is_hexdig is not pedantic

[Stargateur]

abnf-core/src/lib.rs

Lines 42 to 44 in b1fcead

	pub fn is_hexdig(c: char) -> bool {
	c.is_ascii_hexdigit()
	}

Currently is_hexdig allow for either uppercase or lowercase hex digit but abnf dictate:

HEXDIG = DIGIT / "A" / "B" / "C" / "D" / "E" / "F"

That only allow uppercase. I don't know what to do cause this could make a big breaking to be pedantic, even if we introduce a is_hexdig_relaxed like in complete module.

[duesee]

Hm... I think we should try to stick to the RFC as close as possible and deviate from it only for good reasons. So I would consider is_hexdig accepting lowercase alpha characters a mistake. I like the idea to allow this in a _relaxed version, though.

[Stargateur]

nevermind:

ABNF strings are case insensitive and the character set for these strings is US-ASCII.

is_hexdig is expected to match "abcdef" too.

I didn't know this rule.

[duesee]

Argh, you are right. I knew that strings are case-insensitive in ABNF, but my brain ignored that rule for single-char strings like "A", "B", ... somehow. ABNF can be confusing.