Function newcommand

static/katex/katex.mjs:13238–13283

(context, existsOK, nonexistsOK)

// TODO: Optional arguments: \newcommand{\macro}[args][default]{definition}

const newcommand = (context, existsOK, nonexistsOK) => {
  let arg = context.consumeArgs(1)[0];

  if (arg.length !== 1) {
    throw new ParseError("\\newcommand's first argument must be a macro name");
  }

  const name = arg[0].text;
  const exists = context.isDefined(name);

  if (exists && !existsOK) {
    throw new ParseError(`\\newcommand{${name}} attempting to redefine ` + `${name}; use \\renewcommand`);
  }

  if (!exists && !nonexistsOK) {
    throw new ParseError(`\\renewcommand{${name}} when command ${name} ` + `does not yet exist; use \\newcommand`);
  }

  let numArgs = 0;
  arg = context.consumeArgs(1)[0];

  if (arg.length === 1 && arg[0].text === "[") {
    let argText = '';
    let token = context.expandNextToken();

    while (token.text !== "]" && token.text !== "EOF") {
      // TODO: Should properly expand arg, e.g., ignore {}s
      argText += token.text;
      token = context.expandNextToken();
    }

    if (!argText.match(/^\s*[0-9]+\s*$/)) {
      throw new ParseError(`Invalid number of arguments: ${argText}`);
    }

    numArgs = parseInt(argText);
    arg = context.consumeArgs(1)[0];
  } // Final arg is the expansion of the macro


  context.macros.set(name, {
    tokens: arg,
    numArgs
  });
  return '';
};

defineMacro("\\newcommand", context => newcommand(context, false, true));
defineMacro("\\renewcommand", context => newcommand(context, true, false));