Package com.yahoo.fsa

Class FSA

java.lang.Object

com.yahoo.fsa.FSA

All Implemented Interfaces:

java.io.Closeable, java.lang.AutoCloseable

public class FSA
extends java.lang.Object
implements java.io.Closeable

Finite-State Automaton.

Author:

Peter Boros

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
static class	FSA.Iterator	Class used to iterate over all accepted strings in the fsa.
static class	FSA.State	Thread local state object used to traverse a Finite-State Automaton.

Constructor Summary

Constructors

Constructor	Description
FSA(java.io.FileInputStream file)	Loads an FSA from a file input stream using utf-8 encoding
FSA(java.io.FileInputStream file, java.lang.String charsetname)
FSA(java.lang.String filename)	Loads an FSA from a file using utf-8 encoding
FSA(java.lang.String filename, java.lang.String charsetname)	Loads an FSA from a file using the specified character encoding.

Method Summary

Modifier and Type	Method	Description
void	close()
protected java.nio.ByteBuffer	data(int state)	Retrieves data for the given state using the underlying fsa data buffer.
protected java.lang.String	dataString(int state)	Retrieves data for the given state using the underlying fsa data buffer.
protected int	delta(int state, byte symbol)
FSA.State	getState()
protected int	hashDelta(int state, byte symbol)
boolean	hasPerfectHash()
protected boolean	isFinal(int state)
boolean	isOk()
FSA.Iterator	iterator()	Returns a new iterator to the start state.
FSA.Iterator	iterator(FSA.State state)	Returns a new iterator to the given state.
static FSA	loadFromResource(java.lang.String resourceFileName, java.lang.Class loadingClass)	Loads an FSA from a resource file name, which is resolved from the class path of the class loader of the given class.
java.lang.String	lookup(java.lang.String str)	Convenience method that returns the metadata string in the fsa for the input lookup String, or null if the input string does not exist in the fsa.
static void	main(java.lang.String[] args)
int	serial()
protected int	start()
int	version()

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

FSA

public FSA(java.lang.String filename)

Loads an FSA from a file using utf-8 encoding

Throws:

java.lang.IllegalArgumentException - if the file is not found

FSA

public FSA(java.lang.String filename,
           java.lang.String charsetname)

Loads an FSA from a file using the specified character encoding.

Throws:

java.lang.IllegalArgumentException - if the file is not found

FSA

public FSA(java.io.FileInputStream file)

Loads an FSA from a file input stream using utf-8 encoding

FSA

public FSA(java.io.FileInputStream file,
           java.lang.String charsetname)

Method Detail

getState

public FSA.State getState()

iterator

public FSA.Iterator iterator()

Returns a new iterator to the start state.

iterator

public FSA.Iterator iterator(FSA.State state)

Returns a new iterator to the given state.

Parameters:

state - the state to create the iterator from.

loadFromResource

public static FSA loadFromResource(java.lang.String resourceFileName,
                                   java.lang.Class loadingClass)

Loads an FSA from a resource file name, which is resolved from the class path of the class loader of the given class.

This is useful for loading fsa's deployed within OSGi bundles.

Parameters:

resourceFileName - the name of the file, relative to any element on the classpath. For example, if the classpath contains resources/ and the file is resources/myfsa.fsa this argument should be myfsa.fsa

loadingClass - a class which provides the class loader to use for loading. Any class which is loaded from the same class path as the resource will do (e.g with OSGi - any class in the same bundle jar)

Returns:

the loaded FSA

Throws:

java.lang.RuntimeException - if the class could not be loaded

close

public void close()
           throws java.io.IOException

Specified by:

close in interface java.lang.AutoCloseable

Specified by:

close in interface java.io.Closeable

Throws:

java.io.IOException

isOk

public boolean isOk()

hasPerfectHash

public boolean hasPerfectHash()

version

public int version()

serial

public int serial()

start

protected int start()

delta

protected int delta(int state,
                    byte symbol)

hashDelta

protected int hashDelta(int state,
                        byte symbol)

isFinal

protected boolean isFinal(int state)

data

protected java.nio.ByteBuffer data(int state)

Retrieves data for the given state using the underlying fsa data buffer.

Parameters:

state - The fsa state to retrieve data from.

Returns:

A new buffer containing the data for the given state.

dataString

protected java.lang.String dataString(int state)

Retrieves data for the given state using the underlying fsa data buffer.

Parameters:

state - The fsa state to retrieve data from.

Returns:

A string representation of the data for the given state.

lookup

public java.lang.String lookup(java.lang.String str)

Convenience method that returns the metadata string in the fsa for the input lookup String, or null if the input string does not exist in the fsa.

Parameters:

str - The string to look up.

Returns:

Metadata string from the fsa.

main

public static void main(java.lang.String[] args)