EmptyListShim (Drill : 1.20.3 API)

java.lang.Object
- org.apache.drill.exec.vector.accessor.writer.EmptyListShim

All Implemented Interfaces:

UnionWriterImpl.UnionShim, WriterEvents, WriterPosition
```
public class EmptyListShim
extends Object
implements UnionWriterImpl.UnionShim
```
Internal implementation for a list of (possible) variants when the list has no type associated with it at all. This shim is a placeholder that waits for the first type to be added. Used in the case that a list may eventually hold a union, but at present it holds nothing.

Nested Class Summary
- Nested classes/interfaces inherited from interface org.apache.drill.exec.vector.accessor.writer.WriterEvents
  WriterEvents.ColumnWriterListener, WriterEvents.State

Constructor Summary

Constructors
Constructor and Description

EmptyListShim()

Constructors
Constructor and Description
`EmptyListShim()`

Method Summary

All Methods Instance Methods Concrete Methods
Modifier and Type	Method and Description
`void`	`addMember(AbstractObjectWriter colWriter)`
`AbstractObjectWriter`	`addMember(ColumnMetadata colSchema)`
`AbstractObjectWriter`	`addMember(TypeProtos.MinorType type)`
`void`	`bindIndex(ColumnWriterIndex index)` Bind the writer to a writer index.
`void`	`bindListener(WriterEvents.ColumnWriterListener listener)` Bind a listener to the underlying vector writer.
`void`	`bindWriter(UnionWriterImpl writer)`
`void`	`dump(HierarchicalFormatter format)`
`void`	`endArrayValue()` End a value.
`void`	`endWrite()` End a batch: finalize any vector values.
`boolean`	`hasType(TypeProtos.MinorType type)`
`int`	`lastWriteIndex()` Return the last write position in the vector.
`ObjectWriter`	`member(TypeProtos.MinorType type)` Return an existing writer for the given type, or create a new one if needed.
`void`	`postRollover()` The vectors backing this writer rolled over.
`void`	`preRollover()` The vectors backing this vector are about to roll over.
`void`	`restartRow()` During a writer to a row, rewind the the current index position to restart the row.
`int`	`rowStartIndex()` Position within the vector of the first value for the current row.
`void`	`saveRow()` Saves a row.
`void`	`setNull()`
`void`	`setType(TypeProtos.MinorType type)`
`void`	`startRow()` Start a new row.
`void`	`startWrite()` Start a write (batch) operation.
`int`	`writeIndex()` Current write index for the writer.

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

- Constructor Detail
  - EmptyListShim
```
public EmptyListShim()
```
- Method Detail
  - bindWriter
```
public void bindWriter(UnionWriterImpl writer)
```
    Specified by:
    
    bindWriter in interface UnionWriterImpl.UnionShim
  - bindIndex
```
public void bindIndex(ColumnWriterIndex index)
```
    Description copied from interface: WriterEvents
    
    Bind the writer to a writer index.
    
    Specified by:
    
    bindIndex in interface WriterEvents
    
    Parameters:
    
    index - the writer index (top level or nested for arrays)
  - bindListener
```
public void bindListener(WriterEvents.ColumnWriterListener listener)
```
    Description copied from interface: WriterEvents
    
    Bind a listener to the underlying vector writer. This listener reports on vector events (overflow, growth), and so is called only when the writer is backed by a vector. The listener is ignored (and never called) for dummy (non-projected) columns. If the column is compound (such as for a nullable or repeated column, or for a map), then the writer is bound to the individual components.
    
    Specified by:
    
    bindListener in interface WriterEvents
    
    Parameters:
    
    listener - the vector event listener to bind
  - startWrite
```
public void startWrite()
```
    Description copied from interface: WriterEvents
    
    Start a write (batch) operation. Performs any vector initialization required at the start of a batch (especially for offset vectors.)
    
    Specified by:
    
    startWrite in interface WriterEvents
  - startRow
```
public void startRow()
```
    Description copied from interface: WriterEvents
    
    Start a new row. To be called only when a row is not active. To restart a row, call WriterEvents.restartRow() instead.
    
    Specified by:
    
    startRow in interface WriterEvents
  - endArrayValue
```
public void endArrayValue()
```
    Description copied from interface: WriterEvents
    
    End a value. Similar to WriterEvents.saveRow(), but the save of a value is conditional on saving the row. This version is primarily of use in tuples nested inside arrays: it saves each tuple within the array, advancing to a new position in the array. The update of the array's offset vector based on the cumulative value saves is done when saving the row.
    
    Specified by:
    
    endArrayValue in interface WriterEvents
  - restartRow
```
public void restartRow()
```
    Description copied from interface: WriterEvents
    
    During a writer to a row, rewind the the current index position to restart the row. Done when abandoning the current row, such as when filtering out a row at read time.
    
    Specified by:
    
    restartRow in interface WriterEvents
  - saveRow
```
public void saveRow()
```
    Description copied from interface: WriterEvents
    
    Saves a row. Commits offset vector locations and advances each to the next position. Can be called only when a row is active.
    
    Specified by:
    
    saveRow in interface WriterEvents
  - endWrite
```
public void endWrite()
```
    Description copied from interface: WriterEvents
    
    End a batch: finalize any vector values.
    
    Specified by:
    
    endWrite in interface WriterEvents
  - preRollover
```
public void preRollover()
```
    Description copied from interface: WriterEvents
    
    The vectors backing this vector are about to roll over. Finish the current batch up to, but not including, the current row.
    
    Specified by:
    
    preRollover in interface WriterEvents
  - postRollover
```
public void postRollover()
```
    Description copied from interface: WriterEvents
    
    The vectors backing this writer rolled over. This means that data for the current row has been rolled over into a new vector. Offsets and indexes should be shifted based on the understanding that data for the current row now resides at the start of a new vector instead of its previous location elsewhere in an old vector.
    
    Specified by:
    
    postRollover in interface WriterEvents
  - setNull
```
public void setNull()
```
    Specified by:
    
    setNull in interface UnionWriterImpl.UnionShim
  - hasType
```
public boolean hasType(TypeProtos.MinorType type)
```
    Specified by:
    
    hasType in interface UnionWriterImpl.UnionShim
  - member
```
public ObjectWriter member(TypeProtos.MinorType type)
```
    Description copied from interface: UnionWriterImpl.UnionShim
    
    Return an existing writer for the given type, or create a new one if needed.
    
    Specified by:
    
    member in interface UnionWriterImpl.UnionShim
    
    Parameters:
    
    type - desired variant type
    
    Returns:
    
    a writer for that type
  - setType
```
public void setType(TypeProtos.MinorType type)
```
    Specified by:
    
    setType in interface UnionWriterImpl.UnionShim
  - addMember
```
public AbstractObjectWriter addMember(ColumnMetadata colSchema)
```
    Specified by:
    
    addMember in interface UnionWriterImpl.UnionShim
  - addMember
```
public AbstractObjectWriter addMember(TypeProtos.MinorType type)
```
    Specified by:
    
    addMember in interface UnionWriterImpl.UnionShim
  - lastWriteIndex
```
public int lastWriteIndex()
```
    Description copied from interface: WriterPosition
    
    Return the last write position in the vector. This may be the same as the writer index position (if the vector was written at that point), or an earlier point. In either case, this value points to the last valid value in the vector.
    
    Specified by:
    
    lastWriteIndex in interface UnionWriterImpl.UnionShim
    
    Specified by:
    
    lastWriteIndex in interface WriterPosition
    
    Returns:
    
    index of the last valid value in the vector
  - rowStartIndex
```
public int rowStartIndex()
```
    Description copied from interface: WriterPosition
    
    Position within the vector of the first value for the current row. Note that this is always the first value for the row, even for a writer deeply nested within a hierarchy of arrays. (The first position for the current array is not exposed in this API.)
    
    Specified by:
    
    rowStartIndex in interface UnionWriterImpl.UnionShim
    
    Specified by:
    
    rowStartIndex in interface WriterPosition
    
    Returns:
    
    the vector offset of the first value for the current row
  - writeIndex
```
public int writeIndex()
```
    Description copied from interface: WriterPosition
    
    Current write index for the writer. This is the global array location for arrays, same as the row index for top-level columns.
    
    Specified by:
    
    writeIndex in interface WriterPosition
    
    Returns:
    
    current write index
  - addMember
```
public void addMember(AbstractObjectWriter colWriter)
```
    Specified by:
    
    addMember in interface UnionWriterImpl.UnionShim
  - dump
```
public void dump(HierarchicalFormatter format)
```
    Specified by:
    
    dump in interface WriterEvents

Class EmptyListShim

Nested Class Summary

Nested classes/interfaces inherited from interface org.apache.drill.exec.vector.accessor.writer.WriterEvents

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Constructor Detail

EmptyListShim

Method Detail

bindWriter

bindIndex

bindListener

startWrite

startRow

endArrayValue

restartRow

saveRow

endWrite

preRollover

postRollover

setNull

hasType

member

setType

addMember

addMember

lastWriteIndex

rowStartIndex

writeIndex

addMember

dump