pl.softech.eav.domain.specification.Specifications.java Source code

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Here is the source code for pl.softech.eav.domain.specification.Specifications.java

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/*
 * Copyright 2013 Sawomir led <slawomir.sledz@sof-tech.pl>.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package pl.softech.eav.domain.specification;

import static com.google.common.base.Preconditions.checkArgument;
import static com.google.common.base.Preconditions.checkNotNull;

import java.util.List;

import com.google.common.base.Predicate;
import com.google.common.collect.Iterables;
import com.google.common.collect.Lists;

/**
 * @author Sawomir led <slawomir.sledz@sof-tech.pl>
 * @since 1.0
 */
public class Specifications {

    @SuppressWarnings("unchecked")
    public static <T> Specification<T> and(final Specification<T>... specifications) {
        checkNotNull(specifications);
        checkArgument(specifications.length > 1, "There must be at least 2 specifications");
        return new Specification<T>() {

            @Override
            public boolean isSafisfiedBy(T t) {
                for (Specification<T> s : specifications) {
                    if (!s.isSafisfiedBy(t)) {
                        return false;
                    }
                }
                return true;
            }
        };
    }

    @SuppressWarnings("unchecked")
    public static <T> Specification<T> or(final Specification<T>... specifications) {
        checkNotNull(specifications);
        checkArgument(specifications.length > 1, "There must be at least 2 specifications");
        return new Specification<T>() {

            @Override
            public boolean isSafisfiedBy(T t) {
                for (Specification<T> s : specifications) {
                    if (s.isSafisfiedBy(t)) {
                        return true;
                    }
                }
                return false;
            }
        };

    }

    public static <T> Specification<T> not(final Specification<T> specification) {
        checkNotNull(specification);
        return new Specification<T>() {

            @Override
            public boolean isSafisfiedBy(T t) {
                return !specification.isSafisfiedBy(t);
            }
        };
    }

    public static <T> List<T> filter(List<T> elements, final Specification<T> specification) {
        checkNotNull(specification);
        checkNotNull(elements);
        return Lists.newArrayList(Iterables.filter(elements, new Predicate<T>() {

            @Override
            public boolean apply(T input) {
                return specification.isSafisfiedBy(input);
            }
        }));
    }

}