Package org.apache.lucene.util.fst

Class ListOfOutputs<T>

java.lang.Object

org.apache.lucene.util.fst.Outputs<Object>

org.apache.lucene.util.fst.ListOfOutputs<T>

public final class ListOfOutputs<T>
extends Outputs<Object>

Wraps another Outputs implementation and encodes one or more of its output values. You can use this when a single input may need to map to more than one output, maintaining order: pass the same input with a different output by calling Builder.add(IntsRef,Object) multiple times. The builder will then combine the outputs using the Outputs.merge(Object,Object) method.

The resulting FST may not be minimal when an input has more than one output, as this requires pushing all multi-output values to a final state.

NOTE: the only way to create multiple outputs is to add the same input to the FST multiple times in a row. This is how the FST maps a single input to multiple outputs (e.g. you cannot pass a List<Object> to Builder.add(org.apache.lucene.util.IntsRef, T)). If your outputs are longs, and you need at most 2, then use UpToTwoPositiveIntOutputs instead since it stores the outputs more compactly (by stealing a bit from each long value).

NOTE: this cannot wrap itself (ie you cannot make an FST with List<List<Object>> outputs using this).

Constructor Summary

Constructors

Constructor	Description
ListOfOutputs(Outputs<T> outputs)

Method Summary

Modifier and Type	Method	Description
Object	add(Object prefix, Object output)	Eg add("foo", "bar") -> "foobar"
List<T>	asList(Object output)
Object	common(Object output1, Object output2)	Eg common("foobar", "food") -> "foo"
Object	getNoOutput()	NOTE: this output is compared with == so you must ensure that all methods return the single object if it's really no output
Object	merge(Object first, Object second)
String	outputToString(Object output)
Object	read(DataInput in)	Decode an output value previously written with Outputs.write(Object, DataOutput).
Object	readFinalOutput(DataInput in)	Decode an output value previously written with Outputs.writeFinalOutput(Object, DataOutput).
Object	subtract(Object object, Object inc)	Eg subtract("foobar", "foo") -> "bar"
String	toString()
void	write(Object output, DataOutput out)	Encode an output value into a DataOutput.
void	writeFinalOutput(Object output, DataOutput out)	Encode an final node output value into a DataOutput.

Methods inherited from class java.lang.Object

equals, getClass, hashCode, notify, notifyAll, wait, wait, wait

Constructor Detail

ListOfOutputs

public ListOfOutputs(Outputs<T> outputs)

Method Detail

common

public Object common(Object output1,
                     Object output2)

Description copied from class: Outputs

Eg common("foobar", "food") -> "foo"

Specified by:

common in class Outputs<Object>

subtract

public Object subtract(Object object,
                       Object inc)

Description copied from class: Outputs

Eg subtract("foobar", "foo") -> "bar"

Specified by:

subtract in class Outputs<Object>

add

public Object add(Object prefix,
                  Object output)

Description copied from class: Outputs

Eg add("foo", "bar") -> "foobar"

Specified by:

add in class Outputs<Object>

write

public void write(Object output,
                  DataOutput out)
           throws IOException

Description copied from class: Outputs

Encode an output value into a DataOutput.

Specified by:

write in class Outputs<Object>

Throws:

IOException

writeFinalOutput

public void writeFinalOutput(Object output,
                             DataOutput out)
                      throws IOException

Description copied from class: Outputs

Encode an final node output value into a DataOutput. By default this just calls Outputs.write(Object, DataOutput).

Overrides:

writeFinalOutput in class Outputs<Object>

Throws:

IOException

read

public Object read(DataInput in)
            throws IOException

Description copied from class: Outputs

Decode an output value previously written with Outputs.write(Object, DataOutput).

Specified by:

read in class Outputs<Object>

Throws:

IOException

readFinalOutput

public Object readFinalOutput(DataInput in)
                       throws IOException

Description copied from class: Outputs

Decode an output value previously written with Outputs.writeFinalOutput(Object, DataOutput). By default this just calls Outputs.read(DataInput).

Overrides:

readFinalOutput in class Outputs<Object>

Throws:

IOException

getNoOutput

public Object getNoOutput()

Description copied from class: Outputs

NOTE: this output is compared with == so you must ensure that all methods return the single object if it's really no output

Specified by:

getNoOutput in class Outputs<Object>

outputToString

public String outputToString(Object output)

Specified by:

outputToString in class Outputs<Object>

merge

public Object merge(Object first,
                    Object second)

Overrides:

merge in class Outputs<Object>

toString

public String toString()

Overrides:

toString in class Object

asList

public List<T> asList(Object output)