[SPARK-40688][SQL] Support data masking built-in function 'mask_first_n'

[vinodkc]

What changes were proposed in this pull request?

This PR supports data masking built-in Function mask_first_n,

Returns a masked version of str with the first n values masked.
By default, first 4 characters will be masked, upper case letters will be converted to "X", lower case letters will be converted to "x" and numbers will be converted to "n".

For example, mask_first_n("1234-5678-8765-4321", 4) results in nnnn-5678-8765-4321.
Can override the characters used in the mask by supplying additional arguments: second argument control the number of charatcters to be masked, the third argument controls the mask character for upper case letters, the fourth argument for lower case letters and the fifth argument for numbers.

For example, mask_first_n("abcd-EFGH-8765-4321-abcd-EFGH-8765-4321", 19, "U", "l", "#") will return
llll-UUUU-####-####-abcd-EFGH-8765-4321

Examples:

  > SELECT _FUNC_('abcd-EFGH-8765-4321');
    xxxx-EFGH-8765-4321
  > SELECT _FUNC_('abcd-EFGH-8765-4321', 9);
    xxxx-XXXX-8765-4321
  > SELECT _FUNC_('abcd-EFGH-8765-@$#', 14);
    xxxx-XXXX-nnnn-@$#
  > SELECT _FUNC_('abcd-EFGH-8765-@$#', 15, 'x', 'X', 'n', 'o');
    XXXXoxxxxonnnno@$#
  > SELECT _FUNC_('abcd-EFGH-8765-@$#', 20, 'x', 'X', 'n', 'o');
    XXXXoxxxxonnnnoooo
  > SELECT _FUNC_('AbCD123-@$#', 10,'Q', 'q', 'd', 'o');
    QqQQdddooo#
  > SELECT _FUNC_('AbCD123-@$#', 10, -1, 'q', 'd', 'o');
    AqCDdddooo#
  > SELECT _FUNC_('AbCD123-@$#', 10, -1, -1, 'd', 'o');
    AbCDdddooo#
  > SELECT _FUNC_('AbCD123-@$#', 10, -1, -1, -1, 'o');
    AbCD123ooo#
  > SELECT _FUNC_(NULL);
    NULL
  > SELECT _FUNC_(NULL, 1, -1, -1, 'o');
    NULL

Why are the changes needed?

To support data masking built-in function mask_first_n, which returns a masked version of the input string
Ref : Data masking functions

Does this PR introduce any user-facing change?

Yes, added a new build-in function named 'mask_first_n'

How was this patch tested?

Added test cases

[vinodkc]

@gengliangwang Can you please review this PR ?

[vinodkc]

@dtenedor @srielau , Could please review this PR?

[dtenedor]

This is very helpful. Thank you @vinodkc for working on this. We will take a look.

[dtenedor]

@vinodkc please ping again when you're ready for another review.

[vinodkc]

@dtenedor , Thank you for the code review comments, I applied the suggested code changes. Can you please do another review

[dtenedor]

This looks good. Thanks again for doing the work to implement this functionality!

[dtenedor]

@gengliangwang do you want to take a look and possibly help with merging this once we feel all the reviewers have approved?

[vinodkc]

@gengliangwang Could please review this PR?

[dtenedor]

@cloud-fan would you mind helping review this as well? It LGTM as of now.

[vinodkc]

@cloud-fan Would please help review this PR?

[github-actions]

We're closing this PR because it hasn't been updated in a while. This isn't a judgement on the merit of the PR in any way. It's just a way of keeping the PR queue manageable.
If you'd like to revive this PR, please reopen it and ask a committer to remove the Stale tag!