1.4 KiB
1.4 KiB
utf8-ranges
This crate converts contiguous ranges of Unicode scalar values to UTF-8 byte ranges. This is useful when constructing byte based automata from Unicode. Stated differently, this lets one embed UTF-8 decoding as part of one's automaton.
Dual-licensed under MIT or the UNLICENSE.
Documentation
http://burntsushi.net/rustdoc/utf8_ranges/
Example
This shows how to convert a scalar value range (e.g., the basic multilingual plane) to a sequence of byte based character classes.
extern crate utf8_ranges;
use utf8_ranges::Utf8Sequences;
fn main() {
for range in Utf8Sequences::new('\u{0}', '\u{FFFF}') {
println!("{:?}", range);
}
}
The output:
[0-7F]
[C2-DF][80-BF]
[E0][A0-BF][80-BF]
[E1-EC][80-BF][80-BF]
[ED][80-9F][80-BF]
[EE-EF][80-BF][80-BF]
These ranges can then be used to build an automaton. Namely:
- Every arbitrary sequence of bytes matches exactly one of the sequences of ranges or none of them.
- Every match sequence of bytes is guaranteed to be valid UTF-8. (Erroneous encodings of surrogate codepoints in UTF-8 cannot match any of the byte ranges above.)