content: package act.util;
  
  /*-
   * #%L
   * ACT Framework
   * %%
   * Copyright (C) 2014 - 2017 ActFramework
   * %%
   * Licensed 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.
   * #L%
   */
  
  import act.asm.ClassVisitor;
  import act.asm.ClassWriter;
  import act.asm.Opcodes;
  import org.osgl.$;
  import org.osgl.util.E;
  
  import java.util.Iterator;
  import java.util.List;
  
  /**
   * Base class for all bytecode visitor, either detector or enhancer
   */
  public class ByteCodeVisitor extends ClassVisitor implements Opcodes {
  
      private $.Var<? extends ClassVisitor> _cv;
  
      protected ByteCodeVisitor(ClassVisitor cv) {
          super(ASM5, cv);
      }
  
      protected ByteCodeVisitor() {
          super(ASM5);
      }
  
      public ByteCodeVisitor commitDownstream() {
          if (null == _cv && null != cv && cv instanceof ByteCodeVisitor) {
              ((ByteCodeVisitor) cv).commitDownstream();
              return this;
          }
          E.illegalStateIf(null == _cv || null != cv);
          cv = _cv.get();
          return this;
      }
  
      private ByteCodeVisitor setDownstream($.Var<? extends ClassVisitor> cv) {
          E.illegalStateIf(null != this.cv);
          _cv = cv;
          return this;
      }
  
      public ByteCodeVisitor setDownstream(ClassVisitor cv) {
          E.illegalStateIf(null != this.cv);
          this.cv = cv;
          return this;
      }
  
      public static ByteCodeVisitor chain($.Var<ClassWriter> cw, List<? extends ByteCodeVisitor> visitors) {
          if (visitors.isEmpty()) {
              return null;
          }
          Iterator<? extends ByteCodeVisitor> i = visitors.iterator();
          ByteCodeVisitor v = i.next();
          v.setDownstream(cw);
          while (i.hasNext()) {
              ByteCodeVisitor v0 = i.next();
              v0.setDownstream(v);
              v = v0;
          }
          return v;
      }
  
      public static ByteCodeVisitor chain(List<? extends ByteCodeVisitor> visitors) {
          if (visitors.isEmpty()) {
              return null;
          }
          Iterator<? extends ByteCodeVisitor> i = visitors.iterator();
          ByteCodeVisitor v = i.next();
          while (i.hasNext()) {
              ByteCodeVisitor v0 = i.next();
              v0.setDownstream(v);
              v = v0;
          }
          return v;
      }
  
      public static ClassVisitor chain(ClassWriter cw, ByteCodeVisitor v0, ByteCodeVisitor... visitors) {
          v0.setDownstream(cw);
          int len = visitors.length;
          if (0 == len) {
              return v0;
          }
          for (int i = 0; i < len - 1; ++i) {
              ByteCodeVisitor v = visitors[i];
              v.setDownstream(v0);
              v0 = v;
          }
          return v0;
      }
  
      public static boolean isConstructor(String methodName) {
          return methodName.contains("<init>");
      }
      public static boolean isPublic(int access) {
          return (ACC_PUBLIC & access) > 0;
      }
      public static boolean isPrivate(int access) {
          return (ACC_PRIVATE & access) > 0;
      }
  
      public static boolean isStatic(int access) {
          return (ACC_STATIC & access) > 0;
      }
      public static boolean isAbstract(int access) {
          return (ACC_ABSTRACT & access) > 0;
      }
  
  }
  