org.apache.lucene.codecs

## Class PostingsWriterBase

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

- All Implemented Interfaces:
    Closeable, AutoCloseable
  Direct Known Subclasses:
    PushPostingsWriterBase

      public abstract class PostingsWriterBase
      extends Object
      implements Closeable

  Class that plugs into term dictionaries, such as `BlockTreeTermsWriter`, and handles writing postings.
  See Also:
    `PostingsReaderBase`
  WARNING: This API is experimental and might change in incompatible ways in the next release.

- - ### Constructor Summary

    Constructors
    Modifier | Constructor and Description
    --- | ---
    `protected` | `PostingsWriterBase()` Sole constructor.

  - ### Method Summary

    All Methods Instance Methods Abstract Methods
    Modifier and Type | Method and Description
    --- | ---
    `abstract void` | `close()`
    `abstract void` | `encodeTerm(long[] longs, DataOutput out, FieldInfo fieldInfo, BlockTermState state, boolean absolute)` Encode metadata as long[] and byte[].
    `abstract void` | `init(IndexOutput termsOut, SegmentWriteState state)` Called once after startup, before any terms have been added.
    `abstract int` | `setField(FieldInfo fieldInfo)` Sets the current field for writing, and returns the fixed length of long[] metadata (which is fixed per field), called when the writing switches to another field.
    `abstract BlockTermState` | `writeTerm(BytesRef term, TermsEnum termsEnum, FixedBitSet docsSeen)` Write all postings for one term; use the provided `TermsEnum` to pull a `PostingsEnum`.

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

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

- - ### Constructor Detail

    - #### PostingsWriterBase

          protected PostingsWriterBase()

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

  - ### Method Detail

    - #### init

          public abstract void init(IndexOutput termsOut,
                                    SegmentWriteState state)
                             throws IOException

      Called once after startup, before any terms have been added. Implementations typically write a header to the provided `termsOut`.
      Throws:
        `IOException`

    - #### writeTerm

          public abstract BlockTermState writeTerm(BytesRef term,
                                                   TermsEnum termsEnum,
                                                   FixedBitSet docsSeen)
                                            throws IOException

      Write all postings for one term; use the provided `TermsEnum` to pull a `PostingsEnum`. This method should not re-position the `TermsEnum`! It is already positioned on the term that should be written. This method must set the bit in the provided `FixedBitSet` for every docID written. If no docs were written, this method should return null, and the terms dict will skip the term.
      Throws:
        `IOException`

    - #### encodeTerm

          public abstract void encodeTerm(long[] longs,
                                          DataOutput out,
                                          FieldInfo fieldInfo,
                                          BlockTermState state,
                                          boolean absolute)
                                   throws IOException

      Encode metadata as long[] and byte[]. `absolute` controls whether current term is delta encoded according to latest term. Usually elements in `longs` are file pointers, so each one always increases when a new term is consumed. `out` is used to write generic bytes, which are not monotonic. NOTE: sometimes long[] might contain "don't care" values that are unused, e.g. the pointer to postings list may not be defined for some terms but is defined for others, if it is designed to inline some postings data in term dictionary. In this case, the postings writer should always use the last value, so that each element in metadata long[] remains monotonic.
      Throws:
        `IOException`

    - #### setField

          public abstract int setField(FieldInfo fieldInfo)

      Sets the current field for writing, and returns the fixed length of long[] metadata (which is fixed per field), called when the writing switches to another field.

    - #### close

          public abstract void close()
                              throws IOException

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

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