mirror of https://github.com/Wilfred/difftastic/
270 lines
15 KiB
HTML
270 lines
15 KiB
HTML
<!DOCTYPE HTML>
|
|
<html lang="en" class="light" dir="ltr">
|
|
<head>
|
|
<!-- Book generated using mdBook -->
|
|
<meta charset="UTF-8">
|
|
<title>Introduction - Difftastic Manual</title>
|
|
|
|
|
|
<!-- Custom HTML head -->
|
|
|
|
<meta name="description" content="The manual for difftastic, the structural diff tool">
|
|
<meta name="viewport" content="width=device-width, initial-scale=1">
|
|
<meta name="theme-color" content="#ffffff">
|
|
|
|
<link rel="icon" href="favicon.svg">
|
|
<link rel="stylesheet" href="css/variables.css">
|
|
<link rel="stylesheet" href="css/general.css">
|
|
<link rel="stylesheet" href="css/chrome.css">
|
|
<link rel="stylesheet" href="css/print.css" media="print">
|
|
|
|
<!-- Fonts -->
|
|
<link rel="stylesheet" href="FontAwesome/css/font-awesome.css">
|
|
<link rel="stylesheet" href="fonts/fonts.css">
|
|
|
|
<!-- Highlight.js Stylesheets -->
|
|
<link rel="stylesheet" href="highlight.css">
|
|
<link rel="stylesheet" href="tomorrow-night.css">
|
|
<link rel="stylesheet" href="ayu-highlight.css">
|
|
|
|
<!-- Custom theme stylesheets -->
|
|
|
|
</head>
|
|
<body class="sidebar-visible no-js">
|
|
<div id="body-container">
|
|
<!-- Provide site root to javascript -->
|
|
<script>
|
|
var path_to_root = "";
|
|
var default_theme = window.matchMedia("(prefers-color-scheme: dark)").matches ? "navy" : "light";
|
|
</script>
|
|
|
|
<!-- Work around some values being stored in localStorage wrapped in quotes -->
|
|
<script>
|
|
try {
|
|
var theme = localStorage.getItem('mdbook-theme');
|
|
var sidebar = localStorage.getItem('mdbook-sidebar');
|
|
|
|
if (theme.startsWith('"') && theme.endsWith('"')) {
|
|
localStorage.setItem('mdbook-theme', theme.slice(1, theme.length - 1));
|
|
}
|
|
|
|
if (sidebar.startsWith('"') && sidebar.endsWith('"')) {
|
|
localStorage.setItem('mdbook-sidebar', sidebar.slice(1, sidebar.length - 1));
|
|
}
|
|
} catch (e) { }
|
|
</script>
|
|
|
|
<!-- Set the theme before any content is loaded, prevents flash -->
|
|
<script>
|
|
var theme;
|
|
try { theme = localStorage.getItem('mdbook-theme'); } catch(e) { }
|
|
if (theme === null || theme === undefined) { theme = default_theme; }
|
|
var html = document.querySelector('html');
|
|
html.classList.remove('light')
|
|
html.classList.add(theme);
|
|
var body = document.querySelector('body');
|
|
body.classList.remove('no-js')
|
|
body.classList.add('js');
|
|
</script>
|
|
|
|
<input type="checkbox" id="sidebar-toggle-anchor" class="hidden">
|
|
|
|
<!-- Hide / unhide sidebar before it is displayed -->
|
|
<script>
|
|
var body = document.querySelector('body');
|
|
var sidebar = null;
|
|
var sidebar_toggle = document.getElementById("sidebar-toggle-anchor");
|
|
if (document.body.clientWidth >= 1080) {
|
|
try { sidebar = localStorage.getItem('mdbook-sidebar'); } catch(e) { }
|
|
sidebar = sidebar || 'visible';
|
|
} else {
|
|
sidebar = 'hidden';
|
|
}
|
|
sidebar_toggle.checked = sidebar === 'visible';
|
|
body.classList.remove('sidebar-visible');
|
|
body.classList.add("sidebar-" + sidebar);
|
|
</script>
|
|
|
|
<nav id="sidebar" class="sidebar" aria-label="Table of contents">
|
|
<div class="sidebar-scrollbox">
|
|
<ol class="chapter"><li class="chapter-item expanded "><a href="introduction.html" class="active"><strong aria-hidden="true">1.</strong> Introduction</a></li><li class="chapter-item expanded "><a href="installation.html"><strong aria-hidden="true">2.</strong> Installation</a></li><li><ol class="section"><li class="chapter-item expanded "><a href="from_source.html"><strong aria-hidden="true">2.1.</strong> From Source</a></li><li class="chapter-item expanded "><a href="packaging_difftastic.html"><strong aria-hidden="true">2.2.</strong> Packaging Difftastic</a></li></ol></li><li class="chapter-item expanded "><a href="usage.html"><strong aria-hidden="true">3.</strong> Usage</a></li><li><ol class="section"><li class="chapter-item expanded "><a href="git.html"><strong aria-hidden="true">3.1.</strong> Git</a></li><li class="chapter-item expanded "><a href="mercurial.html"><strong aria-hidden="true">3.2.</strong> Mercurial</a></li><li class="chapter-item expanded "><a href="fossil.html"><strong aria-hidden="true">3.3.</strong> Fossil</a></li><li class="chapter-item expanded "><a href="jj.html"><strong aria-hidden="true">3.4.</strong> Jujutsu</a></li></ol></li><li class="chapter-item expanded "><a href="languages_supported.html"><strong aria-hidden="true">4.</strong> Languages Supported</a></li><li><ol class="section"><li class="chapter-item expanded "><a href="language_detection.html"><strong aria-hidden="true">4.1.</strong> Language Detection</a></li></ol></li><li class="chapter-item expanded "><a href="parsing.html"><strong aria-hidden="true">5.</strong> Internals: Parsing</a></li><li class="chapter-item expanded "><a href="diffing.html"><strong aria-hidden="true">6.</strong> Internals: Diffing</a></li><li><ol class="section"><li class="chapter-item expanded "><a href="tricky_cases.html"><strong aria-hidden="true">6.1.</strong> Tricky Cases</a></li></ol></li><li class="chapter-item expanded "><a href="contributing.html"><strong aria-hidden="true">7.</strong> Contributing</a></li><li><ol class="section"><li class="chapter-item expanded "><a href="adding_a_parser.html"><strong aria-hidden="true">7.1.</strong> Adding A Parser</a></li><li class="chapter-item expanded "><a href="parser_vendoring.html"><strong aria-hidden="true">7.2.</strong> Parser Vendoring</a></li><li class="chapter-item expanded "><a href="profiling.html"><strong aria-hidden="true">7.3.</strong> Profiling</a></li></ol></li><li class="chapter-item expanded "><a href="glossary.html"><strong aria-hidden="true">8.</strong> Glossary</a></li><li class="chapter-item expanded "><a href="alternative_projects.html"><strong aria-hidden="true">9.</strong> Alternative Projects</a></li><li><ol class="section"><li class="chapter-item expanded "><a href="tree_diffing.html"><strong aria-hidden="true">9.1.</strong> Tree Diffing</a></li></ol></li></ol>
|
|
</div>
|
|
<div id="sidebar-resize-handle" class="sidebar-resize-handle">
|
|
<div class="sidebar-resize-indicator"></div>
|
|
</div>
|
|
</nav>
|
|
|
|
<!-- Track and set sidebar scroll position -->
|
|
<script>
|
|
var sidebarScrollbox = document.querySelector('#sidebar .sidebar-scrollbox');
|
|
sidebarScrollbox.addEventListener('click', function(e) {
|
|
if (e.target.tagName === 'A') {
|
|
sessionStorage.setItem('sidebar-scroll', sidebarScrollbox.scrollTop);
|
|
}
|
|
}, { passive: true });
|
|
var sidebarScrollTop = sessionStorage.getItem('sidebar-scroll');
|
|
sessionStorage.removeItem('sidebar-scroll');
|
|
if (sidebarScrollTop) {
|
|
// preserve sidebar scroll position when navigating via links within sidebar
|
|
sidebarScrollbox.scrollTop = sidebarScrollTop;
|
|
} else {
|
|
// scroll sidebar to current active section when navigating via "next/previous chapter" buttons
|
|
var activeSection = document.querySelector('#sidebar .active');
|
|
if (activeSection) {
|
|
activeSection.scrollIntoView({ block: 'center' });
|
|
}
|
|
}
|
|
</script>
|
|
|
|
<div id="page-wrapper" class="page-wrapper">
|
|
|
|
<div class="page">
|
|
<div id="menu-bar-hover-placeholder"></div>
|
|
<div id="menu-bar" class="menu-bar sticky">
|
|
<div class="left-buttons">
|
|
<label id="sidebar-toggle" class="icon-button" for="sidebar-toggle-anchor" title="Toggle Table of Contents" aria-label="Toggle Table of Contents" aria-controls="sidebar">
|
|
<i class="fa fa-bars"></i>
|
|
</label>
|
|
<button id="theme-toggle" class="icon-button" type="button" title="Change theme" aria-label="Change theme" aria-haspopup="true" aria-expanded="false" aria-controls="theme-list">
|
|
<i class="fa fa-paint-brush"></i>
|
|
</button>
|
|
<ul id="theme-list" class="theme-popup" aria-label="Themes" role="menu">
|
|
<li role="none"><button role="menuitem" class="theme" id="light">Light</button></li>
|
|
<li role="none"><button role="menuitem" class="theme" id="rust">Rust</button></li>
|
|
<li role="none"><button role="menuitem" class="theme" id="coal">Coal</button></li>
|
|
<li role="none"><button role="menuitem" class="theme" id="navy">Navy</button></li>
|
|
<li role="none"><button role="menuitem" class="theme" id="ayu">Ayu</button></li>
|
|
</ul>
|
|
<button id="search-toggle" class="icon-button" type="button" title="Search. (Shortkey: s)" aria-label="Toggle Searchbar" aria-expanded="false" aria-keyshortcuts="S" aria-controls="searchbar">
|
|
<i class="fa fa-search"></i>
|
|
</button>
|
|
</div>
|
|
|
|
<h1 class="menu-title">Difftastic Manual</h1>
|
|
|
|
<div class="right-buttons">
|
|
<a href="print.html" title="Print this book" aria-label="Print this book">
|
|
<i id="print-button" class="fa fa-print"></i>
|
|
</a>
|
|
<a href="https://github.com/wilfred/difftastic" title="Git repository" aria-label="Git repository">
|
|
<i id="git-repository-button" class="fa fa-github"></i>
|
|
</a>
|
|
|
|
</div>
|
|
</div>
|
|
|
|
<div id="search-wrapper" class="hidden">
|
|
<form id="searchbar-outer" class="searchbar-outer">
|
|
<input type="search" id="searchbar" name="searchbar" placeholder="Search this book ..." aria-controls="searchresults-outer" aria-describedby="searchresults-header">
|
|
</form>
|
|
<div id="searchresults-outer" class="searchresults-outer hidden">
|
|
<div id="searchresults-header" class="searchresults-header"></div>
|
|
<ul id="searchresults">
|
|
</ul>
|
|
</div>
|
|
</div>
|
|
|
|
<!-- Apply ARIA attributes after the sidebar and the sidebar toggle button are added to the DOM -->
|
|
<script>
|
|
document.getElementById('sidebar-toggle').setAttribute('aria-expanded', sidebar === 'visible');
|
|
document.getElementById('sidebar').setAttribute('aria-hidden', sidebar !== 'visible');
|
|
Array.from(document.querySelectorAll('#sidebar a')).forEach(function(link) {
|
|
link.setAttribute('tabIndex', sidebar === 'visible' ? 0 : -1);
|
|
});
|
|
</script>
|
|
|
|
<div id="content" class="content">
|
|
<main>
|
|
<h1 id="introduction"><a class="header" href="#introduction">Introduction</a></h1>
|
|
<p>Difftastic is a structural diff tool that understands syntax. It
|
|
supports <a href="./languages_supported.html">over 30 programming languages</a>
|
|
and when it works, it's <em>fantastic</em>.</p>
|
|
<p>Difftastic is open source software (MIT license) and <a href="https://github.com/wilfred/difftastic">available on
|
|
GitHub</a>.</p>
|
|
<p>This copy of the manual describes version 0.68.0. The
|
|
<a href="https://github.com/Wilfred/difftastic/blob/master/CHANGELOG.md">changelog</a>
|
|
records which features and bug fixes are in each version.</p>
|
|
<p><em>This manual is also available in <a href="https://difftastic.wilfred.me.uk/zh-CN/">Chinese</a>.</em></p>
|
|
<h2 id="syntactic-diffing"><a class="header" href="#syntactic-diffing">Syntactic Diffing</a></h2>
|
|
<p>Difftastic <a href="./usage.html#language-detection">detects the language</a>, parses the code, and then
|
|
compares the syntax trees. Let's look at an example.</p>
|
|
<pre><code>// old.rs
|
|
let ts_lang = guess(path, guess_src).map(tsp::from_language);
|
|
</code></pre>
|
|
<pre><code>// new.rs
|
|
let ts_lang = language_override
|
|
.or_else(|| guess(path, guess_src))
|
|
.map(tsp::from_language);
|
|
</code></pre>
|
|
<pre><code style="display:block">$ difft old.rs new.rs
|
|
|
|
1 <span style="background-color: PaleGreen; color: #000">1</span> let ts_lang = <span style="background-color: PaleGreen; color: #000">language_override</span>
|
|
. <span style="background-color: PaleGreen; color: #000">2</span> <span style="background-color: PaleGreen; color: #000">.or_else(||</span> guess(path, guess_src)<span style="background-color: PaleGreen; color: #000">)</span>
|
|
. 3 .map(tsp::from_language);
|
|
</code>
|
|
</pre>
|
|
<p>Notice how difftastic recognises that <code>.map</code> is unchanged, even though
|
|
it's now on a new line with whitespace.</p>
|
|
<p>A line-oriented diff does a much worse job here.</p>
|
|
<pre><code style="display:block">$ diff -u old.rs new.rs
|
|
|
|
@@ -1 +1,3 @@
|
|
<span style="background-color: #fbbd98; color: #000">-let ts_lang = guess(path, guess_src).map(tsp::from_language);</span>
|
|
<span style="background-color: PaleGreen; color: #000">+let ts_lang = language_override
|
|
+ .or_else(|| guess(path, guess_src))
|
|
+ .map(tsp::from_language);</span>
|
|
</code>
|
|
</pre>
|
|
<p>Some line-oriented diff tools also highlight word changes (e.g. GitHub
|
|
or git's <code>--word-diff</code>). They still don't understand the code
|
|
though. Difftastic will always find matched delimiters: you can see
|
|
the closing <code>)</code> from <code>or_else</code> has been highlighted.</p>
|
|
<h2 id="fallback-line-oriented-diffing"><a class="header" href="#fallback-line-oriented-diffing">Fallback Line-Oriented Diffing</a></h2>
|
|
<p>If input files are not in a format that difftastic understands, it
|
|
uses a conventional line-oriented diff with word highlighting.</p>
|
|
<p>Difftastic will also use line-oriented diffing when given extremely
|
|
large inputs.</p>
|
|
|
|
</main>
|
|
|
|
<nav class="nav-wrapper" aria-label="Page navigation">
|
|
<!-- Mobile navigation buttons -->
|
|
|
|
<a rel="next prefetch" href="installation.html" class="mobile-nav-chapters next" title="Next chapter" aria-label="Next chapter" aria-keyshortcuts="Right">
|
|
<i class="fa fa-angle-right"></i>
|
|
</a>
|
|
|
|
<div style="clear: both"></div>
|
|
</nav>
|
|
</div>
|
|
</div>
|
|
|
|
<nav class="nav-wide-wrapper" aria-label="Page navigation">
|
|
|
|
<a rel="next prefetch" href="installation.html" class="nav-chapters next" title="Next chapter" aria-label="Next chapter" aria-keyshortcuts="Right">
|
|
<i class="fa fa-angle-right"></i>
|
|
</a>
|
|
</nav>
|
|
|
|
</div>
|
|
|
|
|
|
|
|
|
|
|
|
|
|
<script src="elasticlunr.min.js"></script>
|
|
<script src="mark.min.js"></script>
|
|
<script src="searcher.js"></script>
|
|
|
|
<script src="clipboard.min.js"></script>
|
|
<script src="highlight.js"></script>
|
|
<script src="book.js"></script>
|
|
|
|
<!-- Custom JS scripts -->
|
|
|
|
|
|
</div>
|
|
</body>
|
|
</html>
|