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This changes the syntax for range repeat so that it handles inclusive
and exclusive upper bounds with `..=` and `..`.
The old syntax was confusing. It used `..` for inclusive bound, but
that's not how Rust syntax works. This changes it so that it uses `..=`
for inclusive bounds to be consistent with Rust syntax.
There are some other options for range syntax that I considered:
- `{a,b}` which is the syntax used by most regex engines, and some
parsers like Pest and Parsimonious.
- IETF ABNF and W3C EBNF uses `a*bexpr` where `a` and `b` are optional.
- Peg-rs uses `*<n,m>` where `n` and `m` are optional.
- Various languages use `:` (Python, Julia, Excel, etc.) or `..` (Rust,
Kotlin, Swift, C#, F#, Zig, Perl, etc.) to represent ranges.
This will become more relevant when we switch the raw string literals to
use a bounded range. We can't easily avoid the use of bounded repetition
because of raw-string's bound of 255. Listing out 255 variants would be
just too much, and it is convenient to avoid English-descriptive rules.
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This changes the syntax for range repeat so that it handles inclusive and exclusive upper bounds with
..=and...The old syntax was confusing. It used
..for inclusive bound, but that's not how Rust syntax works. This changes it so that it uses..=for inclusive bounds to be consistent with Rust syntax.There are some other options for range syntax that I considered:
{a,b}which is the syntax used by most regex engines, and some parsers like Pest and Parsimonious.a*bexprwhereaandbare optional.*<n,m>wherenandmare optional.:(Python, Julia, Excel, etc.) or..(Rust, Kotlin, Swift, C#, F#, Zig, Perl, etc.) to represent ranges.This will become more relevant when we switch the raw string literals to use a bounded range. We can't easily avoid the use of bounded repetition because of raw-string's bound of 255. Listing out 255 variants would be just too much, and it is convenient to avoid English-descriptive rules.