| /* |
| * |
| * 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.metron.stellar.common; |
| |
| import org.apache.metron.stellar.dsl.Context; |
| |
| import java.util.Map; |
| |
| /** |
| * Executes Stellar expressions and maintains state across multiple invocations. |
| */ |
| public interface StellarStatefulExecutor { |
| |
| /** |
| * Assign a variable a specific value. |
| * @param variable The variable name. |
| * @param value The value to assign to the variable. |
| */ |
| void assign(String variable, Object value); |
| |
| /** |
| * Execute an expression and assign the result to a variable. The variable is maintained |
| * in the context of this executor and is available to all subsequent expressions. |
| * |
| * @param variable The name of the variable to assign to. |
| * @param expression The expression to execute. |
| * @param state Additional state available to the expression. This most often represents |
| * the values available to the expression from an individual message. The state |
| * maps a variable name to a variable's value. |
| */ |
| void assign(String variable, String expression, Map<String, Object> state); |
| |
| /** |
| * Execute a Stellar expression and return the result. The internal state of the executor |
| * is not modified. |
| * |
| * @param expression The expression to execute. |
| * @param state Additional state available to the expression. This most often represents |
| * the values available to the expression from an individual message. The state |
| * maps a variable name to a variable's value. |
| * @param clazz The expected type of the expression's result. |
| * @param <T> The expected type of the expression's result. |
| */ |
| <T> T execute(String expression, Map<String, Object> state, Class<T> clazz); |
| |
| /** |
| * The current state of the Stellar execution environment. |
| */ |
| Map<String, Object> getState(); |
| |
| /** |
| * Removes all state from the execution environment. |
| */ |
| void clearState(); |
| |
| /** |
| * Sets the Context for the Stellar execution environment. This provides global data used |
| * to initialize Stellar functions. |
| * |
| * @param context The Stellar context. |
| */ |
| void setContext(Context context); |
| } |