macros-header.html

<script>
(function () {
  (function forceRevealMathJax3() {
    const prior = Object.prototype.hasOwnProperty.call(window, "RevealMath")
      ? window.RevealMath
      : undefined;

    let revealMathValue;
    Object.defineProperty(window, "RevealMath", {
      configurable: true,
      enumerable: true,
      get() {
        return revealMathValue;
      },
      set(value) {
        if (value && typeof value.MathJax3 === "function") {
          revealMathValue = value.MathJax3();
        } else {
          revealMathValue = value;
        }
      },
    });

    if (prior !== undefined) {
      window.RevealMath = prior;
    }
  })();

  const macroSources = ["macros.qmd", "macros/macros.qmd"];

  function extractBraceContent(text, startIndex) {
    if (text[startIndex] !== "{") return null;
    let depth = 0;
    const isEscaped = (index) => {
      let backslashes = 0;
      for (let j = index - 1; j >= 0 && text[j] === "\\"; j -= 1) backslashes += 1;
      return backslashes % 2 === 1;
    };

    for (let i = startIndex; i < text.length; i += 1) {
      const ch = text[i];
      if (ch === "{" && !isEscaped(i)) depth += 1;
      if (ch === "}" && !isEscaped(i)) {
        depth -= 1;
        if (depth === 0) {
          return { content: text.slice(startIndex + 1, i), nextIndex: i + 1 };
        }
      }
    }

    return null;
  }

  function parseDef(line, macros) {
    if (!line.startsWith("\\def\\")) return false;

    let index = "\\def\\".length;
    let name = "";

    while (index < line.length && !/[\s{]/.test(line[index])) {
      name += line[index];
      index += 1;
    }

    while (index < line.length && /\s/.test(line[index])) index += 1;
    const body = extractBraceContent(line, index);
    if (!name || !body) return false;

    const argMatches = [...body.content.matchAll(/#(\d+)/g)].map((m) => Number(m[1]));
    const argc = argMatches.length ? Math.max(...argMatches) : 0;
    macros[name] = argc > 0 ? [body.content, argc] : body.content;
    return true;
  }

  function parseCommand(line, macros) {
    const commandMatch = line.match(/^\\(providecommand|newcommand|renewcommand)/);
    if (!commandMatch) return false;

    let index = commandMatch[0].length;
    while (index < line.length && /\s/.test(line[index])) index += 1;

    const nameBlock = extractBraceContent(line, index);
    if (!nameBlock || !nameBlock.content.startsWith("\\")) return false;
    const name = nameBlock.content.slice(1);
    index = nameBlock.nextIndex;

    while (index < line.length && /\s/.test(line[index])) index += 1;

    let argc = 0;
    if (line[index] === "[") {
      const close = line.indexOf("]", index + 1);
      if (close === -1) return false;
      argc = Number(line.slice(index + 1, close)) || 0;
      index = close + 1;
    }

    while (index < line.length && /\s/.test(line[index])) index += 1;

    const body = extractBraceContent(line, index);
    if (!body) return false;

    macros[name] = argc > 0 ? [body.content, argc] : body.content;
    return true;
  }

  function parseMacros(sourceText) {
    const macros = {};
    const commandStart = /^\\(def|providecommand|newcommand|renewcommand)\b/;

    function braceBalance(text) {
      let balance = 0;
      let backslashes = 0;

      for (let i = 0; i < text.length; i++) {
        const ch = text[i];
        if (ch === "\\") {
          backslashes += 1;
          continue;
        }

        const escaped = backslashes % 2 === 1;
        backslashes = 0;

        if (ch === "{" && !escaped) balance += 1;
        if (ch === "}" && !escaped) balance -= 1;
      }

      return balance;
    }

    let current = "";

    for (const rawLine of sourceText.split(/\r?\n/)) {
      const line = rawLine.trim();
      if (!line || line.startsWith("%") || line.startsWith("<!--")) continue;

      if (current || commandStart.test(line)) {
        current = current ? `${current}\n${line}` : line;
      } else {
        continue;
      }

      const balance = braceBalance(current);
      if (balance < 0) {
        current = "";
        continue;
      }
      if (balance !== 0) continue;

      if (parseDef(current, macros)) {
        current = "";
        continue;
      }

      parseCommand(current, macros);
      current = "";
    }

    return macros;
  }

  async function loadMacroSource() {
    for (const path of macroSources) {
      try {
        const response = await fetch(path, { cache: "default" });
        if (response.ok) return await response.text();
      } catch (_) {
        // try next path
      }
    }

    throw new Error("Unable to load macros.qmd from known paths");
  }

  function applyMacros(parsed) {
    window.MathJax = window.MathJax || {};
    const skipTags = ["script", "noscript", "style", "textarea", "pre", "code"];

    window.MathJax.tex = window.MathJax.tex || {};
    window.MathJax.tex.macros = Object.assign({}, window.MathJax.tex.macros || {}, parsed);
    window.MathJax.options = window.MathJax.options || {};
    const existingSkipTags = Array.isArray(window.MathJax.options.skipHtmlTags)
      ? window.MathJax.options.skipHtmlTags
      : [];
    window.MathJax.options.skipHtmlTags = Array.from(new Set([...existingSkipTags, ...skipTags]));
    window.MathJax.config = window.MathJax.config || {};
    window.MathJax.config.tex = window.MathJax.config.tex || {};
    window.MathJax.config.tex.macros = Object.assign(
      {},
      window.MathJax.config.tex.macros || {},
      parsed
    );

    window.MathJax.TeX = window.MathJax.TeX || {};
    window.MathJax.TeX.Macros = Object.assign({}, window.MathJax.TeX.Macros || {}, parsed);

    if (window.MathJax.Hub && window.MathJax.Hub.Config) {
      window.MathJax.Hub.Config({
        TeX: { Macros: window.MathJax.TeX.Macros },
        tex2jax: { skipTags: skipTags },
      });
    }
  }

  window.MathJax = window.MathJax || {};
  window.MathJax.delayStartupUntil = window.MathJax.delayStartupUntil || "configured";
  window.MathJax.startup = window.MathJax.startup || {};

  const sourcePromise = loadMacroSource();
  const priorReady = window.MathJax.startup.ready;

  window.MathJax.startup.ready = async () => {
    try {
      applyMacros(parseMacros(await sourcePromise));
    } catch (error) {
      console.warn("[macros-header] Failed to load macros.qmd for MathJax:", error);
    }

    if (typeof priorReady === "function") {
      return priorReady();
    }

    if (window.MathJax.startup.defaultReady) {
      return window.MathJax.startup.defaultReady();
    }
  };

  sourcePromise
    .then((sourceText) => {
      applyMacros(parseMacros(sourceText));
      if (window.MathJax.Hub && window.MathJax.Hub.Configured) {
        window.MathJax.Hub.Configured();
      }
    })
    .catch((error) => {
      console.warn("[macros-header] Failed to load macros.qmd for MathJax:", error);
      if (window.MathJax.Hub && window.MathJax.Hub.Configured) {
        window.MathJax.Hub.Configured();
      }
    });
})();
</script>