| <!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/git/checkouts/tantivy-65d0bbbddbbd5d02/433372d/common/src/vint.rs`."><meta name="keywords" content="rust, rustlang, rust-lang"><title>vint.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_common/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_common/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>std::io::{Read, Write}; |
| |
| <span class="kw">use </span>byteorder::{ByteOrder, LittleEndian}; |
| |
| <span class="kw">use </span><span class="kw">super</span>::BinarySerializable; |
| |
| <span class="doccomment">/// Variable int serializes a u128 number |
| </span><span class="kw">pub fn </span>serialize_vint_u128(<span class="kw-2">mut </span>val: u128, output: <span class="kw-2">&mut </span>Vec<u8>) { |
| <span class="kw">loop </span>{ |
| <span class="kw">let </span>next_byte: u8 = (val % <span class="number">128u128</span>) <span class="kw">as </span>u8; |
| val /= <span class="number">128u128</span>; |
| <span class="kw">if </span>val == <span class="number">0 </span>{ |
| output.push(next_byte | STOP_BIT); |
| <span class="kw">return</span>; |
| } <span class="kw">else </span>{ |
| output.push(next_byte); |
| } |
| } |
| } |
| |
| <span class="doccomment">/// Deserializes a u128 number |
| /// |
| /// Returns the number and the slice after the vint |
| </span><span class="kw">pub fn </span>deserialize_vint_u128(data: <span class="kw-2">&</span>[u8]) -> io::Result<(u128, <span class="kw-2">&</span>[u8])> { |
| <span class="kw">let </span><span class="kw-2">mut </span>result = <span class="number">0u128</span>; |
| <span class="kw">let </span><span class="kw-2">mut </span>shift = <span class="number">0u64</span>; |
| <span class="kw">for </span>i <span class="kw">in </span><span class="number">0</span>..<span class="number">19 </span>{ |
| <span class="kw">let </span>b = data[i]; |
| result |= u128::from(b % <span class="number">128u8</span>) << shift; |
| <span class="kw">if </span>b >= STOP_BIT { |
| <span class="kw">return </span><span class="prelude-val">Ok</span>((result, <span class="kw-2">&</span>data[i + <span class="number">1</span>..])); |
| } |
| shift += <span class="number">7</span>; |
| } |
| <span class="prelude-val">Err</span>(io::Error::new( |
| io::ErrorKind::InvalidData, |
| <span class="string">"Failed to deserialize u128 vint"</span>, |
| )) |
| } |
| |
| <span class="doccomment">/// Wrapper over a `u128` that serializes as a variable int. |
| </span><span class="attribute">#[derive(Clone, Copy, Debug, Eq, PartialEq)] |
| </span><span class="kw">pub struct </span>VIntU128(<span class="kw">pub </span>u128); |
| |
| <span class="kw">impl </span>BinarySerializable <span class="kw">for </span>VIntU128 { |
| <span class="kw">fn </span>serialize<W: Write>(<span class="kw-2">&</span><span class="self">self</span>, writer: <span class="kw-2">&mut </span>W) -> io::Result<()> { |
| <span class="kw">let </span><span class="kw-2">mut </span>buffer = <span class="macro">vec!</span>[]; |
| serialize_vint_u128(<span class="self">self</span>.<span class="number">0</span>, <span class="kw-2">&mut </span>buffer); |
| writer.write_all(<span class="kw-2">&</span>buffer) |
| } |
| |
| <span class="kw">fn </span>deserialize<R: Read>(reader: <span class="kw-2">&mut </span>R) -> io::Result<<span class="self">Self</span>> { |
| <span class="kw">let </span><span class="kw-2">mut </span>bytes = reader.bytes(); |
| <span class="kw">let </span><span class="kw-2">mut </span>result = <span class="number">0u128</span>; |
| <span class="kw">let </span><span class="kw-2">mut </span>shift = <span class="number">0u64</span>; |
| <span class="kw">loop </span>{ |
| <span class="kw">match </span>bytes.next() { |
| <span class="prelude-val">Some</span>(<span class="prelude-val">Ok</span>(b)) => { |
| result |= u128::from(b % <span class="number">128u8</span>) << shift; |
| <span class="kw">if </span>b >= STOP_BIT { |
| <span class="kw">return </span><span class="prelude-val">Ok</span>(VIntU128(result)); |
| } |
| shift += <span class="number">7</span>; |
| } |
| <span class="kw">_ </span>=> { |
| <span class="kw">return </span><span class="prelude-val">Err</span>(io::Error::new( |
| io::ErrorKind::InvalidData, |
| <span class="string">"Reach end of buffer while reading VInt"</span>, |
| )); |
| } |
| } |
| } |
| } |
| } |
| |
| <span class="doccomment">/// Wrapper over a `u64` that serializes as a variable int. |
| </span><span class="attribute">#[derive(Clone, Copy, Debug, Eq, PartialEq)] |
| </span><span class="kw">pub struct </span>VInt(<span class="kw">pub </span>u64); |
| |
| <span class="kw">const </span>STOP_BIT: u8 = <span class="number">128</span>; |
| |
| <span class="kw">pub fn </span>serialize_vint_u32(val: u32, buf: <span class="kw-2">&mut </span>[u8; <span class="number">8</span>]) -> <span class="kw-2">&</span>[u8] { |
| <span class="kw">const </span>START_2: u64 = <span class="number">1 </span><< <span class="number">7</span>; |
| <span class="kw">const </span>START_3: u64 = <span class="number">1 </span><< <span class="number">14</span>; |
| <span class="kw">const </span>START_4: u64 = <span class="number">1 </span><< <span class="number">21</span>; |
| <span class="kw">const </span>START_5: u64 = <span class="number">1 </span><< <span class="number">28</span>; |
| |
| <span class="kw">const </span>STOP_1: u64 = START_2 - <span class="number">1</span>; |
| <span class="kw">const </span>STOP_2: u64 = START_3 - <span class="number">1</span>; |
| <span class="kw">const </span>STOP_3: u64 = START_4 - <span class="number">1</span>; |
| <span class="kw">const </span>STOP_4: u64 = START_5 - <span class="number">1</span>; |
| |
| <span class="kw">const </span>MASK_1: u64 = <span class="number">127</span>; |
| <span class="kw">const </span>MASK_2: u64 = MASK_1 << <span class="number">7</span>; |
| <span class="kw">const </span>MASK_3: u64 = MASK_2 << <span class="number">7</span>; |
| <span class="kw">const </span>MASK_4: u64 = MASK_3 << <span class="number">7</span>; |
| <span class="kw">const </span>MASK_5: u64 = MASK_4 << <span class="number">7</span>; |
| |
| <span class="kw">let </span>val = u64::from(val); |
| <span class="kw">const </span>STOP_BIT: u64 = <span class="number">128u64</span>; |
| <span class="kw">let </span>(res, num_bytes) = <span class="kw">match </span>val { |
| <span class="number">0</span>..=STOP_1 => (val | STOP_BIT, <span class="number">1</span>), |
| START_2..=STOP_2 => ( |
| (val & MASK_1) | ((val & MASK_2) << <span class="number">1</span>) | (STOP_BIT << (<span class="number">8</span>)), |
| <span class="number">2</span>, |
| ), |
| START_3..=STOP_3 => ( |
| (val & MASK_1) | ((val & MASK_2) << <span class="number">1</span>) | ((val & MASK_3) << <span class="number">2</span>) | (STOP_BIT << (<span class="number">8 </span>* <span class="number">2</span>)), |
| <span class="number">3</span>, |
| ), |
| START_4..=STOP_4 => ( |
| (val & MASK_1) |
| | ((val & MASK_2) << <span class="number">1</span>) |
| | ((val & MASK_3) << <span class="number">2</span>) |
| | ((val & MASK_4) << <span class="number">3</span>) |
| | (STOP_BIT << (<span class="number">8 </span>* <span class="number">3</span>)), |
| <span class="number">4</span>, |
| ), |
| <span class="kw">_ </span>=> ( |
| (val & MASK_1) |
| | ((val & MASK_2) << <span class="number">1</span>) |
| | ((val & MASK_3) << <span class="number">2</span>) |
| | ((val & MASK_4) << <span class="number">3</span>) |
| | ((val & MASK_5) << <span class="number">4</span>) |
| | (STOP_BIT << (<span class="number">8 </span>* <span class="number">4</span>)), |
| <span class="number">5</span>, |
| ), |
| }; |
| LittleEndian::write_u64(<span class="kw-2">&mut </span>buf[..], res); |
| <span class="kw-2">&</span>buf[<span class="number">0</span>..num_bytes] |
| } |
| |
| <span class="doccomment">/// Returns the number of bytes covered by a |
| /// serialized vint `u32`. |
| /// |
| /// Expects a buffer data that starts |
| /// by the serialized `vint`, scans at most 5 bytes ahead until |
| /// it finds the vint final byte. |
| /// |
| /// # May Panic |
| /// If the payload does not start by a valid `vint` |
| </span><span class="kw">fn </span>vint_len(data: <span class="kw-2">&</span>[u8]) -> usize { |
| <span class="kw">for </span>(i, <span class="kw-2">&</span>val) <span class="kw">in </span>data.iter().enumerate().take(<span class="number">5</span>) { |
| <span class="kw">if </span>val >= STOP_BIT { |
| <span class="kw">return </span>i + <span class="number">1</span>; |
| } |
| } |
| <span class="macro">panic!</span>(<span class="string">"Corrupted data. Invalid VInt 32"</span>); |
| } |
| |
| <span class="doccomment">/// Reads a vint `u32` from a buffer, and |
| /// consumes its payload data. |
| /// |
| /// # Panics |
| /// |
| /// If the buffer does not start by a valid |
| /// vint payload |
| </span><span class="kw">pub fn </span>read_u32_vint(data: <span class="kw-2">&mut &</span>[u8]) -> u32 { |
| <span class="kw">let </span>(result, vlen) = read_u32_vint_no_advance(data); |
| <span class="kw-2">*</span>data = <span class="kw-2">&</span>data[vlen..]; |
| result |
| } |
| |
| <span class="kw">pub fn </span>read_u32_vint_no_advance(data: <span class="kw-2">&</span>[u8]) -> (u32, usize) { |
| <span class="kw">let </span>vlen = vint_len(data); |
| <span class="kw">let </span><span class="kw-2">mut </span>result = <span class="number">0u32</span>; |
| <span class="kw">let </span><span class="kw-2">mut </span>shift = <span class="number">0u64</span>; |
| <span class="kw">for </span><span class="kw-2">&</span>b <span class="kw">in </span><span class="kw-2">&</span>data[..vlen] { |
| result |= u32::from(b & <span class="number">127u8</span>) << shift; |
| shift += <span class="number">7</span>; |
| } |
| (result, vlen) |
| } |
| <span class="doccomment">/// Write a `u32` as a vint payload. |
| </span><span class="kw">pub fn </span>write_u32_vint<W: io::Write>(val: u32, writer: <span class="kw-2">&mut </span>W) -> io::Result<()> { |
| <span class="kw">let </span><span class="kw-2">mut </span>buf = [<span class="number">0u8</span>; <span class="number">8</span>]; |
| <span class="kw">let </span>data = serialize_vint_u32(val, <span class="kw-2">&mut </span>buf); |
| writer.write_all(data) |
| } |
| |
| <span class="kw">impl </span>VInt { |
| <span class="kw">pub fn </span>val(<span class="kw-2">&</span><span class="self">self</span>) -> u64 { |
| <span class="self">self</span>.<span class="number">0 |
| </span>} |
| |
| <span class="kw">pub fn </span>deserialize_u64<R: Read>(reader: <span class="kw-2">&mut </span>R) -> io::Result<u64> { |
| VInt::deserialize(reader).map(|vint| vint.<span class="number">0</span>) |
| } |
| |
| <span class="kw">pub fn </span>serialize_into_vec(<span class="kw-2">&</span><span class="self">self</span>, output: <span class="kw-2">&mut </span>Vec<u8>) { |
| <span class="kw">let </span><span class="kw-2">mut </span>buffer = [<span class="number">0u8</span>; <span class="number">10</span>]; |
| <span class="kw">let </span>num_bytes = <span class="self">self</span>.serialize_into(<span class="kw-2">&mut </span>buffer); |
| output.extend(<span class="kw-2">&</span>buffer[<span class="number">0</span>..num_bytes]); |
| } |
| |
| <span class="kw">pub fn </span>serialize_into(<span class="kw-2">&</span><span class="self">self</span>, buffer: <span class="kw-2">&mut </span>[u8; <span class="number">10</span>]) -> usize { |
| <span class="kw">let </span><span class="kw-2">mut </span>remaining = <span class="self">self</span>.<span class="number">0</span>; |
| <span class="kw">for </span>(i, b) <span class="kw">in </span>buffer.iter_mut().enumerate() { |
| <span class="kw">let </span>next_byte: u8 = (remaining % <span class="number">128u64</span>) <span class="kw">as </span>u8; |
| remaining /= <span class="number">128u64</span>; |
| <span class="kw">if </span>remaining == <span class="number">0u64 </span>{ |
| <span class="kw-2">*</span>b = next_byte | STOP_BIT; |
| <span class="kw">return </span>i + <span class="number">1</span>; |
| } <span class="kw">else </span>{ |
| <span class="kw-2">*</span>b = next_byte; |
| } |
| } |
| <span class="macro">unreachable!</span>(); |
| } |
| } |
| |
| <span class="kw">impl </span>BinarySerializable <span class="kw">for </span>VInt { |
| <span class="kw">fn </span>serialize<W: Write>(<span class="kw-2">&</span><span class="self">self</span>, writer: <span class="kw-2">&mut </span>W) -> io::Result<()> { |
| <span class="kw">let </span><span class="kw-2">mut </span>buffer = [<span class="number">0u8</span>; <span class="number">10</span>]; |
| <span class="kw">let </span>num_bytes = <span class="self">self</span>.serialize_into(<span class="kw-2">&mut </span>buffer); |
| writer.write_all(<span class="kw-2">&</span>buffer[<span class="number">0</span>..num_bytes]) |
| } |
| |
| <span class="kw">fn </span>deserialize<R: Read>(reader: <span class="kw-2">&mut </span>R) -> io::Result<<span class="self">Self</span>> { |
| <span class="kw">let </span><span class="kw-2">mut </span>bytes = reader.bytes(); |
| <span class="kw">let </span><span class="kw-2">mut </span>result = <span class="number">0u64</span>; |
| <span class="kw">let </span><span class="kw-2">mut </span>shift = <span class="number">0u64</span>; |
| <span class="kw">loop </span>{ |
| <span class="kw">match </span>bytes.next() { |
| <span class="prelude-val">Some</span>(<span class="prelude-val">Ok</span>(b)) => { |
| result |= u64::from(b % <span class="number">128u8</span>) << shift; |
| <span class="kw">if </span>b >= STOP_BIT { |
| <span class="kw">return </span><span class="prelude-val">Ok</span>(VInt(result)); |
| } |
| shift += <span class="number">7</span>; |
| } |
| <span class="kw">_ </span>=> { |
| <span class="kw">return </span><span class="prelude-val">Err</span>(io::Error::new( |
| io::ErrorKind::InvalidData, |
| <span class="string">"Reach end of buffer while reading VInt"</span>, |
| )); |
| } |
| } |
| } |
| } |
| } |
| |
| <span class="attribute">#[cfg(test)] |
| </span><span class="kw">mod </span>tests { |
| |
| <span class="kw">use super</span>::{serialize_vint_u32, BinarySerializable, VInt}; |
| <span class="kw">use </span><span class="kw">crate</span>::vint::{deserialize_vint_u128, serialize_vint_u128, VIntU128}; |
| |
| <span class="kw">fn </span>aux_test_vint(val: u64) { |
| <span class="kw">let </span><span class="kw-2">mut </span>v = [<span class="number">14u8</span>; <span class="number">10</span>]; |
| <span class="kw">let </span>num_bytes = VInt(val).serialize_into(<span class="kw-2">&mut </span>v); |
| <span class="kw">for </span>el <span class="kw">in </span><span class="kw-2">&</span>v[num_bytes..<span class="number">10</span>] { |
| <span class="macro">assert_eq!</span>(el, <span class="kw-2">&</span><span class="number">14u8</span>); |
| } |
| <span class="macro">assert!</span>(num_bytes > <span class="number">0</span>); |
| <span class="kw">if </span>num_bytes < <span class="number">10 </span>{ |
| <span class="macro">assert!</span>(<span class="number">1u64 </span><< (<span class="number">7 </span>* num_bytes) > val); |
| } |
| <span class="kw">if </span>num_bytes > <span class="number">1 </span>{ |
| <span class="macro">assert!</span>(<span class="number">1u64 </span><< (<span class="number">7 </span>* (num_bytes - <span class="number">1</span>)) <= val); |
| } |
| <span class="kw">let </span>serdeser_val = VInt::deserialize(<span class="kw-2">&mut &</span>v[..]).unwrap(); |
| <span class="macro">assert_eq!</span>(val, serdeser_val.<span class="number">0</span>); |
| } |
| |
| <span class="attribute">#[test] |
| </span><span class="kw">fn </span>test_vint() { |
| aux_test_vint(<span class="number">0</span>); |
| aux_test_vint(<span class="number">1</span>); |
| aux_test_vint(<span class="number">5</span>); |
| aux_test_vint(u64::MAX); |
| <span class="kw">for </span>i <span class="kw">in </span><span class="number">1</span>..<span class="number">9 </span>{ |
| <span class="kw">let </span>power_of_128 = <span class="number">1u64 </span><< (<span class="number">7 </span>* i); |
| aux_test_vint(power_of_128 - <span class="number">1u64</span>); |
| aux_test_vint(power_of_128); |
| aux_test_vint(power_of_128 + <span class="number">1u64</span>); |
| } |
| aux_test_vint(<span class="number">10</span>); |
| } |
| |
| <span class="kw">fn </span>aux_test_serialize_vint_u32(val: u32) { |
| <span class="kw">let </span><span class="kw-2">mut </span>buffer = [<span class="number">0u8</span>; <span class="number">10</span>]; |
| <span class="kw">let </span><span class="kw-2">mut </span>buffer2 = [<span class="number">0u8</span>; <span class="number">8</span>]; |
| <span class="kw">let </span>len_vint = VInt(val <span class="kw">as </span>u64).serialize_into(<span class="kw-2">&mut </span>buffer); |
| <span class="kw">let </span>res2 = serialize_vint_u32(val, <span class="kw-2">&mut </span>buffer2); |
| <span class="macro">assert_eq!</span>(<span class="kw-2">&</span>buffer[..len_vint], res2, <span class="string">"array wrong for {}"</span>, val); |
| } |
| |
| <span class="kw">fn </span>aux_test_vint_u128(val: u128) { |
| <span class="kw">let </span><span class="kw-2">mut </span>data = <span class="macro">vec!</span>[]; |
| serialize_vint_u128(val, <span class="kw-2">&mut </span>data); |
| <span class="kw">let </span>(deser_val, _data) = deserialize_vint_u128(<span class="kw-2">&</span>data).unwrap(); |
| <span class="macro">assert_eq!</span>(val, deser_val); |
| |
| <span class="kw">let </span><span class="kw-2">mut </span>out = <span class="macro">vec!</span>[]; |
| VIntU128(val).serialize(<span class="kw-2">&mut </span>out).unwrap(); |
| <span class="kw">let </span>deser_val = VIntU128::deserialize(<span class="kw-2">&mut &</span>out[..]).unwrap(); |
| <span class="macro">assert_eq!</span>(val, deser_val.<span class="number">0</span>); |
| } |
| |
| <span class="attribute">#[test] |
| </span><span class="kw">fn </span>test_vint_u128() { |
| aux_test_vint_u128(<span class="number">0</span>); |
| aux_test_vint_u128(<span class="number">1</span>); |
| aux_test_vint_u128(u128::MAX / <span class="number">3</span>); |
| aux_test_vint_u128(u128::MAX); |
| } |
| |
| <span class="attribute">#[test] |
| </span><span class="kw">fn </span>test_vint_u32() { |
| aux_test_serialize_vint_u32(<span class="number">0</span>); |
| aux_test_serialize_vint_u32(<span class="number">1</span>); |
| aux_test_serialize_vint_u32(<span class="number">5</span>); |
| <span class="kw">for </span>i <span class="kw">in </span><span class="number">1</span>..<span class="number">3 </span>{ |
| <span class="kw">let </span>power_of_128 = <span class="number">1u32 </span><< (<span class="number">7 </span>* i); |
| aux_test_serialize_vint_u32(power_of_128 - <span class="number">1u32</span>); |
| aux_test_serialize_vint_u32(power_of_128); |
| aux_test_serialize_vint_u32(power_of_128 + <span class="number">1u32</span>); |
| } |
| aux_test_serialize_vint_u32(u32::MAX); |
| } |
| } |
| </code></pre></div> |
| </section></div></main><div id="rustdoc-vars" data-root-path="../../" data-current-crate="tantivy_common" data-themes="ayu,dark,light" data-resource-suffix="" data-rustdoc-version="1.66.0-nightly (5c8bff74b 2022-10-21)" ></div></body></html> |
