override def visitCall()

in flink-table/flink-table-planner/src/main/scala/org/apache/flink/table/planner/plan/utils/FlinkRelMdUtil.scala [817:895]
75 lines of code
37 McCabe index (conditional complexity)

    override def visitCall(call: RexCall): JDouble = {
      val rowCount = mq.getRowCount(calc)
      val distinctRowCount: JDouble = if (call.isA(SqlKind.MINUS_PREFIX)) {
        cardOfCalcExpr(mq, calc, call.getOperands.get(0))
      } else if (call.isA(ImmutableList.of(SqlKind.PLUS, SqlKind.MINUS))) {
        val card0 = cardOfCalcExpr(mq, calc, call.getOperands.get(0))
        if (card0 == null) {
          null
        } else {
          val card1 = cardOfCalcExpr(mq, calc, call.getOperands.get(1))
          if (card1 == null) {
            null
          } else {
            Math.max(card0, card1)
          }
        }
      } else if (call.isA(ImmutableList.of(SqlKind.TIMES, SqlKind.DIVIDE))) {
        NumberUtil.multiply(
          cardOfCalcExpr(mq, calc, call.getOperands.get(0)),
          cardOfCalcExpr(mq, calc, call.getOperands.get(1)))
      } else if (call.isA(SqlKind.EXTRACT)) {
        val extractUnit = call.getOperands.get(0)
        val timeOperand = call.getOperands.get(1)
        extractUnit match {
          // go https://www.postgresql.org/docs/9.1/static/
          // functions-datetime.html#FUNCTIONS-DATETIME-EXTRACT to get the definitions of timeunits
          case unit: RexLiteral =>
            val unitValue = unit.getValue
            val timeOperandType = timeOperand.getType.getSqlTypeName
            // assume min time is 1970-01-01 00:00:00, max time is 2100-12-31 21:59:59
            unitValue match {
              case YEAR => 130d // [1970, 2100]
              case MONTH => 12d
              case DAY => 31d
              case HOUR => 24d
              case MINUTE => 60d
              case SECOND =>
                timeOperandType match {
                  case TIMESTAMP | TIME => 60 * 1000d // [0.000, 59.999]
                  case _ => 60d // [0, 59]
                }
              case QUARTER => 4d
              case WEEK => 53d // [1, 53]
              case MILLISECOND =>
                timeOperandType match {
                  case TIMESTAMP | TIME => 60 * 1000d // [0.000, 59.999]
                  case _ => 60d // [0, 59]
                }
              case MICROSECOND =>
                timeOperandType match {
                  case TIMESTAMP | TIME => 60 * 1000d * 1000d // [0.000, 59.999]
                  case _ => 60d // [0, 59]
                }
              case DOW => 7d // [0, 6]
              case DOY => 366d // [1, 366]
              case EPOCH =>
                timeOperandType match {
                  // the number of seconds since 1970-01-01 00:00:00 UTC
                  case TIMESTAMP | TIME => 130 * 24 * 60 * 60 * 1000d
                  case _ => 130 * 24 * 60 * 60d
                }
              case DECADE => 13d // The year field divided by 10
              case CENTURY => 2d
              case MILLENNIUM => 2d
              case _ => cardOfCalcExpr(mq, calc, timeOperand)
            }
          case _ => cardOfCalcExpr(mq, calc, timeOperand)
        }
      } else if (call.getOperands.size() == 1) {
        cardOfCalcExpr(mq, calc, call.getOperands.get(0))
      } else {
        if (rowCount != null) rowCount / 10 else null
      }
      if (distinctRowCount == null) {
        null
      } else {
        FlinkRelMdUtil.numDistinctVals(distinctRowCount, rowCount)
      }
    }