The TokenStream type exposes the following members.

Constructors

  NameDescription
Protected methodTokenStream()()()()
A TokenStream using the default attribute factory.
Protected methodTokenStream(AttributeSource)
A TokenStream that uses the same attributes as the supplied one.
Protected methodTokenStream(AttributeSource..::..AttributeFactory)
A TokenStream using the supplied AttributeFactory for creating new {@link Attribute} instances.

Methods

  NameDescription
Public methodAddAttribute
The caller must pass in a Class<? extends Attribute> value. This method first checks if an instance of that class is already in this AttributeSource and returns it. Otherwise a new instance is created, added to this AttributeSource and returned. Signature for Java 1.5:
CopyC#
public <T extends Attribute> T addAttribute(Class<T>)
(Inherited from AttributeSource.)
Public methodAddAttributeImpl
Adds a custom AttributeImpl instance with one or more Attribute interfaces.
(Inherited from AttributeSource.)
Public methodCaptureState
Captures the state of all Attributes. The return value can be passed to {@link #restoreState} to restore the state of this or another AttributeSource.
(Inherited from AttributeSource.)
Public methodClearAttributes
Resets all Attributes in this AttributeSource by calling {@link AttributeImpl#Clear()} on each Attribute implementation.
(Inherited from AttributeSource.)
Public methodCloneAttributes
Performs a clone of all {@link AttributeImpl} instances returned in a new AttributeSource instance. This method can be used to e.g. create another TokenStream with exactly the same attributes (using {@link #AttributeSource(AttributeSource)})
(Inherited from AttributeSource.)
Public methodClose
Releases resources associated with this stream.
Public methodEnd
This method is called by the consumer after the last token has been consumed, after {@link #IncrementToken()} returned
CopyC#
false
(using the new
CopyC#
TokenStream
API). Streams implementing the old API should upgrade to use this feature.

This method can be used to perform any end-of-stream operations, such as setting the final offset of a stream. The final offset of a stream might differ from the offset of the last token eg in case one or more whitespaces followed after the last token, but a {@link WhitespaceTokenizer} was used.

Public methodEquals (Inherited from AttributeSource.)
Protected methodFinalize
Allows an Object to attempt to free resources and perform other cleanup operations before the Object is reclaimed by garbage collection.
(Inherited from Object.)
Public methodGetAttribute
The caller must pass in a Class<? extends Attribute> value. Returns the instance of the passed in Attribute contained in this AttributeSource Signature for Java 1.5:
CopyC#
public <T extends Attribute> T getAttribute(Class<T>)
(Inherited from AttributeSource.)
Public methodGetAttributeClassesIterator
Returns a new iterator that iterates the attribute classes in the same order they were added in. Signature for Java 1.5:
CopyC#
public Iterator<Class<? extends Attribute>> getAttributeClassesIterator()
Note that this return value is different from Java in that it enumerates over the values and not the keys
(Inherited from AttributeSource.)
Public methodGetAttributeFactory
returns the used AttributeFactory.
(Inherited from AttributeSource.)
Public methodGetAttributeImplsIterator
Returns a new iterator that iterates all unique Attribute implementations. This iterator may contain less entries that {@link #getAttributeClassesIterator}, if one instance implements more than one Attribute interface. Signature for Java 1.5:
CopyC#
public Iterator<AttributeImpl> getAttributeImplsIterator()
(Inherited from AttributeSource.)
Public methodGetHashCode (Inherited from AttributeSource.)
Public methodStatic memberGetOnlyUseNewAPI Obsolete.
Returns if only the new API is used.
Public methodGetType
Gets the Type of the current instance.
(Inherited from Object.)
Public methodHasAttribute
The caller must pass in a Class<? extends Attribute> value. Returns true, iff this AttributeSource contains the passed-in Attribute. Signature for Java 1.5:
CopyC#
public boolean hasAttribute(Class<? extends Attribute>)
(Inherited from AttributeSource.)
Public methodHasAttributes
Returns true, iff this AttributeSource has any attributes
(Inherited from AttributeSource.)
Public methodIncrementToken
Consumers (i.e., {@link IndexWriter}) use this method to advance the stream to the next token. Implementing classes must implement this method and update the appropriate {@link AttributeImpl}s 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 {@link #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 {@link #AddAttribute(Class)} and {@link #GetAttribute(Class)} or downcasts, references to all {@link AttributeImpl}s 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 {@link #IncrementToken()}.
Protected methodMemberwiseClone
Creates a shallow copy of the current Object.
(Inherited from Object.)
Public methodNext()()()() Obsolete.
Returns the next {@link Token} in the stream, or null at EOS.
Public methodNext(Token) Obsolete.
Returns the next token in the stream, or null at EOS. When possible, the input Token should be used as the returned Token (this gives fastest tokenization performance), but this is not required and a new Token may be returned. Callers may re-use a single Token instance for successive calls to this method. This implicitly defines a "contract" between consumers (callers of this method) and producers (implementations of this method that are the source for tokens):
  • A consumer must fully consume the previously returned {@link Token} before calling this method again.
  • A producer must call {@link Token#Clear()} before setting the fields in it and returning it
Also, the producer must make no assumptions about a {@link Token} after it has been returned: the caller may arbitrarily change it. If the producer needs to hold onto the {@link Token} for subsequent calls, it must clone() it before storing it. Note that a {@link TokenFilter} is considered a consumer.
Public methodReset
Resets this stream to the beginning. This is an optional operation, so subclasses may or may not implement this method. {@link #Reset()} is not needed for the standard indexing process. However, if the tokens of a
CopyC#
TokenStream
are intended to be consumed more than once, it is necessary to implement {@link #Reset()}. Note that if your TokenStream caches tokens and feeds them back again after a reset, it is imperative that you clone the tokens when you store them away (on the first pass) as well as when you return them (on future passes after {@link #Reset()}).
Public methodRestoreState
Restores this state by copying the values of all attribute implementations that this state contains into the attributes implementations of the targetStream. The targetStream must contain a corresponding instance for each argument contained in this state (e.g. it is not possible to restore the state of an AttributeSource containing a TermAttribute into a AttributeSource using a Token instance as implementation). Note that this method does not affect attributes of the targetStream that are not contained in this state. In other words, if for example the targetStream contains an OffsetAttribute, but this state doesn't, then the value of the OffsetAttribute remains unchanged. It might be desirable to reset its value to the default, in which case the caller should first call {@link TokenStream#ClearAttributes()} on the targetStream.
(Inherited from AttributeSource.)
Public methodStatic memberSetOnlyUseNewAPI Obsolete.
For extra performance you can globally enable the new {@link #IncrementToken} API using {@link Attribute}s. There will be a small, but in most cases negligible performance increase by enabling this, but it only works if all
CopyC#
TokenStream
s use the new API and implement {@link #IncrementToken}. This setting can only be enabled globally.

This setting only affects

CopyC#
TokenStream
s instantiated after this call. All
CopyC#
TokenStream
s already created use the other setting.

All core {@link Analyzer}s are compatible with this setting, if you have your own

CopyC#
TokenStream
s that are also compatible, you should enable this.

When enabled, tokenization may throw {@link UnsupportedOperationException} s, if the whole tokenizer chain is not compatible eg one of the

CopyC#
TokenStream
s does not implement the new
CopyC#
TokenStream
API.

The default is

CopyC#
false
, so there is the fallback to the old API available.
Public methodToString (Inherited from AttributeSource.)

See Also