Add `string:reverse` function

[SasinduDilshara]

Description: There is no in-built function to reverse a Ballerina String. There are few other methods available

• string:fromBytes(s.toBytes().reverse())
• string r = check string:fromCodePointInts(s.toCodePointInts().reverse())

But there is no in-built function to reverse a string.

Suggested Labels:

• Improvement Suggestion

[SasinduDilshara]

This document contains the string reverse functionality of other Programming Languages. https://docs.google.com/document/d/1yQu1fjvhMFSMDr1UfoC-OXVtk_mrb4I9_2clpX4Z7kw/edit?usp=sharing

[jclark]

The solution with toBytes/fromBytes won't work for non-ASCII characters.

What is this useful for?

Does reversing characters really make sense with Unicode combining characters? For example, if I have the letter A followed combining circumflex accent, and then reverse it, I will get a combining circumflex accent followed A, which won't be displayable sensibly. Would reversing grapheme clusters make more sense?

[SasinduDilshara]

This reverse method will be helpful for algorithms that use palindromes. And also reverse method will help to deal with some regular expressions efficiently.

[SasinduDilshara]

The solution with toBytes/fromBytes won't work for non-ASCII characters.

What is this useful for?

Does reversing characters really make sense with Unicode combining characters? For example, if I have the letter A followed combining circumflex accent, and then reverse it, I will get a combining circumflex accent followed A, which won't be displayable sensibly. Would reversing grapheme clusters make more sense?

+1 for adding functionality for reversing grapheme clusters.