Add support for Unicode regex patterns in validators.

[joshcampbell191]

Is your feature request related to a problem? Please describe.
I'd like to be able to use Unicode character classes in my regex patterns for validators (https://www.regular-expressions.info/unicode.html#prop).

ex. \p{L} could be used to capture all letters from various languages.

Describe the solution you'd like
Ideally, this would be in the form of a checkbox similar to the one for caseInsensitve which would allow someone to enable the functionality. It can be turned off by default.

[andrewtelnov]

@joshcampbell191 I'll discuss this functionality with the team. I think it makes sense to introduce an event or callback that allows developers to customize options during RegExp object creation, such as adding flags like 'u' for Unicode support.

Here's a snippet of our current code for reference:

private createRegExp(): RegExp {
  return new RegExp(this.regex, this.caseInsensitive ? "i" : "");
}

We could implement this as an event in Survey or a callback in global settings, enabling you to override the expression and flags as needed.

I believe end-users shouldn't need to worry about details like Unicode support and that decision should be left to the developer. What are your thoughts?

Thank you,
Andrew

[joshcampbell191]

I agree that it's more of a developer setting.

That being said, a global setting for this would be ideal so that it gets serialized with the survey.

[andrewtelnov]

@joshcampbell191 It has been implemented in this PR.
You will be able to use the following code from the version we will release this week, likely today:

  survey.onCreateRegexValidator.add((sender, options) => {
    options.flags = "u";
  });

Where options is the following interface:

export interface CreateRegexValidatorEvent extends QuestionEventMixin {
  /**
   * A validator instance for which the event is raised.
   */
  validator: RegexValidator;
  /**
   * A regular expression pattern used by the validator. You can modify this value to change the validation logic.
   */
  pattern: string;
  /**
   * Optional regular expression flags that control additional matching behavior, such as case-insensitive searching. You can modify this value. For more information about supported flags, refer to the MDN article: [Advanced searching with flags](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Guide/Regular_expressions#advanced_searching_with_flags).
   */
  flags: string;
}

Thank you,
Andrew