Package 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, Unwrappable<TokenStream>
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"

  • Constructor Details

    • 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 Details