/*
 * Copyright 1999-2012 Alibaba Group.
 *  
 * 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.
 */
/**
 * (created at 2011-2-9)
 */
package com.alibaba.cobar.parser.ast.fragment.tableref;

import com.alibaba.cobar.parser.ast.expression.misc.QueryExpression;
import com.alibaba.cobar.parser.visitor.SQLASTVisitor;

/**
 * @author <a href="mailto:shuo.qius@alibaba-inc.com">QIU Shuo</a>
 */
public class SubqueryFactor extends AliasableTableReference {
    private final QueryExpression subquery;

    public SubqueryFactor(QueryExpression subquery, String alias) {
        super(alias);
        if (alias == null)
            throw new IllegalArgumentException("alias is required for subquery factor");
        if (subquery == null)
            throw new IllegalArgumentException("subquery is null");
        this.subquery = subquery;
    }

    public QueryExpression getSubquery() {
        return subquery;
    }

    @Override
    public Object removeLastConditionElement() {
        return null;
    }

    @Override
    public boolean isSingleTable() {
        return false;
    }

    @Override
    public int getPrecedence() {
        return TableReference.PRECEDENCE_FACTOR;
    }

    @Override
    public void accept(SQLASTVisitor visitor) {
        visitor.visit(this);
    }
}