Method _getExpansion

static/katex/katex.mjs:14122–14162

* Returns the expanded macro as a reversed array of tokens and a macro * argument count. Or returns `null` if no such macro.

(name)

  _getExpansion(name) {
    const definition = this.macros.get(name);

    if (definition == null) {
      // mainly checking for undefined here
      return definition;
    }

    const expansion = typeof definition === "function" ? definition(this) : definition;

    if (typeof expansion === "string") {
      let numArgs = 0;

      if (expansion.indexOf("#") !== -1) {
        const stripped = expansion.replace(/##/g, "");

        while (stripped.indexOf("#" + (numArgs + 1)) !== -1) {
          ++numArgs;
        }
      }

      const bodyLexer = new Lexer(expansion, this.settings);
      const tokens = [];
      let tok = bodyLexer.lex();

      while (tok.text !== "EOF") {
        tokens.push(tok);
        tok = bodyLexer.lex();
      }

      tokens.reverse(); // to fit in with stack using push and pop

      const expanded = {
        tokens,
        numArgs
      };
      return expanded;
    }

    return expansion;
  }
  /**
   * Determine whether a command is currently "defined" (has some
   * functionality), meaning that it's a macro (in the current group),