phoenix-core-client/src/main/java/org/apache/phoenix/parse/ComparisonParseNode.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.phoenix.parse;

import java.sql.SQLException;
import java.util.Collections;
import java.util.List;

import org.apache.hadoop.hbase.CompareOperator;
import org.apache.phoenix.compile.ColumnResolver;
import org.apache.phoenix.util.QueryUtil;

/**
 * 
 * Common base class {@code =, >, >=, <, <=, != }
 *
 * 
 * @since 0.1
 */
public abstract class ComparisonParseNode extends BinaryParseNode {

    public ComparisonParseNode(ParseNode lhs, ParseNode rhs) {
        super(lhs, rhs);
    }

    @Override
    public final <T> T accept(ParseNodeVisitor<T> visitor) throws SQLException {
        List<T> l = Collections.emptyList();
        if (visitor.visitEnter(this)) {
            l = acceptChildren(visitor);
        }
        return visitor.visitLeave(this, l);
    }

    /**
     * Return the comparison operator associated with the given comparison expression node
     */
    public abstract CompareOperator getFilterOp();
    
    /**
     * Return the inverted operator for the CompareOp
     */
    public abstract CompareOperator getInvertFilterOp();
    
    @Override
    public void toSQL(ColumnResolver resolver, StringBuilder buf) {
        List<ParseNode> children = getChildren();
        children.get(0).toSQL(resolver, buf);
        buf.append(" " + QueryUtil.toSQL(getFilterOp()) + " ");
        children.get(1).toSQL(resolver, buf);
    }
}