code: /*
   * 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.skywalking.oap.server.core.alarm.provider.expression;
  
  import lombok.Getter;
  import org.mvel2.ParserContext;
  import java.lang.reflect.Method;
  import java.lang.reflect.Modifier;
  
  /***
   * Expression context can support custom function in expression,
   * for example `md5(a) == '111111'`, the md5 function add register in the context
   */
  public class ExpressionContext {
  
      @Getter
      private ParserContext context;
  
      public ExpressionContext() {
          context = new ParserContext();
      }
  
      /**
       * Register a single method in the context
       */
      public void registerFunc(String func, Method method) {
          context.addImport(func, method);
      }
  
      /**
       * Register hole class public static methods in the context
       */
      public void registerFunc(Class<?> clz) {
          Method[] methods = clz.getDeclaredMethods();
          for (Method method : methods) {
              int mod = method.getModifiers();
              if (Modifier.isStatic(mod) && Modifier.isPublic(mod)) {
                  registerFunc(method.getName(), method);
              }
          }
      }
  }
  