/*
 * Copyright 2012, Mysema Ltd
 * 
 * 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.mysema.query.sql;

import com.mysema.query.types.Expression;
import com.mysema.query.types.ExpressionUtils;
import com.mysema.query.types.OperationImpl;
import com.mysema.query.types.Operator;
import com.mysema.query.types.Path;
import com.mysema.query.types.SubQueryExpression;

/**
 * UnionUtils provides static utility methods for Union handling
 * 
 * @author tiwe
 *
 */
public final class UnionUtils {
    
    public static Expression<?> union(SubQueryExpression<?>[] union, boolean unionAll) {
        final Operator<Object> operator = unionAll ? SQLTemplates.UNION_ALL : SQLTemplates.UNION;
        Expression<?> rv = union[0];
        for (int i = 1; i < union.length; i++) {
            rv = OperationImpl.create(rv.getType(), operator, rv, union[i]);
        }        
        return rv;
    }
     
    public static Expression<?> union(SubQueryExpression<?>[] union, Path<?> alias, 
            boolean unionAll) {
        final Expression<?> rv = union(union, unionAll);        
        return ExpressionUtils.as((Expression)rv, alias);
    }
    
    private UnionUtils() {}

}