ArrayReaderImpl (Drill : 1.20.3 API)

java.lang.Object
- org.apache.drill.exec.vector.accessor.reader.ArrayReaderImpl

All Implemented Interfaces:

ArrayReader, ColumnReader, ReaderEvents

Direct Known Subclasses:

DictReaderImpl
```
public class ArrayReaderImpl
extends Object
implements ArrayReader, ReaderEvents
```
Reader for an array-valued column. This reader provides access to specific array members via an array index. This class implements all arrays. The behavior for specific array types (scalar, map, lists, etc.) is provided through composition.

Nested Class Summary

Nested Classes
Modifier and Type	Class and Description
`static class`	`ArrayReaderImpl.ArrayObjectReader` Object representation of an array reader.
`static class`	`ArrayReaderImpl.ElementReaderIndex` Index into the vector of elements for a repeated vector.

Field Summary

Fields
Modifier and Type	Field and Description
`protected ArrayReaderImpl.ElementReaderIndex`	`elementIndex`
`protected AbstractObjectReader`	`elementReader`
`protected NullStateReader`	`nullStateReader`

Constructor Summary

Constructors
Constructor and Description

ArrayReaderImpl(ColumnMetadata schema, VectorAccessor va, AbstractObjectReader elementReader)

Constructors
Constructor and Description
`ArrayReaderImpl(ColumnMetadata schema, VectorAccessor va, AbstractObjectReader elementReader)`

Method Summary

All Methods Static Methods Instance Methods Concrete Methods
Modifier and Type	Method and Description
`ArrayReader`	`array()`
`void`	`bindBuffer()`
`void`	`bindIndex(ColumnReaderIndex index)`
`void`	`bindNullState(NullStateReader nullStateReader)`
`static AbstractObjectReader`	`buildList(ColumnMetadata schema, VectorAccessor listAccessor, AbstractObjectReader elementReader)` Build a list reader.
`static AbstractObjectReader`	`buildRepeatedList(ColumnMetadata schema, VectorAccessor listAccessor, AbstractObjectReader elementReader)` Build a 2+D array reader.
`static ArrayReaderImpl.ArrayObjectReader`	`buildScalar(ColumnMetadata schema, VectorAccessor arrayAccessor, BaseScalarReader elementReader)` Build a scalar array for a Repeated type.
`static AbstractObjectReader`	`buildTuple(ColumnMetadata schema, VectorAccessor arrayAccessor, AbstractObjectReader elementReader)` Build a repeated map reader.
`ColumnReaderIndex`	`elementIndex()`
`ObjectReader`	`entry()` Return the generic object reader for the array element.
`ObjectType`	`entryType()` The object type of the list entry.
`String`	`getAsString()` Return the entire object as a string.
`Object`	`getObject()` Return the value of the underlying data as a Java object.
`boolean`	`isNull()` Determine if this value is null.
`boolean`	`next()` Move forward one position.
`NullStateReader`	`nullStateReader()`
`void`	`reposition()`
`void`	`rewind()`
`ScalarReader`	`scalar()`
`ColumnMetadata`	`schema()`
`void`	`setPosn(int posn)` Set the array reader to read a given array entry.
`int`	`size()` Number of elements in the array.
`TupleReader`	`tuple()`
`ObjectType`	`type()` The type of this reader.
`VariantReader`	`variant()`

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

- Field Detail
  - elementReader
```
protected final AbstractObjectReader elementReader
```
  - elementIndex
```
protected ArrayReaderImpl.ElementReaderIndex elementIndex
```
  - nullStateReader
```
protected NullStateReader nullStateReader
```
- Constructor Detail
  - ArrayReaderImpl
```
public ArrayReaderImpl(ColumnMetadata schema,
                       VectorAccessor va,
                       AbstractObjectReader elementReader)
```
- Method Detail
  - buildScalar
```
public static ArrayReaderImpl.ArrayObjectReader buildScalar(ColumnMetadata schema,
                                                            VectorAccessor arrayAccessor,
                                                            BaseScalarReader elementReader)
```
    Build a scalar array for a Repeated type. Such arrays are not nullable.
    
    Parameters:
    
    arrayAccessor - vector accessor for the repeated vector that holds the scalar values
    
    elementReader - scalar reader used to decode each scalar value
    
    Returns:
    
    object reader which wraps the scalar array reader
  - buildTuple
```
public static AbstractObjectReader buildTuple(ColumnMetadata schema,
                                              VectorAccessor arrayAccessor,
                                              AbstractObjectReader elementReader)
```
    Build a repeated map reader.
    
    Parameters:
    
    arrayAccessor - vector accessor for the repeated map vector
    
    elementReader - tuple reader that provides access to each tuple in the array
    
    Returns:
    
    object reader that wraps the map array reader
  - buildList
```
public static AbstractObjectReader buildList(ColumnMetadata schema,
                                             VectorAccessor listAccessor,
                                             AbstractObjectReader elementReader)
```
    Build a list reader. Lists entries can be null. The reader can be a simple scalar, a map, a union, or another list.
    
    Parameters:
    
    listAccessor -
    
    elementReader -
    
    Returns:
  - buildRepeatedList
```
public static AbstractObjectReader buildRepeatedList(ColumnMetadata schema,
                                                     VectorAccessor listAccessor,
                                                     AbstractObjectReader elementReader)
```
    Build a 2+D array reader. The backing vector must be a repeated list. The element reader must itself be a repeated list, or a repeated of some other type.
    
    Parameters:
    
    schema -
    
    listAccessor -
    
    elementReader -
    
    Returns:
  - bindIndex
```
public void bindIndex(ColumnReaderIndex index)
```
    Specified by:
    
    bindIndex in interface ReaderEvents
  - bindNullState
```
public void bindNullState(NullStateReader nullStateReader)
```
    Specified by:
    
    bindNullState in interface ReaderEvents
  - type
```
public ObjectType type()
```
    Description copied from interface: ColumnReader
    
    The type of this reader.
    
    Specified by:
    
    type in interface ColumnReader
    
    Returns:
    
    type of reader
  - schema
```
public ColumnMetadata schema()
```
    Specified by:
    
    schema in interface ColumnReader
  - nullStateReader
```
public NullStateReader nullStateReader()
```
    Specified by:
    
    nullStateReader in interface ReaderEvents
  - isNull
```
public boolean isNull()
```
    Description copied from interface: ColumnReader
    Determine if this value is null.
    - Nullable scalar: determine if the value is null.
    - Non-nullable scalar: always returns false.
    - Arrays: always returns false
    - Lists: determine if the list for the current row is null. In a list, an array entry can be null, empty, or can contain items. In repeated types, the array itself is never null. If the array is null, then it implicitly has no entries.
    - Map or Repeated Map: Always returns false.
    - Map inside a union, or in a list that contains a union, the tuple itself can be null.
    - Union: Determine if the current value is null. Null values have no type and no associated reader.
    Specified by:
    
    isNull in interface ColumnReader
    
    Returns:
    
    true if this value is null; false otherwise
  - reposition
```
public void reposition()
```
    Specified by:
    
    reposition in interface ReaderEvents
  - next
```
public boolean next()
```
    Description copied from interface: ArrayReader
    
    Move forward one position.
    
    Specified by:
    
    next in interface ArrayReader
    
    Returns:
    
    true if another position is available, false if the end of the array is reached
  - elementIndex
```
public ColumnReaderIndex elementIndex()
```
  - size
```
public int size()
```
    Description copied from interface: ArrayReader
    
    Number of elements in the array.
    
    Specified by:
    
    size in interface ArrayReader
    
    Returns:
    
    the number of elements
  - setPosn
```
public void setPosn(int posn)
```
    Description copied from interface: ArrayReader
    
    Set the array reader to read a given array entry. Not used for scalars, only for maps and arrays when using the non-indexed methods ArrayReader.entry(), ArrayReader.tuple() and ArrayReader.array().
    
    Specified by:
    
    setPosn in interface ArrayReader
  - rewind
```
public void rewind()
```
    Specified by:
    
    rewind in interface ArrayReader
  - bindBuffer
```
public void bindBuffer()
```
    Specified by:
    
    bindBuffer in interface ReaderEvents
  - entry
```
public ObjectReader entry()
```
    Description copied from interface: ArrayReader
    
    Return the generic object reader for the array element. This version does not position the reader, the client must call ArrayReader.setPosn(int) to set the position. This form allows up-front setup of the readers when convenient for the caller.
    
    Specified by:
    
    entry in interface ArrayReader
  - entryType
```
public ObjectType entryType()
```
    Description copied from interface: ArrayReader
    
    The object type of the list entry. All entries have the same type.
    
    Specified by:
    
    entryType in interface ArrayReader
    
    Returns:
    
    the object type of each entry
  - scalar
```
public ScalarReader scalar()
```
    Specified by:
    
    scalar in interface ArrayReader
  - tuple
```
public TupleReader tuple()
```
    Specified by:
    
    tuple in interface ArrayReader
  - array
```
public ArrayReader array()
```
    Specified by:
    
    array in interface ArrayReader
  - variant
```
public VariantReader variant()
```
    Specified by:
    
    variant in interface ArrayReader
  - getObject
```
public Object getObject()
```
    Description copied from interface: ColumnReader
    Return the value of the underlying data as a Java object. Primarily for testing
    - Array: Return the entire array as an List of objects. Note, even if the array is scalar, the elements are still returned as a list.
    Specified by:
    
    getObject in interface ColumnReader
    
    Returns:
    
    the value as a Java object
  - getAsString
```
public String getAsString()
```
    Description copied from interface: ColumnReader
    
    Return the entire object as a string. Primarily for debugging.
    
    Specified by:
    
    getAsString in interface ColumnReader
    
    Returns:
    
    string representation of the object

Class ArrayReaderImpl

Nested Class Summary

Field Summary

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Field Detail

elementReader

elementIndex

nullStateReader

Constructor Detail

ArrayReaderImpl

Method Detail

buildScalar

buildTuple

buildList

buildRepeatedList

bindIndex

bindNullState

type

schema

nullStateReader

isNull

reposition

next

elementIndex

size

setPosn

rewind

bindBuffer

entry

entryType

scalar

tuple

array

variant

getObject

getAsString