Class Util

Static helper methods.

This is a Lucene.NET EXPERIMENTAL API, use at your own risk

Inheritance

System.Object

Util

Inherited Members

System.Object.Equals(System.Object)

System.Object.Equals(System.Object, System.Object)

System.Object.GetHashCode()

System.Object.GetType()

System.Object.MemberwiseClone()

System.Object.ReferenceEquals(System.Object, System.Object)

System.Object.ToString()

Namespace: Lucene.Net.Util.Fst

Assembly: Lucene.Net.dll

Syntax

public static class Util

Methods

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Get<T>(FST<T>, BytesRef)

Looks up the output for this input, or null if the input is not accepted

Declaration

public static T Get<T>(FST<T> fst, BytesRef input)

Parameters

Type	Name	Description
FST<T>	fst
BytesRef	input

Returns

Type	Description
T

Type Parameters

Name	Description
T

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Get<T>(FST<T>, Int32sRef)

Looks up the output for this input, or null if the input is not accepted.

Declaration

public static T Get<T>(FST<T> fst, Int32sRef input)

Parameters

Type	Name	Description
FST<T>	fst
Int32sRef	input

Returns

Type	Description
T

Type Parameters

Name	Description
T

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GetByOutput(FST<Nullable<Int64>>, Int64)

Reverse lookup (lookup by output instead of by input), in the special case when your FSTs outputs are strictly ascending. This locates the input/output pair where the output is equal to the target, and will return null if that output does not exist.

NOTE: this only works with , only works when the outputs are ascending in order with the inputs. For example, simple ordinals (0, 1, 2, ...), or file offets (when appending to a file) fit this.

Declaration

public static Int32sRef GetByOutput(FST<long?> fst, long targetOutput)

Parameters

Type	Name	Description
FST<System.Nullable<System.Int64>>	fst
System.Int64	targetOutput

Returns

Type	Description
Int32sRef

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GetByOutput(FST<Nullable<Int64>>, Int64, FST.BytesReader, FST.Arc<Nullable<Int64>>, FST.Arc<Nullable<Int64>>, Int32sRef)

Expert: like GetByOutput(FST<Nullable<Int64>>, Int64) except reusing FST.BytesReader, initial and scratch Arc, and result.

Declaration

public static Int32sRef GetByOutput(FST<long?> fst, long targetOutput, FST.BytesReader in, FST.Arc<long?> arc, FST.Arc<long?> scratchArc, Int32sRef result)

Parameters

Type	Name	Description
FST<System.Nullable<System.Int64>>	fst
System.Int64	targetOutput
FST.BytesReader	in
FST.Arc<System.Nullable<System.Int64>>	arc
FST.Arc<System.Nullable<System.Int64>>	scratchArc
Int32sRef	result

Returns

Type	Description
Int32sRef

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ReadCeilArc<T>(Int32, FST<T>, FST.Arc<T>, FST.Arc<T>, FST.BytesReader)

Reads the first arc greater or equal that the given label into the provided arc in place and returns it iff found, otherwise return null.

Declaration

public static FST.Arc<T> ReadCeilArc<T>(int label, FST<T> fst, FST.Arc<T> follow, FST.Arc<T> arc, FST.BytesReader in)

Parameters

Type	Name	Description
System.Int32	label	the label to ceil on
FST<T>	fst	the fst to operate on
FST.Arc<T>	follow	the arc to follow reading the label from
FST.Arc<T>	arc	the arc to read into in place
FST.BytesReader	in	the fst's FST.BytesReader

Returns

Type	Description
FST.Arc<T>

Type Parameters

Name	Description
T

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ShortestPaths<T>(FST<T>, FST.Arc<T>, T, IComparer<T>, Int32, Boolean)

Starting from node, find the top N min cost completions to a final node.

Declaration

public static Util.TopResults<T> ShortestPaths<T>(FST<T> fst, FST.Arc<T> fromNode, T startOutput, IComparer<T> comparer, int topN, bool allowEmptyString)

Parameters

Type	Name	Description
FST<T>	fst
FST.Arc<T>	fromNode
T	startOutput
System.Collections.Generic.IComparer<T>	comparer
System.Int32	topN
System.Boolean	allowEmptyString

Returns

Type	Description
Util.TopResults<T>

Type Parameters

Name	Description
T

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ToBytesRef(Int32sRef, BytesRef)

Just converts Int32sRef to BytesRef; you must ensure the System.Int32 values fit into a System.Byte.

Declaration

public static BytesRef ToBytesRef(Int32sRef input, BytesRef scratch)

Parameters

Type	Name	Description
Int32sRef	input
BytesRef	scratch

Returns

Type	Description
BytesRef

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ToDot<T>(FST<T>, TextWriter, Boolean, Boolean)

Dumps an FST<T> to a GraphViz's dot language description for visualization. Example of use:

using (TextWriter sw = new StreamWriter("out.dot"))
{
    Util.ToDot(fst, sw, true, true);
}

and then, from command line:

dot -Tpng -o out.png out.dot

Note: larger FSTs (a few thousand nodes) won't even render, don't bother. If the FST is > 2.1 GB in size then this method will throw strange exceptions.

Declaration

public static void ToDot<T>(FST<T> fst, TextWriter out, bool sameRank, bool labelStates)

Parameters

Type	Name	Description
FST<T>	fst
System.IO.TextWriter	out
System.Boolean	sameRank	If `true`, the resulting `dot` file will try to order states in layers of breadth-first traversal. This may mess up arcs, but makes the output FST's structure a bit clearer.
System.Boolean	labelStates	If `true` states will have labels equal to their offsets in their binary format. Expands the graph considerably.

Type Parameters

Name	Description
T

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ToInt32sRef(BytesRef, Int32sRef)

Just takes unsigned byte values from the BytesRef and converts into an Int32sRef.

NOTE: This was toIntsRef() in Lucene

Declaration

public static Int32sRef ToInt32sRef(BytesRef input, Int32sRef scratch)

Parameters

Type	Name	Description
BytesRef	input
Int32sRef	scratch

Returns

Type	Description
Int32sRef

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ToUTF16(String, Int32sRef)

Just maps each UTF16 unit (char) to the System.Int32s in an Int32sRef.

Declaration

public static Int32sRef ToUTF16(string s, Int32sRef scratch)

Parameters

Type	Name	Description
System.String	s
Int32sRef	scratch

Returns

Type	Description
Int32sRef

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ToUTF32(Char[], Int32, Int32, Int32sRef)

Decodes the Unicode codepoints from the provided char[] and places them in the provided scratch Int32sRef, which must not be null, returning it.

Declaration

public static Int32sRef ToUTF32(char[] s, int offset, int length, Int32sRef scratch)

Parameters

Type	Name	Description
System.Char[]	s
System.Int32	offset
System.Int32	length
Int32sRef	scratch

Returns

Type	Description
Int32sRef

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ToUTF32(String, Int32sRef)

Decodes the Unicode codepoints from the provided J2N.Text.ICharSequence and places them in the provided scratch Int32sRef, which must not be null, returning it.

Declaration

public static Int32sRef ToUTF32(string s, Int32sRef scratch)

Parameters

Type	Name	Description
System.String	s
Int32sRef	scratch

Returns

Type	Description
Int32sRef