/*
 * Copyright 2016-2018 shardingsphere.io.
 * <p>
 * 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.
 * </p>
 */

package io.shardingsphere.core.parsing.antlr.extractor.statement.handler;

import java.util.Collection;

import org.antlr.v4.runtime.ParserRuleContext;
import org.antlr.v4.runtime.tree.ParseTree;

import io.shardingsphere.core.parsing.antlr.extractor.statement.handler.result.DropColumnExtractResult;
import io.shardingsphere.core.parsing.antlr.extractor.statement.handler.result.ExtractResult;
import io.shardingsphere.core.parsing.antlr.extractor.statement.util.ASTUtils;
import io.shardingsphere.core.parsing.antlr.sql.ddl.AlterTableStatement;
import io.shardingsphere.core.parsing.parser.sql.SQLStatement;
import io.shardingsphere.core.util.SQLUtil;

/**
 * Drop column extract handler.
 * 
 * @author duhongjun
 */
public final class DropColumnExtractHandler implements ASTExtractHandler,ASTExtractHandler1 {
    
    @Override
    public void extract(final ParserRuleContext ancestorNode, final SQLStatement statement) {
        AlterTableStatement alterStatement = (AlterTableStatement) statement;
        for (ParserRuleContext each : ASTUtils.getAllDescendantNodes(ancestorNode, RuleName.DROP_COLUMN)) {
            for (ParseTree columnNode : ASTUtils.getAllDescendantNodes(each, RuleName.COLUMN_NAME)) {
                alterStatement.getDropColumns().add(SQLUtil.getExactlyValue(columnNode.getText()));
            }
        }
    }

    @Override
    public ExtractResult extract(ParserRuleContext ancestorNode) {
        Collection<ParserRuleContext> result = ASTUtils.getAllDescendantNodes(ancestorNode, RuleName.DROP_COLUMN);
        if(result.isEmpty()) {
            return null;
        }
        DropColumnExtractResult extractResult = new DropColumnExtractResult();
        for (ParserRuleContext each : result) {
            for (ParseTree columnNode : ASTUtils.getAllDescendantNodes(each, RuleName.COLUMN_NAME)) {
                extractResult.getDropColumnNames().add(SQLUtil.getExactlyValue(columnNode.getText()));
            }
        }
        return extractResult;
    }
}

@@ -1091,144 +1091,8 @@
 ls;%0A
-import io.shardingsphere.core.parsing.antlr.sql.ddl.AlterTableStatement;%0Aimport io.shardingsphere.core.parsing.parser.sql.SQLStatement;%0A
 impo
@@ -1273,560 +1273,10 @@
 dler
-,ASTExtractHandler1 %7B%0A    %0A    @Override%0A    public void extract(final ParserRuleContext ancestorNode, final SQLStatement statement) %7B%0A        AlterTableStatement alterStatement = (AlterTableStatement) statement;%0A        for (ParserRuleContext each : ASTUtils.getAllDescendantNodes(ancestorNode, RuleName.DROP_COLUMN)) %7B%0A            for (ParseTree columnNode : ASTUtils.getAllDescendantNodes(each, RuleName.COLUMN_NAME)) %7B%0A                alterStatement.getDropColumns().add(SQLUtil.getExactlyValue(columnNode.getText()));%0A            %7D%0A        %7D%0A    %7D
+ %7B
 %0A%0A  

remove unused code