de.cosmocode.commons.PredicateConstraint.java Source code

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Here is the source code for de.cosmocode.commons.PredicateConstraint.java

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/**
 * Copyright 2010 - 2013 CosmoCode GmbH
 *
 * 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 de.cosmocode.commons;

import com.google.common.base.Preconditions;
import com.google.common.base.Predicate;
import com.google.common.collect.Constraint;

/**
 * Implementation of {@link Conditions#asContraint(Predicate)}.
 *
 * @since 1.9
 * @author Willi Schoenborn
 * @param <T> generic parameter type
 */
final class PredicateConstraint<T> implements Constraint<T> {

    private final Predicate<? super T> predicate;

    public PredicateConstraint(Predicate<? super T> predicate) {
        this.predicate = Preconditions.checkNotNull(predicate, "Predicate");
    }

    @Override
    public T checkElement(T element) {
        return Conditions.checkArgument(predicate, element);
    }

    @Override
    public boolean equals(Object that) {
        if (this == that) {
            return true;
        } else if (that instanceof PredicateConstraint<?>) {
            final PredicateConstraint<?> other = PredicateConstraint.class.cast(that);
            return predicate.equals(other.predicate);
        } else {
            return false;
        }
    }

    @Override
    public int hashCode() {
        return predicate.hashCode() ^ -921210296;
    }

    @Override
    public String toString() {
        return "Conditions.asConstraint(" + predicate + ")";
    }

}