Refactor: Parse traits

[steffahn]

Hi there, I’ve been noticing the weird-looking trait bounds appearing on the public API, such as pub fn parse<T: Parser<T> + ParserPos<T>>.

The trait’s type parameters aren’t actually necessary. Perhaps they were used because the author didn’t realize they could achieve the default implementations for Parse, which used to rely on a trait bound in the argument, trait Parser<T: ParserPos<T>>, by using a supertrait bound instead.

Anyways, this PR contains multiple commits, starting off with

• removal of the redundant generic argument on Parser, ParserPos, ParserNeg
  • so it’d be pub fn parse<T: Parser + ParserPos> then
• renaming of these traits to use “parse” instead of “parser” – this will look a lot more fitting in the documentation, in my opinion
  • so it’d be pub fn parse<T: Parse + ParsePos> then
• simplification of the bounds, another thing that becomes possibly with the supertrait bound trait Parse: ParsePos
  • so it’d be pub fn parse<T: Parse> then
• using only Parse and ParseNeg, no longer ParsePos, in public API. The set of types implementing Parse and ParsePos seems to be identical. (Please comment if this observation is wrong under any cfgs, or is intended to become wrong in the future.)
  • this turns e.g. pub fn parse_pos<T: ParsePos> into pub fn parse_pos<T: Parse>
• I could not help but stumble over the impl_signed macro, which I felt was more tidy if the impl was created by the macro fully, which also stylistically follows common precedent in std – sorry this is relatively unrelated to the main refactor here, but it’s still something about the Parse[r] trait I’ve come across

Feel free to give feedback in case you’re interested in merging only part of these changes.

[RoDmitry]

Thank you! I like it 😊

[RoDmitry]

It's not a public API though 😁

[steffahn]

My bad, my wording wasn’t the best perhaps, I meant that they appear visibly in the trait bounds in the public API’s documentation as created by rustdoc. I’m aware that the traits themselves are not part of the public API.