Quantifiers
Control how many times to match a pattern.
Basic Quantifiers
| Syntax | Description | Example |
|---|---|---|
* | Zero or more | ab* matches “a”, “ab”, “abb” |
+ | One or more | ab+ matches “ab”, “abb” |
? | Zero or one | ab? matches “a”, “ab” |
{n} | Exactly n | a{3} matches “aaa” |
{n,} | At least n | a{2,} matches “aa”, “aaa” |
{n,m} | Between n and m | a{2,4} matches “aa”, “aaa”, “aaaa” |
Lazy Quantifiers
Add ? to make quantifiers lazy (match as few as possible):
fn main() {
use fuzzy_regex::FuzzyRegex;
// Greedy: matches as much as possible
let re1 = FuzzyRegex::new(r"<.+>").unwrap();
// Lazy: matches as little as possible
let re2 = FuzzyRegex::new(r"<.+?>").unwrap();
let text = "<tag>more</tag>";
assert!(re1.find(text).unwrap().as_str() == "<tag>more</tag>");
assert!(re2.find(text).unwrap().as_str() == "<tag>");
}Possessive Quantifiers
Prevent backtracking (useful for performance):
fn main() {
use fuzzy_regex::FuzzyRegex;
// a*+ doesn't backtrack
let re = FuzzyRegex::new("a*+b").unwrap();
println!("{}", re.is_match("ab"));
}Quantifiers with Fuzzy Matching
fn main() {
use fuzzy_regex::FuzzyRegex;
// Match "ab" with up to 1 error, repeated 1-3 times
let re = FuzzyRegex::new("(?:ab){e<=1}{1,3}").unwrap();
println!("{}", re.is_match("ab"));
}