org.apache.lucene.util.automaton

Class SpecialOperations

java.lang.Object

org.apache.lucene.util.automaton.SpecialOperations

public final class SpecialOperations
extends Object

Special automata operations.

WARNING: This API is experimental and might change in incompatible ways in the next release.

Method Summary

Methods

Modifier and Type	Method and Description
static 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 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 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 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

clone, equals, finalize, 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 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 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 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 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.