import java.util.regex.*;
import java.util.Arrays;

public class RegularExpressions {
    public static void main(String[] args) {
        // This tests whether a pattern matches a string.
        boolean match = Pattern.matches("p([a-z]+)ch", "peach");
        System.out.println(match);

        // For other regex tasks, we need to compile a Pattern object.
        Pattern r = Pattern.compile("p([a-z]+)ch");

        // Many methods are available on these objects. Here's a match test like we saw earlier.
        Matcher m = r.matcher("peach");
        System.out.println(m.matches());

        // This finds the match for the regex.
        m = r.matcher("peach punch");
        m.find();
        System.out.println(m.group());

        // This also finds the first match but returns the start and end indexes for the match.
        m = r.matcher("peach punch");
        m.find();
        System.out.println("idx: [" + m.start() + " " + m.end() + "]");

        // The group methods include information about both the whole-pattern matches 
        // and the submatches within those matches.
        m = r.matcher("peach punch");
        m.find();
        System.out.println(Arrays.asList(m.group(), m.group(1)));

        // Similarly, this will return information about the indexes of matches and submatches.
        m = r.matcher("peach punch");
        m.find();
        System.out.println(Arrays.asList(m.start(), m.end(), m.start(1), m.end(1)));

        // To find all matches for a regex, we can use a while loop with find().
        m = r.matcher("peach punch pinch");
        while (m.find()) {
            System.out.print(m.group() + " ");
        }
        System.out.println();

        // The replaceAll method can be used to replace subsets of strings with other values.
        String result = r.matcher("a peach").replaceAll("<fruit>");
        System.out.println(result);

        // The replaceAll method with a lambda allows you to transform matched text with a given function.
        result = r.matcher("a peach").replaceAll(matchResult -> matchResult.group().toUpperCase());
        System.out.println(result);
    }
}