org.apache.lucene.analysis
Class Token

java.lang.Object
  extended by org.apache.lucene.util.AttributeImpl
      extended by org.apache.lucene.analysis.Token
All Implemented Interfaces:
Serializable, Cloneable, FlagsAttribute, OffsetAttribute, PayloadAttribute, PositionIncrementAttribute, TermAttribute, TypeAttribute, Attribute

public class Token
extends AttributeImpl
implements Cloneable, TermAttribute, TypeAttribute, PositionIncrementAttribute, FlagsAttribute, OffsetAttribute, PayloadAttribute

A Token is an occurrence of a term from the text of a field. It consists of a term's text, the start and end offset of the term in the text of the field, and a type string.

The start and end offsets permit applications to re-associate a token with its source text, e.g., to display highlighted query terms in a document browser, or to show matching text fragments in a KWIC display, etc.

The type is a string, assigned by a lexical analyzer (a.k.a. tokenizer), naming the lexical or syntactic class that the token belongs to. For example an end of sentence marker token might be implemented with type "eos". The default token type is "word".

A Token can optionally have metadata (a.k.a. Payload) in the form of a variable length byte array. Use TermPositions.getPayloadLength() and TermPositions.getPayload(byte[], int) to retrieve the payloads from the index.

NOTE: As of 2.9, Token implements all Attribute interfaces that are part of core Lucene and can be found in the tokenattributes subpackage. Even though it is not necessary to use Token anymore, with the new TokenStream API it can be used as convenience class that implements all Attributes, which is especially useful to easily switch from the old to the new TokenStream API.

NOTE: As of 2.3, Token stores the term text internally as a malleable char[] termBuffer instead of String termText. The indexing code and core tokenizers have been changed to re-use a single Token instance, changing its buffer and other fields in-place as the Token is processed. This provides substantially better indexing performance as it saves the GC cost of new'ing a Token and String for every term. The APIs that accept String termText are still available but a warning about the associated performance cost has been added (below). The termText() method has been deprecated.

Tokenizers and TokenFilters should try to re-use a Token instance when possible for best performance, by implementing the TokenStream.incrementToken() API. Failing that, to create a new Token you should first use one of the constructors that starts with null text. To load the token from a char[] use setTermBuffer(char[], int, int). To load from a String use setTermBuffer(String) or setTermBuffer(String, int, int). Alternatively you can get the Token's termBuffer by calling either termBuffer(), if you know that your text is shorter than the capacity of the termBuffer or resizeTermBuffer(int), if there is any possibility that you may need to grow the buffer. Fill in the characters of your term into this buffer, with String.getChars(int, int, char[], int) if loading from a string, or with System.arraycopy(Object, int, Object, int, int), and finally call setTermLength(int) to set the length of the term text. See LUCENE-969 for details.

Typical Token reuse patterns:

A few things to note:

See Also:
Payload, Serialized Form

Field Summary
static String DEFAULT_TYPE
           
 
Constructor Summary
Token()
          Constructs a Token will null text.
Token(char[] startTermBuffer, int termBufferOffset, int termBufferLength, int start, int end)
          Constructs a Token with the given term buffer (offset & length), start and end offsets
Token(int start, int end)
          Constructs a Token with null text and start & end offsets.
Token(int start, int end, int flags)
          Constructs a Token with null text and start & end offsets plus flags.
Token(int start, int end, String typ)
          Constructs a Token with null text and start & end offsets plus the Token type.
Token(String text, int start, int end)
          Constructs a Token with the given term text, and start & end offsets.
Token(String text, int start, int end, int flags)
          Constructs a Token with the given text, start and end offsets, & type.
Token(String text, int start, int end, String typ)
          Constructs a Token with the given text, start and end offsets, & type.
 
Method Summary
 void clear()
          Resets the term text, payload, flags, and positionIncrement, startOffset, endOffset and token type to default.
 Object clone()
          Shallow clone.
 Token clone(char[] newTermBuffer, int newTermOffset, int newTermLength, int newStartOffset, int newEndOffset)
          Makes a clone, but replaces the term buffer & start/end offset in the process.
 void copyTo(AttributeImpl target)
          Copies the values from this Attribute into the passed-in target attribute.
 int endOffset()
          Returns this Token's ending offset, one greater than the position of the last character corresponding to this token in the source text.
 boolean equals(Object obj)
          All values used for computation of AttributeImpl.hashCode() should be checked here for equality.
 int getFlags()
          EXPERIMENTAL: While we think this is here to stay, we may want to change it to be a long.
 Payload getPayload()
          Returns this Token's payload.
 int getPositionIncrement()
          Returns the position increment of this Token.
 int hashCode()
          Subclasses must implement this method and should compute a hashCode similar to this:
 Token reinit(char[] newTermBuffer, int newTermOffset, int newTermLength, int newStartOffset, int newEndOffset)
          Shorthand for calling clear(), setTermBuffer(char[], int, int), setStartOffset(int), setEndOffset(int) setType(java.lang.String) on Token.DEFAULT_TYPE
 Token reinit(char[] newTermBuffer, int newTermOffset, int newTermLength, int newStartOffset, int newEndOffset, String newType)
          Shorthand for calling clear(), setTermBuffer(char[], int, int), setStartOffset(int), setEndOffset(int), setType(java.lang.String)
 Token reinit(String newTerm, int newStartOffset, int newEndOffset)
          Shorthand for calling clear(), setTermBuffer(String), setStartOffset(int), setEndOffset(int) setType(java.lang.String) on Token.DEFAULT_TYPE
 Token reinit(String newTerm, int newTermOffset, int newTermLength, int newStartOffset, int newEndOffset)
          Shorthand for calling clear(), setTermBuffer(String, int, int), setStartOffset(int), setEndOffset(int) setType(java.lang.String) on Token.DEFAULT_TYPE
 Token reinit(String newTerm, int newTermOffset, int newTermLength, int newStartOffset, int newEndOffset, String newType)
          Shorthand for calling clear(), setTermBuffer(String, int, int), setStartOffset(int), setEndOffset(int) setType(java.lang.String)
 Token reinit(String newTerm, int newStartOffset, int newEndOffset, String newType)
          Shorthand for calling clear(), setTermBuffer(String), setStartOffset(int), setEndOffset(int) setType(java.lang.String)
 void reinit(Token prototype)
          Copy the prototype token's fields into this one.
 void reinit(Token prototype, char[] newTermBuffer, int offset, int length)
          Copy the prototype token's fields into this one, with a different term.
 void reinit(Token prototype, String newTerm)
          Copy the prototype token's fields into this one, with a different term.
 char[] resizeTermBuffer(int newSize)
          Grows the termBuffer to at least size newSize, preserving the existing content.
 void setEndOffset(int offset)
          Set the ending offset.
 void setFlags(int flags)
           
 void setOffset(int startOffset, int endOffset)
          Set the starting and ending offset.
 void setPayload(Payload payload)
          Sets this Token's payload.
 void setPositionIncrement(int positionIncrement)
          Set the position increment.
 void setStartOffset(int offset)
          Set the starting offset.
 void setTermBuffer(char[] buffer, int offset, int length)
          Copies the contents of buffer, starting at offset for length characters, into the termBuffer array.
 void setTermBuffer(String buffer)
          Copies the contents of buffer into the termBuffer array.
 void setTermBuffer(String buffer, int offset, int length)
          Copies the contents of buffer, starting at offset and continuing for length characters, into the termBuffer array.
 void setTermLength(int length)
          Set number of valid characters (length of the term) in the termBuffer array.
 void setTermText(String text)
          Deprecated. use setTermBuffer(char[], int, int) or setTermBuffer(String) or setTermBuffer(String, int, int).
 void setType(String type)
          Set the lexical type.
 int startOffset()
          Returns this Token's starting offset, the position of the first character corresponding to this token in the source text.
 String term()
          Returns the Token's term text.
 char[] termBuffer()
          Returns the internal termBuffer character array which you can then directly alter.
 int termLength()
          Return number of valid characters (length of the term) in the termBuffer array.
 String termText()
          Deprecated. This method now has a performance penalty because the text is stored internally in a char[]. If possible, use termBuffer() and termLength() directly instead. If you really need a String, use term()
 String toString()
          The default implementation of this method accesses all declared fields of this object and prints the values in the following syntax:
 String type()
          Returns this Token's lexical type.
 
Methods inherited from class java.lang.Object
finalize, getClass, notify, notifyAll, wait, wait, wait
 

Field Detail

DEFAULT_TYPE

public static final String DEFAULT_TYPE
See Also:
Constant Field Values
Constructor Detail

Token

public Token()
Constructs a Token will null text.


Token

public Token(int start,
             int end)
Constructs a Token with null text and start & end offsets.

Parameters:
start - start offset in the source text
end - end offset in the source text

Token

public Token(int start,
             int end,
             String typ)
Constructs a Token with null text and start & end offsets plus the Token type.

Parameters:
start - start offset in the source text
end - end offset in the source text
typ - the lexical type of this Token

Token

public Token(int start,
             int end,
             int flags)
Constructs a Token with null text and start & end offsets plus flags. NOTE: flags is EXPERIMENTAL.

Parameters:
start - start offset in the source text
end - end offset in the source text
flags - The bits to set for this token

Token

public Token(String text,
             int start,
             int end)
Constructs a Token with the given term text, and start & end offsets. The type defaults to "word." NOTE: for better indexing speed you should instead use the char[] termBuffer methods to set the term text.

Parameters:
text - term text
start - start offset
end - end offset

Token

public Token(String text,
             int start,
             int end,
             String typ)
Constructs a Token with the given text, start and end offsets, & type. NOTE: for better indexing speed you should instead use the char[] termBuffer methods to set the term text.

Parameters:
text - term text
start - start offset
end - end offset
typ - token type

Token

public Token(String text,
             int start,
             int end,
             int flags)
Constructs a Token with the given text, start and end offsets, & type. NOTE: for better indexing speed you should instead use the char[] termBuffer methods to set the term text.

Parameters:
text -
start -
end -
flags - token type bits

Token

public Token(char[] startTermBuffer,
             int termBufferOffset,
             int termBufferLength,
             int start,
             int end)
Constructs a Token with the given term buffer (offset & length), start and end offsets

Parameters:
startTermBuffer -
termBufferOffset -
termBufferLength -
start -
end -
Method Detail

setPositionIncrement

public void setPositionIncrement(int positionIncrement)
Set the position increment. This determines the position of this token relative to the previous Token in a TokenStream, used in phrase searching.

The default value is one.

Some common uses for this are:

Specified by:
setPositionIncrement in interface PositionIncrementAttribute
Parameters:
positionIncrement - the distance from the prior term
See Also:
TermPositions

getPositionIncrement

public int getPositionIncrement()
Returns the position increment of this Token.

Specified by:
getPositionIncrement in interface PositionIncrementAttribute
See Also:
setPositionIncrement(int)

setTermText

public void setTermText(String text)
Deprecated. use setTermBuffer(char[], int, int) or setTermBuffer(String) or setTermBuffer(String, int, int).

Sets the Token's term text. NOTE: for better indexing speed you should instead use the char[] termBuffer methods to set the term text.


termText

public final String termText()
Deprecated. This method now has a performance penalty because the text is stored internally in a char[]. If possible, use termBuffer() and termLength() directly instead. If you really need a String, use term()

Returns the Token's term text.


term

public final String term()
Returns the Token's term text. This method has a performance penalty because the text is stored internally in a char[]. If possible, use termBuffer() and termLength() directly instead. If you really need a String, use this method, which is nothing more than a convenience call to new String(token.termBuffer(), 0, token.termLength())

Specified by:
term in interface TermAttribute

setTermBuffer

public final void setTermBuffer(char[] buffer,
                                int offset,
                                int length)
Copies the contents of buffer, starting at offset for length characters, into the termBuffer array.

Specified by:
setTermBuffer in interface TermAttribute
Parameters:
buffer - the buffer to copy
offset - the index in the buffer of the first character to copy
length - the number of characters to copy

setTermBuffer

public final void setTermBuffer(String buffer)
Copies the contents of buffer into the termBuffer array.

Specified by:
setTermBuffer in interface TermAttribute
Parameters:
buffer - the buffer to copy

setTermBuffer

public final void setTermBuffer(String buffer,
                                int offset,
                                int length)
Copies the contents of buffer, starting at offset and continuing for length characters, into the termBuffer array.

Specified by:
setTermBuffer in interface TermAttribute
Parameters:
buffer - the buffer to copy
offset - the index in the buffer of the first character to copy
length - the number of characters to copy

termBuffer

public final char[] termBuffer()
Returns the internal termBuffer character array which you can then directly alter. If the array is too small for your token, use resizeTermBuffer(int) to increase it. After altering the buffer be sure to call setTermLength(int) to record the number of valid characters that were placed into the termBuffer.

Specified by:
termBuffer in interface TermAttribute

resizeTermBuffer

public char[] resizeTermBuffer(int newSize)
Grows the termBuffer to at least size newSize, preserving the existing content. Note: If the next operation is to change the contents of the term buffer use setTermBuffer(char[], int, int), setTermBuffer(String), or setTermBuffer(String, int, int) to optimally combine the resize with the setting of the termBuffer.

Specified by:
resizeTermBuffer in interface TermAttribute
Parameters:
newSize - minimum size of the new termBuffer
Returns:
newly created termBuffer with length >= newSize

termLength

public final int termLength()
Return number of valid characters (length of the term) in the termBuffer array.

Specified by:
termLength in interface TermAttribute

setTermLength

public final void setTermLength(int length)
Set number of valid characters (length of the term) in the termBuffer array. Use this to truncate the termBuffer or to synchronize with external manipulation of the termBuffer. Note: to grow the size of the array, use resizeTermBuffer(int) first.

Specified by:
setTermLength in interface TermAttribute
Parameters:
length - the truncated length

startOffset

public final int startOffset()
Returns this Token's starting offset, the position of the first character corresponding to this token in the source text. Note that the difference between endOffset() and startOffset() may not be equal to termText.length(), as the term text may have been altered by a stemmer or some other filter.

Specified by:
startOffset in interface OffsetAttribute

setStartOffset

public void setStartOffset(int offset)
Set the starting offset.

See Also:
startOffset()

endOffset

public final int endOffset()
Returns this Token's ending offset, one greater than the position of the last character corresponding to this token in the source text. The length of the token in the source text is (endOffset - startOffset).

Specified by:
endOffset in interface OffsetAttribute

setEndOffset

public void setEndOffset(int offset)
Set the ending offset.

See Also:
endOffset()

setOffset

public void setOffset(int startOffset,
                      int endOffset)
Set the starting and ending offset.

Specified by:
setOffset in interface OffsetAttribute
See Also:
and #endOffset()

type

public final String type()
Returns this Token's lexical type. Defaults to "word".

Specified by:
type in interface TypeAttribute

setType

public final void setType(String type)
Set the lexical type.

Specified by:
setType in interface TypeAttribute
See Also:
type()

getFlags

public int getFlags()
EXPERIMENTAL: While we think this is here to stay, we may want to change it to be a long.

Get the bitset for any bits that have been set. This is completely distinct from type(), although they do share similar purposes. The flags can be used to encode information about the token for use by other TokenFilters.

Specified by:
getFlags in interface FlagsAttribute
Returns:
The bits

setFlags

public void setFlags(int flags)
Specified by:
setFlags in interface FlagsAttribute
See Also:
getFlags()

getPayload

public Payload getPayload()
Returns this Token's payload.

Specified by:
getPayload in interface PayloadAttribute

setPayload

public void setPayload(Payload payload)
Sets this Token's payload.

Specified by:
setPayload in interface PayloadAttribute

toString

public String toString()
Description copied from class: AttributeImpl
The default implementation of this method accesses all declared fields of this object and prints the values in the following syntax:
   public String toString() {
     return "start=" + startOffset + ",end=" + endOffset;
   }
 
This method may be overridden by subclasses.

Overrides:
toString in class AttributeImpl

clear

public void clear()
Resets the term text, payload, flags, and positionIncrement, startOffset, endOffset and token type to default.

Specified by:
clear in class AttributeImpl

clone

public Object clone()
Description copied from class: AttributeImpl
Shallow clone. Subclasses must override this if they need to clone any members deeply,

Overrides:
clone in class AttributeImpl

clone

public Token clone(char[] newTermBuffer,
                   int newTermOffset,
                   int newTermLength,
                   int newStartOffset,
                   int newEndOffset)
Makes a clone, but replaces the term buffer & start/end offset in the process. This is more efficient than doing a full clone (and then calling setTermBuffer) because it saves a wasted copy of the old termBuffer.


equals

public boolean equals(Object obj)
Description copied from class: AttributeImpl
All values used for computation of AttributeImpl.hashCode() should be checked here for equality. see also Object.equals(Object)

Specified by:
equals in class AttributeImpl

hashCode

public int hashCode()
Description copied from class: AttributeImpl
Subclasses must implement this method and should compute a hashCode similar to this:
   public int hashCode() {
     int code = startOffset;
     code = code * 31 + endOffset;
     return code;
   }
 
see also AttributeImpl.equals(Object)

Specified by:
hashCode in class AttributeImpl

reinit

public Token reinit(char[] newTermBuffer,
                    int newTermOffset,
                    int newTermLength,
                    int newStartOffset,
                    int newEndOffset,
                    String newType)
Shorthand for calling clear(), setTermBuffer(char[], int, int), setStartOffset(int), setEndOffset(int), setType(java.lang.String)

Returns:
this Token instance

reinit

public Token reinit(char[] newTermBuffer,
                    int newTermOffset,
                    int newTermLength,
                    int newStartOffset,
                    int newEndOffset)
Shorthand for calling clear(), setTermBuffer(char[], int, int), setStartOffset(int), setEndOffset(int) setType(java.lang.String) on Token.DEFAULT_TYPE

Returns:
this Token instance

reinit

public Token reinit(String newTerm,
                    int newStartOffset,
                    int newEndOffset,
                    String newType)
Shorthand for calling clear(), setTermBuffer(String), setStartOffset(int), setEndOffset(int) setType(java.lang.String)

Returns:
this Token instance

reinit

public Token reinit(String newTerm,
                    int newTermOffset,
                    int newTermLength,
                    int newStartOffset,
                    int newEndOffset,
                    String newType)
Shorthand for calling clear(), setTermBuffer(String, int, int), setStartOffset(int), setEndOffset(int) setType(java.lang.String)

Returns:
this Token instance

reinit

public Token reinit(String newTerm,
                    int newStartOffset,
                    int newEndOffset)
Shorthand for calling clear(), setTermBuffer(String), setStartOffset(int), setEndOffset(int) setType(java.lang.String) on Token.DEFAULT_TYPE

Returns:
this Token instance

reinit

public Token reinit(String newTerm,
                    int newTermOffset,
                    int newTermLength,
                    int newStartOffset,
                    int newEndOffset)
Shorthand for calling clear(), setTermBuffer(String, int, int), setStartOffset(int), setEndOffset(int) setType(java.lang.String) on Token.DEFAULT_TYPE

Returns:
this Token instance

reinit

public void reinit(Token prototype)
Copy the prototype token's fields into this one. Note: Payloads are shared.

Parameters:
prototype -

reinit

public void reinit(Token prototype,
                   String newTerm)
Copy the prototype token's fields into this one, with a different term. Note: Payloads are shared.

Parameters:
prototype -
newTerm -

reinit

public void reinit(Token prototype,
                   char[] newTermBuffer,
                   int offset,
                   int length)
Copy the prototype token's fields into this one, with a different term. Note: Payloads are shared.

Parameters:
prototype -
newTermBuffer -
offset -
length -

copyTo

public void copyTo(AttributeImpl target)
Description copied from class: AttributeImpl
Copies the values from this Attribute into the passed-in target attribute. The target implementation must support all the Attributes this implementation supports.

Specified by:
copyTo in class AttributeImpl


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