C# Class org.apache.lucene.analysis.miscellaneous.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: TokenFilter

Exibir arquivo Open project: paulirwin/lucene.net Class Usage Examples

Public Methods

Method	Description
WordDelimiterFilter ( System.Version matchVersion, TokenStream @in, int configurationFlags, CharArraySet protWords ) : System	Creates a new WordDelimiterFilter using WordDelimiterIterator#DEFAULT_WORD_DELIM_TABLE as its charTypeTable
WordDelimiterFilter ( System.Version matchVersion, TokenStream @in, sbyte charTypeTable, int configurationFlags, CharArraySet protWords ) : System	Creates a new WordDelimiterFilter
incrementToken ( ) : bool
reset ( ) : void

Private Methods

Method	Description
InitializeInstanceFields ( ) : void
buffer ( ) : void
concatenate ( WordDelimiterConcatenation concatenation ) : void	Concatenates the saved buffer to the given WordDelimiterConcatenation
flushConcatenation ( WordDelimiterConcatenation concatenation ) : bool	Flushes the given WordDelimiterConcatenation by either writing its concat and then clearing, or just clearing.
generatePart ( bool isSingleWord ) : void	Generates a word/number part, updating the appropriate attributes
has ( int flag ) : bool	Determines whether the given flag is set
isAlpha ( int type ) : bool	Checks if the given word type includes #ALPHA
isDigit ( int type ) : bool	Checks if the given word type includes #DIGIT
isSubwordDelim ( int type ) : bool	Checks if the given word type includes #SUBWORD_DELIM
isUpper ( int type ) : bool	Checks if the given word type includes #UPPER
position ( bool inject ) : int	Get the position increment gap for a subword or concatenation
saveState ( ) : void	Saves the existing attribute states
shouldConcatenate ( int wordType ) : bool	Determines whether to concatenate a word or number if the current word is the given type
shouldGenerateParts ( int wordType ) : bool	Determines whether a word/number part should be generated for a word of the given type

Method Details

WordDelimiterFilter() public method

Creates a new WordDelimiterFilter using WordDelimiterIterator#DEFAULT_WORD_DELIM_TABLE as its charTypeTable

public WordDelimiterFilter ( System.Version matchVersion, TokenStream @in, int configurationFlags, CharArraySet protWords ) : System
matchVersion	System.Version
@in	TokenStream
configurationFlags	int	Flags configuring the filter
protWords	CharArraySet	If not null is the set of tokens to protect from being delimited
return	System

WordDelimiterFilter() public method

Creates a new WordDelimiterFilter

public WordDelimiterFilter ( System.Version matchVersion, TokenStream @in, sbyte charTypeTable, int configurationFlags, CharArraySet protWords ) : System
matchVersion	System.Version
@in	TokenStream
charTypeTable	sbyte	table containing character types
configurationFlags	int	Flags configuring the filter
protWords	CharArraySet	If not null is the set of tokens to protect from being delimited
return	System

incrementToken() public method

public incrementToken ( ) : bool
return	bool

reset() public method

public reset ( ) : void
return	void