src/main/java/org/apache/commons/scxml/Evaluator.java

/*
 *
 *   Copyright 2005 The Apache Software Foundation.
 *
 *  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 org.apache.commons.scxml;

/**
 * Interface for a component that may be used by the SCXML engines to
 * evaluate the expressions within the SCXML document.
 *
 */
public interface Evaluator {

    /**
     * Evaluate an expression.
     *
     * @param ctx variable context
     * @param expr expression
     * @return a result of the evaluation
     * @throws SCXMLExpressionException A malformed exception
     */
    Object eval(Context ctx, String expr) throws SCXMLExpressionException;

    /**
     * Create a new child context.
     *
     * @param parent parent context
     * @return new child context
     */
    Context newContext(Context parent);

    /**
     * Evaluate a condition.
     *
     * @param ctx variable context
     * @param expr expression
     * @return true/false
     * @throws SCXMLExpressionException A malformed exception
     */
    Boolean evalCond(Context ctx, String expr) throws SCXMLExpressionException;

}