org.metasyntactic.math.automata
Class Empty

java.lang.Object
  |
  +--org.metasyntactic.math.automata.AbstractRegularExpression
        |
        +--org.metasyntactic.math.automata.Empty

All Implemented Interfaces:

FiniteAutomata, RegularExpression, java.io.Serializable

public class Empty

extends AbstractRegularExpression

Class representing the Regular Expression ε. I.e. the expression ε represents the language containing the single string, namely, the empty string.

See Also:

RegularExpression, AbstractRegularExpression, RegularExpressionFactory.empty(), Serialized Form

Nested Class Summary

Nested classes inherited from class org.metasyntactic.math.automata.AbstractRegularExpression

AbstractRegularExpression.NFAState

Field Summary

static Empty

EMPTY The one instance of the empty language

Fields inherited from class org.metasyntactic.math.automata.AbstractRegularExpression

complement

Method Summary

boolean	equals(RegularExpression regexp)
int	hashCode()
NondeterministicFiniteAutomata	toNondeterministicFiniteAutomata() Returns an NFA that accepts the same regular language that this regular expression accepts.
java.lang.String	toString()

Methods inherited from class org.metasyntactic.math.automata.AbstractRegularExpression

accept, complement, concatenate, equals, equivalent, escapedRegexpChars, internalConcatenate, internalStar, internalUnion, parenthesizedRegexp, parenthesizedRegexp, properlyParenthesized, star, union

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Field Detail

EMPTY

public static final Empty EMPTY

The one instance of the empty language

Method Detail

toString

public java.lang.String toString()

Specified by:

toString in interface RegularExpression

Overrides:

toString in class java.lang.Object

hashCode

public int hashCode()

Specified by:

hashCode in interface RegularExpression

Overrides:

hashCode in class java.lang.Object

equals

public boolean equals(RegularExpression regexp)

Specified by:

equals in interface RegularExpression

Specified by:

equals in class AbstractRegularExpression

toNondeterministicFiniteAutomata

public NondeterministicFiniteAutomata toNondeterministicFiniteAutomata()

Description copied from interface: RegularExpression

Returns an NFA that accepts the same regular language that this regular expression accepts.

Returns:

An NFA equivalent to this