Escapable commas in CLI options?

The commander argument parser for the --ignore option:
https://github.com/reactjs/react-docgen/blob/f5d644a3041c227c4889059e787fcbaab57ec70e/packages/react-docgen-cli/src/commands/parse/command.ts#L26-L39
https://github.com/reactjs/react-docgen/blob/f5d644a3041c227c4889059e787fcbaab57ec70e/packages/react-docgen-cli/src/commands/parse/command.ts#L62-L67

... splits on a comma, which makes it impossible to use glob brace expansion for this option or commas in general for any option that also uses this argument parser.

Would supporting escapable commas be possible?

To avoid breaking changes you may need to make it opt-in (behind a new option --comma-escaping or similar.)

The problem seems common enough and has been solved different ways in different languages. Here is a rough first pass after a little (very little) research:

/**
 * Split on commas (","), unless they are escaped with a backslash("\,").
 *
 * Escaped commas are replaced with individual commas.
 */
export function splitOnComma(str: string): string[] {
  if (typeof str !== 'string') {
    const errorMessage = 'input must be a string'
    throw new TypeError(errorMessage)
  }
  const DELIMETER = ','
  const ESCAPE_CHAR = '\\'
  const ESCAPED_DELIMETER = ESCAPE_CHAR + DELIMETER
  const hasEscapedDelimeter = str.includes(ESCAPED_DELIMETER)

  // Negative Lookbehind: https://www.regular-expressions.info/lookaround.html
  const result = str.split(/,(?<!\\,)/)

  if (hasEscapedDelimeter) {
    return result.map((subStr) => subStr.replace(/\\,/gi, DELIMETER))
  }
  return result
}

I don't have experience with negative lookbehinds. I wrote the example to favor being excessively self-documenting. Refinements could include:

• improved error message
• reducing the number of lines needed
• adding unit tests
• if the build tools are configured for ES2021+, String.prototype.replaceAll could be used instead.
  • subStr.replaceAll(ESCAPED_DELIMETER, DELIMETER))
• perform the replacement in fewer operations / general performance improvement

packages/react-docgen-cli/src/commands/parse/command.ts にある --ignore の定義とパースフローから始め、リンク先の typings/index.d.ts の該当行にある Commander の引数パーサーの型定義と比較します。既存のカンマ分割を変更せずにエスケープされたカンマを有効にする方法を確認し、--ignore がカンマを含む値を受け付ける一方で、通常の値が現在の動作を維持することを検証します。