content: /*
   * Copyright (C) 2016-2023 ActionTech.
   * License: http://www.gnu.org/licenses/gpl.html GPL version 2 or higher.
   */
  
  package com.actiontech.dble.plan.common.item.function.mathsfunc;
  
  import com.actiontech.dble.plan.common.item.Item;
  import com.actiontech.dble.plan.common.item.function.ItemFunc;
  import com.actiontech.dble.plan.common.item.function.primary.ItemDecFunc;
  
  import java.math.BigDecimal;
  import java.util.List;
  
  
  public class ItemFuncLog extends ItemDecFunc {
  
      public ItemFuncLog(List<Item> args, int charsetIndex) {
          super(args, charsetIndex);
      }
  
      @Override
      public final String funcName() {
          return "log";
      }
  
      /**
       * Extended but so slower LOG function.
       * <p>
       * We have to check if all values are > zero and first one is not one as
       * these are the cases then result is not a number.
       */
      public BigDecimal valReal() {
          double value = args.get(0).valReal().doubleValue();
          if ((nullValue = args.get(0).isNullValue()))
              return BigDecimal.ZERO;
          if (value <= 0.0) {
              signalDivideByNull();
              return BigDecimal.ZERO;
          }
          if (args.size() == 2) {
              double value2 = args.get(1).valReal().doubleValue();
              if ((nullValue = args.get(1).isNullValue()))
                  return BigDecimal.ZERO;
              if (value2 <= 0.0 || value == 1.0) {
                  signalDivideByNull();
                  return BigDecimal.ZERO;
              }
              return new BigDecimal(Math.log(value2) / Math.log(value));
          }
          return new BigDecimal(Math.log(value));
      }
  
      @Override
      public ItemFunc nativeConstruct(List<Item> realArgs) {
          return new ItemFuncLog(realArgs, charsetIndex);
      }
  }
  