/*
* dk.brics.automaton
*
* Copyright (c) 2001-2009 Anders Moeller
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. The name of the author may not be used to endorse or promote products
* derived from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
package org.apache.lucene.util.automaton;
import java.util.Arrays;
/**
* Finite-state automaton with fast run operation. The initial state is always 0.
*
* @lucene.experimental
*/
public abstract class RunAutomaton {
final Automaton automaton;
final int alphabetSize;
final int size;
final boolean[] accept;
final int[] transitions; // delta(state,c) = transitions[state*points.length +
// getCharClass(c)]
final int[] points; // char interval start points
final int[] classmap; // map from char number to class
/**
* Constructs a new <code>RunAutomaton</code> from a deterministic
* <code>Automaton</code>.
*
* @param a an automaton
*/
protected RunAutomaton(Automaton a, int alphabetSize) {
this(a, alphabetSize, Operations.DEFAULT_MAX_DETERMINIZED_STATES);
}
/**
* Constructs a new <code>RunAutomaton</code> from a deterministic
* <code>Automaton</code>.
*
* @param a an automaton
* @param maxDeterminizedStates maximum number of states that can be created
* while determinizing a
*/
protected RunAutomaton(Automaton a, int alphabetSize, int maxDeterminizedStates) {
this.alphabetSize = alphabetSize;
a = Operations.determinize(a, maxDeterminizedStates);
this.automaton = a;
points = a.getStartPoints();
size = Math.max(1,a.getNumStates());
accept = new boolean[size];
transitions = new int[size * points.length];
Arrays.fill(transitions, -1);
for (int n=0;n<size;n++) {
accept[n] = a.isAccept(n);
for (int c = 0; c < points.length; c++) {
int dest = a.step(n, points[c]);
assert dest == -1 || dest < size;
transitions[n * points.length + c] = dest;
}
}
/*
* Set alphabet table for optimal run performance.
*/
classmap = new int[Math.min(256, alphabetSize)];
int i = 0;
for (int j = 0; j < classmap.length; j++) {
if (i + 1 < points.length && j == points[i + 1]) {
i++;
}
classmap[j] = i;
}
}
/**
* Returns a string representation of this automaton.
*/
@Override
public String toString() {
StringBuilder b = new StringBuilder();
b.append("initial state: 0\n");
for (int i = 0; i < size; i++) {
b.append("state " + i);
if (accept[i]) b.append(" [accept]:\n");
else b.append(" [reject]:\n");
for (int j = 0; j < points.length; j++) {
int k = transitions[i * points.length + j];
if (k != -1) {
int min = points[j];
int max;
if (j + 1 < points.length) max = (points[j + 1] - 1);
else max = alphabetSize;
b.append(" ");
Automaton.appendCharString(min, b);
if (min != max) {
b.append("-");
Automaton.appendCharString(max, b);
}
b.append(" -> ").append(k).append("\n");
}
}
}
return b.toString();
}
/**
* Returns number of states in automaton.
*/
public final int getSize() {
return size;
}
/**
* Returns acceptance status for given state.
*/
public final boolean isAccept(int state) {
return accept[state];
}
/**
* Returns array of codepoint class interval start points. The array should
* not be modified by the caller.
*/
public final int[] getCharIntervals() {
return points.clone();
}
/**
* Gets character class of given codepoint
*/
final int getCharClass(int c) {
// binary search
int a = 0;
int b = points.length;
while (b - a > 1) {
int d = (a + b) >>> 1;
if (points[d] > c) b = d;
else if (points[d] < c) a = d;
else return d;
}
return a;
}
/**
* Returns the state obtained by reading the given char from the given state.
* Returns -1 if not obtaining any such state. (If the original
* <code>Automaton</code> had no dead states, -1 is returned here if and only
* if a dead state is entered in an equivalent automaton with a total
* transition function.)
*/
public final int step(int state, int c) {
assert c < alphabetSize;
if (c >= classmap.length) {
return transitions[state * points.length + getCharClass(c)];
} else {
return transitions[state * points.length + classmap[c]];
}
}
@Override
public int hashCode() {
final int prime = 31;
int result = 1;
result = prime * result + alphabetSize;
result = prime * result + points.length;
result = prime * result + size;
return result;
}
@Override
public boolean equals(Object obj) {
if (this == obj) return true;
if (obj == null) return false;
if (getClass() != obj.getClass()) return false;
RunAutomaton other = (RunAutomaton) obj;
if (alphabetSize != other.alphabetSize) return false;
if (size != other.size) return false;
if (!Arrays.equals(points, other.points)) return false;
if (!Arrays.equals(accept, other.accept)) return false;
if (!Arrays.equals(transitions, other.transitions)) return false;
return true;
}
}