org.apache.lucene.util.automaton
Class BasicAutomata

java.lang.Object
  org.apache.lucene.util.automaton.BasicAutomata

public final class BasicAutomata
extends Object

Construction of basic automata.

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

Method Summary

static Automaton	makeAnyChar() Returns a new (deterministic) automaton that accepts any single codepoint.
static Automaton	makeAnyString() Returns a new (deterministic) automaton that accepts all strings.
static Automaton	makeChar(int c) Returns a new (deterministic) automaton that accepts a single codepoint of the given value.
static Automaton	makeCharRange(int min, int max) Returns a new (deterministic) automaton that accepts a single codepoint whose value is in the given interval (including both end points).
static Automaton	makeEmpty() Returns a new (deterministic) automaton with the empty language.
static Automaton	makeEmptyString() Returns a new (deterministic) automaton that accepts only the empty string.
static Automaton	makeInterval(int min, int max, int digits) Returns a new automaton that accepts strings representing decimal non-negative integers in the given interval.
static Automaton	makeString(int[] word, int offset, int length)
static Automaton	makeString(String s) Returns a new (deterministic) automaton that accepts the single given string.
static Automaton	makeStringUnion(Collection<BytesRef> utf8Strings) Returns a new (deterministic and minimal) automaton that accepts the union of the given collection of BytesRefs representing UTF-8 encoded strings.

Methods inherited from class java.lang.Object

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

Method Detail

makeEmpty

public static Automaton makeEmpty()

Returns a new (deterministic) automaton with the empty language.

makeEmptyString

public static Automaton makeEmptyString()

Returns a new (deterministic) automaton that accepts only the empty string.

makeAnyString

public static Automaton makeAnyString()

Returns a new (deterministic) automaton that accepts all strings.

makeAnyChar

public static Automaton makeAnyChar()

Returns a new (deterministic) automaton that accepts any single codepoint.

makeChar

public static Automaton makeChar(int c)

Returns a new (deterministic) automaton that accepts a single codepoint of the given value.

makeCharRange

public static Automaton makeCharRange(int min,
                                      int max)

Returns a new (deterministic) automaton that accepts a single codepoint whose value is in the given interval (including both end points).

makeInterval

public static Automaton makeInterval(int min,
                                     int max,
                                     int digits)
                              throws IllegalArgumentException

Returns a new automaton that accepts strings representing decimal non-negative integers in the given interval.

Parameters:

min - minimal value of interval

max - maximal value of interval (both end points are included in the interval)

digits - if >0, use fixed number of digits (strings must be prefixed by 0's to obtain the right length) - otherwise, the number of digits is not fixed

Throws:

IllegalArgumentException - if min>max or if numbers in the interval cannot be expressed with the given fixed number of digits

makeString

public static Automaton makeString(String s)

Returns a new (deterministic) automaton that accepts the single given string.

makeString

public static Automaton makeString(int[] word,
                                   int offset,
                                   int length)

makeStringUnion

public static Automaton makeStringUnion(Collection<BytesRef> utf8Strings)

Returns a new (deterministic and minimal) automaton that accepts the union of the given collection of BytesRefs representing UTF-8 encoded strings.

Parameters:

utf8Strings - The input strings, UTF-8 encoded. The collection must be in sorted order.

Returns:

An Automaton accepting all input strings. The resulting automaton is codepoint based (full unicode codepoints on transitions).