Module org.apache.lucene.core

Package org.apache.lucene.util.automaton

Class FiniteStringsIterator

java.lang.Object

org.apache.lucene.util.automaton.FiniteStringsIterator

Direct Known Subclasses:

LimitedFiniteStringsIterator

public class FiniteStringsIterator
extends Object

Iterates all accepted strings.

If the Automaton has cycles then this iterator may throw an IllegalArgumentException, but this is not guaranteed!

Be aware that the iteration order is implementation dependent and may change across releases.

If the automaton is not determinized then it's possible this iterator will return duplicates.

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
private static class	FiniteStringsIterator.PathNode	Nodes for path stack.

Field Summary

Fields

Modifier and Type	Field	Description
private final Automaton	a	Automaton to create finite string from.
private boolean	emitEmptyString	Emit empty string?.
private static final IntsRef	EMPTY	Empty string.
private final int	endState	The state where each path should stop or -1 if only accepted states should be final.
private FiniteStringsIterator.PathNode[]	nodes	Stack to hold our current state in the recursion/iteration.
private final BitSet	pathStates	Tracks which states are in the current path, for cycle detection.
private final IntsRefBuilder	string	Builder for current finite string.

Constructor Summary

Constructors

Constructor	Description
FiniteStringsIterator(Automaton a)	Constructor.
FiniteStringsIterator(Automaton a, int startState, int endState)	Constructor.

Method Summary

Modifier and Type	Method	Description
private void	growStack(int depth)	Grow path stack, if required.
IntsRef	next()	Generate next finite string.

Methods inherited from class java.lang.Object

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

Field Details

EMPTY

private static final IntsRef EMPTY

Empty string.

a

private final Automaton a

Automaton to create finite string from.

endState

private final int endState

The state where each path should stop or -1 if only accepted states should be final.

pathStates

private final BitSet pathStates

Tracks which states are in the current path, for cycle detection.

string

private final IntsRefBuilder string

Builder for current finite string.

nodes

private FiniteStringsIterator.PathNode[] nodes

Stack to hold our current state in the recursion/iteration.

emitEmptyString

private boolean emitEmptyString

Emit empty string?.

Constructor Details

FiniteStringsIterator

public FiniteStringsIterator(Automaton a)

Constructor.

Parameters:

a - Automaton to create finite string from.

FiniteStringsIterator

public FiniteStringsIterator(Automaton a,
 int startState,
 int endState)

Constructor.

Parameters:

a - Automaton to create finite string from.

startState - The starting state for each path.

endState - The state where each path should stop or -1 if only accepted states should be final.

Method Details

next

public IntsRef next()

Generate next finite string. The return value is just valid until the next call of this method!

Returns:

Finite string or null, if no more finite strings are available.

growStack

private void growStack(int depth)

Grow path stack, if required.