content: /*
   * Copyright 2021-2022 Alibaba Group Holding Ltd.
   *
   *    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.aliyun.fastmodel.transform.fml.format;
  
  import com.aliyun.fastmodel.core.formatter.ExpressionVisitor;
  import com.aliyun.fastmodel.core.tree.expr.Identifier;
  import com.aliyun.fastmodel.core.tree.util.IdentifierUtil;
  import com.aliyun.fastmodel.parser.lexer.ReservedIdentifier;
  
  /**
   * Fml Expression Visitor
   * 扩展了默认的表达式visitor，增加按照关键字转义方法
   * 比如：
   * following -> `following`
   *
   * @author panguanjing
   * @date 2022/1/9
   */
  public class FmlExpressionVisitor extends ExpressionVisitor {
  
      @Override
      public String visitIdentifier(Identifier node, Void context) {
          if (node.isDelimited()) {
              return super.visitIdentifier(node, context);
          }
          String value = node.getValue();
          //如果是关键字，那么增加转义处理
          if (ReservedIdentifier.isKeyWord(value)) {
              return IdentifierUtil.delimit(value);
          }
          return super.visitIdentifier(node, context);
      }
  }
  