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    1   /*
    2    * Licensed to the Apache Software Foundation (ASF) under one or more
    3    * contributor license agreements.  See the NOTICE file distributed with
    4    * this work for additional information regarding copyright ownership.
    5    * The ASF licenses this file to You under the Apache License, Version 2.0
    6    * (the "License"); you may not use this file except in compliance with
    7    * the License.  You may obtain a copy of the License at
    8    *
    9    *     http://www.apache.org/licenses/LICENSE-2.0
    10   *
    11   * Unless required by applicable law or agreed to in writing, software
    12   * distributed under the License is distributed on an "AS IS" BASIS,
    13   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    14   * See the License for the specific language governing permissions and
    15   * limitations under the License.
    16   */
    17  package org.apache.commons.scxml;
    18
    19  import java.util.Map;
    20
    21  /***
    22   * A Context or &quot;scope&quot; for storing variables; usually tied to
    23   * a SCXML root or State object.
    24   */
    25  public interface Context {
    26      /***
    27       * Assigns a new value to an existing variable or creates a new one.
    28       * The method searches the chain of parent Contexts for variable
    29       * existence.
    30       *
    31       * @param name The variable name
    32       * @param value The variable value
    33       */
    34      void set(String name, Object value);
    35
    36      /***
    37       * Assigns a new value to an existing variable or creates a new one.
    38       * The method allows to shaddow a variable of the same name up the
    39       * Context chain.
    40       *
    41       * @param name The variable name
    42       * @param value The variable value
    43       */
    44      void setLocal(String name, Object value);
    45
    46      /***
    47       * Get the value of this variable; delegating to parent.
    48       *
    49       * @param name The name of the variable
    50       * @return The value (or null)
    51       */
    52      Object get(String name);
    53
    54      /***
    55       * Check if this variable exists, delegating to parent.
    56       *
    57       * @param name The name of the variable
    58       * @return Whether a variable with the name exists in this Context
    59       */
    60      boolean has(String name);
    61
    62      /***
    63       * Get the Map of all variables in this Context.
    64       *
    65       * @return Local variable entries Map
    66       * To get variables in parent Context, call getParent().getVars().
    67       * @see #getParent()
    68       */
    69      Map getVars();
    70
    71      /***
    72       * Clear this Context.
    73       */
    74      void reset();
    75
    76      /***
    77       * Get the parent Context, may be null.
    78       *
    79       * @return The parent Context in a chained Context environment
    80       */
    81      Context getParent();
    82
    83  }