func()

in table/arrow_utils.go [707:771]
55 lines of code
25 McCabe index (conditional complexity)

func (a *arrowProjectionVisitor) castIfNeeded(field iceberg.NestedField, vals arrow.Array) arrow.Array {
	fileField, ok := a.fileSchema.FindFieldByID(field.ID)
	if !ok {
		panic(fmt.Errorf("could not find field id %d in schema", field.ID))
	}

	typ, ok := fileField.Type.(iceberg.PrimitiveType)
	if !ok {
		vals.Retain()

		return vals
	}

	if !field.Type.Equals(typ) {
		promoted := retOrPanic(iceberg.PromoteType(fileField.Type, field.Type))
		targetType := retOrPanic(TypeToArrowType(promoted, a.includeFieldIDs, a.useLargeTypes))
		if !a.useLargeTypes {
			targetType = retOrPanic(ensureSmallArrowTypes(targetType))
		}

		return retOrPanic(compute.CastArray(a.ctx, vals,
			compute.SafeCastOptions(targetType)))
	}

	targetType := retOrPanic(TypeToArrowType(field.Type, a.includeFieldIDs, a.useLargeTypes))
	if !arrow.TypeEqual(targetType, vals.DataType()) {
		switch field.Type.(type) {
		case iceberg.TimestampType:
			tt, tgtok := targetType.(*arrow.TimestampType)
			vt, valok := vals.DataType().(*arrow.TimestampType)

			if tgtok && valok && tt.TimeZone == "" && vt.TimeZone == "" && tt.Unit == arrow.Microsecond {
				if vt.Unit == arrow.Nanosecond && a.downcastNsTimestamp {
					return retOrPanic(compute.CastArray(a.ctx, vals, compute.UnsafeCastOptions(tt)))
				} else if vt.Unit == arrow.Second || vt.Unit == arrow.Millisecond {
					return retOrPanic(compute.CastArray(a.ctx, vals, compute.SafeCastOptions(tt)))
				}
			}

			panic(fmt.Errorf("unsupported schema projection from %s to %s",
				vals.DataType(), targetType))
		case iceberg.TimestampTzType:
			tt, tgtok := targetType.(*arrow.TimestampType)
			vt, valok := vals.DataType().(*arrow.TimestampType)

			if tgtok && valok && tt.TimeZone == "UTC" &&
				slices.Contains(utcAliases, vt.TimeZone) && tt.Unit == arrow.Microsecond {
				if vt.Unit == arrow.Nanosecond && a.downcastNsTimestamp {
					return retOrPanic(compute.CastArray(a.ctx, vals, compute.UnsafeCastOptions(tt)))
				} else if vt.Unit != arrow.Nanosecond {
					return retOrPanic(compute.CastArray(a.ctx, vals, compute.SafeCastOptions(tt)))
				}
			}

			panic(fmt.Errorf("unsupported schema projection from %s to %s",
				vals.DataType(), targetType))
		default:
			return retOrPanic(compute.CastArray(a.ctx, vals,
				compute.SafeCastOptions(targetType)))
		}
	}
	vals.Retain()

	return vals
}