GroupByItem.java

/**
 * 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 org.apache.metamodel.query;

import java.util.List;

import org.apache.metamodel.util.BaseObject;

/**
 * Represents a GROUP BY item. GroupByItems always use a select item (that may
 * or not be a part of the query already) for grouping.
 * 
 * @see GroupByClause
 */
public class GroupByItem extends BaseObject implements QueryItem, Cloneable {

    private static final long serialVersionUID = 5218878395877852919L;
    private final SelectItem _selectItem;
    private Query _query;

    /**
     * Constructs a GROUP BY item based on a select item that should be grouped.
     * 
     * @param selectItem
     */
    public GroupByItem(SelectItem selectItem) {
        if (selectItem == null) {
            throw new IllegalArgumentException("SelectItem cannot be null");
        }
        _selectItem = selectItem;
    }

    public SelectItem getSelectItem() {
        return _selectItem;
    }

    @Override
    public String toSql() {
        return toSql(false);
    }

    @Override
    public String toSql(boolean includeSchemaInColumnPaths) {
        final String sameQueryAlias = _selectItem.getSameQueryAlias(includeSchemaInColumnPaths);
        return sameQueryAlias;
    }

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

    public Query getQuery() {
        return _query;
    }

    public GroupByItem setQuery(Query query) {
        _query = query;
        if (_selectItem != null) {
            _selectItem.setQuery(query);
        }
        return this;
    }

    @Override
    protected GroupByItem clone() {
        GroupByItem g = new GroupByItem(_selectItem.clone());
        return g;
    }

    @Override
    protected void decorateIdentity(List<Object> identifiers) {
        identifiers.add(_selectItem);
    }
}