net.automatalib.util.minimizer.OneSEVPAMinimizer Maven / Gradle / Ivy
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This artifact provides various common utility operations for analyzing and manipulating
automata and graphs, such as traversal, minimization and copying.
/* Copyright (C) 2013-2019 TU Dortmund
* This file is part of AutomataLib, http://www.automatalib.net/.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package net.automatalib.util.minimizer;
import net.automatalib.automata.vpda.DefaultOneSEVPA;
import net.automatalib.automata.vpda.Location;
import net.automatalib.automata.vpda.OneSEVPA;
import net.automatalib.commons.smartcollections.ArrayStorage;
import net.automatalib.util.partitionrefinement.Block;
import net.automatalib.util.partitionrefinement.PaigeTarjan;
import net.automatalib.util.partitionrefinement.PaigeTarjanInitializers;
import net.automatalib.words.VPDAlphabet;
/**
* A Paige/Tarjan partition refinement based minimizer for {@link OneSEVPA}s.
*
* @author Malte Isberner
*/
public final class OneSEVPAMinimizer {
private OneSEVPAMinimizer() {
}
public static DefaultOneSEVPA minimize(final OneSEVPA sevpa, final VPDAlphabet alphabet) {
final PaigeTarjan pt = new PaigeTarjan();
initPaigeTarjan(pt, sevpa, alphabet);
pt.initWorklist(false);
pt.computeCoarsestStablePartition();
return fromPaigeTarjan(pt, sevpa, alphabet);
}
private static void initPaigeTarjan(PaigeTarjan pt, OneSEVPA sevpa, VPDAlphabet alphabet) {
final int numStates = sevpa.size();
final int numInputs =
alphabet.getNumInternals() + alphabet.getNumCalls() * alphabet.getNumReturns() * sevpa.size() * 2;
final int posDataLow = numStates;
final int predOfsDataLow = posDataLow + numStates;
final int numTransitions = numStates * numInputs;
final int predDataLow = predOfsDataLow + numTransitions + 1;
final int dataSize = predDataLow + numTransitions;
final int[] data = new int[dataSize];
final Block[] blockForState = new Block[numStates];
final Block[] initBlocks = new Block[2];
for (int i = 0; i < numStates; i++) {
final L loc = sevpa.getLocation(i);
final int initBlockIdx = sevpa.isAcceptingLocation(loc) ? 1 : 0;
Block block = initBlocks[initBlockIdx];
if (block == null) {
block = pt.createBlock();
block.high = 0;
initBlocks[initBlockIdx] = block;
}
block.high++;
blockForState[i] = block;
int predCountBase = predOfsDataLow;
for (I intSym : alphabet.getInternalSymbols()) {
final L succ = sevpa.getInternalSuccessor(loc, intSym);
if (succ == null) {
throw new IllegalArgumentException();
}
final int succId = sevpa.getLocationId(succ);
data[predCountBase + succId]++;
predCountBase += numStates;
}
for (I callSym : alphabet.getCallSymbols()) {
for (I retSym : alphabet.getReturnSymbols()) {
for (L src : sevpa.getLocations()) {
int stackSym = sevpa.encodeStackSym(src, callSym);
L succ = sevpa.getReturnSuccessor(loc, retSym, stackSym);
int succId = sevpa.getLocationId(succ);
data[predCountBase + succId]++;
predCountBase += numStates;
stackSym = sevpa.encodeStackSym(loc, callSym);
succ = sevpa.getReturnSuccessor(src, retSym, stackSym);
succId = sevpa.getLocationId(succ);
data[predCountBase + succId]++;
predCountBase += numStates;
}
}
}
}
int curr = 0;
for (Block b : pt.blockList()) {
curr += b.high;
b.high = curr;
b.low = curr;
}
data[predOfsDataLow] += predDataLow;
PaigeTarjanInitializers.prefixSum(data, predOfsDataLow, predDataLow);
for (int i = 0; i < numStates; i++) {
final Block b = blockForState[i];
final int pos = --b.low;
data[pos] = i;
data[posDataLow + i] = pos;
int predOfsBase = predOfsDataLow;
final L loc = sevpa.getLocation(i);
for (I intSym : alphabet.getInternalSymbols()) {
final L succ = sevpa.getInternalSuccessor(loc, intSym);
if (succ == null) {
throw new IllegalArgumentException();
}
final int succId = sevpa.getLocationId(succ);
data[--data[predOfsBase + succId]] = i;
predOfsBase += numStates;
}
for (I callSym : alphabet.getCallSymbols()) {
for (I retSym : alphabet.getReturnSymbols()) {
for (L src : sevpa.getLocations()) {
int stackSym = sevpa.encodeStackSym(src, callSym);
L succ = sevpa.getReturnSuccessor(loc, retSym, stackSym);
int succId = sevpa.getLocationId(succ);
data[--data[predOfsBase + succId]] = i;
predOfsBase += numStates;
stackSym = sevpa.encodeStackSym(loc, callSym);
succ = sevpa.getReturnSuccessor(src, retSym, stackSym);
succId = sevpa.getLocationId(succ);
data[--data[predOfsBase + succId]] = i;
predOfsBase += numStates;
}
}
}
}
pt.setBlockData(data);
pt.setPosData(data, posDataLow);
pt.setPredOfsData(data, predOfsDataLow);
pt.setPredData(data);
pt.setBlockForState(blockForState);
pt.setSize(numStates, numInputs);
}
private static DefaultOneSEVPA fromPaigeTarjan(final PaigeTarjan pt,
final OneSEVPA original,
final VPDAlphabet alphabet) {
final int numBlocks = pt.getNumBlocks();
final DefaultOneSEVPA result = new DefaultOneSEVPA<>(alphabet, numBlocks);
final ArrayStorage resultLocs =
new ArrayStorage<>(numBlocks, () -> result.addLocation(false));
for (Block curr : pt.blockList()) {
final int blockId = curr.id;
final int rep = pt.getRepresentative(curr);
final L repLoc = original.getLocation(rep);
final Location resultLoc = resultLocs.get(blockId);
resultLoc.setAccepting(original.isAcceptingLocation(repLoc));
for (I intSym : alphabet.getInternalSymbols()) {
final L origSucc = original.getInternalSuccessor(repLoc, intSym);
final int origSuccId = original.getLocationId(origSucc);
final int resSuccId = pt.getBlockForState(origSuccId).id;
final Location resSucc = resultLocs.get(resSuccId);
result.setInternalSuccessor(resultLoc, intSym, resSucc);
}
for (I callSym : alphabet.getCallSymbols()) {
for (I retSym : alphabet.getReturnSymbols()) {
for (Block b : pt.blockList()) {
final int stackRepId = pt.getRepresentative(b);
final L stackRep = original.getLocation(stackRepId);
final Location resultStackRep = resultLocs.get(b.id);
final int origStackSym = original.encodeStackSym(stackRep, callSym);
final L origSucc = original.getReturnSuccessor(repLoc, retSym, origStackSym);
final int origSuccId = original.getLocationId(origSucc);
final int resSuccId = pt.getBlockForState(origSuccId).id;
final Location resSucc = resultLocs.get(resSuccId);
final int stackSym = result.encodeStackSym(resultStackRep, callSym);
result.setReturnSuccessor(resultLoc, retSym, stackSym, resSucc);
}
}
}
}
final int origInit = original.getLocationId(original.getInitialLocation());
result.setInitialLocation(resultLocs.get(pt.getBlockForState(origInit).id));
return result;
}
}