Class WordDelimiterFilter

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.

The combinations 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" -gt; 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).
Inheritance
object
AttributeSource
TokenStream
TokenFilter
WordDelimiterFilter
Implements
Inherited Members
TokenFilter.End()
TokenStream.Dispose()
AttributeSource.GetAttributeFactory()
AttributeSource.GetAttributeClassesEnumerator()
AttributeSource.GetAttributeImplsEnumerator()
AttributeSource.AddAttributeImpl(Attribute)
AttributeSource.AddAttribute<T>()
AttributeSource.HasAttributes
AttributeSource.HasAttribute<T>()
AttributeSource.GetAttribute<T>()
AttributeSource.ClearAttributes()
AttributeSource.CaptureState()
AttributeSource.RestoreState(AttributeSource.State)
AttributeSource.GetHashCode()
AttributeSource.ReflectWith(IAttributeReflector)
AttributeSource.CloneAttributes()
AttributeSource.CopyTo(AttributeSource)
AttributeSource.ToString()
Namespace: Lucene.Net.Analysis.Miscellaneous
Assembly: Lucene.Net.Analysis.Common.dll
Syntax
public sealed class WordDelimiterFilter : TokenFilter, IDisposable

Constructors

WordDelimiterFilter(LuceneVersion, TokenStream, WordDelimiterFlags, CharArraySet)

Creates a new WordDelimiterFilter using DEFAULT_WORD_DELIM_TABLE as its charTypeTable

Declaration
public WordDelimiterFilter(LuceneVersion matchVersion, TokenStream @in, WordDelimiterFlags configurationFlags, CharArraySet protWords)
Parameters
Type Name Description
LuceneVersion matchVersion

lucene compatibility version
TokenStream in

Lucene.Net.Analysis.TokenStream to be filtered
WordDelimiterFlags configurationFlags

Flags configuring the filter
CharArraySet protWords

If not null is the set of tokens to protect from being delimited

WordDelimiterFilter(LuceneVersion, TokenStream, byte[], WordDelimiterFlags, CharArraySet)

Creates a new WordDelimiterFilter

Declaration
public WordDelimiterFilter(LuceneVersion matchVersion, TokenStream @in, byte[] charTypeTable, WordDelimiterFlags configurationFlags, CharArraySet protWords)
Parameters
Type Name Description
LuceneVersion matchVersion

lucene compatibility version
TokenStream in

TokenStream to be filtered
byte[] charTypeTable

table containing character types
WordDelimiterFlags configurationFlags

Flags configuring the filter
CharArraySet protWords

If not null is the set of tokens to protect from being delimited

Fields

ALPHA

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.

The combinations 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" -gt; 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).
Declaration
public const int ALPHA = 3
Field Value
Type Description
int

ALPHANUM

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.

The combinations 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" -gt; 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).
Declaration
public const int ALPHANUM = 7
Field Value
Type Description
int

DIGIT

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.

The combinations 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" -gt; 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).
Declaration
public const int DIGIT = 4
Field Value
Type Description
int

LOWER

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.

The combinations 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" -gt; 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).
Declaration
public const int LOWER = 1
Field Value
Type Description
int

SUBWORD_DELIM

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.

The combinations 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" -gt; 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).
Declaration
public const int SUBWORD_DELIM = 8
Field Value
Type Description
int

UPPER

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.

The combinations 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" -gt; 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).
Declaration
public const int UPPER = 2
Field Value
Type Description
int

Methods

IncrementToken()

Consumers (i.e., Lucene.Net.Index.IndexWriter) use this method to advance the stream to the next token. Implementing classes must implement this method and update the appropriate Lucene.Net.Util.IAttributes with the attributes of the next token.

The producer must make no assumptions about the attributes after the method has been returned: the caller may arbitrarily change it. If the producer needs to preserve the state for subsequent calls, it can use Lucene.Net.Util.AttributeSource.CaptureState() to create a copy of the current attribute state.

this method is called for every token of a document, so an efficient implementation is crucial for good performance. To avoid calls to Lucene.Net.Util.AttributeSource.AddAttribute<T>() and Lucene.Net.Util.AttributeSource.GetAttribute<T>(), references to all Lucene.Net.Util.IAttributes that this stream uses should be retrieved during instantiation.

To ensure that filters and consumers know which attributes are available, the attributes must be added during instantiation. Filters and consumers are not required to check for availability of attributes in Lucene.Net.Analysis.TokenStream.IncrementToken().
Declaration
public override bool IncrementToken()
Returns
Type Description
bool

false for end of stream; true otherwise
Overrides
Lucene.Net.Analysis.TokenStream.IncrementToken()

Reset()

This method is called by a consumer before it begins consumption using Lucene.Net.Analysis.TokenStream.IncrementToken().

Resets this stream to a clean state. Stateful implementations must implement this method so that they can be reused, just as if they had been created fresh.

If you override this method, always call base.Reset(), otherwise some internal state will not be correctly reset (e.g., Lucene.Net.Analysis.Tokenizer will throw InvalidOperationException on further usage).
Declaration
public override void Reset()
Overrides
Lucene.Net.Analysis.TokenFilter.Reset()
Remarks

NOTE: The default implementation chains the call to the input Lucene.Net.Analysis.TokenStream, so be sure to call base.Reset() when overriding this method.

Implements