com.radeonsys.data.querystore.support.CompositeQueryStore.java Source code

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Here is the source code for com.radeonsys.data.querystore.support.CompositeQueryStore.java

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/*
 * @(#)CompositeQueryStore.java            Jun 17, 2012 11:07:23 PM
 *
 * Copyright 2012 Radeon Systems
 *
 *    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 com.radeonsys.data.querystore.support;

import java.util.Set;

import com.google.common.base.Preconditions;
import com.google.common.base.Predicate;
import com.google.common.collect.Iterables;
import com.google.common.collect.Sets;
import com.radeonsys.data.querystore.QueryNotFoundException;
import com.radeonsys.data.querystore.QueryStore;

/**
 * An implementation of {@link QueryStore} which looks up one or more other query stores
 * to find a query with a specified name.
 * 
 * <p>{@link QueryStore}s can be added to this query store using the {@link #addQueryStore(QueryStore)}
 * method.</p>
 * 
 * @see QueryStore
 * 
 * @author oddjobsman
 * @since 1.0
 */
public final class CompositeQueryStore implements QueryStore {

    /**
     * Stores the initial size of the stores
     */
    private static final int DEFAULT_INITIAL_SIZE = 10;

    /**
     * Stores the query stores to be looked up
     */
    private final Set<QueryStore> stores = Sets.newLinkedHashSetWithExpectedSize(DEFAULT_INITIAL_SIZE);

    /**
     * Creates a new instance of {@code CompositeQueryStore}
     */
    public CompositeQueryStore() {
        // DO NOTHING
    }

    /* (non-Javadoc)
     * @see com.radeonsys.data.querystore.QueryStore#getQuery(java.lang.String)
     */
    @Override
    public final String getQuery(String nameOfQuery) {
        for (QueryStore store : stores)
            if (store.containsQuery(nameOfQuery))
                return store.getQuery(nameOfQuery);
        throw new QueryNotFoundException(nameOfQuery);
    }

    /* (non-Javadoc)
     * @see com.radeonsys.data.querystore.QueryStore#containsQuery(java.lang.String)
     */
    @Override
    public boolean containsQuery(final String queryName) {
        return Iterables.any(stores, new Predicate<QueryStore>() {
            @Override
            public boolean apply(QueryStore store) {
                return store.containsQuery(queryName);
            }
        });
    }

    /**
     * Adds the specified query store to this query store
     * 
     * @param queryStoreToAdd   reference to an instance of {@link QueryStore} to be added
     * 
     * @throws IllegalArgumentException
     *          if the specified query store was {@code null}
     */
    public final void addQueryStore(QueryStore queryStoreToAdd) {
        Preconditions.checkArgument(queryStoreToAdd != null, "A valid query store must be specified.");
        stores.add(queryStoreToAdd);
    }

}