/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You 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.scxml2.semantics;

/**
 * Errors reported by the default SCXMLSemantics implementation.
 *
 */
public class ErrorConstants {

    /**
     * Missing initial state for a composite state or for the scxml root.
     *
     * @see org.apache.commons.scxml2.model.SCXML#getInitialTransition()
     * @see org.apache.commons.scxml2.model.State#getInitial()
     */
    public static final String NO_INITIAL = "NO_INITIAL";

    /**
     * An initial state for a composite state whose Transition does not.
     * Map to a descendant of the composite state.
     *
     */
    public static final String ILLEGAL_INITIAL = "ILLEGAL_INITIAL";

    /**
     * Unknown action - unsupported executable content. List of supported.
     * actions: assign, cancel, elseif, else, if, log, send, var
     */
    public static final String UNKNOWN_ACTION = "UNKNOWN_ACTION";

    /**
     * Illegal state machine configuration.
     * Either a parallel exists which does not have all its AND sub-states
     * active or there are multiple enabled OR states on the same level.
     */
    public static final String ILLEGAL_CONFIG = "ILLEGAL_CONFIG";

    /**
     * A variable referred to by assign name attribute is undefined.
     */
    public static final String UNDEFINED_VARIABLE = "UNDEFINED_VARIABLE";

    /**
     * An expression language error.
     */
    public static final String EXPRESSION_ERROR = "EXPRESSION_ERROR";

    /**
     * An execution error.
     */
    public static final String EXECUTION_ERROR = "EXECUTION_ERROR";

    //---------------------------------------------- STATIC CONSTANTS ONLY

    /**
     * Discourage instantiation.
     */
    private ErrorConstants() { // humor checkstyle
    }

}