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 builds 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);

// supported regex flags: 'i', 'm', 's', 'x', 'U'
// see https://docs.rs/regex/1.5.4/regex/struct.RegexBuilder.html

// 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:
// let r = regex!("(unclosed");

What you really get from this macro call is a reference to a regex::Regex, statically checked, and behind a static once_cell lazy initializer.

Test

use lazy_regex::regex_is_match;

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

Extract

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");

The size of the tuple is checked at compile time and ensures you have the right number of capturing groups.