com.intelligentsia.dowsers.entity.view.processor.Source.java Source code

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Here is the source code for com.intelligentsia.dowsers.entity.view.processor.Source.java

Source

/**
 *        Licensed to the Apache Software Foundation (ASF) under one
 *        or more contributor license agreements.  See the NOTICE file
 *        distributed with this work for additional information
 *        regarding copyright ownership.  The ASF licenses this file
 *        to you 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.intelligentsia.dowsers.entity.view.processor;

import java.util.Iterator;
import java.util.Set;

import com.google.common.base.Preconditions;
import com.google.common.collect.ImmutableSet;
import com.intelligentsia.dowsers.entity.Entity;
import com.intelligentsia.dowsers.entity.reference.Reference;

/**
 * Source transform an Entity in an Item with aliasing possibility.
 * 
 * @author <a href="mailto:jguibert@intelligents-ia.com" >Jerome Guibert</a>
 */
public final class Source implements Processor {

    /**
     * {@link Class} of source {@link Entity}.
     */
    private final Class<? extends Entity> entityType;

    /**
     * Alias.
     */
    private final String alias;

    /**
     * {@link Set} of attribute to include.
     */
    private final ImmutableSet<String> attributeNames;

    /**
     * The string form of this {@link Source}.
     * 
     * @serial
     */
    private final transient String value;

    /**
     * Build a new instance of Source.
     * 
     * @param expectedType
     *            expected type of {@link Entity}
     * @param alias
     *            alias to prefix all attribute name
     */
    public Source(final Class<? extends Entity> entityType, final String alias) throws NullPointerException {
        this(entityType, alias, null);
    }

    /**
     * Build a new instance of Source.
     * 
     * @param expectedType
     *            expected type of {@link Entity}
     * @param alias
     *            alias to prefix all attribute name
     * @param attributeNames
     *            set of attribute name, null parameter meaning is "include all
     *            attributes".
     */
    public Source(final Class<? extends Entity> entityType, final String alias,
            final ImmutableSet<String> attributeNames) throws NullPointerException {
        super();
        this.entityType = Preconditions.checkNotNull(entityType);
        this.attributeNames = attributeNames;

        final StringBuilder builder = new StringBuilder("(source ");

        if ((alias == null) || "".equals(alias)) {
            this.alias = "";
            builder.append(entityType.getName());
        } else {
            this.alias = alias + ".";
            builder.append("(").append(entityType.getName()).append(" ").append(alias).append(")");
        }
        if (attributeNames != null) {
            builder.append(" ");
            final Iterator<String> iterator = attributeNames.iterator();
            while (iterator.hasNext()) {
                builder.append(iterator.next()).append(" ");
            }
        }
        value = builder.append(")").toString();
    }

    @Override
    public Item apply(final Entity entity) {
        final Item item = new Item();
        final Iterator<String> iterator = entity.attributeNames().iterator();
        while (iterator.hasNext()) {
            final String name = iterator.next();
            if (include(name)) {
                item.put(alias + name, entity.attribute(name));
            }
        }
        if (include(Reference.IDENTITY)) {
            item.put(alias + Reference.IDENTITY, entity.identity());
        }
        return item;
    }

    /**
     * @param name
     * @return true if we must include this attribute.
     */
    protected boolean include(final String name) {
        return (attributeNames == null) || attributeNames.contains(name);
    }

    @Override
    public String toString() {
        return value;
    }

    public Class<? extends Entity> getEntityType() {
        return entityType;
    }
}