def unapply()

in hudi-spark-datasource/hudi-spark3.5.x/src/main/scala/org/apache/spark/sql/HoodieSpark35CatalystExpressionUtils.scala [65:115]
37 lines of code
34 McCabe index (conditional complexity)

    def unapply(expr: Expression): Option[AttributeReference] = {
      expr match {
        // Date/Time Expressions
        case DateFormatClass(OrderPreservingTransformation(attrRef), _, _) => Some(attrRef)
        case DateAdd(OrderPreservingTransformation(attrRef), _) => Some(attrRef)
        case DateSub(OrderPreservingTransformation(attrRef), _) => Some(attrRef)
        case DateDiff(OrderPreservingTransformation(attrRef), _) => Some(attrRef)
        case DateDiff(_, OrderPreservingTransformation(attrRef)) => Some(attrRef)
        case FromUnixTime(OrderPreservingTransformation(attrRef), _, _) => Some(attrRef)
        case FromUTCTimestamp(OrderPreservingTransformation(attrRef), _) => Some(attrRef)
        case ParseToDate(OrderPreservingTransformation(attrRef), _, _, _) => Some(attrRef)
        case ParseToTimestamp(OrderPreservingTransformation(attrRef), _, _, _, _) => Some(attrRef)
        case ToUnixTimestamp(OrderPreservingTransformation(attrRef), _, _, _) => Some(attrRef)
        case ToUTCTimestamp(OrderPreservingTransformation(attrRef), _) => Some(attrRef)

        // String Expressions
        case Lower(OrderPreservingTransformation(attrRef)) => Some(attrRef)
        case Upper(OrderPreservingTransformation(attrRef)) => Some(attrRef)
        // Left API change: Improve RuntimeReplaceable
        // https://issues.apache.org/jira/browse/SPARK-38240
        case org.apache.spark.sql.catalyst.expressions.Left(OrderPreservingTransformation(attrRef), _) => Some(attrRef)

        // Math Expressions
        // Binary
        case Add(OrderPreservingTransformation(attrRef), _, _) => Some(attrRef)
        case Add(_, OrderPreservingTransformation(attrRef), _) => Some(attrRef)
        case Multiply(OrderPreservingTransformation(attrRef), _, _) => Some(attrRef)
        case Multiply(_, OrderPreservingTransformation(attrRef), _) => Some(attrRef)
        case Divide(OrderPreservingTransformation(attrRef), _, _) => Some(attrRef)
        case BitwiseOr(OrderPreservingTransformation(attrRef), _) => Some(attrRef)
        case BitwiseOr(_, OrderPreservingTransformation(attrRef)) => Some(attrRef)
        // Unary
        case Exp(OrderPreservingTransformation(attrRef)) => Some(attrRef)
        case Expm1(OrderPreservingTransformation(attrRef)) => Some(attrRef)
        case Log(OrderPreservingTransformation(attrRef)) => Some(attrRef)
        case Log10(OrderPreservingTransformation(attrRef)) => Some(attrRef)
        case Log1p(OrderPreservingTransformation(attrRef)) => Some(attrRef)
        case Log2(OrderPreservingTransformation(attrRef)) => Some(attrRef)
        case ShiftLeft(OrderPreservingTransformation(attrRef), _) => Some(attrRef)
        case ShiftRight(OrderPreservingTransformation(attrRef), _) => Some(attrRef)

        // Other
        case cast @ Cast(OrderPreservingTransformation(attrRef), _, _, _)
          if isCastPreservingOrdering(cast.child.dataType, cast.dataType) => Some(attrRef)

        // Identity transformation
        case attrRef: AttributeReference => Some(attrRef)
        // No match
        case _ => None
      }
    }