StringUtilities.java

package net.filebot.util;

import static java.util.Arrays.*;
import static java.util.Collections.*;
import static java.util.stream.Collectors.*;
import static java.util.stream.StreamSupport.*;
import static net.filebot.util.RegularExpressions.*;

import java.util.ArrayList;
import java.util.Collection;
import java.util.List;
import java.util.Objects;
import java.util.Optional;
import java.util.Spliterators.AbstractSpliterator;
import java.util.function.Consumer;
import java.util.function.Function;
import java.util.regex.MatchResult;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
import java.util.stream.IntStream;
import java.util.stream.Stream;

public final class StringUtilities {

	public static List<Integer> matchIntegers(CharSequence s) {
		if (s == null || s.length() == 0) {
			return emptyList();
		}

		List<Integer> numbers = new ArrayList<Integer>();
		Matcher matcher = DIGIT.matcher(s);
		while (matcher.find()) {
			try {
				numbers.add(new Integer(matcher.group()));
			} catch (NumberFormatException e) {
				// ignore
			}
		}
		return numbers;
	}

	public static Integer matchInteger(CharSequence s) {
		if (s == null || s.length() == 0) {
			return null;
		}

		Matcher matcher = DIGIT.matcher(s);
		if (matcher.find()) {
			try {
				return new Integer(matcher.group());
			} catch (NumberFormatException e) {
				// ignore
			}
		}
		return null;
	}

	public static Stream<String> tokenize(CharSequence s) {
		return tokenize(s, SPACE);
	}

	public static Stream<String> tokenize(CharSequence s, Pattern pattern) {
		return pattern.splitAsStream(s).filter(w -> w.length() > 0);
	}

	public static Stream<String> streamMatches(CharSequence s, Pattern pattern) {
		return streamMatches(s, pattern, MatchResult::group);
	}

	public static <T> Stream<T> streamMatches(CharSequence s, Pattern pattern, Function<MatchResult, T> mapper) {
		return stream(new MatcherSpliterator(pattern.matcher(s)), false).map(mapper);
	}

	public static Stream<String> streamCapturingGroups(MatchResult match) {
		// Group 0 is the entire match and not the first capturing group
		return IntStream.rangeClosed(1, match.groupCount()).mapToObj(match::group).filter(Objects::nonNull);
	}

	public static boolean find(String s, Pattern pattern) {
		if (s == null || s.length() == 0) {
			return false;
		}

		return pattern.matcher(s).find();
	}

	public static Optional<String> after(String s, Pattern pattern) {
		Matcher matcher = pattern.matcher(s);
		return matcher.find() ? Optional.of(s.substring(matcher.end()).trim()) : Optional.empty();
	}

	public static String asString(Object object) {
		return object == null ? null : object.toString();
	}

	public static String asNonEmptyString(Object object) {
		if (object != null) {
			String string = object.toString();
			if (string.length() > 0) {
				return string;
			}
		}
		return null;
	}

	public static boolean isEmpty(Object object) {
		return object == null || object.toString().length() == 0;
	}

	public static boolean nonEmpty(Object object) {
		return object != null && object.toString().length() > 0;
	}

	public static String join(Collection<?> values, CharSequence delimiter) {
		return join(values.stream(), delimiter);
	}

	public static String join(Object[] values, CharSequence delimiter) {
		return join(stream(values), delimiter);
	}

	public static String join(Stream<?> values, CharSequence delimiter) {
		return join(values, delimiter, "", "");
	}

	public static String join(Stream<?> values, CharSequence delimiter, CharSequence prefix, CharSequence suffix) {
		return values.map(StringUtilities::asNonEmptyString).filter(Objects::nonNull).collect(joining(delimiter, prefix, suffix));
	}

	public static class MatcherSpliterator extends AbstractSpliterator<MatchResult> {

		private final Matcher m;

		public MatcherSpliterator(Matcher m) {
			super(Long.MAX_VALUE, ORDERED | NONNULL | IMMUTABLE);
			this.m = m;
		}

		@Override
		public boolean tryAdvance(Consumer<? super MatchResult> f) {
			if (!m.find()) {
				return false;
			}

			f.accept(m);
			return true;
		}

	}

	private StringUtilities() {
		throw new UnsupportedOperationException();
	}

}