| <!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/unicode-bidi-0.3.13/src/explicit.rs`."><meta name="keywords" content="rust, rustlang, rust-lang"><title>explicit.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="../../unicode_bidi/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="../../unicode_bidi/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="comment">// Copyright 2015 The Servo Project Developers. See the |
| // COPYRIGHT file at the top-level directory of this distribution. |
| // |
| // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or |
| // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license |
| // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your |
| // option. This file may not be copied, modified, or distributed |
| // except according to those terms. |
| |
| </span><span class="doccomment">//! 3.3.2 Explicit Levels and Directions |
| //! |
| //! <http://www.unicode.org/reports/tr9/#Explicit_Levels_and_Directions> |
| |
| </span><span class="kw">use </span>alloc::vec::Vec; |
| |
| <span class="kw">use </span><span class="kw">super</span>::char_data::{ |
| is_rtl, |
| BidiClass::{<span class="self">self</span>, <span class="kw-2">*</span>}, |
| }; |
| <span class="kw">use </span><span class="kw">super</span>::level::Level; |
| |
| <span class="doccomment">/// Compute explicit embedding levels for one paragraph of text (X1-X8). |
| /// |
| /// `processing_classes[i]` must contain the `BidiClass` of the char at byte index `i`, |
| /// for each char in `text`. |
| </span><span class="attribute">#[cfg_attr(feature = <span class="string">"flame_it"</span>, flamer::flame)] |
| </span><span class="kw">pub fn </span>compute( |
| text: <span class="kw-2">&</span>str, |
| para_level: Level, |
| original_classes: <span class="kw-2">&</span>[BidiClass], |
| levels: <span class="kw-2">&mut </span>[Level], |
| processing_classes: <span class="kw-2">&mut </span>[BidiClass], |
| ) { |
| <span class="macro">assert_eq!</span>(text.len(), original_classes.len()); |
| |
| <span class="comment">// <http://www.unicode.org/reports/tr9/#X1> |
| </span><span class="kw">let </span><span class="kw-2">mut </span>stack = DirectionalStatusStack::new(); |
| stack.push(para_level, OverrideStatus::Neutral); |
| |
| <span class="kw">let </span><span class="kw-2">mut </span>overflow_isolate_count = <span class="number">0u32</span>; |
| <span class="kw">let </span><span class="kw-2">mut </span>overflow_embedding_count = <span class="number">0u32</span>; |
| <span class="kw">let </span><span class="kw-2">mut </span>valid_isolate_count = <span class="number">0u32</span>; |
| |
| <span class="kw">for </span>(i, c) <span class="kw">in </span>text.char_indices() { |
| <span class="kw">match </span>original_classes[i] { |
| <span class="comment">// Rules X2-X5c |
| </span>RLE | LRE | RLO | LRO | RLI | LRI | FSI => { |
| <span class="kw">let </span>last_level = stack.last().level; |
| |
| <span class="comment">// <https://www.unicode.org/reports/tr9/#Retaining_Explicit_Formatting_Characters> |
| </span>levels[i] = last_level; |
| |
| <span class="comment">// X5a-X5c: Isolate initiators get the level of the last entry on the stack. |
| </span><span class="kw">let </span>is_isolate = <span class="kw">match </span>original_classes[i] { |
| RLI | LRI | FSI => <span class="bool-val">true</span>, |
| <span class="kw">_ </span>=> <span class="bool-val">false</span>, |
| }; |
| <span class="kw">if </span>is_isolate { |
| <span class="comment">// Redundant due to "Retaining explicit formatting characters" step. |
| // levels[i] = last_level; |
| </span><span class="kw">match </span>stack.last().status { |
| OverrideStatus::RTL => processing_classes[i] = R, |
| OverrideStatus::LTR => processing_classes[i] = L, |
| <span class="kw">_ </span>=> {} |
| } |
| } |
| |
| <span class="kw">let </span>new_level = <span class="kw">if </span>is_rtl(original_classes[i]) { |
| last_level.new_explicit_next_rtl() |
| } <span class="kw">else </span>{ |
| last_level.new_explicit_next_ltr() |
| }; |
| <span class="kw">if </span>new_level.is_ok() && overflow_isolate_count == <span class="number">0 </span>&& overflow_embedding_count == <span class="number">0 |
| </span>{ |
| <span class="kw">let </span>new_level = new_level.unwrap(); |
| stack.push( |
| new_level, |
| <span class="kw">match </span>original_classes[i] { |
| RLO => OverrideStatus::RTL, |
| LRO => OverrideStatus::LTR, |
| RLI | LRI | FSI => OverrideStatus::Isolate, |
| <span class="kw">_ </span>=> OverrideStatus::Neutral, |
| }, |
| ); |
| <span class="kw">if </span>is_isolate { |
| valid_isolate_count += <span class="number">1</span>; |
| } <span class="kw">else </span>{ |
| <span class="comment">// The spec doesn't explicitly mention this step, but it is necessary. |
| // See the reference implementations for comparison. |
| </span>levels[i] = new_level; |
| } |
| } <span class="kw">else if </span>is_isolate { |
| overflow_isolate_count += <span class="number">1</span>; |
| } <span class="kw">else if </span>overflow_isolate_count == <span class="number">0 </span>{ |
| overflow_embedding_count += <span class="number">1</span>; |
| } |
| |
| <span class="kw">if </span>!is_isolate { |
| <span class="comment">// X9 + |
| // <https://www.unicode.org/reports/tr9/#Retaining_Explicit_Formatting_Characters> |
| // (PDF handled below) |
| </span>processing_classes[i] = BN; |
| } |
| } |
| |
| <span class="comment">// <http://www.unicode.org/reports/tr9/#X6a> |
| </span>PDI => { |
| <span class="kw">if </span>overflow_isolate_count > <span class="number">0 </span>{ |
| overflow_isolate_count -= <span class="number">1</span>; |
| } <span class="kw">else if </span>valid_isolate_count > <span class="number">0 </span>{ |
| overflow_embedding_count = <span class="number">0</span>; |
| <span class="kw">loop </span>{ |
| <span class="comment">// Pop everything up to and including the last Isolate status. |
| </span><span class="kw">match </span>stack.vec.pop() { |
| <span class="prelude-val">None |
| </span>| <span class="prelude-val">Some</span>(Status { |
| status: OverrideStatus::Isolate, |
| .. |
| }) => <span class="kw">break</span>, |
| <span class="kw">_ </span>=> <span class="kw">continue</span>, |
| } |
| } |
| valid_isolate_count -= <span class="number">1</span>; |
| } |
| <span class="kw">let </span>last = stack.last(); |
| levels[i] = last.level; |
| <span class="kw">match </span>last.status { |
| OverrideStatus::RTL => processing_classes[i] = R, |
| OverrideStatus::LTR => processing_classes[i] = L, |
| <span class="kw">_ </span>=> {} |
| } |
| } |
| |
| <span class="comment">// <http://www.unicode.org/reports/tr9/#X7> |
| </span>PDF => { |
| <span class="kw">if </span>overflow_isolate_count > <span class="number">0 </span>{ |
| <span class="comment">// do nothing |
| </span>} <span class="kw">else if </span>overflow_embedding_count > <span class="number">0 </span>{ |
| overflow_embedding_count -= <span class="number">1</span>; |
| } <span class="kw">else if </span>stack.last().status != OverrideStatus::Isolate && stack.vec.len() >= <span class="number">2 </span>{ |
| stack.vec.pop(); |
| } |
| <span class="comment">// <https://www.unicode.org/reports/tr9/#Retaining_Explicit_Formatting_Characters> |
| </span>levels[i] = stack.last().level; |
| <span class="comment">// X9 part of retaining explicit formatting characters. |
| </span>processing_classes[i] = BN; |
| } |
| |
| <span class="comment">// Nothing. |
| // BN case moved down to X6, see <https://www.unicode.org/reports/tr9/#Retaining_Explicit_Formatting_Characters> |
| </span>B => {} |
| |
| <span class="comment">// <http://www.unicode.org/reports/tr9/#X6> |
| </span><span class="kw">_ </span>=> { |
| <span class="kw">let </span>last = stack.last(); |
| levels[i] = last.level; |
| <span class="comment">// This condition is not in the spec, but I am pretty sure that is a spec bug. |
| // https://www.unicode.org/L2/L2023/23014-amd-to-uax9.pdf |
| </span><span class="kw">if </span>original_classes[i] != BN { |
| <span class="kw">match </span>last.status { |
| OverrideStatus::RTL => processing_classes[i] = R, |
| OverrideStatus::LTR => processing_classes[i] = L, |
| <span class="kw">_ </span>=> {} |
| } |
| } |
| } |
| } |
| |
| <span class="comment">// Handle multi-byte characters. |
| </span><span class="kw">for </span>j <span class="kw">in </span><span class="number">1</span>..c.len_utf8() { |
| levels[i + j] = levels[i]; |
| processing_classes[i + j] = processing_classes[i]; |
| } |
| } |
| } |
| |
| <span class="doccomment">/// Entries in the directional status stack: |
| </span><span class="kw">struct </span>Status { |
| level: Level, |
| status: OverrideStatus, |
| } |
| |
| <span class="attribute">#[derive(PartialEq)] |
| </span><span class="kw">enum </span>OverrideStatus { |
| Neutral, |
| RTL, |
| LTR, |
| Isolate, |
| } |
| |
| <span class="kw">struct </span>DirectionalStatusStack { |
| vec: Vec<Status>, |
| } |
| |
| <span class="kw">impl </span>DirectionalStatusStack { |
| <span class="kw">fn </span>new() -> <span class="self">Self </span>{ |
| DirectionalStatusStack { |
| vec: Vec::with_capacity(Level::max_explicit_depth() <span class="kw">as </span>usize + <span class="number">2</span>), |
| } |
| } |
| |
| <span class="kw">fn </span>push(<span class="kw-2">&mut </span><span class="self">self</span>, level: Level, status: OverrideStatus) { |
| <span class="self">self</span>.vec.push(Status { level, status }); |
| } |
| |
| <span class="kw">fn </span>last(<span class="kw-2">&</span><span class="self">self</span>) -> <span class="kw-2">&</span>Status { |
| <span class="self">self</span>.vec.last().unwrap() |
| } |
| } |
| </code></pre></div> |
| </section></div></main><div id="rustdoc-vars" data-root-path="../../" data-current-crate="unicode_bidi" data-themes="ayu,dark,light" data-resource-suffix="" data-rustdoc-version="1.66.0-nightly (5c8bff74b 2022-10-21)" ></div></body></html> |
