org.javers.common.collections.Lists Maven / Gradle / Ivy

Show more of this group Show more artifacts with this name
Show all versions of javers-core Show documentation
JaVers - object auditing and diff framework for Java
There is a newer version: 7.6.1
package org.javers.common.collections;

import org.javers.core.metamodel.property.MissingProperty;

import java.util.*;
import java.util.Collections;
import java.util.function.Function;
import java.util.function.Predicate;
import java.util.stream.Collector;
import java.util.stream.Collectors;

import static java.util.Collections.EMPTY_LIST;
import static java.util.Collections.unmodifiableList;
import static org.javers.common.validation.Validate.argumentsAreNotNull;

public class Lists {

    public static List wrapNull(Object list) {
        if (list == null || list == MissingProperty.INSTANCE) {
            return Collections.emptyList();
        }
        return (List)list;
    }

    public static  List add(List list, T element) {
        List l = new ArrayList<>(list);
        l.add(element);
        return unmodifiableList(l);
    }

    public static  List immutableListOf(T... elements) {
        if (elements == null) {
            return Collections.emptyList();
        }
        return unmodifiableList(java.util.Arrays.asList(elements));
    }

    public static  List immutableListOf(Collection elements) {
        if (elements == null || elements.size() == 0) {
            return Collections.emptyList();
        }
        return unmodifiableList(new ArrayList<>(elements));
    }

    public static  List immutableCopyOf(List elements) {
        if (elements == null || elements.size() == 0) {
            return Collections.emptyList();
        }
        return unmodifiableList(new ArrayList<>(elements));
    }

    public static  List asList(E... elements) {
        return (List) Arrays.asList(elements);
    }

    public static  List immutableListOf(List elements, E element) {
        List list = new ArrayList<>(elements);
        list.add(element);
        return unmodifiableList(list);
    }

    /**
     * @return index -> value
     */
    public static  Map asMap(List input) {
        if (input == null) {
            return null;
        }

        Map result = new HashMap<>();
        int i = 0;

        for (T element : input) {
            result.put(i, element);
            i++;
        }

        return result;
    }

    /**
     * returns new list with elements from input that satisfies given filter condition
     */
    public static  List positiveFilter(List input, Predicate filter) {
        argumentsAreNotNull(input, filter);
        return input.stream().filter(filter).collect(Collectors.toList());
    }

    /**
     * returns new list with elements from input that doesn't satisfies given filter condition
     */
    public static  List negativeFilter(List input, final Predicate filter) {
        argumentsAreNotNull(input, filter);
        return input.stream().filter(element -> !filter.test(element)).collect(Collectors.toList());
    }

    public static  List transform(Collection input, Function transformation) {
        argumentsAreNotNull(input, transformation);
        return input.stream().map(transformation::apply).collect(Collectors.toList());
    }

    public static  List difference(List first, List second) {
        if (first == null) {
            return EMPTY_LIST;
        }

        if (second == null) {
            return first;
        }

        List difference = new ArrayList<>(first);
        difference.removeAll(second);
        return difference;
    }

    public static  Collector, List> toImmutableList() {
        return Collector.of(ArrayList::new, List::add, (left, right) -> {
            left.addAll(right);
            return left;
        }, Collections::unmodifiableList);
    }
}