| <!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="Source of the Rust file `/root/.cargo/registry/src/github.com-1ecc6299db9ec823/tantivy-fst-0.4.0/src/raw/pack.rs`."><meta name="keywords" content="rust, rustlang, rust-lang"><title>pack.rs - source</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" href="../../../normalize.css"><link rel="stylesheet" href="../../../rustdoc.css" id="mainThemeStyle"><link rel="stylesheet" href="../../../ayu.css" disabled><link rel="stylesheet" href="../../../dark.css" disabled><link rel="stylesheet" href="../../../light.css" id="themeStyle"><script id="default-settings" ></script><script src="../../../storage.js"></script><script defer src="../../../source-script.js"></script><script defer src="../../../source-files.js"></script><script defer src="../../../main.js"></script><noscript><link rel="stylesheet" href="../../../noscript.css"></noscript><link rel="alternate icon" type="image/png" href="../../../favicon-16x16.png"><link rel="alternate icon" type="image/png" href="../../../favicon-32x32.png"><link rel="icon" type="image/svg+xml" href="../../../favicon.svg"></head><body class="rustdoc source"><!--[if lte IE 11]><div class="warning">This old browser is unsupported and will most likely display funky things.</div><![endif]--><nav class="sidebar"><a class="sidebar-logo" href="../../../tantivy_fst/index.html"><div class="logo-container"><img class="rust-logo" src="../../../rust-logo.svg" alt="logo"></div></a></nav><main><div class="width-limiter"><nav class="sub"><a class="sub-logo-container" href="../../../tantivy_fst/index.html"><img class="rust-logo" src="../../../rust-logo.svg" alt="logo"></a><form class="search-form"><div class="search-container"><span></span><input class="search-input" name="search" autocomplete="off" spellcheck="false" placeholder="Click or press ‘S’ to search, ‘?’ for more options…" type="search"><div id="help-button" title="help" tabindex="-1"><a href="../../../help.html">?</a></div><div id="settings-menu" tabindex="-1"><a href="../../../settings.html" title="settings"><img width="22" height="22" alt="Change settings" src="../../../wheel.svg"></a></div></div></form></nav><section id="main-content" class="content"><div class="example-wrap"><pre class="src-line-numbers"><span id="1">1</span> |
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| </pre><pre class="rust"><code><span class="kw">use </span>std::io; |
| |
| <span class="kw">use </span>byteorder::{ByteOrder, LittleEndian, WriteBytesExt}; |
| |
| <span class="doccomment">/// pack_uint packs the given integer in the smallest number of bytes possible, |
| /// and writes it to the given writer. The number of bytes written is returned |
| /// on success. |
| </span><span class="kw">pub fn </span>pack_uint<W: io::Write>(wtr: W, n: u64) -> io::Result<u8> { |
| <span class="kw">let </span>nbytes = pack_size(n); |
| pack_uint_in(wtr, n, nbytes).map(|<span class="kw">_</span>| nbytes) |
| } |
| |
| <span class="doccomment">/// pack_uint_in is like pack_uint, but always uses the number of bytes given |
| /// to pack the number given. |
| /// |
| /// `nbytes` must be >= pack_size(n) and <= 8, where `pack_size(n)` is the |
| /// smallest number of bytes that can store the integer given. |
| </span><span class="kw">pub fn </span>pack_uint_in<W: io::Write>(<span class="kw-2">mut </span>wtr: W, n: u64, nbytes: u8) -> io::Result<()> { |
| wtr.write_uint::<LittleEndian>(n, nbytes <span class="kw">as </span>usize) |
| .map_err(From::from) |
| } |
| |
| <span class="doccomment">/// unpack_uint is the dual of pack_uint. It unpacks the integer at the current |
| /// position in `slice` after reading `nbytes` bytes. |
| /// |
| /// `nbytes` must be >= 1 and <= 8. |
| </span><span class="attribute">#[inline(always)] |
| </span><span class="kw">pub fn </span>unpack_uint(slice: <span class="kw-2">&</span>[u8], nbytes: u8) -> u64 { |
| LittleEndian::read_uint(slice, nbytes <span class="kw">as </span>usize) |
| } |
| |
| <span class="doccomment">/// pack_size returns the smallest number of bytes that can encode `n`. |
| </span><span class="kw">pub fn </span>pack_size(n: u64) -> u8 { |
| <span class="kw">if </span>n < <span class="number">1 </span><< <span class="number">8 </span>{ |
| <span class="number">1 |
| </span>} <span class="kw">else if </span>n < <span class="number">1 </span><< <span class="number">16 </span>{ |
| <span class="number">2 |
| </span>} <span class="kw">else if </span>n < <span class="number">1 </span><< <span class="number">24 </span>{ |
| <span class="number">3 |
| </span>} <span class="kw">else if </span>n < <span class="number">1 </span><< <span class="number">32 </span>{ |
| <span class="number">4 |
| </span>} <span class="kw">else if </span>n < <span class="number">1 </span><< <span class="number">40 </span>{ |
| <span class="number">5 |
| </span>} <span class="kw">else if </span>n < <span class="number">1 </span><< <span class="number">48 </span>{ |
| <span class="number">6 |
| </span>} <span class="kw">else if </span>n < <span class="number">1 </span><< <span class="number">56 </span>{ |
| <span class="number">7 |
| </span>} <span class="kw">else </span>{ |
| <span class="number">8 |
| </span>} |
| } |
| |
| <span class="attribute">#[cfg(test)] |
| </span><span class="kw">mod </span>tests { |
| <span class="kw">use super</span>::<span class="kw-2">*</span>; |
| <span class="kw">use </span>quickcheck::{QuickCheck, StdGen}; |
| <span class="kw">use </span>std::io; |
| |
| <span class="attribute">#[test] |
| </span><span class="kw">fn </span>prop_pack_in_out() { |
| <span class="kw">fn </span>p(num: u64) -> bool { |
| <span class="kw">let </span><span class="kw-2">mut </span>buf = io::Cursor::new(<span class="macro">vec!</span>[]); |
| <span class="kw">let </span>size = pack_uint(<span class="kw-2">&mut </span>buf, num).unwrap(); |
| buf.set_position(<span class="number">0</span>); |
| num == unpack_uint(buf.get_ref(), size) |
| } |
| QuickCheck::new() |
| .gen(StdGen::new(::rand::thread_rng(), <span class="number">257</span>)) <span class="comment">// pick byte boundary |
| </span>.quickcheck(p <span class="kw">as fn</span>(u64) -> bool); |
| } |
| } |
| </code></pre></div> |
| </section></div></main><div id="rustdoc-vars" data-root-path="../../../" data-current-crate="tantivy_fst" data-themes="ayu,dark,light" data-resource-suffix="" data-rustdoc-version="1.66.0-nightly (5c8bff74b 2022-10-21)" ></div></body></html> |
