org.apache.lucene.codecs

## Class TermVectorsWriter

- java.lang.Object
- - org.apache.lucene.codecs.TermVectorsWriter

All Implemented Interfaces:
  Closeable, AutoCloseable

Direct Known Subclasses:
  CompressingTermVectorsWriter, Lucene40TermVectorsWriter

    public abstract class TermVectorsWriter
    extends Object
    implements Closeable

Codec API for writing term vectors:

1. For every document, `startDocument(int)` is called, informing the Codec how many fields will be written.
2. `startField(FieldInfo, int, boolean, boolean, boolean)` is called for each field in the document, informing the codec how many terms will be written for that field, and whether or not positions, offsets, or payloads are enabled.
3. Within each field, `startTerm(BytesRef, int)` is called for each term.
4. If offsets and/or positions are enabled, then `addPosition(int, int, int, BytesRef)` will be called for each term occurrence.
5. After all documents have been written, `finish(FieldInfos, int)` is called for verification/sanity-checks.
6. Finally the writer is closed (`close()`)

WARNING: This API is experimental and might change in incompatible ways in the next release.

### Constructor Summary

Constructors
`protected` `TermVectorsWriter()` Sole constructor.

### Method Summary

Methods
`abstract void` `abort()` Aborts writing entirely, implementation should remove any partially-written files, etc.
`protected void` `addAllDocVectors(Fields vectors, MergeState mergeState)` Safe (but, slowish) default method to write every vector field in the document.
`abstract void` `addPosition(int position, int startOffset, int endOffset, BytesRef payload)` Adds a term position and offsets
`void` `addProx(int numProx, DataInput positions, DataInput offsets)` Called by IndexWriter when writing new segments.
`abstract void` `close()`
`abstract void` `finish(FieldInfos fis, int numDocs)` Called before `close()`, passing in the number of documents that were written.
`void` `finishDocument()` Called after a doc and all its fields have been added.
`void` `finishField()` Called after a field and all its terms have been added.
`void` `finishTerm()` Called after a term and all its positions have been added.
`abstract Comparator<BytesRef>` `getComparator()` Return the BytesRef Comparator used to sort terms before feeding to this API.
`int` `merge(MergeState mergeState)` Merges in the term vectors from the readers in `mergeState`.
`abstract void` `startDocument(int numVectorFields)` Called before writing the term vectors of the document.
`abstract void` `startField(FieldInfo info, int numTerms, boolean positions, boolean offsets, boolean payloads)` Called before writing the terms of the field.
`abstract void` `startTerm(BytesRef term, int freq)` Adds a term and its term frequency `freq`.

### Methods inherited from class java.lang.Object

`clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait`

### Constructor Detail

#### TermVectorsWriter

    protected TermVectorsWriter()

Sole constructor. (For invocation by subclass constructors, typically implicit.)

### Method Detail

#### startDocument

    public abstract void startDocument(int numVectorFields)
                                throws IOException

Called before writing the term vectors of the document. `startField(FieldInfo, int, boolean, boolean, boolean)` will be called `numVectorFields` times. Note that if term vectors are enabled, this is called even if the document has no vector fields, in this case `numVectorFields` will be zero.

Throws:
  `IOException`

#### finishDocument

    public void finishDocument()
                        throws IOException

Called after a doc and all its fields have been added.

Throws:
  `IOException`

#### startField

    public abstract void startField(FieldInfo info,
                  int numTerms,
                  boolean positions,
                  boolean offsets,
                  boolean payloads)
                             throws IOException

Called before writing the terms of the field. `startTerm(BytesRef, int)` will be called `numTerms` times.

Throws:
  `IOException`

#### finishField

    public void finishField()
                     throws IOException

Called after a field and all its terms have been added.

Throws:
  `IOException`

#### startTerm

    public abstract void startTerm(BytesRef term,
                 int freq)
                            throws IOException

Adds a term and its term frequency `freq`. If this field has positions and/or offsets enabled, then `addPosition(int, int, int, BytesRef)` will be called `freq` times respectively.

Throws:
  `IOException`

#### finishTerm

    public void finishTerm()
                    throws IOException

Called after a term and all its positions have been added.

Throws:
  `IOException`

#### addPosition

    public abstract void addPosition(int position,
                   int startOffset,
                   int endOffset,
                   BytesRef payload)
                              throws IOException

Adds a term position and offsets

Throws:
  `IOException`

#### abort

    public abstract void abort()

Aborts writing entirely, implementation should remove any partially-written files, etc.

#### finish

    public abstract void finish(FieldInfos fis,
              int numDocs)
                         throws IOException

Called before `close()`, passing in the number of documents that were written. Note that this is intentionally redundant (equivalent to the number of calls to `startDocument(int)`, but a Codec should check that this is the case to detect the JRE bug described in LUCENE-1282.

Throws:
  `IOException`

#### addProx

    public void addProx(int numProx,
               DataInput positions,
               DataInput offsets)
                 throws IOException

Called by IndexWriter when writing new segments.

This is an expert API that allows the codec to consume positions and offsets directly from the indexer.

The default implementation calls `addPosition(int, int, int, BytesRef)`, but subclasses can override this if they want to efficiently write all the positions, then all the offsets, for example.

NOTE: This API is extremely expert and subject to change or removal!!!

Throws:
  `IOException`
NOTE: This API is for internal purposes only and might change in incompatible ways in the next release.

#### merge

    public int merge(MergeState mergeState)
              throws IOException

Merges in the term vectors from the readers in `mergeState`. The default implementation skips over deleted documents, and uses `startDocument(int)`, `startField(FieldInfo, int, boolean, boolean, boolean)`, `startTerm(BytesRef, int)`, `addPosition(int, int, int, BytesRef)`, and `finish(FieldInfos, int)`, returning the number of documents that were written. Implementations can override this method for more sophisticated merging (bulk-byte copying, etc).

Throws:
  `IOException`

#### addAllDocVectors

    protected final void addAllDocVectors(Fields vectors,
                        MergeState mergeState)
                                   throws IOException

Safe (but, slowish) default method to write every vector field in the document.

Throws:
  `IOException`

#### getComparator

    public abstract Comparator<BytesRef> getComparator()
                                                throws IOException

Return the BytesRef Comparator used to sort terms before feeding to this API.

Throws:
  `IOException`

#### close

    public abstract void close()
                        throws IOException

Specified by:
  `close` in interface `Closeable`
Specified by:
  `close` in interface `AutoCloseable`
Throws:
  `IOException`