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/*
*
* 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);
}