoc-toggle method-toggle" open><summary><div id="method.read" class="method trait-impl has-srclink"><div class="rightside"><a class="srclink" href="../src/rand_core/lib.rs.html#474-477" title="goto source code">source</a></div><a href="#method.read" class="anchor"></a><h4 class="code-header">fn <a href="https://doc.rust-lang.org/nightly/std/io/trait.Read.html#tymethod.read" class="fnname">read</a>(&mut self, buf: <a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.slice.html">&mut [</a><a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.u8.html">u8</a><a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.slice.html">]</a>) -> <a class="enum" href="https://doc.rust-lang.org/nightly/core/result/enum.Result.html" title="enum core::result::Result">Result</a><<a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.usize.html">usize</a>, <a class="struct" href="https://doc.rust-lang.org/nightly/std/io/error/struct.Error.html" title="struct std::io::error::Error">Error</a>></h4></div></summary><div class='docblock'><p>Pull some bytes from this source into the specified buffer, returning |
| how many bytes were read. <a href="https://doc.rust-lang.org/nightly/std/io/trait.Read.html#tymethod.read">Read more</a></p> |
| </div></details><details class="rustdoc-toggle method-toggle" open><summary><div id="method.read_vectored" class="method trait-impl has-srclink"><div class="rightside"><span class="since" title="Stable since Rust version 1.36.0">1.36.0</span> · <a class="srclink" href="https://doc.rust-lang.org/nightly/src/std/io/mod.rs.html#637" title="goto source code">source</a></div><a href="#method.read_vectored" class="anchor"></a><h4 class="code-header">fn <a href="https://doc.rust-lang.org/nightly/std/io/trait.Read.html#method.read_vectored" class="fnname">read_vectored</a>(&mut self, bufs: <a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.slice.html">&mut [</a><a class="struct" href="https://doc.rust-lang.org/nightly/std/io/struct.IoSliceMut.html" title="struct std::io::IoSliceMut">IoSliceMut</a><'_><a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.slice.html">]</a>) -> <a class="enum" href="https://doc.rust-lang.org/nightly/core/result/enum.Result.html" title="enum core::result::Result">Result</a><<a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.usize.html">usize</a>, <a class="struct" href="https://doc.rust-lang.org/nightly/std/io/error/struct.Error.html" title="struct std::io::error::Error">Error</a>></h4></div></summary><div class='docblock'><p>Like <code>read</code>, except that it reads into a slice of buffers. <a href="https://doc.rust-lang.org/nightly/std/io/trait.Read.html#method.read_vectored">Read more</a></p> |
| </div></details><details class="rustdoc-toggle method-toggle" open><summary><div id="method.is_read_vectored" class="method trait-impl has-srclink"><div class="rightside"><a class="srclink" href="https://doc.rust-lang.org/nightly/src/std/io/mod.rs.html#650" title="goto source code">source</a></div><a href="#method.is_read_vectored" class="anchor"></a><h4 class="code-header">fn <a href="https://doc.rust-lang.org/nightly/std/io/trait.Read.html#method.is_read_vectored" class="fnname">is_read_vectored</a>(&self) -> <a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.bool.html">bool</a></h4></div></summary><div class="item-info"><div class="stab unstable"><span class="emoji">🔬</span> This is a nightly-only experimental API. (<code>can_vector</code>)</div></div><div class='docblock'><p>Determines if this <code>Read</code>er has an efficient <code>read_vectored</code> |
| implementation. <a href="https://doc.rust-lang.org/nightly/std/io/trait.Read.html#method.is_read_vectored">Read more</a></p> |
| </div></details><details class="rustdoc-toggle method-toggle" open><summary><div id="method.read_to_end" class="method trait-impl has-srclink"><div class="rightside"><span class="since" title="Stable since Rust version 1.0.0">1.0.0</span> · <a class="srclink" href="https://doc.rust-lang.org/nightly/src/std/io/mod.rs.html#701" title="goto source code">source</a></div><a href="#method.read_to_end" class="anchor"></a><h4 class="code-header">fn <a href="https://doc.rust-lang.org/nightly/std/io/trait.Read.html#method.read_to_end" class="fnname">read_to_end</a>(&mut self, buf: &mut <a class="struct" href="https://doc.rust-lang.org/nightly/alloc/vec/struct.Vec.html" title="struct alloc::vec::Vec">Vec</a><<a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.u8.html">u8</a>, <a class="struct" href="https://doc.rust-lang.org/nightly/alloc/alloc/struct.Global.html" title="struct alloc::alloc::Global">Global</a>>) -> <a class="enum" href="https://doc.rust-lang.org/nightly/core/result/enum.Result.html" title="enum core::result::Result">Result</a><<a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.usize.html">usize</a>, <a class="struct" href="https://doc.rust-lang.org/nightly/std/io/error/struct.Error.html" title="struct std::io::error::Error">Error</a>></h4></div></summary><div class='docblock'><p>Read all bytes until EOF in this source, placing them into <code>buf</code>. <a href="https://doc.rust-lang.org/nightly/std/io/trait.Read.html#method.read_to_end">Read more</a></p> |
| </div></details><details class="rustdoc-toggle method-toggle" open><summary><div id="method.read_to_string" class="method trait-impl has-srclink"><div class="rightside"><span class="since" title="Stable since Rust version 1.0.0">1.0.0</span> · <a class="srclink" href="https://doc.rust-lang.org/nightly/src/std/io/mod.rs.html#744" title="goto source code">source</a></div><a href="#method.read_to_string" class="anchor"></a><h4 class="code-header">fn <a href="https://doc.rust-lang.org/nightly/std/io/trait.Read.html#method.read_to_string" class="fnname">read_to_string</a>(&mut self, buf: &mut <a class="struct" href="https://doc.rust-lang.org/nightly/alloc/string/struct.String.html" title="struct alloc::string::String">String</a>) -> <a class="enum" href="https://doc.rust-lang.org/nightly/core/result/enum.Result.html" title="enum core::result::Result">Result</a><<a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.usize.html">usize</a>, <a class="struct" href="https://doc.rust-lang.org/nightly/std/io/error/struct.Error.html" title="struct std::io::error::Error">Error</a>></h4></div></summary><div class='docblock'><p>Read all bytes until EOF in this source, appending them to <code>buf</code>. <a href="https://doc.rust-lang.org/nightly/std/io/trait.Read.html#method.read_to_string">Read more</a></p> |
| </div></details><details class="rustdoc-toggle method-toggle" open><summary><div id="method.read_exact" class="method trait-impl has-srclink"><div class="rightside"><span class="since" title="Stable since Rust version 1.6.0">1.6.0</span> · <a class="srclink" href="https://doc.rust-lang.org/nightly/src/std/io/mod.rs.html#799" title="goto source code">source</a></div><a href="#method.read_exact" class="anchor"></a><h4 class="code-header">fn <a href="https://doc.rust-lang.org/nightly/std/io/trait.Read.html#method.read_exact" class="fnname">read_exact</a>(&mut self, buf: <a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.slice.html">&mut [</a><a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.u8.html">u8</a><a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.slice.html">]</a>) -> <a class="enum" href="https://doc.rust-lang.org/nightly/core/result/enum.Result.html" title="enum core::result::Result">Result</a><<a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.unit.html">()</a>, <a class="struct" href="https://doc.rust-lang.org/nightly/std/io/error/struct.Error.html" title="struct std::io::error::Error">Error</a>></h4></div></summary><div class='docblock'><p>Read the exact number of bytes required to fill <code>buf</code>. <a href="https://doc.rust-lang.org/nightly/std/io/trait.Read.html#method.read_exact">Read more</a></p> |
| </div></details><details class="rustdoc-toggle method-toggle" open><summary><div id="method.read_buf" class="method trait-impl has-srclink"><div class="rightside"><a class="srclink" href="https://doc.rust-lang.org/nightly/src/std/io/mod.rs.html#810" title="goto source code">source</a></div><a href="#method.read_buf" class="anchor"></a><h4 class="code-header">fn <a href="https://doc.rust-lang.org/nightly/std/io/trait.Read.html#method.read_buf" class="fnname">read_buf</a>(&mut self, buf: &mut <a class="struct" href="https://doc.rust-lang.org/nightly/std/io/readbuf/struct.ReadBuf.html" title="struct std::io::readbuf::ReadBuf">ReadBuf</a><'_>) -> <a class="enum" href="https://doc.rust-lang.org/nightly/core/result/enum.Result.html" title="enum core::result::Result">Result</a><<a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.unit.html">()</a>, <a class="struct" href="https://doc.rust-lang.org/nightly/std/io/error/struct.Error.html" title="struct std::io::error::Error">Error</a>></h4></div></summary><div class="item-info"><div class="stab unstable"><span class="emoji">🔬</span> This is a nightly-only experimental API. (<code>read_buf</code>)</div></div><div class='docblock'><p>Pull some bytes from this source into the specified buffer. <a href="https://doc.rust-lang.org/nightly/std/io/trait.Read.html#method.read_buf">Read more</a></p> |
| </div></details><details class="rustdoc-toggle method-toggle" open><summary><div id="method.read_buf_exact" class="method trait-impl has-srclink"><div class="rightside"><a class="srclink" href="https://doc.rust-lang.org/nightly/src/std/io/mod.rs.html#819" title="goto source code">source</a></div><a href="#method.read_buf_exact" class="anchor"></a><h4 class="code-header">fn <a href="https://doc.rust-lang.org/nightly/std/io/trait.Read.html#method.read_buf_exact" class="fnname">read_buf_exact</a>(&mut self, buf: &mut <a class="struct" href="https://doc.rust-lang.org/nightly/std/io/readbuf/struct.ReadBuf.html" title="struct std::io::readbuf::ReadBuf">ReadBuf</a><'_>) -> <a class="enum" href="https://doc.rust-lang.org/nightly/core/result/enum.Result.html" title="enum core::result::Result">Result</a><<a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.unit.html">()</a>, <a class="struct" href="https://doc.rust-lang.org/nightly/std/io/error/struct.Error.html" title="struct std::io::error::Error">Error</a>></h4></div></summary><div class="item-info"><div class="stab unstable"><span class="emoji">🔬</span> This is a nightly-only experimental API. (<code>read_buf</code>)</div></div><div class='docblock'><p>Read the exact number of bytes required to fill <code>buf</code>. <a href="https://doc.rust-lang.org/nightly/std/io/trait.Read.html#method.read_buf_exact">Read more</a></p> |
| </div></details><details class="rustdoc-toggle method-toggle" open><summary><div id="method.by_ref" class="method trait-impl has-srclink"><div class="rightside"><span class="since" title="Stable since Rust version 1.0.0">1.0.0</span> · <a class="srclink" href="https://doc.rust-lang.org/nightly/src/std/io/mod.rs.html#871-873" title="goto source code">source</a></div><a href="#method.by_ref" class="anchor"></a><h4 class="code-header">fn <a href="https://doc.rust-lang.org/nightly/std/io/trait.Read.html#method.by_ref" class="fnname">by_ref</a>(&mut self) -> <a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.reference.html">&mut </a>Self</h4></div></summary><div class='docblock'><p>Creates a “by reference” adaptor for this instance of <code>Read</code>. <a href="https://doc.rust-lang.org/nightly/std/io/trait.Read.html#method.by_ref">Read more</a></p> |
| </div></details><details class="rustdoc-toggle method-toggle" open><summary><div id="method.bytes" class="method trait-impl has-srclink"><div class="rightside"><span class="since" title="Stable since Rust version 1.0.0">1.0.0</span> · <a class="srclink" href="https://doc.rust-lang.org/nightly/src/std/io/mod.rs.html#909-911" title="goto source code">source</a></div><a href="#method.bytes" class="anchor"></a><h4 class="code-header">fn <a href="https://doc.rust-lang.org/nightly/std/io/trait.Read.html#method.bytes" class="fnname">bytes</a>(self) -> <a class="struct" href="https://doc.rust-lang.org/nightly/std/io/struct.Bytes.html" title="struct std::io::Bytes">Bytes</a><Self></h4></div></summary><div class='docblock'><p>Transforms this <code>Read</code> instance to an <a href="https://doc.rust-lang.org/nightly/core/iter/traits/iterator/trait.Iterator.html" title="Iterator"><code>Iterator</code></a> over its bytes. <a href="https://doc.rust-lang.org/nightly/std/io/trait.Read.html#method.bytes">Read more</a></p> |
| </div></details><details class="rustdoc-toggle method-toggle" open><summary><div id="method.chain" class="method trait-impl has-srclink"><div class="rightside"><span class="since" title="Stable since Rust version 1.0.0">1.0.0</span> · <a class="srclink" href="https://doc.rust-lang.org/nightly/src/std/io/mod.rs.html#947-949" title="goto source code">source</a></div><a href="#method.chain" class="anchor"></a><h4 class="code-header">fn <a href="https://doc.rust-lang.org/nightly/std/io/trait.Read.html#method.chain" class="fnname">chain</a><R>(self, next: R) -> <a class="struct" href="https://doc.rust-lang.org/nightly/std/io/struct.Chain.html" title="struct std::io::Chain">Chain</a><Self, R> <span class="where fmt-newline">where<br> R: <a class="trait" href="https://doc.rust-lang.org/nightly/std/io/trait.Read.html" title="trait std::io::Read">Read</a>, </span></h4></div></summary><div class='docblock'><p>Creates an adapter which will chain this stream with another. <a href="https://doc.rust-lang.org/nightly/std/io/trait.Read.html#method.chain">Read more</a></p> |
| </div></details><details class="rustdoc-toggle method-toggle" open><summary><div id="method.take" class="method trait-impl has-srclink"><div class="rightside"><span class="since" title="Stable since Rust version 1.0.0">1.0.0</span> · <a class="srclink" href="https://doc.rust-lang.org/nightly/src/std/io/mod.rs.html#986-988" title="goto source code">source</a></div><a href="#method.take" class="anchor"></a><h4 class="code-header">fn <a href="https://doc.rust-lang.org/nightly/std/io/trait.Read.html#method.take" class="fnname">take</a>(self, limit: <a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.u64.html">u64</a>) -> <a class="struct" href="https://doc.rust-lang.org/nightly/std/io/struct.Take.html" title="struct std::io::Take">Take</a><Self></h4></div></summary><div class='docblock'><p>Creates an adapter which will read at most <code>limit</code> bytes from it. <a href="https://doc.rust-lang.org/nightly/std/io/trait.Read.html#method.take">Read more</a></p> |
| </div></details></div></details></div><h2 id="foreign-impls" class="small-section-header">Implementations on Foreign Types<a href="#foreign-impls" class="anchor"></a></h2><details class="rustdoc-toggle implementors-toggle"><summary><div id="impl-RngCore-for-%26%27a%20mut%20R" class="impl has-srclink"><div class="rightside"><a class="srclink" href="../src/rand_core/lib.rs.html#424-444" title="goto source code">source</a></div><a href="#impl-RngCore-for-%26%27a%20mut%20R" class="anchor"></a><h3 class="code-header in-band">impl<'a, R: <a class="trait" href="trait.RngCore.html" title="trait rand_core::RngCore">RngCore</a> + ?<a class="trait" href="https://doc.rust-lang.org/nightly/core/marker/trait.Sized.html" title="trait core::marker::Sized">Sized</a>> <a class="trait" href="trait.RngCore.html" title="trait rand_core::RngCore">RngCore</a> for <a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.reference.html">&'a mut </a>R</h3></div></summary><div class="impl-items"><div id="method.next_u32" class="method trait-impl has-srclink"><div class="rightside"><a class="srclink" href="../src/rand_core/lib.rs.html#426-428" title="goto source code">source</a></div><a href="#method.next_u32" class="anchor"></a><h4 class="code-header">fn <a href="#tymethod.next_u32" class="fnname">next_u32</a>(&mut self) -> <a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.u32.html">u32</a></h4></div><div id="method.next_u64" class="method trait-impl has-srclink"><div class="rightside"><a class="srclink" href="../src/rand_core/lib.rs.html#431-433" title="goto source code">source</a></div><a href="#method.next_u64" class="anchor"></a><h4 class="code-header">fn <a href="#tymethod.next_u64" class="fnname">next_u64</a>(&mut self) -> <a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.u64.html">u64</a></h4></div><div id="method.fill_bytes" class="method trait-impl has-srclink"><div class="rightside"><a class="srclink" href="../src/rand_core/lib.rs.html#436-438" title="goto source code">source</a></div><a href="#method.fill_bytes" class="anchor"></a><h4 class="code-header">fn <a href="#tymethod.fill_bytes" class="fnname">fill_bytes</a>(&mut self, dest: <a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.slice.html">&mut [</a><a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.u8.html">u8</a><a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.slice.html">]</a>)</h4></div><div id="method.try_fill_bytes" class="method trait-impl has-srclink"><div class="rightside"><a class="srclink" href="../src/rand_core/lib.rs.html#441-443" title="goto source code">source</a></div><a href="#method.try_fill_bytes" class="anchor"></a><h4 class="code-header">fn <a href="#tymethod.try_fill_bytes" class="fnname">try_fill_bytes</a>(&mut self, dest: <a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.slice.html">&mut [</a><a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.u8.html">u8</a><a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.slice.html">]</a>) -> <a class="enum" href="https://doc.rust-lang.org/nightly/core/result/enum.Result.html" title="enum core::result::Result">Result</a><<a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.unit.html">()</a>, <a class="struct" href="struct.Error.html" title="struct rand_core::Error">Error</a>></h4></div></div></details><details class="rustdoc-toggle implementors-toggle"><summary><div id="impl-RngCore-for-Box%3CR%3E" class="impl has-srclink"><div class="rightside"><a class="srclink" href="../src/rand_core/lib.rs.html#450-470" title="goto source code">source</a></div><a href="#impl-RngCore-for-Box%3CR%3E" class="anchor"></a><h3 class="code-header in-band">impl<R: <a class="trait" href="trait.RngCore.html" title="trait rand_core::RngCore">RngCore</a> + ?<a class="trait" href="https://doc.rust-lang.org/nightly/core/marker/trait.Sized.html" title="trait core::marker::Sized">Sized</a>> <a class="trait" href="trait.RngCore.html" title="trait rand_core::RngCore">RngCore</a> for <a class="struct" href="https://doc.rust-lang.org/nightly/alloc/boxed/struct.Box.html" title="struct alloc::boxed::Box">Box</a><R></h3></div></summary><div class="impl-items"><div id="method.next_u32-1" class="method trait-impl has-srclink"><div class="rightside"><a class="srclink" href="../src/rand_core/lib.rs.html#452-454" title="goto source code">source</a></div><a href="#method.next_u32-1" class="anchor"></a><h4 class="code-header">fn <a href="#tymethod.next_u32" class="fnname">next_u32</a>(&mut self) -> <a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.u32.html">u32</a></h4></div><div id="method.next_u64-1" class="method trait-impl has-srclink"><div class="rightside"><a class="srclink" href="../src/rand_core/lib.rs.html#457-459" title="goto source code">source</a></div><a href="#method.next_u64-1" class="anchor"></a><h4 class="code-header">fn <a href="#tymethod.next_u64" class="fnname">next_u64</a>(&mut self) -> <a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.u64.html">u64</a></h4></div><div id="method.fill_bytes-1" class="method trait-impl has-srclink"><div class="rightside"><a class="srclink" href="../src/rand_core/lib.rs.html#462-464" title="goto source code">source</a></div><a href="#method.fill_bytes-1" class="anchor"></a><h4 class="code-header">fn <a href="#tymethod.fill_bytes" class="fnname">fill_bytes</a>(&mut self, dest: <a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.slice.html">&mut [</a><a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.u8.html">u8</a><a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.slice.html">]</a>)</h4></div><div id="method.try_fill_bytes-1" class="method trait-impl has-srclink"><div class="rightside"><a class="srclink" href="../src/rand_core/lib.rs.html#467-469" title="goto source code">source</a></div><a href="#method.try_fill_bytes-1" class="anchor"></a><h4 class="code-header">fn <a href="#tymethod.try_fill_bytes" class="fnname">try_fill_bytes</a>(&mut self, dest: <a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.slice.html">&mut [</a><a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.u8.html">u8</a><a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.slice.html">]</a>) -> <a class="enum" href="https://doc.rust-lang.org/nightly/core/result/enum.Result.html" title="enum core::result::Result">Result</a><<a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.unit.html">()</a>, <a class="struct" href="struct.Error.html" title="struct rand_core::Error">Error</a>></h4></div></div></details><h2 id="implementors" class="small-section-header">Implementors<a href="#implementors" class="anchor"></a></h2><div class="item-list" id="implementors-list"><div id="impl-RngCore" class="impl has-srclink"><div class="rightside"><a class="srclink" href="../src/rand_core/os.rs.html#52-71" title="goto source code">source</a></div><a href="#impl-RngCore" class="anchor"></a><h3 class="code-header in-band">impl <a class="trait" href="trait.RngCore.html" title="trait rand_core::RngCore">RngCore</a> for <a class="struct" href="struct.OsRng.html" title="struct rand_core::OsRng">OsRng</a></h3></div><div id="impl-RngCore-1" class="impl has-srclink"><div class="rightside"><a class="srclink" href="../src/rand_core/block.rs.html#181-241" title="goto source code">source</a></div><a href="#impl-RngCore-1" class="anchor"></a><h3 class="code-header in-band">impl<R: <a class="trait" href="block/trait.BlockRngCore.html" title="trait rand_core::block::BlockRngCore">BlockRngCore</a><Item = <a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.u32.html">u32</a>>> <a class="trait" href="trait.RngCore.html" title="trait rand_core::RngCore">RngCore</a> for <a class="struct" href="block/struct.BlockRng.html" title="struct rand_core::block::BlockRng">BlockRng</a><R> <span class="where fmt-newline">where<br> <R as <a class="trait" href="block/trait.BlockRngCore.html" title="trait rand_core::block::BlockRngCore">BlockRngCore</a>>::<a class="associatedtype" href="block/trait.BlockRngCore.html#associatedtype.Results" title="type rand_core::block::BlockRngCore::Results">Results</a>: <a class="trait" href="https://doc.rust-lang.org/nightly/core/convert/trait.AsRef.html" title="trait core::convert::AsRef">AsRef</a><<a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.slice.html">[</a><a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.u32.html">u32</a><a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.slice.html">]</a>> + <a class="trait" href="https://doc.rust-lang.org/nightly/core/convert/trait.AsMut.html" title="trait core::convert::AsMut">AsMut</a><<a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.slice.html">[</a><a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.u32.html">u32</a><a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.slice.html">]</a>>, </span></h3></div><div id="impl-RngCore-2" class="impl has-srclink"><div class="rightside"><a class="srclink" href="../src/rand_core/block.rs.html#349-410" title="goto source code">source</a></div><a href="#impl-RngCore-2" class="anchor"></a><h3 class="code-header in-band">impl<R: <a class="trait" href="block/trait.BlockRngCore.html" title="trait rand_core::block::BlockRngCore">BlockRngCore</a><Item = <a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.u64.html">u64</a>>> <a class="trait" href="trait.RngCore.html" title="trait rand_core::RngCore">RngCore</a> for <a class="struct" href="block/struct.BlockRng64.html" title="struct rand_core::block::BlockRng64">BlockRng64</a><R> <span class="where fmt-newline">where<br> <R as <a class="trait" href="block/trait.BlockRngCore.html" title="trait rand_core::block::BlockRngCore">BlockRngCore</a>>::<a class="associatedtype" href="block/trait.BlockRngCore.html#associatedtype.Results" title="type rand_core::block::BlockRngCore::Results">Results</a>: <a class="trait" href="https://doc.rust-lang.org/nightly/core/convert/trait.AsRef.html" title="trait core::convert::AsRef">AsRef</a><<a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.slice.html">[</a><a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.u64.html">u64</a><a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.slice.html">]</a>> + <a class="trait" href="https://doc.rust-lang.org/nightly/core/convert/trait.AsMut.html" title="trait core::convert::AsMut">AsMut</a><<a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.slice.html">[</a><a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.u64.html">u64</a><a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.slice.html">]</a>>, </span></h3></div></div><script type="text/javascript" src="../implementors/rand_core/trait.RngCore.js" async></script></section><section id="search" class="content hidden"></section></div></main><div id="rustdoc-vars" data-root-path="../" data-current-crate="rand_core" data-themes="ayu,dark,light" data-resource-suffix="" data-rustdoc-version="1.60.0-nightly (1bd4fdc94 2022-01-12)" ></div> |
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