Initializes a new instance of the EmptyTokenStream class

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:

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public <T extends Attribute> T addAttribute(Class<T>)

Adds a custom AttributeImpl instance with one or more Attribute interfaces.

Captures the state of all Attributes. The return value can be passed to {@link #restoreState} to restore the state of this or another AttributeSource.

Resets all Attributes in this AttributeSource by calling {@link AttributeImpl#Clear()} on each Attribute implementation.

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)})

Releases resources associated with this stream.

This method is called by the consumer after the last token has been consumed, after {@link #IncrementToken()} returned

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false

(using the new

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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.

Allows an Object to attempt to free resources and perform other cleanup operations before the Object is reclaimed by garbage collection.

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:

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public <T extends Attribute> T getAttribute(Class<T>)

Returns a new iterator that iterates the attribute classes in the same order they were added in. Signature for Java 1.5:

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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

returns the used AttributeFactory.

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:

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public Iterator<AttributeImpl> getAttributeImplsIterator()

Gets the Type of the current instance.

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:

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public boolean hasAttribute(Class<? extends Attribute>)

Returns true, iff this AttributeSource has any attributes

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()}.

Creates a shallow copy of the current Object.

Returns the next {@link Token} in the stream, or null at EOS.

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

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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()}).

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.