#lexer #regular #expression #regex

relex

a library for building a regex-based lexer

4 releases (1 stable)

1.0.0 May 23, 2021
0.1.2 May 20, 2021
0.1.1 May 20, 2021
0.1.0 May 17, 2021

#5 in #regular

22 downloads per month

MIT license

18KB
376 lines

relex (a regex lexer)

This crate provides several utilities for creating regex-based lexers. A lexer uses RegexSet's from the regex crate for maximum efficiency. Use this when you want to spin up a lexer quickly.

Here is a quick example to get you started:

use relex::*;

#[derive(Debug, Clone, PartialEq)]
enum MyToken {
  Whitespace,
  ID,
  Float,
  Eof,
  Unrecognized,
}
impl TokenKind for MyToken {
  fn eof() -> Self { MyToken::Eof }
  fn unrecognized() -> Self { MyToken::Unrecognized }
}

let lex = LexerBuilder::new()
  .token(Rule::new(MyToken::Whitespace, r"\s+").unwrap().skip(true))
  .token(Rule::new(MyToken::ID, r"[A-Za-z]+").unwrap())
  .token(Rule::new(MyToken::Float, r"(\d+)(?:\.(\d+))?").unwrap().capture(true)) // this one captures groups
                                                                                 // because it calls `.capture(true)`
  .build();

let mut scanner = lex.iter(" abc", 0);
let token = scanner.next().unwrap();
assert_eq!(token.kind, MyToken::ID);
assert_eq!(token.text, "abc");
assert_eq!(token.skipped[0].kind, MyToken::Whitespace);

Collecting Code Coverage

 cargo test
    Finished test [unoptimized + debuginfo] target(s) in 0.01s
     Running unittests (target/debug/deps/relex-f41d18d0b3597fac)
...                     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^-- note this executable and then run:
 kcov target/cov --include-pattern=relex/src ./target/debug/deps/relex-f41d18d0b3597fac
...
 open target/cov/index.html

License (MIT)

The MIT License (MIT)

Copyright © 2021 Jonathan Apodaca jrapodaca@gmail.com

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the “Software”), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED “AS IS”, WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

Dependencies

~2.1–3MB
~53K SLoC