content: /*
   * Copyright (c) 2013, 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
   * or visit www.oracle.com if you need additional information or have any
   * questions.
   */
  
  package openjdk.tools.classfile;
  
  import java.util.ArrayList;
  import java.util.HashSet;
  import java.util.List;
  import java.util.Objects;
  import java.util.Set;
  import openjdk.tools.classfile.Instruction.TypeKind;
  import static openjdk.tools.classfile.ConstantPool.*;
  
  /**
   * A utility class to find where in a ClassFile references
   * a {@link CONSTANT_Methodref_info method},
   * a {@link CONSTANT_InterfaceMethodref_info interface method},
   * or a {@link CONSTANT_Fieldref_info field}.
   */
  public final class ReferenceFinder {
      /**
       * Filter for ReferenceFinder of what constant pool entries for reference lookup.
       */
      public interface Filter {
          /**
           * Decides if the given CPRefInfo entry should be accepted or filtered.
           *
           * @param cpool  ConstantPool of the ClassFile being parsed
           * @param cpref  constant pool entry representing a reference to
           *               a fields method, and interface method.
           * @return {@code true} if accepted; otherwise {@code false}
           */
          boolean accept(ConstantPool cpool, CPRefInfo cpref);
      }
  
      /**
       * Visitor of individual method of a ClassFile that references the
       * accepted field, method, or interface method references.
       */
      public interface Visitor {
          /**
           * Invoked for a method containing one or more accepted CPRefInfo entries
           *
           * @param cf      ClassFile
           * @param method  Method that does the references the accepted references
           * @param refs    Accepted constant pool method/field reference
           */
          void visit(ClassFile cf, Method method, List<CPRefInfo> refConstantPool);
      }
  
      private final Filter filter;
      private final Visitor visitor;
  
      /**
       * Constructor.
       */
      public ReferenceFinder(Filter filter, Visitor visitor) {
          this.filter = Objects.requireNonNull(filter);
          this.visitor = Objects.requireNonNull(visitor);
      }
  
      /**
       * Parses a given ClassFile and invoke the visitor if there is any reference
       * to the constant pool entries referencing field, method, or
       * interface method that are accepted. This method will return
       * {@code true} if there is one or more accepted constant pool entries
       * to lookup; otherwise, it will return {@code false}.
       *
       * @param  cf  ClassFile
       * @return {@code true} if the given class file is processed to lookup
       *         references
       * @throws ConstantPoolException if an error of the constant pool
       */
      public boolean parse(ClassFile cf) throws ConstantPoolException {
          List<Integer> cprefs = new ArrayList<>();
          int index = 1;
          for (ConstantPool.CPInfo cpInfo : cf.constant_pool.entries()) {
              if (cpInfo.accept(cpVisitor, cf.constant_pool)) {
                  cprefs.add(index);
              }
              index += cpInfo.size();
          }
  
          if (cprefs.isEmpty()) {
              return false;
          }
  
          for (Method m : cf.methods) {
              Set<Integer> ids = new HashSet<>();
              Code_attribute c_attr = (Code_attribute) m.attributes.get(Attribute.Code);
              if (c_attr != null) {
                  for (Instruction instr : c_attr.getInstructions()) {
                      int idx = instr.accept(codeVisitor, cprefs);
                      if (idx > 0) {
                          ids.add(idx);
                      }
                  }
              }
              if (ids.size() > 0) {
                  List<CPRefInfo> refInfos = new ArrayList<>(ids.size());
                  for (int id : ids) {
                      refInfos.add(CPRefInfo.class.cast(cf.constant_pool.get(id)));
                  }
                  visitor.visit(cf, m, refInfos);
              }
          }
          return true;
      }
  
      private ConstantPool.Visitor<Boolean,ConstantPool> cpVisitor =
              new ConstantPool.Visitor<Boolean,ConstantPool>()
      {
          public Boolean visitClass(CONSTANT_Class_info info, ConstantPool cpool) {
              return false;
          }
  
          public Boolean visitFieldref(CONSTANT_Fieldref_info info, ConstantPool cpool) {
              return filter.accept(cpool, info);
          }
  
          public Boolean visitDouble(CONSTANT_Double_info info, ConstantPool cpool) {
              return false;
          }
  
          public Boolean visitFloat(CONSTANT_Float_info info, ConstantPool cpool) {
              return false;
          }
  
          public Boolean visitInteger(CONSTANT_Integer_info info, ConstantPool cpool) {
              return false;
          }
  
          public Boolean visitInterfaceMethodref(CONSTANT_InterfaceMethodref_info info, ConstantPool cpool) {
              return filter.accept(cpool, info);
          }
  
          public Boolean visitInvokeDynamic(CONSTANT_InvokeDynamic_info info, ConstantPool cpool) {
              return false;
          }
  
          @Override
          public Boolean visitDynamicConstant(CONSTANT_Dynamic_info info, ConstantPool constantPool) {
              return false;
          }
  
          public Boolean visitLong(CONSTANT_Long_info info, ConstantPool cpool) {
              return false;
          }
  
          public Boolean visitMethodHandle(CONSTANT_MethodHandle_info info, ConstantPool cpool) {
              return false;
          }
  
          public Boolean visitMethodref(CONSTANT_Methodref_info info, ConstantPool cpool) {
              return filter.accept(cpool, info);
          }
  
          public Boolean visitMethodType(CONSTANT_MethodType_info info, ConstantPool cpool) {
              return false;
          }
  
          public Boolean visitModule(CONSTANT_Module_info info, ConstantPool cpool) {
              return false;
          }
  
          public Boolean visitNameAndType(CONSTANT_NameAndType_info info, ConstantPool cpool) {
              return false;
          }
  
          public Boolean visitPackage(CONSTANT_Package_info info, ConstantPool cpool) {
              return false;
          }
  
          public Boolean visitString(CONSTANT_String_info info, ConstantPool cpool) {
              return false;
          }
  
          public Boolean visitUtf8(CONSTANT_Utf8_info info, ConstantPool cpool) {
              return false;
          }
      };
  
      private Instruction.KindVisitor<Integer, List<Integer>> codeVisitor =
              new Instruction.KindVisitor<Integer, List<Integer>>()
      {
          public Integer visitNoOperands(Instruction instr, List<Integer> p) {
              return 0;
          }
  
          public Integer visitArrayType(Instruction instr, TypeKind kind, List<Integer> p) {
              return 0;
          }
  
          public Integer visitBranch(Instruction instr, int offset, List<Integer> p) {
              return 0;
          }
  
          public Integer visitConstantPoolRef(Instruction instr, int index, List<Integer> p) {
              return p.contains(index) ? index : 0;
          }
  
          public Integer visitConstantPoolRefAndValue(Instruction instr, int index, int value, List<Integer> p) {
              return p.contains(index) ? index : 0;
          }
  
          public Integer visitLocal(Instruction instr, int index, List<Integer> p) {
              return 0;
          }
  
          public Integer visitLocalAndValue(Instruction instr, int index, int value, List<Integer> p) {
              return 0;
          }
  
          public Integer visitLookupSwitch(Instruction instr, int default_, int npairs, int[] matches, int[] offsets, List<Integer> p) {
              return 0;
          }
  
          public Integer visitTableSwitch(Instruction instr, int default_, int low, int high, int[] offsets, List<Integer> p) {
              return 0;
          }
  
          public Integer visitValue(Instruction instr, int value, List<Integer> p) {
              return 0;
          }
  
          public Integer visitUnknown(Instruction instr, List<Integer> p) {
              return 0;
          }
      };
  }
  
  