Add parts of methods for Char.

[SyoujyoujiNaiki]

Related issue: #1487

[peter-jerry-ye-code-review]

‼️ This code review is generated by a bot. Please verify the content before trusting it.

I'll analyze the git diff and point out potential issues I've observed:

1. In the is_digit function (around line 90), there seems to be a potential logic issue in the range check:

match radix {
    2..=10 => v >= 48 && v <= radix + 47
    _ => ...
}

The condition v <= radix + 47 might accept characters that shouldn't be valid digits for smaller radixes. For example, for radix 2 (binary), it would accept characters '0' through '9', when it should only accept '0' and '1'.

2. In the is_control function (around line 84), there's inconsistency in the style of character literals. Some parts of the code use \x notation (like \x7F), while this function uses \u notation (\u0000). For consistency, it might be better to stick to one style throughout the codebase.

3. The is_ascii_whitespace function (around line 75) might be missing some common whitespace characters, such as \v (vertical tab). Consider whether supporting all ASCII whitespace characters is desired for completeness.

These are potential issues that might need attention, though they may be intentional design choices depending on the requirements of the codebase.

[coveralls]

Pull Request Test Coverage Report for Build 4815

Details

• 17 of 19 (89.47%) changed or added relevant lines in 1 file are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage increased (+0.02%) to 83.146%

---

Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
char/char.mbt	17	19	89.47%

Totals
Change from base Build 4812:	0.02%
Covered Lines:	4889
Relevant Lines:	5880

---

💛 - Coveralls

[peter-jerry-ye]

This is false

[SyoujyoujiNaiki]

What does 'This' refer to?

[bobzhang]

he probaly means it should return Bool

[peter-jerry-ye]

is_digit('1', 100) == None ==> is_digit('1', 100) == true

_ => None

==>

1 => false
11..<_ => (v >= 48 && v <= 57) ||
        (v >= 65 && v <= radix + 54) ||
        (v >= 97 && v <= radix + 86)

[peter-jerry-ye]

or maybe we can simply just panic if you want to follow the Rust's way

[peter-jerry-ye]

Or else, you can just follow the Java's API: https://docs.oracle.com/javase/8/docs/api/java/lang/Character.html#isDigit-int-

[peter-jerry-ye]

This condition. If it’s not number nor ascii, it’s certainly not a digit.

[bobzhang]

you can pattern match over char too.

match self {
  'A'..='Z' => true
  _ => false 
}