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The core artifact of AutomataLib. This library contains concrete implementations for many of the automaton model interfaces defined in the API artifact, as well as abstract base classes that facilitate implementing new automaton model classes. Note that concrete algorithms (traversal, reachability analysis etc.) are not in the scope of this artifact.
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/* Copyright (C) 2013-2018 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.automata.vpda;

import java.util.ArrayList;
import java.util.Collection;
import java.util.Collections;
import java.util.List;
import java.util.Map;

import javax.annotation.Nonnull;

import net.automatalib.graphs.Graph;
import net.automatalib.visualization.DefaultVisualizationHelper;
import net.automatalib.visualization.VisualizationHelper;
import net.automatalib.words.VPDAlphabet;

/**
 * Abstract class for 1-SEVPAs that implements functionality shared across different subtypes.
 *
 * @param 
 *         location type
 * @param 
 *         input alphabet type
 *
 * @author Malte Isberner
 */
public abstract class AbstractOneSEVPA implements OneSEVPA, Graph> {

    protected final VPDAlphabet alphabet;

    public AbstractOneSEVPA(final VPDAlphabet alphabet) {
        this.alphabet = alphabet;
    }

    public VPDAlphabet getAlphabet() {
        return alphabet;
    }

    @Override
    public State getTransition(final State state, final I input) {
        if (state.isSink()) {
            return State.getSink();
        }

        final VPDAlphabet.SymbolType type = alphabet.getSymbolType(input);
        switch (type) {
            case CALL:
                final int newStackElem = encodeStackSym(state.getLocation(), input);
                return new State<>(getInitialLocation(), StackContents.push(newStackElem, state.getStackContents()));
            case RETURN: {
                if (state.getStackContents() == null) {
                    return State.getSink();
                }
                final int stackElem = state.getStackContents().peek();
                final L succ = getReturnSuccessor(state.getLocation(), input, stackElem);
                if (succ == null) {
                    return State.getSink();
                }
                return new State<>(succ, state.getStackContents().pop());
            }
            case INTERNAL: {
                final L succ = getInternalSuccessor(state.getLocation(), input);
                if (succ == null) {
                    return State.getSink();
                }
                return new State<>(succ, state.getStackContents());
            }
            default:
                throw new IllegalStateException("Unkown symbol type " + type);
        }
    }

    @Override
    public int encodeStackSym(final L srcLoc, final I callSym) {
        return encodeStackSym(srcLoc, alphabet.getCallSymbolIndex(callSym));
    }

    public int encodeStackSym(final L srcLoc, final int callSymIdx) {
        return alphabet.getNumCalls() * getLocationId(srcLoc) + callSymIdx;
    }

    @Override
    public int getNumStackSymbols() {
        return size() * alphabet.getNumCalls();
    }

    // Explicitly declare method, since multiple interfaces define it
    @Override
    public abstract int size();

    @Nonnull
    @Override
    public Collection getNodes() {
        return Collections.unmodifiableCollection(getLocations());
    }

    @Nonnull
    @Override
    public Collection> getOutgoingEdges(final L location) {

        final List> result = new ArrayList<>(alphabet.size());

        // all internal transitions
        for (final I i : alphabet.getInternalAlphabet()) {
            result.add(new SevpaViewEdge<>(location, i, -1));
        }

        // all return transitions for every possible stack contents
        for (final I i : alphabet.getReturnAlphabet()) {
            for (final L stackLocation : getLocations()) {
                for (final I stackSymbol : alphabet.getCallAlphabet()) {
                    result.add(new SevpaViewEdge<>(location, i, encodeStackSym(stackLocation, stackSymbol)));
                }
            }
        }

        return result;
    }

    @Nonnull
    @Override
    public L getTarget(final SevpaViewEdge edge) {

        final L from = edge.from;
        final I by = edge.by;
        final int stack = edge.stack;

        switch (alphabet.getSymbolType(by)) {
            case INTERNAL:
                return getInternalSuccessor(from, by);
            case RETURN:
                return getReturnSuccessor(from, by, stack);
            default:
                throw new IllegalArgumentException();
        }
    }

    @Override
    public VisualizationHelper> getVisualizationHelper() {
        return new DefaultVisualizationHelper>() {

            @Override
            protected Collection initialNodes() {
                return Collections.singleton(getInitialLocation());
            }

            @Override
            public boolean getNodeProperties(final L node, final Map properties) {
                super.getNodeProperties(node, properties);

                properties.put(NodeAttrs.SHAPE,
                               isAcceptingLocation(node) ? NodeShapes.DOUBLECIRCLE : NodeShapes.CIRCLE);
                properties.put(NodeAttrs.LABEL, Integer.toString(getLocationId(node)));

                return true;
            }

            @Override
            public boolean getEdgeProperties(final L src,
                                             final SevpaViewEdge edge,
                                             final L tgt,
                                             final Map properties) {

                final I by = edge.by;
                final int stack = edge.stack;

                if (alphabet.isInternalSymbol(by)) {
                    properties.put(EdgeAttrs.LABEL, by.toString());
                } else if (alphabet.isReturnSymbol(by)) {
                    properties.put(EdgeAttrs.LABEL,
                                   by.toString() + "/(" + getStackLoc(stack) + ',' + getCallSym(stack) + ')');
                } else {
                    throw new IllegalArgumentException();
                }

                return true;
            }
        };
    }

    public L getStackLoc(final int stackSym) {
        return getLocation(stackSym / alphabet.getNumCalls());
    }

    public I getCallSym(final int stackSym) {
        return alphabet.getCallSymbol(stackSym % alphabet.getNumCalls());
    }

    static class SevpaViewEdge {

        private final S from;
        private final I by;
        private final int stack;

        SevpaViewEdge(S from, I by, int stack) {
            this.from = from;
            this.by = by;
            this.stack = stack;
        }
    }
}