lazy-regex

Use the regex! macro to build regexes:

they're checked at compile time
they're wrapped in once_cell lazy static initializers so that they're compiled only once
they can hold flags as suffix: let case_insensitive_regex = regex!("ab*"i);
regex creation is less verbose

This macro returns references to normal instances of regex::Regex so all the usual features are available.

You may also use shortcut macros for testing a match or capturing groups as substrings:

regex_is_match!
regex_find!
regex_captures!

Build Regexes

use lazy_regex::regex;

// build a simple regex
let r = regex!("sa+$");
assert_eq!(r.is_match("Saa"), false);

// build a regex with flag(s)
let r = regex!("sa+$"i);
assert_eq!(r.is_match("Saa"), true);

// you can use a raw literal
let r = regex!(r#"^"+$"#);
assert_eq!(r.is_match("\"\""), true);

// or a raw literal with flag(s)
let r = regex!(r#"^\s*("[a-t]*"\s*)+$"#i);
assert_eq!(r.is_match(r#" "Aristote" "Platon" "#), true);

// this line wouldn't compile because the regex is invalid:
// let r = regex!("(unclosed");

Supported regex flags: 'i', 'm', 's', 'x', 'U'.

Test a match

use lazy_regex::regex_is_match;

let b = regex_is_match!("[ab]+", "car");
assert_eq!(b, true);

Extract a value

use lazy_regex::regex_find;

let f_word = regex_find!(r#"\bf\w+\b"#, "The fox jumps.");
assert_eq!(f_word, Some("fox"));

Capture

use lazy_regex::regex_captures;

let (_, letter) = regex_captures!("([a-z])[0-9]+"i, "form A42").unwrap();
assert_eq!(letter, "A");

let (whole, name, version) = regex_captures!(
    r#"(\w+)-([0-9.]+)"#, // a literal regex
    "This is lazy_regex-2.0!", // any expression
).unwrap();
assert_eq!(whole, "lazy_regex-2.0");
assert_eq!(name, "lazy_regex");
assert_eq!(version, "2.0");

There's no limit to the size of the tupple. It's checked at compile time to ensure you have the right number of capturing groups.

Shared lazy static

When a regular expression is used in several functions, you sometimes don't want to repeat it but have a shared static instance.

The regex! macro, while being backed by a lazy static regex, returns a reference.

If you want to have a shared lazy static regex, use the lazy_regex! macro:

use lazy_regex::*;

pub static GLOBAL_REX: Lazy<Regex> = lazy_regex!("^ab+$"i);