org.apache.lucene.util.automaton

Class SpecialOperations

java.lang.Object

org.apache.lucene.util.automaton.SpecialOperations

public final class SpecialOperations
extends java.lang.Object

Special automata operations.

Method Summary

Modifier and Type	Method and Description
static java.lang.String	getCommonPrefix(Automaton a) Returns the longest string that is a prefix of all accepted strings and visits each state at most once.
static BytesRef	getCommonPrefixBytesRef(Automaton a)
static java.lang.String	getCommonSuffix(Automaton a) Returns the longest string that is a suffix of all accepted strings and visits each state at most once.
static BytesRef	getCommonSuffixBytesRef(Automaton a)
static java.util.Set<IntsRef>	getFiniteStrings(Automaton a, int limit) Returns the set of accepted strings, assuming that at most limit strings are accepted.
static boolean	isFinite(Automaton a) Returns true if the language of this automaton is finite.
static java.util.Set<State>	reverse(Automaton a) Reverses the language of the given (non-singleton) automaton while returning the set of new initial states.

Methods inherited from class java.lang.Object

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

Method Detail

isFinite

public static boolean isFinite(Automaton a)

Returns true if the language of this automaton is finite.

getCommonPrefix

public static java.lang.String getCommonPrefix(Automaton a)

Returns the longest string that is a prefix of all accepted strings and visits each state at most once.

Returns:

common prefix

getCommonPrefixBytesRef

public static BytesRef getCommonPrefixBytesRef(Automaton a)

getCommonSuffix

public static java.lang.String getCommonSuffix(Automaton a)

Returns the longest string that is a suffix of all accepted strings and visits each state at most once.

Returns:

common suffix

getCommonSuffixBytesRef

public static BytesRef getCommonSuffixBytesRef(Automaton a)

reverse

public static java.util.Set<State> reverse(Automaton a)

Reverses the language of the given (non-singleton) automaton while returning the set of new initial states.

getFiniteStrings

public static java.util.Set<IntsRef> getFiniteStrings(Automaton a,
                                                      int limit)

Returns the set of accepted strings, assuming that at most limit strings are accepted. If more than limit strings are accepted, the first limit strings found are returned. If limit<0, then the limit is infinite.