All Known Implementing Classes:

ComplexFieldReader, DoubleArrayFieldReader, DoubleFieldReader, FloatArrayFieldReader, FloatFieldReader, LongArrayFieldReader, LongFieldReader, NumericArrayFieldReader, NumericFieldReader, StringArrayFieldReader, StringFieldReader
```
public interface FieldReader
```
Embeds the logic to read a specific field from row-based frames or from RowKey.
Most callers should use FrameReader or RowKeyReader rather than using this interface directly.
Stateless and immutable.

Method Summary

All Methods Instance Methods Abstract Methods
Modifier and Type	Method	Description
`boolean`	`isNull(org.apache.datasketches.memory.Memory memory, long position)`	Whether the provided memory position points to a null value.
`ColumnValueSelector<?>`	`makeColumnValueSelector(org.apache.datasketches.memory.Memory memory, ReadableFieldPointer fieldPointer)`	Create a `ColumnValueSelector` backed by some memory and a moveable pointer.
`DimensionSelector`	`makeDimensionSelector(org.apache.datasketches.memory.Memory memory, ReadableFieldPointer fieldPointer, ExtractionFn extractionFn)`	Create a `DimensionSelector` backed by some memory and a moveable pointer.
`Column`	`makeRACColumn(Frame frame, RowSignature signature, String columnName)`	Create a `Column` which provides accses to the rows in the frame, via the `Column.toAccessor()`.

Method Detail

makeRACColumn

Column makeRACColumn(Frame frame,
                     RowSignature signature,
                     String columnName)

Create a Column which provides accses to the rows in the frame, via the Column.toAccessor().

makeColumnValueSelector

ColumnValueSelector<?> makeColumnValueSelector(org.apache.datasketches.memory.Memory memory,
                                               ReadableFieldPointer fieldPointer)

Create a ColumnValueSelector backed by some memory and a moveable pointer.

makeDimensionSelector

DimensionSelector makeDimensionSelector(org.apache.datasketches.memory.Memory memory,
                                        ReadableFieldPointer fieldPointer,
                                        @Nullable
                                        ExtractionFn extractionFn)

Create a DimensionSelector backed by some memory and a moveable pointer.

isNull

boolean isNull(org.apache.datasketches.memory.Memory memory,
               long position)