net.conquiris.lucene.document.FieldSelectors.java Source code

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Here is the source code for net.conquiris.lucene.document.FieldSelectors.java

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/*
 * Copyright (C) the original author or authors.
 *
 * 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 net.conquiris.lucene.document;

import java.util.Arrays;
import java.util.Set;

import net.conquiris.schema.SchemaItem;

import org.apache.lucene.document.FieldSelector;
import org.apache.lucene.document.SetBasedFieldSelector;

import com.google.common.collect.ImmutableSet;
import com.google.common.collect.Iterables;

/**
 * Support class for {@link FieldSelector field selectors}.
 * @author Andres Rodriguez
 */
public final class FieldSelectors {
    /** Constructor with no selector. */
    private FieldSelectors() {
        throw new AssertionError();
    }

    /**
     * Creates a mapper with a selector that loads a certain set of fields eagerly, another set lazily
     * and the rest are not loaded.
     * @param fieldsToLoad Fields to load eagerly.
     * @param fieldsToLoadLazily Fields to load lazily.
     * @throws NullPointerException if any of the argument or any of their members is {@code null}.
     */
    public static FieldSelector loadFields(Iterable<String> fieldsToLoad, Iterable<String> fieldsToLoadLazily) {
        Set<String> eager = ImmutableSet.copyOf(fieldsToLoad);
        Set<String> lazy = ImmutableSet.copyOf(fieldsToLoadLazily);
        return new SetBasedFieldSelector(eager, lazy);
    }

    /**
     * Creates a mapper with a selector that loads a certain set of fields eagerly and the rest are
     * not loaded.
     * @param fieldsToLoad Fields to load eagerly.
     * @throws NullPointerException if any the argument or any of its members is {@code null}.
     */
    public static FieldSelector loadFields(Iterable<String> fieldsToLoad) {
        return loadFields(fieldsToLoad, ImmutableSet.<String>of());
    }

    /**
     * Creates a mapper with a selector that loads a certain set of fields eagerly and the rest are
     * not loaded.
     * @param fieldsToLoad Fields to load eagerly.
     * @throws NullPointerException if any the arguments is {@code null}.
     */
    public static FieldSelector loadFields(String... fieldsToLoad) {
        return loadFields(Arrays.asList(fieldsToLoad));
    }

    /**
     * Creates a mapper with a selector that loads a certain set of fields (represented by schema
     * items) eagerly, another set lazily and the rest are not loaded.
     * @param itemsToLoad Fields to load eagerly.
     * @param itemsToLoadLazily Fields to load lazily.
     * @throws NullPointerException if any of the argument or any of their members is {@code null}.
     */
    public static FieldSelector loadItems(Iterable<? extends SchemaItem> itemsToLoad,
            Iterable<? extends SchemaItem> itemsToLoadLazily) {
        return loadFields(Iterables.transform(itemsToLoad, SchemaItem.NAME),
                Iterables.transform(itemsToLoadLazily, SchemaItem.NAME));
    }

    /**
     * Creates a mapper with a selector that loads a certain set of fields (represented by schema
     * items) eagerly and the rest are not loaded.
     * @param itemsToLoad Fields to load eagerly.
     * @throws NullPointerException if any the argument or any of its members is {@code null}.
     */
    public static FieldSelector loadItems(Iterable<? extends SchemaItem> itemsToLoad) {
        return loadFields(Iterables.transform(itemsToLoad, SchemaItem.NAME), ImmutableSet.<String>of());
    }

    /**
     * Creates a mapper with a selector that loads a certain set of fields (represented by schema
     * items) eagerly and the rest are not loaded.
     * @param itemsToLoad Fields to load eagerly.
     * @throws NullPointerException if any the arguments is {@code null}.
     */
    public static FieldSelector loadItems(SchemaItem... itemsToLoad) {
        return loadItems(Arrays.asList(itemsToLoad));
    }

}