Groovy supports regular expressions natively using the ~"pattern" expression, which compiles a Java Pattern object from the given pattern string. Groovy also supports the =~ (create Matcher) and ==~ (matches regex) operators.
For matchers having groups, matcher[index] is either a matched String or a List of matched group Strings, since jsr-03 release.
import java.util.regex.Matcher import java.util.regex.Pattern assert "cheesecheese" =~ "cheese" assert "cheesecheese" =~ /cheese/ assert "cheese" == /cheese/ /*they are both string syntaxes*/ // lets create a regex Pattern def pattern = ~/foo/ assert pattern instanceof Pattern assert pattern.matcher("foo").matches() // lets create a Matcher def matcher = "cheesecheese" =~ /cheese/ assert matcher instanceof Matcher answer = matcher.replaceAll("edam") // lets do some replacement def cheese = ("cheesecheese" =~ /cheese/).replaceFirst("nice") assert cheese == "nicecheese" // simple group demo // You can also match a pattern that includes groups. First create a matcher object, either // using the Java API, or more simply with the =~ operator. Then, you can index the matcher // object to find the matches. matcher[0][1] means the 0th match of the whole pattern (with the // =~ operator the pattern may match the string in more than one place), and the 1st group within // that match. Here's how it works: def m = "foobarfoo" =~ /o(b.*r)f/ assert m[0][1] == "bar" // fancier group demo matcher = "\$abc." =~ "\\\$(.*)\\." matcher.matches(); // must be invoked [Question: is this still true? Not in my experience with jsr-04.] assert matcher.group(1) == "abc" // is one, not zero // assert matcher[1] == "abc" // This has worked before jsr-03-release assert matcher[0] == ["\$abc.", "abc"] // But this should work since jsr-03-release assert matcher[0][1] == "abc" // This should work since jsr-03-release
The pattern can be expressed more simply using the "/" delimiter for the pattern, so we don't have to double all the backslashes.
def matcher = "\$abc." =~ /\$(.*)\./ // no need to double-escape! assert "\\\$(.*)\\." == /\$(.*)\./ matcher.matches(); // must be invoked assert matcher.group(1) == "abc" // is one, not zero // assert matcher[1] == "abc" // This has worked before jsr-03-release assert matcher[0] == ["\$abc.", "abc"] // But this should work since jsr-03-release assert matcher[0][1] == "abc" // This should work since jsr-03-release
Since a Matcher coerces to a boolean by calling its find method, the =~ operator is consistent with the simple use of Perl's =~ operator, when it appears as a predicate (in 'if', 'while', etc.). The "stricter-looking" ==~ operator requires an exact match of the whole subject string.
Regular expression support is imported from Java. Java's regular expression language and API is documented here.
