com.srotya.sidewinder.core.sql.SQLDriver.java Source code

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Here is the source code for com.srotya.sidewinder.core.sql.SQLDriver.java

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/**
 * Copyright 2017 Ambud Sharma
 * 
 * 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.srotya.sidewinder.core.sql;

import java.util.Iterator;
import java.util.List;

import org.antlr.v4.runtime.ANTLRInputStream;
import org.antlr.v4.runtime.CommonTokenStream;
import org.antlr.v4.runtime.tree.ParseTreeWalker;

import com.srotya.sidewinder.core.sql.SQLParser.SqlContext;
import com.srotya.sidewinder.core.sql.operators.ComplexOperator;
import com.srotya.sidewinder.core.sql.operators.Operator;

/**
 * @author ambud
 *
 */
public class SQLDriver {

    /**
     * @param sql
     * @return
     */
    public static SQLParserBaseListener parseSQL(String sql) {
        SQLLexer lexer = new SQLLexer(new ANTLRInputStream(sql));
        CommonTokenStream tokens = new CommonTokenStream(lexer);
        SQLParser parser = new SQLParser(tokens);
        SqlContext select_stmt = parser.sql();

        ParseTreeWalker walker = new ParseTreeWalker();
        SQLParserBaseListener listener = new SQLParserBaseListener();
        walker.walk(listener, select_stmt);

        return listener;
    }

    public static void prune(Operator tree) {
        if (tree instanceof ComplexOperator) {
            List<Operator> operators = ((ComplexOperator) tree).getOperators();
            Iterator<Operator> iterator = operators.iterator();
            while (iterator.hasNext()) {
                Operator op = iterator.next();
                if (op.getClass().equals(tree.getClass())) {
                    ((ComplexOperator) tree).addOperator(op);
                }
            }
        }
    }
}