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Java example source code file (reflectionUtils.hpp)

This example Java source code file (reflectionUtils.hpp) is included in the alvinalexander.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" TM.

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Java - Java tags/keywords

accessflags, allstatic, array, cheapobj, fieldstream, filteredfieldsmap, filteredfieldsmap\:\:filtered_fields_count, filteredfieldstream, growablearray, klassstream, methodstream, share_vm_runtime_reflectionutils_hpp, symbol, value_obj_class_spec

The reflectionUtils.hpp Java example source code

/*
 * Copyright (c) 1999, 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.
 *
 * 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.
 *
 */

#ifndef SHARE_VM_RUNTIME_REFLECTIONUTILS_HPP
#define SHARE_VM_RUNTIME_REFLECTIONUTILS_HPP

#include "memory/allocation.hpp"
#include "oops/instanceKlass.hpp"
#include "oops/objArrayOop.hpp"
#include "oops/oopsHierarchy.hpp"
#include "runtime/handles.inline.hpp"
#include "runtime/reflection.hpp"
#include "utilities/accessFlags.hpp"
#include "utilities/globalDefinitions.hpp"

// A KlassStream is an abstract stream for streaming over self, superclasses
// and (super)interfaces. Streaming is done in reverse order (subclasses first,
// interfaces last).
//
//    for (KlassStream st(k, false, false, false); !st.eos(); st.next()) {
//      Klass* k = st.klass();
//      ...
//    }

class KlassStream VALUE_OBJ_CLASS_SPEC {
 protected:
  instanceKlassHandle _klass;           // current klass/interface iterated over
  instanceKlassHandle _base_klass;      // initial klass/interface to iterate over
  Array<Klass*>*      _interfaces;      // transitive interfaces for initial class
  int                 _interface_index; // current interface being processed
  bool                _local_only;      // process initial class/interface only
  bool                _classes_only;    // process classes only (no interfaces)
  bool                _walk_defaults;   // process default methods
  bool                _base_class_search_defaults; // time to process default methods
  bool                _defaults_checked; // already checked for default methods
  int                 _index;

  virtual int length() = 0;

 public:
  // constructor
  KlassStream(instanceKlassHandle klass, bool local_only, bool classes_only, bool walk_defaults);

  // testing
  bool eos();

  // iterating
  virtual void next() = 0;

  // accessors
  instanceKlassHandle klass() const { return _klass; }
  int index() const                 { return _index; }
  bool base_class_search_defaults() const { return _base_class_search_defaults; }
  void base_class_search_defaults(bool b) { _base_class_search_defaults = b; }
};


// A MethodStream streams over all methods in a class, superclasses and (super)interfaces.
// Streaming is done in reverse order (subclasses first, methods in reverse order)
// Usage:
//
//    for (MethodStream st(k, false, false); !st.eos(); st.next()) {
//      Method* m = st.method();
//      ...
//    }

class MethodStream : public KlassStream {
 private:
  int length()                    { return methods()->length(); }
  Array<Method*>* methods() {
    if (base_class_search_defaults()) {
      base_class_search_defaults(false);
      return _klass->default_methods();
    } else {
      return _klass->methods();
    }
  }
 public:
  MethodStream(instanceKlassHandle klass, bool local_only, bool classes_only)
    : KlassStream(klass, local_only, classes_only, true) {
    _index = length();
    next();
  }

  void next() { _index--; }
  Method* method() { return methods()->at(index()); }
};


// A FieldStream streams over all fields in a class, superclasses and (super)interfaces.
// Streaming is done in reverse order (subclasses first, fields in reverse order)
// Usage:
//
//    for (FieldStream st(k, false, false); !st.eos(); st.next()) {
//      Symbol* field_name = st.name();
//      ...
//    }


class FieldStream : public KlassStream {
 private:
  int length() { return _klass->java_fields_count(); }

  fieldDescriptor _fd_buf;

 public:
  FieldStream(instanceKlassHandle klass, bool local_only, bool classes_only)
    : KlassStream(klass, local_only, classes_only, false) {
    _index = length();
    next();
  }

  void next() { _index -= 1; }

  // Accessors for current field
  AccessFlags access_flags() const {
    AccessFlags flags;
    flags.set_flags(_klass->field_access_flags(_index));
    return flags;
  }
  Symbol* name() const {
    return _klass->field_name(_index);
  }
  Symbol* signature() const {
    return _klass->field_signature(_index);
  }
  // missing: initval()
  int offset() const {
    return _klass->field_offset( index() );
  }
  // bridge to a heavier API:
  fieldDescriptor& field_descriptor() const {
    fieldDescriptor& field = const_cast<fieldDescriptor&>(_fd_buf);
    field.reinitialize(_klass(), _index);
    return field;
  }
};

class FilteredField : public CHeapObj<mtInternal>  {
 private:
  Klass* _klass;
  int    _field_offset;

 public:
  FilteredField(Klass* klass, int field_offset) {
    _klass = klass;
    _field_offset = field_offset;
  }
  Klass* klass() { return _klass; }
  int  field_offset() { return _field_offset; }
};

class FilteredFieldsMap : AllStatic {
 private:
  static GrowableArray<FilteredField *> *_filtered_fields;
 public:
  static void initialize();
  static bool is_filtered_field(Klass* klass, int field_offset) {
    for (int i=0; i < _filtered_fields->length(); i++) {
      if (klass == _filtered_fields->at(i)->klass() &&
        field_offset == _filtered_fields->at(i)->field_offset()) {
        return true;
      }
    }
    return false;
  }
  static int  filtered_fields_count(Klass* klass, bool local_only) {
    int nflds = 0;
    for (int i=0; i < _filtered_fields->length(); i++) {
      if (local_only && klass == _filtered_fields->at(i)->klass()) {
        nflds++;
      } else if (klass->is_subtype_of(_filtered_fields->at(i)->klass())) {
        nflds++;
      }
    }
    return nflds;
  }
  // Enhance Class Redefinition Support
  static void classes_do(KlassClosure* f) {
    for (int i = 0; i < _filtered_fields->length(); i++) {
      f->do_klass(_filtered_fields->at(i)->klass());
    }
  }
};


// A FilteredFieldStream streams over all fields in a class, superclasses and
// (super)interfaces. Streaming is done in reverse order (subclasses first,
// fields in reverse order)
//
// Usage:
//
//    for (FilteredFieldStream st(k, false, false); !st.eos(); st.next()) {
//      Symbol* field_name = st.name();
//      ...
//    }

class FilteredFieldStream : public FieldStream {
 private:
  int  _filtered_fields_count;
  bool has_filtered_field() { return (_filtered_fields_count > 0); }

 public:
  FilteredFieldStream(instanceKlassHandle klass, bool local_only, bool classes_only)
    : FieldStream(klass, local_only, classes_only) {
    _filtered_fields_count = FilteredFieldsMap::filtered_fields_count((Klass*)klass(), local_only);
  }
  int field_count();
  void next() {
    _index -= 1;
    if (has_filtered_field()) {
      while (_index >=0 && FilteredFieldsMap::is_filtered_field((Klass*)_klass(), offset())) {
        _index -= 1;
      }
    }
  }
};

#endif // SHARE_VM_RUNTIME_REFLECTIONUTILS_HPP

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