content: /*
   * Copyright 1999-2017 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.alibaba.druid.sql.visitor.functions;
  
  import com.alibaba.druid.sql.ast.SQLExpr;
  import com.alibaba.druid.sql.ast.expr.SQLMethodInvokeExpr;
  import com.alibaba.druid.sql.visitor.SQLEvalVisitor;
  
  import static com.alibaba.druid.sql.visitor.SQLEvalVisitor.EVAL_VALUE;
  
  public class Elt implements Function {
      public static final Elt instance = new Elt();
  
      public Object eval(SQLEvalVisitor visitor, SQLMethodInvokeExpr x) {
          if (x.getArguments().size() <= 1) {
              return SQLEvalVisitor.EVAL_ERROR;
          }
  
          SQLExpr param0 = x.getArguments().get(0);
          param0.accept(visitor);
  
          Object param0Value = param0.getAttribute(EVAL_VALUE);
          int param0IntValue;
          if (!(param0Value instanceof Number)) {
              return SQLEvalVisitor.EVAL_ERROR;
          }
          param0IntValue = ((Number) param0Value).intValue();
  
          if (param0IntValue >= x.getArguments().size()) {
              return SQLEvalVisitor.EVAL_VALUE_NULL;
          }
  
          SQLExpr item = x.getArguments().get(param0IntValue);
          item.accept(visitor);
  
          Object itemValue = item.getAttributes().get(EVAL_VALUE);
          return itemValue;
      }
  }
  