Package jflex.dfa

Class DFA

java.lang.Object

jflex.dfa.DFA

Direct Known Subclasses:

DeprecatedDfa

public class DFA
extends Object

Deterministic finite automata representation in JFlex. Contains minimization algorithm.

Version:

JFlex 1.8.1

Author:

Gerwin Klein

Field Summary

Fields

Modifier and Type	Field	Description
static int	NO_TARGET	The code for "no target state" in the transition table.

Constructor Summary

Constructors

Constructor	Description
DFA(int numEntryStates, int numInputs, int numLexStates)	Constructor for a deterministic finite automata.

Method Summary

Modifier and Type	Method	Description
Action	action(int i)
void	addTransition(int start, int input, int dest)	addTransition.
void	checkActions(LexScan scanner, LexParse parser)	Checks that all actions can actually be matched in this DFA.
int	entryState(int i)
boolean	equals(Object obj)
int	hashCode()
boolean	isFinal(int i)
boolean	isMinimized()
boolean	lookaheadUsed()
void	minimize()	Implementation of Hopcroft's O(n log n) minimization algorithm, follows description by D.
int	numInput()
int	numLexStates()
int	numStates()
void	setAction(int state, Action stateAction)	Sets the action.
void	setEntryState(int eState, int trueState)	Sets the state of the entry.
void	setFinal(int state, boolean isFinalState)	setFinal.
int	table(int i, int j)
String	toString()
String	toString(int[] a)	Returns a representation of this DFA.
void	writeDot(File file)	Writes a dot-file representing this DFA.

Methods inherited from class java.lang.Object

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

Field Detail

NO_TARGET

public static final int NO_TARGET

The code for "no target state" in the transition table.

See Also:

Constant Field Values

Constructor Detail

DFA

public DFA(int numEntryStates,
           int numInputs,
           int numLexStates)

Constructor for a deterministic finite automata.

Method Detail

setEntryState

public void setEntryState(int eState,
                          int trueState)

Sets the state of the entry.

Parameters:

eState - entry state.

trueState - whether it is the current state.

setAction

public void setAction(int state,
                      Action stateAction)

Sets the action.

Parameters:

state - a int.

stateAction - a Action object.

setFinal

public void setFinal(int state,
                     boolean isFinalState)

setFinal.

Parameters:

state - a int.

isFinalState - a boolean.

addTransition

public void addTransition(int start,
                          int input,
                          int dest)

addTransition.

Parameters:

start - a int.

input - a int.

dest - a int.

lookaheadUsed

public boolean lookaheadUsed()

toString

public String toString()

Overrides:

toString in class Object

hashCode

public int hashCode()

Overrides:

hashCode in class Object

equals

public boolean equals(Object obj)

Overrides:

equals in class Object

writeDot

public void writeDot(File file)

Writes a dot-file representing this DFA.

Parameters:

file - output file.

checkActions

public void checkActions(LexScan scanner,
                         LexParse parser)

Checks that all actions can actually be matched in this DFA.

minimize

public void minimize()

Implementation of Hopcroft's O(n log n) minimization algorithm, follows description by D. Gries.

Time: O(n log n) Space: O(c n), size < 4*(5*c*n + 13*n + 3*c) byte

isMinimized

public boolean isMinimized()

toString

public String toString(int[] a)

Returns a representation of this DFA.

numInput

public int numInput()

numStates

public int numStates()

numLexStates

public int numLexStates()

entryState

public int entryState(int i)

isFinal

public boolean isFinal(int i)

table

public int table(int i,
                 int j)

action

public Action action(int i)