org.hobsoft.entangle.guava.GuavaConverters.java Source code

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Here is the source code for org.hobsoft.entangle.guava.GuavaConverters.java

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/*
 * 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 org.hobsoft.entangle.guava;

import org.hobsoft.entangle.Converter;

import com.google.common.base.Function;
import com.google.common.base.Functions;
import com.google.common.base.Predicate;
import com.google.common.base.Supplier;

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

/**
 * Factory for adapting Guava to converters.
 * 
 * @author Mark Hobson
 */
public final class GuavaConverters {
    // constructors -----------------------------------------------------------

    private GuavaConverters() {
        throw new AssertionError();
    }

    // public methods ---------------------------------------------------------

    public static <S> Converter<S, Boolean> forPredicate(Predicate<? super S> predicate) {
        return forFunction(Functions.forPredicate(predicate));
    }

    public static <T> Converter<Object, T> forSupplier(Supplier<? extends T> supplier) {
        return forFunction(Functions.forSupplier(supplier));
    }

    public static <S, T> Converter<S, T> forFunction(Function<? super S, ? extends T> function) {
        return forFunction(function, null);
    }

    public static <S, T> Converter<S, T> forFunction(final Function<? super S, ? extends T> toFunction,
            final Function<? super T, ? extends S> fromFunction) {
        checkNotNull(toFunction, "toFunction cannot be null");

        return new Converter<S, T>() {
            public T convert(S source) {
                return toFunction.apply(source);
            }

            public S unconvert(T target) {
                if (fromFunction == null) {
                    throw new UnsupportedOperationException();
                }

                return fromFunction.apply(target);
            }
        };
    }
}