com.google.re2j.package.html Maven / Gradle / Ivy
This package provides an implementation of regular expression
matching based on Russ Cox's linear-time RE2 algorithm.
The API presented by {@code com.google.re2j} mimics that of {@code
java.util.regex.Matcher} and {@code java.util.regex.Pattern}.
While not identical, they are similar enough that most users can
switch implementations simply by changing their {@code import}s.
The syntax of the regular expressions accepted is the same general
syntax used by Perl, Python, and other languages. More precisely,
it is the syntax accepted by the C++ and Go implementations of RE2
described at http://code.google.com/p/re2/wiki/Syntax,
except for \C (match any byte), which is not
supported because in this implementation, the matcher's input is
conceptually a stream of Unicode code points, not bytes.
The current API is rather small and intended for compatibility
with {@code java.util.regex}, but the underlying implementation
supports some additional features, such as the ability to process
input character streams encoded as UTF-8 byte arrays. These may
be exposed in a future release if there is sufficient interest.
Example use:
import com.google.re2j.Matcher;
import com.google.re2j.Pattern;
Pattern p = Pattern.compile("b(an)*(.)");
Matcher m = p.matcher("by, band, banana");
assertTrue(m.lookingAt());
m.reset(); // "by, band, banana"
assertTrue(m.find());
assertEquals("by", m.group(0)); // --
assertEquals(null, m.group(1)); //
assertEquals("y", m.group(2)); // ^
assertTrue(m.find());
assertEquals("band", m.group(0)); // ----
assertEquals("an", m.group(1)); // ^^
assertEquals("d", m.group(2)); // ^
assertTrue(m.find());
assertEquals("banana", m.group(0)); // -------
assertEquals("an", m.group(1)); // ^^
assertEquals("a", m.group(2)); // ^
assertFalse(m.find());