perfdb/pdb-utils/src/main/java/org/lucares/utils/CollectionUtils.java

package org.lucares.utils;

import java.util.ArrayList;
import java.util.Collection;
import java.util.Collections;
import java.util.Comparator;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.Objects;
import java.util.function.Function;
import java.util.function.Predicate;
import java.util.function.Supplier;
import java.util.stream.Collectors;
import java.util.stream.Stream;

public class CollectionUtils {

    public interface Compare<T> {

        public boolean test(T valueA);

        public static <T, V> Compare<T> compare(Function<? super T, ? extends V> keyExtractor, V value) {
            Objects.requireNonNull(keyExtractor);
            return t -> Objects.equals(keyExtractor.apply(t), value);
        }

        default Compare<T> thenCompare(Compare<? super T> other) {
            Objects.requireNonNull(other);
            return t -> {
                final boolean res = test(t);
                return res ? other.test(t) : false;
            };
        }

        default <V> Compare<T> thenCompare(Function<T, ? extends V> keyExtractor, V value) {
            return thenCompare(compare(keyExtractor, value));
        }
    }

    public static <T> List<T> copySort(Collection<? extends T> collection, Comparator<T> comparator) {
        final List<T> result = new ArrayList<T>(collection);
        Collections.sort(result, comparator);
        return result;
    }

    public static <T, R extends T> void mapInPlace(final List<T> list, final Function<T, R> mapper) {
        for (int i = 0; i < list.size(); i++) {
            final T value = list.get(i);
            final T newValue = mapper.apply(value);
            list.set(i, newValue);
        }
    }

    public static <T, R> List<R> map(final Collection<T> list, final Function<T, R> mapper) {
        final List<R> result = new ArrayList<>(list.size());

        for (final T t : list) {
            result.add(mapper.apply(t));
        }

        return result;
    }

    public static <T, R> List<R> map(final T[] input, final Function<T, R> mapper) {
        return Stream.of(input).map(mapper).collect(Collectors.toList());
    }

    public static <O extends Collection<R>, T, R> O map(final Collection<T> input, final O result,
            final Function<T, R> mapper) {

        for (final T t : input) {
            final R e = mapper.apply(t);
            result.add(e);
        }

        return result;
    }

    public static <T, V> Map<T, V> createMapFromValues(final Iterable<V> iterable, final Function<V, T> keyMapper) {
        final Map<T, V> result = new HashMap<>();

        for (final V value : iterable) {
            final T key = keyMapper.apply(value);

            result.put(key, value);
        }

        return result;
    }

    public static <KEY, VALUE> Map<KEY, VALUE> createMapFromKeys(final Iterable<KEY> iterable,
            final Function<KEY, VALUE> valueMapper) {
        final Map<KEY, VALUE> result = new HashMap<>();

        for (final KEY key : iterable) {
            final VALUE value = valueMapper.apply(key);

            result.put(key, value);
        }

        return result;
    }

    public static <T> List<T> filter(final Collection<T> collection, final Predicate<T> predicate) {
        return collection.stream().filter(predicate).collect(Collectors.toList());
    }

    public static <T> int indexOf(final List<T> list, final Predicate<T> predicate) {
        for (int i = 0; i < list.size(); i++) {
            if (predicate.test(list.get(i))) {
                return i;
            }
        }
        return -1;
    }

    public static <T> boolean contains(Collection<T> collection, final Compare<T> compare) {
        for (T t : collection) {
            boolean found = compare.test(t);
            if (found) {
                return true;
            }
        }
        return false;
    }

    public static <T> long count(Collection<T> collection, final Compare<T> compare) {
        long count = 0;
        for (T t : collection) {
            boolean found = compare.test(t);
            if (found) {
                count++;
            }
        }
        return count;
    }

    public static <V, T extends Collection<V>> T removeAll(final T collection, final T remove,
            final Supplier<T> generator) {

        final T result = generator.get();
        result.addAll(collection);
        result.removeAll(remove);
        return result;
    }

    public static <V, T extends Collection<V>> T retainAll(final T collection, final T retain,
            final Supplier<T> generator) {

        final T result = generator.get();
        result.addAll(collection);
        result.retainAll(retain);
        return result;
    }

}