org.apache.aurora.scheduler.http.api.security.FieldGetters.java Source code

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Here is the source code for org.apache.aurora.scheduler.http.api.security.FieldGetters.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.apache.aurora.scheduler.http.api.security;

import com.google.common.base.Optional;

import org.apache.thrift.TBase;

final class FieldGetters {
    private FieldGetters() {
        // Utility class.
    }

    public static <P extends TBase<P, ?>, C extends TBase<C, ?>, G extends TBase<G, ?>> FieldGetter<P, G> compose(
            final FieldGetter<P, C> parent, final FieldGetter<C, G> child) {

        return new FieldGetter<P, G>() {
            @Override
            public Class<P> getStructClass() {
                return parent.getStructClass();
            }

            @Override
            public Class<G> getValueClass() {
                return child.getValueClass();
            }

            @Override
            public Optional<G> apply(P input) {
                Optional<C> parentValue = parent.apply(input);
                if (parentValue.isPresent()) {
                    return child.apply(parentValue.get());
                } else {
                    return Optional.absent();
                }
            }
        };
    }
}