AtCoderのシンタックスハイライトをちゃんと言語に応じて動作させるUserScriptです

atcoder-code-prettify.user.js

// ==UserScript==
// @name      AtCoder Code Prettify
// @namespace https://miz-ar.info/
// @include   https://atcoder.jp/contests/*/submissions/*
// @version   3
// @grant     none
// @run-at    document-start
// ==/UserScript==

console.debug("AtCoder Code Prettify is running");

const getElementByXPath = function getElementByXPath(x,root) {
    let r = document.evaluate(x,root||document,null,XPathResult.ORDERED_NODE_SNAPSHOT_TYPE,null);
    return r.snapshotItem(0);
};

const PRETTIFY_BASE_URL = "https://cdn.jsdelivr.net/gh/google/code-prettify@master/loader/";

const INCLUDED_BY_DEFAULT = ["c", "cpp", "java", "cs", "m", "sh", "py", "pl", "rb", "js"];
const NAME_TO_EXT = {
    // Non-default languages:
    "C": "c",
    "C++": "cpp",
    "Java": "java",
    "Python": "py",
    "Bash": "sh",
    "bc": null,
    "Awk": null,
    "C#": "cs",
    "Clojure": "clj",
    "Crystal": null,
    "D": null,
    "Dart": "dart",
    "dc": null,
    "Erlang": "erlang",
    "Elixir": "ex",
    "F#": "ml.fs",
    "Forth": null,
    "Fortran": null,
    "Go": "go",
    "Haskell": "hs",
    "Haxe": null,
    "JavaScript": "js",
    "Julia": null,
    "Kotlin": "kotlin",
    "Lua": "lua",
    "Dash": "sh",
    "Nim": null,
    "Common Lisp": "cl",
    "Objective-C": "m",
    "OCaml": "ml",
    "Octave": null,
    "Pascal": "pascal",
    "Perl": "pl",
    "Raku": null,
    "PHP": null,
    "Prolog": null,
    "PyPy2": "py",
    "PyPy3": "py",
    "Racket": "lisp.rkt",
    "Ruby": "rb",
    "Rust": "rust",
    "Scala": "scala",
    "Scheme": "lisp.scm",
    "Standard ML": "ml.ml", // Re-using OCaml
    "Swift": "swift",
    "Text": null, // not needed
    "TypeScript": "js",
    "Visual Basic": "vb",
    "Zsh": "sh",
    "COBOL - Fixed": null,
    "COBOL - Free": null,
    "Brainfuck": null,
    "Ada2012": null,
    "Unlambda": null,
    "Cython": "py",
    "Sed": null,
    "Vim": null,
};

const main = () => {
    let submissionCode = document.getElementById("submission-code");
    if (!submissionCode) {
        return;
    }
    try {
        let languageTd = getElementByXPath("/html/body/div[3]/div/div[1]/div[2]/div[3]/table/tbody/tr[4]/td");
        if (!languageTd) {
            console.log("<td> not found");
            return;
        }
        let languageAndCompiler = languageTd.firstChild ? languageTd.firstChild.textContent : null;
        if (!languageAndCompiler) {
            console.log("language and compiler not found");
            return;
        }
        let m = languageAndCompiler.match(/([\w+#\- ]+) \(/);
        if (!m) {
            console.log("regexp for language did not match");
            return;
        }
        let language = m[1];
        let mext = NAME_TO_EXT[language];
        if (mext) {
            let mod_ext = mext.match(/^\w+\.\w+$/);
            let mod, ext;
            if (mod_ext) {
                mod = mod_ext[1];
                ext = mod_ext[2];
            } else {
                mod = ext = mext;
            }
            submissionCode.classList.add("lang-" + ext);
            if (INCLUDED_BY_DEFAULT.indexOf(ext) === -1) {
                let script = document.createElement("script");
                script.src = `${PRETTIFY_BASE_URL}lang-${mod}.js`;
                console.log("AtCoder Prettify: Loading ", script.src);
                document.body.appendChild(script);
            }
        } else {
            console.log(`AtCoder Prettify: ${language} is not supported.`);
        }
    } catch (e) {
        console.error("AtCoder Prettify:", e);
    }
};

if (document.readyState === "loading") {
    console.debug("AtCoder Code Prettify: Setting DOMContentLoaded");
    window.addEventListener("DOMContentLoaded", main);
} else {
    console.debug("AtCoder Code Prettify: Running immediately");
    main();
}