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git-svn-id: https://svn.apache.org/repos/asf/lucene/dev/trunk@1525506 13f79535-47bb-0310-9956-ffa450edef68
This commit is contained in:
Shai Erera 2013-09-23 05:06:51 +00:00
parent 49adf29d17
commit 08f690ef16
1 changed files with 48 additions and 28 deletions
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74
lucene/analysis/common/src/java/org/apache/lucene/analysis/miscellaneous/WordDelimiterFilter.java
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@ -19,6 +19,8 @@ package org.apache.lucene.analysis.miscellaneous;
import org.apache.lucene.analysis.TokenFilter;
import org.apache.lucene.analysis.TokenStream;
import org.apache.lucene.analysis.core.WhitespaceTokenizer;
import org.apache.lucene.analysis.standard.StandardTokenizer;
import org.apache.lucene.analysis.tokenattributes.OffsetAttribute;
import org.apache.lucene.analysis.tokenattributes.PositionIncrementAttribute;
import org.apache.lucene.analysis.tokenattributes.CharTermAttribute;
@ -30,36 +32,54 @@ import org.apache.lucene.util.RamUsageEstimator;
import java.io.IOException;
/**
* Splits words into subwords and performs optional transformations on subword groups.
* Words are split into subwords with the following rules:
* - split on intra-word delimiters (by default, all non alpha-numeric characters).
* - "Wi-Fi" -> "Wi", "Fi"
* - split on case transitions
* - "PowerShot" -> "Power", "Shot"
* - split on letter-number transitions
* - "SD500" -> "SD", "500"
* - leading and trailing intra-word delimiters on each subword are ignored
* - "//hello---there, 'dude'" -> "hello", "there", "dude"
* - trailing "'s" are removed for each subword
* - "O'Neil's" -> "O", "Neil"
* - Note: this step isn't performed in a separate filter because of possible subword combinations.
* Splits words into subwords and performs optional transformations on subword
* groups. Words are split into subwords with the following rules:
* <ul>
* <li>split on intra-word delimiters (by default, all non alpha-numeric
* characters): <code>"Wi-Fi"</code> &#8594; <code>"Wi", "Fi"</code></li>
* <li>split on case transitions: <code>"PowerShot"</code> &#8594;
* <code>"Power", "Shot"</code></li>
* <li>split on letter-number transitions: <code>"SD500"</code> &#8594;
* <code>"SD", "500"</code></li>
* <li>leading and trailing intra-word delimiters on each subword are ignored:
* <code>"//hello---there, 'dude'"</code> &#8594;
* <code>"hello", "there", "dude"</code></li>
* <li>trailing "'s" are removed for each subword: <code>"O'Neil's"</code>
* &#8594; <code>"O", "Neil"</code>
* <ul>
* <li>Note: this step isn't performed in a separate filter because of possible
* subword combinations.</li>
* </ul>
* </li>
* </ul>
*
* The <b>combinations</b> parameter affects how subwords are combined:
* - combinations="0" causes no subword combinations.
* - "PowerShot" -> 0:"Power", 1:"Shot" (0 and 1 are the token positions)
* - combinations="1" means that in addition to the subwords, maximum runs of non-numeric subwords are catenated and produced at the same position of the last subword in the run.
* - "PowerShot" -> 0:"Power", 1:"Shot" 1:"PowerShot"
* - "A's+B's&C's" -> 0:"A", 1:"B", 2:"C", 2:"ABC"
* - "Super-Duper-XL500-42-AutoCoder!" -> 0:"Super", 1:"Duper", 2:"XL", 2:"SuperDuperXL", 3:"500" 4:"42", 5:"Auto", 6:"Coder", 6:"AutoCoder"
*
* One use for WordDelimiterFilter is to help match words with different subword delimiters.
* For example, if the source text contained "wi-fi" one may want "wifi" "WiFi" "wi-fi" "wi+fi" queries to all match.
* One way of doing so is to specify combinations="1" in the analyzer used for indexing, and combinations="0" (the default)
* in the analyzer used for querying. Given that the current StandardTokenizer immediately removes many intra-word
* delimiters, it is recommended that this filter be used after a tokenizer that does not do this (such as WhitespaceTokenizer).
*
* <ul>
* <li>combinations="0" causes no subword combinations: <code>"PowerShot"</code>
* &#8594; <code>0:"Power", 1:"Shot"</code> (0 and 1 are the token positions)</li>
* <li>combinations="1" means that in addition to the subwords, maximum runs of
* non-numeric subwords are catenated and produced at the same position of the
* last subword in the run:
* <ul>
* <li><code>"PowerShot"</code> &#8594;
* <code>0:"Power", 1:"Shot" 1:"PowerShot"</code></li>
* <li><code>"A's+B's&C's"</code> -gt; <code>0:"A", 1:"B", 2:"C", 2:"ABC"</code>
* </li>
* <li><code>"Super-Duper-XL500-42-AutoCoder!"</code> &#8594;
* <code>0:"Super", 1:"Duper", 2:"XL", 2:"SuperDuperXL", 3:"500" 4:"42", 5:"Auto", 6:"Coder", 6:"AutoCoder"</code>
* </li>
* </ul>
* </li>
* </ul>
* One use for {@link WordDelimiterFilter} is to help match words with different
* subword delimiters. For example, if the source text contained "wi-fi" one may
* want "wifi" "WiFi" "wi-fi" "wi+fi" queries to all match. One way of doing so
* is to specify combinations="1" in the analyzer used for indexing, and
* combinations="0" (the default) in the analyzer used for querying. Given that
* the current {@link StandardTokenizer} immediately removes many intra-word
* delimiters, it is recommended that this filter be used after a tokenizer that
* does not do this (such as {@link WhitespaceTokenizer}).
*/
public final class WordDelimiterFilter extends TokenFilter {
public static final int LOWER = 0x01;