org.apache.lucene.analysis.pattern

## Class PatternCaptureGroupTokenFilter

- java.lang.Object
- - org.apache.lucene.util.AttributeSource
  - - org.apache.lucene.analysis.TokenStream
    - - org.apache.lucene.analysis.TokenFilter
      - - org.apache.lucene.analysis.pattern.PatternCaptureGroupTokenFilter

- All Implemented Interfaces:
    Closeable, AutoCloseable

      public final class PatternCaptureGroupTokenFilter
      extends TokenFilter

  CaptureGroup uses Java regexes to emit multiple tokens - one for each capture group in one or more patterns.

  For example, a pattern like:

  `"(https?://([a-zA-Z\-_0-9.]+))"`

  when matched against the string "http://www.foo.com/index" would return the tokens "https://www.foo.com" and "www.foo.com".

  If none of the patterns match, or if preserveOriginal is true, the original token will be preserved.

  Each pattern is matched as often as it can be, so the pattern `"(...)"`, when matched against `"abcdefghi"` would produce `["abc","def","ghi"]`

  A camelCaseFilter could be written as:

  `"([A-Z]{2,})", "(?<![A-Z])([A-Z][a-z]+)", "(?:^|\\b|(?<=[0-9_])|(?<=[A-Z]{2}))([a-z]+)", "([0-9]+)"`

  plus if `preserveOriginal` is true, it would also return `"camelCaseFilter"`

- - ### Nested Class Summary

    - ### Nested classes/interfaces inherited from class org.apache.lucene.util.AttributeSource

      `AttributeSource.State`

  - ### Field Summary

    - ### Fields inherited from class org.apache.lucene.analysis.TokenFilter

      `input`

    - ### Fields inherited from class org.apache.lucene.analysis.TokenStream

      `DEFAULT_TOKEN_ATTRIBUTE_FACTORY`

  - ### Constructor Summary

    Constructors
    Constructor and Description
    `PatternCaptureGroupTokenFilter(TokenStream input, boolean preserveOriginal, Pattern... patterns)`

  - ### Method Summary

    Methods
    Modifier and Type | Method and Description
    --- | ---
    `boolean` | `incrementToken()`
    `void` | `reset()`

    - ### Methods inherited from class org.apache.lucene.analysis.TokenFilter

      `close, end`

    - ### Methods inherited from class org.apache.lucene.util.AttributeSource

      `addAttribute, addAttributeImpl, captureState, clearAttributes, cloneAttributes, copyTo, endAttributes, equals, getAttribute, getAttributeClassesIterator, getAttributeFactory, getAttributeImplsIterator, hasAttribute, hasAttributes, hashCode, reflectAsString, reflectWith, removeAllAttributes, restoreState, toString`

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

      `clone, finalize, getClass, notify, notifyAll, wait, wait, wait`

- - ### Constructor Detail

    - #### PatternCaptureGroupTokenFilter

          public PatternCaptureGroupTokenFilter(TokenStream input,
                                        boolean preserveOriginal,
                                        Pattern... patterns)

      Parameters:
        `input` - the input `TokenStream`
        `preserveOriginal` - set to true to return the original token even if one of the patterns matches
        `patterns` - an array of `Pattern` objects to match against each token

  - ### Method Detail

    - #### incrementToken

          public boolean incrementToken()
                                 throws IOException

      Specified by:
        `incrementToken` in class `TokenStream`
      Throws:
        `IOException`

    - #### reset

          public void reset()
                     throws IOException

      Overrides:
        `reset` in class `TokenFilter`
      Throws:
        `IOException`

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