gecko-dev/third_party/rust/utf8-ranges
Kartikaya Gupta 47c3dd535d Bug 1369156 - Re-vendor third-party rust libraries with latest cargo-vendor. r=froydnj
MozReview-Commit-ID: LQicTh0fmk0

--HG--
extra : rebase_source : 7a5ee9c3242fefa72e8d0372b8e9c03170c7df4b
2017-06-20 16:05:17 -04:00
..
benches
src
.cargo-checksum.json
.cargo-ok
.travis.yml
Cargo.toml
COPYING
ctags.rust
LICENSE-MIT
Makefile
README.md
session.vim
UNLICENSE

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.

Linux build status

Dual-licensed under MIT or the UNLICENSE.

Documentation

https://docs.rs/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:

  1. Every arbitrary sequence of bytes matches exactly one of the sequences of ranges or none of them.
  2. 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.)