/*
 * 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 io.shardingsphere.core.parsing.antlr.extractor.statement.handler.result.ExtractResult;
import org.antlr.v4.runtime.ParserRuleContext;

/**
 * AST extract handler.
 * 
 * @author duhongjun
 */
public interface ASTExtractHandler {
   
    /**
     * Extract AST.
     *  
     * @param ancestorNode ancestor node of ast
     * @return Extract Result
     */
    ExtractResult extract(ParserRuleContext ancestorNode);
}

@@ -688,16 +688,105 @@
 ndler;%0A%0A
+import org.antlr.v4.runtime.ParserRuleContext;%0A%0Aimport com.google.common.base.Optional;%0A%0A
 import i
@@ -874,55 +874,8 @@
 ult;
-%0Aimport org.antlr.v4.runtime.ParserRuleContext;
 %0A%0A/*
@@ -1055,11 +1055,11 @@
  of 
-ast
+AST
 %0A   
@@ -1074,17 +1074,16 @@
 urn 
-E
 xtract 
-R
+r
 esul
@@ -1096,16 +1096,25 @@
  */%0A    
+Optional%3C
 ExtractR
@@ -1118,16 +1118,17 @@
 ctResult
+%3E
  extract

use optional for checkstyle