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   * Copyright (c) 2005, 2020, Oracle and/or its affiliates. All rights reserved.
   * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   *
   * This code is free software; you can redistribute it and/or modify it
   * under the terms of the GNU General Public License version 2 only, as
   * published by the Free Software Foundation.  Oracle designates this
   * particular file as subject to the "Classpath" exception as provided
   * by Oracle in the LICENSE file that accompanied this code.
   *
   * This code is distributed in the hope that it will be useful, but WITHOUT
   * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
   * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
   * version 2 for more details (a copy is included in the LICENSE file that
   * accompanied this code).
   *
   * You should have received a copy of the GNU General Public License version
   * 2 along with this work; if not, write to the Free Software Foundation,
   * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
   *
   * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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  package openjdk.source.util;
  
  import java.lang.reflect.Method;
  
  import jdkx.annotation.processing.ProcessingEnvironment;
  import jdkx.lang.model.element.AnnotationMirror;
  import jdkx.lang.model.element.AnnotationValue;
  import jdkx.lang.model.element.Element;
  import jdkx.lang.model.element.ExecutableElement;
  import jdkx.lang.model.element.TypeElement;
  import jdkx.lang.model.type.DeclaredType;
  import jdkx.lang.model.type.ErrorType;
  import jdkx.lang.model.type.TypeMirror;
  import jdkx.tools.Diagnostic;
  import jdkx.tools.JavaCompiler.CompilationTask;
  
  import openjdk.source.tree.CatchTree;
  import openjdk.source.tree.ClassTree;
  import openjdk.source.tree.CompilationUnitTree;
  import openjdk.source.tree.MethodTree;
  import openjdk.source.tree.Scope;
  import openjdk.source.tree.Tree;
  
  /**
   * Bridges JSR 199, JSR 269, and the Tree API.
   *
   * @author Peter von der Ah&eacute;
   */
  public abstract class Trees {
      /**
       * Constructor for subclasses to call.
       */
      public Trees() {}
  
      /**
       * Returns a Trees object for a given CompilationTask.
       * @param task the compilation task for which to get the Trees object
       * @throws IllegalArgumentException if the task does not support the Trees API.
       * @return the Trees object
       */
      public static Trees instance(CompilationTask task) {
          String taskClassName = task.getClass().getName();
          if (!taskClassName.equals("openjdk.tools.javac.api.JavacTaskImpl")
                  && !taskClassName.equals("openjdk.tools.javac.api.BasicJavacTask"))
              throw new IllegalArgumentException();
          return getJavacTrees(CompilationTask.class, task);
      }
  
      /**
       * Returns a Trees object for a given ProcessingEnvironment.
       * @param env the processing environment for which to get the Trees object
       * @throws IllegalArgumentException if the env does not support the Trees API.
       * @return the Trees object
       */
      public static Trees instance(ProcessingEnvironment env) {
          if (!env.getClass().getName().equals("openjdk.tools.javac.processing.JavacProcessingEnvironment"))
              throw new IllegalArgumentException();
          return getJavacTrees(ProcessingEnvironment.class, env);
      }
  
      static Trees getJavacTrees(Class<?> argType, Object arg) {
          try {
              ClassLoader cl = arg.getClass().getClassLoader();
              Class<?> c = Class.forName("openjdk.tools.javac.api.JavacTrees", false, cl);
              argType = Class.forName(argType.getName(), false, cl);
              Method m = c.getMethod("instance", argType);
              return (Trees) m.invoke(null, arg);
          } catch (ReflectiveOperationException e) {
              throw new AssertionError(e);
          }
      }
  
      /**
       * Returns a utility object for obtaining source positions.
       * @return the utility object for obtaining source positions
       */
      public abstract SourcePositions getSourcePositions();
  
      /**
       * Returns the Tree node for a given Element.
       * Returns {@code null} if the node can not be found.
       * @param element the element
       * @return the tree node
       */
      public abstract Tree getTree(Element element);
  
      /**
       * Returns the ClassTree node for a given TypeElement.
       * Returns {@code null} if the node can not be found.
       * @param element the element
       * @return the class tree node
       */
      public abstract ClassTree getTree(TypeElement element);
  
      /**
       * Returns the MethodTree node for a given ExecutableElement.
       * Returns {@code null} if the node can not be found.
       * @param method the executable element
       * @return the method tree node
       */
      public abstract MethodTree getTree(ExecutableElement method);
  
      /**
       * Returns the Tree node for an AnnotationMirror on a given Element.
       * Returns {@code null} if the node can not be found.
       * @param e the element
       * @param a the annotation mirror
       * @return the tree node
       */
      public abstract Tree getTree(Element e, AnnotationMirror a);
  
      /**
       * Returns the Tree node for an AnnotationValue for an AnnotationMirror on a given Element.
       * Returns {@code null} if the node can not be found.
       * @param e the element
       * @param a the annotation mirror
       * @param v the annotation value
       * @return the tree node
       */
      public abstract Tree getTree(Element e, AnnotationMirror a, AnnotationValue v);
  
      /**
       * Returns the path to tree node within the specified compilation unit.
       * @param unit the compilation unit
       * @param node the tree node
       * @return the tree path
       */
      public abstract TreePath getPath(CompilationUnitTree unit, Tree node);
  
      /**
       * Returns the TreePath node for a given Element.
       * Returns {@code null} if the node can not be found.
       * @param e the element
       * @return the tree path
       */
      public abstract TreePath getPath(Element e);
  
      /**
       * Returns the TreePath node for an AnnotationMirror on a given Element.
       * Returns {@code null} if the node can not be found.
       * @param e the element
       * @param a the annotation mirror
       * @return the tree path
       */
      public abstract TreePath getPath(Element e, AnnotationMirror a);
  
      /**
       * Returns the TreePath node for an AnnotationValue for an AnnotationMirror on a given Element.
       * Returns {@code null} if the node can not be found.
       * @param e the element
       * @param a the annotation mirror
       * @param v the annotation value
       * @return the tree path
       */
      public abstract TreePath getPath(Element e, AnnotationMirror a, AnnotationValue v);
  
      /**
       * Returns the Element for the Tree node identified by a given TreePath.
       * Returns {@code null} if the element is not available.
       * @param path the tree path
       * @return the element
       * @throws IllegalArgumentException is the TreePath does not identify
       * a Tree node that might have an associated Element.
       */
      public abstract Element getElement(TreePath path);
  
      /**
       * Returns the TypeMirror for the Tree node identified by a given TreePath.
       * Returns {@code null} if the TypeMirror is not available.
       * @param path the tree path
       * @return the type mirror
       * @throws IllegalArgumentException is the TreePath does not identify
       * a Tree node that might have an associated TypeMirror.
       */
      public abstract TypeMirror getTypeMirror(TreePath path);
  
      /**
       * Returns the Scope for the Tree node identified by a given TreePath.
       * Returns {@code null} if the Scope is not available.
       * @param path the tree path
       * @return the scope
       */
      public abstract Scope getScope(TreePath path);
  
      /**
       * Returns the doc comment, if any, for the Tree node identified by a given TreePath.
       * Returns {@code null} if no doc comment was found.
       * @see DocTrees#getDocCommentTree(TreePath)
       * @param path the tree path
       * @return the doc comment
       */
      public abstract String getDocComment(TreePath path);
  
      /**
       * Checks whether a given type is accessible in a given scope.
       * @param scope the scope to be checked
       * @param type the type to be checked
       * @return true if {@code type} is accessible
       */
      public abstract boolean isAccessible(Scope scope, TypeElement type);
  
      /**
       * Checks whether the given element is accessible as a member of the given
       * type in a given scope.
       * @param scope the scope to be checked
       * @param member the member to be checked
       * @param type the type for which to check if the member is accessible
       * @return true if {@code member} is accessible in {@code type}
       */
      public abstract boolean isAccessible(Scope scope, Element member, DeclaredType type);
  
      /**
        * Returns the original type from the ErrorType object.
        * @param errorType the errorType for which we want to get the original type
        * @return the type mirror corresponding to the original type, replaced by the ErrorType
        */
      public abstract TypeMirror getOriginalType(ErrorType errorType);
  
      /**
       * Prints a message of the specified kind at the location of the
       * tree within the provided compilation unit
       *
       * @param kind the kind of message
       * @param msg  the message, or an empty string if none
       * @param t    the tree to use as a position hint
       * @param root the compilation unit that contains tree
       */
      public abstract void printMessage(Diagnostic.Kind kind, CharSequence msg,
              openjdk.source.tree.Tree t,
              openjdk.source.tree.CompilationUnitTree root);
  
      /**
       * Returns the lub of an exception parameter declared in a catch clause.
       * @param tree the tree for the catch clause
       * @return the lub of the exception parameter
       */
      public abstract TypeMirror getLub(CatchTree tree);
  }
  