public abstract class CharTokenizer extends Tokenizer
The base class also provides factories to create instances of
CharTokenizer
using Java 8 lambdas or method references.
It is possible to create an instance which behaves exactly like
LetterTokenizer
:
Tokenizer tok = CharTokenizer.fromTokenCharPredicate(Character::isLetter);
AttributeSource.State
Modifier and Type | Field and Description |
---|---|
private int |
bufferIndex |
private int |
dataLen |
static int |
DEFAULT_MAX_WORD_LEN |
private int |
finalOffset |
private static int |
IO_BUFFER_SIZE |
private CharacterUtils.CharacterBuffer |
ioBuffer |
private int |
maxTokenLen |
private int |
offset |
private OffsetAttribute |
offsetAtt |
private CharTermAttribute |
termAtt |
DEFAULT_TOKEN_ATTRIBUTE_FACTORY
Constructor and Description |
---|
CharTokenizer()
Creates a new
CharTokenizer instance |
CharTokenizer(AttributeFactory factory)
Creates a new
CharTokenizer instance |
CharTokenizer(AttributeFactory factory,
int maxTokenLen)
Creates a new
CharTokenizer instance |
Modifier and Type | Method and Description |
---|---|
void |
end()
This method is called by the consumer after the last token has been
consumed, after
TokenStream.incrementToken() returned false
(using the new TokenStream API). |
static CharTokenizer |
fromSeparatorCharPredicate(AttributeFactory factory,
java.util.function.IntPredicate separatorCharPredicate)
Creates a new instance of CharTokenizer with the supplied attribute factory using a custom predicate, supplied as method reference or lambda expression.
|
static CharTokenizer |
fromSeparatorCharPredicate(java.util.function.IntPredicate separatorCharPredicate)
Creates a new instance of CharTokenizer using a custom predicate, supplied as method reference or lambda expression.
|
static CharTokenizer |
fromTokenCharPredicate(AttributeFactory factory,
java.util.function.IntPredicate tokenCharPredicate)
Creates a new instance of CharTokenizer with the supplied attribute factory using a custom predicate, supplied as method reference or lambda expression.
|
static CharTokenizer |
fromTokenCharPredicate(java.util.function.IntPredicate tokenCharPredicate)
Creates a new instance of CharTokenizer using a custom predicate, supplied as method reference or lambda expression.
|
boolean |
incrementToken()
Consumers (i.e.,
IndexWriter ) use this method to advance the stream to
the next token. |
protected abstract boolean |
isTokenChar(int c)
Returns true iff a codepoint should be included in a token.
|
void |
reset()
This method is called by a consumer before it begins consumption using
TokenStream.incrementToken() . |
close, correctOffset, setReader
addAttribute, addAttributeImpl, captureState, clearAttributes, cloneAttributes, copyTo, endAttributes, equals, getAttribute, getAttributeClassesIterator, getAttributeFactory, getAttributeImplsIterator, hasAttribute, hasAttributes, hashCode, reflectAsString, reflectWith, removeAllAttributes, restoreState, toString
private int offset
private int bufferIndex
private int dataLen
private int finalOffset
public static final int DEFAULT_MAX_WORD_LEN
private static final int IO_BUFFER_SIZE
private final int maxTokenLen
private final CharTermAttribute termAtt
private final OffsetAttribute offsetAtt
private final CharacterUtils.CharacterBuffer ioBuffer
public CharTokenizer()
CharTokenizer
instancepublic CharTokenizer(AttributeFactory factory)
CharTokenizer
instancefactory
- the attribute factory to use for this Tokenizer
public CharTokenizer(AttributeFactory factory, int maxTokenLen)
CharTokenizer
instancefactory
- the attribute factory to use for this Tokenizer
maxTokenLen
- maximum token length the tokenizer will emit.
Must be greater than 0 and less than MAX_TOKEN_LENGTH_LIMIT (1024*1024)java.lang.IllegalArgumentException
- if maxTokenLen is invalid.public static CharTokenizer fromTokenCharPredicate(java.util.function.IntPredicate tokenCharPredicate)
true
for all valid token characters.
This factory is intended to be used with lambdas or method references. E.g., an elegant way
to create an instance which behaves exactly as LetterTokenizer
is:
Tokenizer tok = CharTokenizer.fromTokenCharPredicate(Character::isLetter);
public static CharTokenizer fromTokenCharPredicate(AttributeFactory factory, java.util.function.IntPredicate tokenCharPredicate)
true
for all valid token characters.
This factory is intended to be used with lambdas or method references. E.g., an elegant way
to create an instance which behaves exactly as LetterTokenizer
is:
Tokenizer tok = CharTokenizer.fromTokenCharPredicate(factory, Character::isLetter);
public static CharTokenizer fromSeparatorCharPredicate(java.util.function.IntPredicate separatorCharPredicate)
true
for all valid token separator characters.
This method is provided for convenience to easily use predicates that are negated
(they match the separator characters, not the token characters).
This factory is intended to be used with lambdas or method references. E.g., an elegant way
to create an instance which behaves exactly as WhitespaceTokenizer
is:
Tokenizer tok = CharTokenizer.fromSeparatorCharPredicate(Character::isWhitespace);
public static CharTokenizer fromSeparatorCharPredicate(AttributeFactory factory, java.util.function.IntPredicate separatorCharPredicate)
true
for all valid token separator characters.
This factory is intended to be used with lambdas or method references. E.g., an elegant way
to create an instance which behaves exactly as WhitespaceTokenizer
is:
Tokenizer tok = CharTokenizer.fromSeparatorCharPredicate(factory, Character::isWhitespace);
protected abstract boolean isTokenChar(int c)
public final boolean incrementToken() throws java.io.IOException
TokenStream
IndexWriter
) use this method to advance the stream to
the next token. Implementing classes must implement this method and update
the appropriate 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
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
AttributeSource.addAttribute(Class)
and AttributeSource.getAttribute(Class)
,
references to all 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
TokenStream.incrementToken()
.
incrementToken
in class TokenStream
java.io.IOException
public final void end() throws java.io.IOException
TokenStream
TokenStream.incrementToken()
returned false
(using the new 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 WhitespaceTokenizer was used.
Additionally any skipped positions (such as those removed by a stopfilter) can be applied to the position increment, or any adjustment of other attributes where the end-of-stream value may be important.
If you override this method, always call super.end()
.
end
in class TokenStream
java.io.IOException
- If an I/O error occurspublic void reset() throws java.io.IOException
TokenStream
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 super.reset()
, otherwise
some internal state will not be correctly reset (e.g., Tokenizer
will
throw IllegalStateException
on further usage).