org.springframework.statemachine.state.ChoicePseudoState.java Source code

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Here is the source code for org.springframework.statemachine.state.ChoicePseudoState.java

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/*
 * Copyright 2017 the original author or authors.
 *
 * 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
 *
 * https://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 org.springframework.statemachine.state;

import java.util.Collection;
import java.util.List;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.springframework.statemachine.StateContext;
import org.springframework.statemachine.action.Action;
import org.springframework.statemachine.guard.Guard;
import org.springframework.util.Assert;

/**
 * Choice implementation of a {@link PseudoState}.
 *
 * @author Janne Valkealahti
 *
 * @param <S> the type of state
 * @param <E> the type of event
 */
public class ChoicePseudoState<S, E> implements PseudoState<S, E> {

    private final static Log log = LogFactory.getLog(ChoicePseudoState.class);
    private final List<ChoiceStateData<S, E>> choices;

    /**
     * Instantiates a new choice pseudo state.
     *
     * @param choices the choices
     */
    public ChoicePseudoState(List<ChoiceStateData<S, E>> choices) {
        this.choices = choices;
    }

    @Override
    public PseudoStateKind getKind() {
        return PseudoStateKind.CHOICE;
    }

    @Override
    public State<S, E> entry(StateContext<S, E> context) {
        State<S, E> s = null;
        ChoiceStateData<S, E> csd = null;
        for (ChoiceStateData<S, E> c : choices) {
            csd = c;
            if (c.guard != null && evaluateInternal(c.guard, context)) {
                break;
            }
        }
        if (csd != null) {
            s = csd.getState();
            executeActions(csd.getActions(), context);
        }
        return s;
    }

    @Override
    public void exit(StateContext<S, E> context) {
    }

    @Override
    public void addPseudoStateListener(PseudoStateListener<S, E> listener) {
    }

    @Override
    public void setPseudoStateListeners(List<PseudoStateListener<S, E>> listeners) {
    }

    private boolean evaluateInternal(Guard<S, E> guard, StateContext<S, E> context) {
        try {
            return guard.evaluate(context);
        } catch (Throwable t) {
            log.warn("Deny guard due to throw as GUARD should not error", t);
            return false;
        }
    }

    private void executeActions(Collection<Action<S, E>> actions, StateContext<S, E> context) {
        if (actions == null) {
            return;
        }
        for (Action<S, E> action : actions) {
            try {
                action.execute(context);
            } catch (Throwable t) {
                log.warn("Action execution resulted error", t);
            }
        }
    }

    /**
     * Data class wrapping choice {@link State} and {@link Guard}
     * together.
     *
     * @param <S> the type of state
     * @param <E> the type of event
     */
    public static class ChoiceStateData<S, E> {
        private final StateHolder<S, E> state;
        private final Guard<S, E> guard;
        private final Collection<Action<S, E>> actions;

        /**
         * Instantiates a new choice state data.
         *
         * @param state the state holder
         * @param guard the guard
         * @param actions the actions
         */
        public ChoiceStateData(StateHolder<S, E> state, Guard<S, E> guard, Collection<Action<S, E>> actions) {
            Assert.notNull(state, "Holder must be set");
            this.state = state;
            this.guard = guard;
            this.actions = actions;
        }

        /**
         * Gets the state holder.
         *
         * @return the state holder
         */
        public StateHolder<S, E> getStateHolder() {
            return state;
        }

        /**
         * Gets the state.
         *
         * @return the state
         */
        public State<S, E> getState() {
            return state.getState();
        }

        /**
         * Gets the guard.
         *
         * @return the guard
         */
        public Guard<S, E> getGuard() {
            return guard;
        }

        /**
         * Gets the actions.
         *
         * @return the actions
         */
        public Collection<Action<S, E>> getActions() {
            return actions;
        }
    }
}