[API Proposal]: char helpers for common ASCII categories #68868
Description
Background and motivation
We have a bunch of IsHex/IsHexChar/IsHexDigit helpers all around our libraries, as well as IsAsciiLetter/IsAsciiLetterOrDigit and such variants. We should expose these simple helpers implemented efficiently in a place all code can use rather than duplicating them into a bunch of libraries. We already have many Is* methods on char, like IsAscii, IsLetter, IsDigit, and so on; we can augment those with the additional methods.
API Proposal
public struct Char
{
+ public static bool IsAsciiDigit(char c); // true iff the char is 0-9
+ public static bool IsAsciiLetter(char c); // true iff the char is A-Z, a-z
+ public static bool IsAsciiLetterLower(char c); // true iff the char is a-z
+ public static bool IsAsciiLetterUpper(char c); // true iff the char is A-Z
+ public static bool IsAsciiLetterOrDigit(char c); // true iff the char is A-Z, a-z, 0-9
+ public static bool IsHexDigit(char c); // true iff the char is 0-9, A-F, a-f
+ public static bool IsHexDigitUpper(char c); // true iff the char is 0-9, A-F
+ public static bool IsHexDigitLower(char c); // true iff the char is 0-9, a-f
+ public static bool IsInRange(char c, char minInclusive, char maxInclusive); // true iff the char is >= minInclusive && <= maxInclusive
}API Usage
if (char.IsAsciiLetterOrDigit(c))
{
writer.Write(c);
}
else
{
writer.Write($@"\u{(int)c:X4}");
}Alternative Designs
We might also want to expose a helper for getting the value of a hex digit, e.g.
public static int GetHexDigitValue(char c); // return 0-15 for 0-9/A-F, and some sentinel otherwise (e.g. -1)Risks
No response