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

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Here is the source code for org.apache.aurora.scheduler.http.api.security.ThriftFieldGetter.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.aurora.scheduler.http.api.security.FieldGetter.AbstractFieldGetter;
import org.apache.thrift.TBase;
import org.apache.thrift.TFieldIdEnum;
import org.apache.thrift.meta_data.FieldMetaData;
import org.apache.thrift.meta_data.FieldValueMetaData;
import org.apache.thrift.meta_data.StructMetaData;

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

/**
 * Retrieves an optional struct-type field from a struct.
 */
class ThriftFieldGetter<T extends TBase<T, F>, F extends TFieldIdEnum, V extends TBase<V, ?>>
        extends AbstractFieldGetter<T, V> {

    private final F fieldId;

    ThriftFieldGetter(Class<T> structClass, F fieldId, Class<V> valueClass) {
        super(structClass, valueClass);

        FieldValueMetaData fieldValueMetaData = FieldMetaData.getStructMetaDataMap(structClass)
                .get(fieldId).valueMetaData;

        checkArgument(fieldValueMetaData instanceof StructMetaData);
        StructMetaData structMetaData = (StructMetaData) fieldValueMetaData;
        checkArgument(valueClass.equals(structMetaData.structClass),
                "Value class %s does not match field metadata for %s (expected %s)", valueClass.getName(), fieldId,
                structMetaData.structClass);

        this.fieldId = fieldId;
    }

    @Override
    @SuppressWarnings("unchecked")
    public Optional<V> apply(T input) {
        if (input.isSet(fieldId)) {
            return Optional.of((V) input.getFieldValue(fieldId));
        } else {
            return Optional.absent();
        }
    }
}