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.meter.analyzer.dsl;
  
  import com.google.common.collect.ImmutableList;
  import groovy.lang.Binding;
  import groovy.lang.GroovyShell;
  import groovy.util.DelegatingScript;
  import java.lang.reflect.Array;
  import java.util.List;
  import java.util.Map;
  
  import org.apache.skywalking.oap.meter.analyzer.dsl.registry.ProcessRegistry;
  import org.apache.skywalking.oap.meter.analyzer.dsl.tagOpt.K8sRetagType;
  import org.apache.skywalking.oap.server.core.analysis.Layer;
  import org.apache.skywalking.oap.server.core.source.DetectPoint;
  import org.codehaus.groovy.ast.stmt.DoWhileStatement;
  import org.codehaus.groovy.ast.stmt.ForStatement;
  import org.codehaus.groovy.ast.stmt.Statement;
  import org.codehaus.groovy.ast.stmt.WhileStatement;
  import org.codehaus.groovy.control.CompilerConfiguration;
  import org.codehaus.groovy.control.customizers.ImportCustomizer;
  import org.codehaus.groovy.control.customizers.SecureASTCustomizer;
  
  /**
   * DSL combines methods to parse groovy based DSL expression.
   */
  public final class DSL {
  
      /**
       * Parse string literal to Expression object, which can be reused.
       *
       * @param expression string literal represents the DSL expression.
       * @return Expression object could be executed.
       */
      public static Expression parse(final String expression) {
          CompilerConfiguration cc = new CompilerConfiguration();
          cc.setScriptBaseClass(DelegatingScript.class.getName());
          ImportCustomizer icz = new ImportCustomizer();
          icz.addImport("K8sRetagType", K8sRetagType.class.getName());
          icz.addImport("DetectPoint", DetectPoint.class.getName());
          icz.addImport("Layer", Layer.class.getName());
          icz.addImport("ProcessRegistry", ProcessRegistry.class.getName());
          cc.addCompilationCustomizers(icz);
  
          final SecureASTCustomizer secureASTCustomizer = new SecureASTCustomizer();
          secureASTCustomizer.setDisallowedStatements(
              ImmutableList.<Class<? extends Statement>>builder()
                           .add(WhileStatement.class)
                           .add(DoWhileStatement.class)
                           .add(ForStatement.class)
                           .build());
          // noinspection rawtypes
          secureASTCustomizer.setAllowedReceiversClasses(
              ImmutableList.<Class>builder()
                           .add(Object.class)
                           .add(Map.class)
                           .add(List.class)
                           .add(Array.class)
                           .add(K8sRetagType.class)
                           .add(DetectPoint.class)
                           .add(Layer.class)
                           .add(ProcessRegistry.class)
                  .build());
          cc.addCompilationCustomizers(secureASTCustomizer);
  
          GroovyShell sh = new GroovyShell(new Binding(), cc);
          DelegatingScript script = (DelegatingScript) sh.parse(expression);
          return new Expression(expression, script);
      }
  }
  