text: /*
   * Copyright (c) 2011, 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.
   *
   * 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_OOPS_FIELDSTREAMS_HPP
  #define SHARE_OOPS_FIELDSTREAMS_HPP
  
  #include "oops/instanceKlass.hpp"
  #include "oops/fieldInfo.hpp"
  #include "runtime/fieldDescriptor.hpp"
  
  // The is the base class for iteration over the fields array
  // describing the declared fields in the class.  Several subclasses
  // are provided depending on the kind of iteration required.  The
  // JavaFieldStream is for iterating over regular Java fields and it
  // generally the preferred iterator.  InternalFieldStream only
  // iterates over fields that have been injected by the JVM.
  // AllFieldStream exposes all fields and should only be used in rare
  // cases.
  class FieldStreamBase : public StackObj {
   protected:
    Array<u2>*          _fields;
    constantPoolHandle  _constants;
    int                 _index;
    int                 _limit;
    int                 _generic_signature_slot;
    fieldDescriptor     _fd_buf;
  
    FieldInfo* field() const { return FieldInfo::from_field_array(_fields, _index); }
  
    int init_generic_signature_start_slot() {
      int length = _fields->length();
      int num_fields = _index;
      int skipped_generic_signature_slots = 0;
      FieldInfo* fi;
      AccessFlags flags;
      /* Scan from 0 to the current _index. Count the number of generic
         signature slots for field[0] to field[_index - 1]. */
      for (int i = 0; i < _index; i++) {
        fi = FieldInfo::from_field_array(_fields, i);
        flags.set_flags(fi->access_flags());
        if (flags.field_has_generic_signature()) {
          length --;
          skipped_generic_signature_slots ++;
        }
      }
      /* Scan from the current _index. */
      for (int i = _index; i*FieldInfo::field_slots < length; i++) {
        fi = FieldInfo::from_field_array(_fields, i);
        flags.set_flags(fi->access_flags());
        if (flags.field_has_generic_signature()) {
          length --;
        }
        num_fields ++;
      }
      _generic_signature_slot = length + skipped_generic_signature_slots;
      assert(_generic_signature_slot <= _fields->length(), "");
      return num_fields;
    }
  
    inline FieldStreamBase(Array<u2>* fields, ConstantPool* constants, int start, int limit);
  
    inline FieldStreamBase(Array<u2>* fields, ConstantPool* constants);
   public:
    inline FieldStreamBase(InstanceKlass* klass);
  
    // accessors
    int index() const                 { return _index; }
    InstanceKlass* field_holder() const { return _constants->pool_holder(); }
  
    void next() {
      if (access_flags().field_has_generic_signature()) {
        _generic_signature_slot ++;
        assert(_generic_signature_slot <= _fields->length(), "");
      }
      _index += 1;
    }
    bool done() const { return _index >= _limit; }
  
    // Accessors for current field
    AccessFlags access_flags() const {
      AccessFlags flags;
      flags.set_flags(field()->access_flags());
      return flags;
    }
  
    void set_access_flags(u2 flags) const {
      field()->set_access_flags(flags);
    }
  
    void set_access_flags(AccessFlags flags) const {
      set_access_flags(flags.as_short());
    }
  
    Symbol* name() const {
      return field()->name(_constants());
    }
  
    Symbol* signature() const {
      return field()->signature(_constants());
    }
  
    Symbol* generic_signature() const {
      if (access_flags().field_has_generic_signature()) {
        assert(_generic_signature_slot < _fields->length(), "out of bounds");
        int index = _fields->at(_generic_signature_slot);
        return _constants->symbol_at(index);
      } else {
        return NULL;
      }
    }
  
    int offset() const {
      return field()->offset();
    }
  
    void set_offset(int offset) {
      field()->set_offset(offset);
    }
  
    bool is_offset_set() const {
      return field()->is_offset_set();
    }
  
    bool is_contended() const {
      return field()->is_contended();
    }
  
    int contended_group() const {
      return field()->contended_group();
    }
  
    // bridge to a heavier API:
    fieldDescriptor& field_descriptor() const {
      fieldDescriptor& field = const_cast<fieldDescriptor&>(_fd_buf);
      field.reinitialize(field_holder(), _index);
      return field;
    }
  };
  
  // Iterate over only the internal fields
  class JavaFieldStream : public FieldStreamBase {
   public:
    JavaFieldStream(const InstanceKlass* k): FieldStreamBase(k->fields(), k->constants(), 0, k->java_fields_count()) {}
  
    int name_index() const {
      assert(!field()->is_internal(), "regular only");
      return field()->name_index();
    }
    void set_name_index(int index) {
      assert(!field()->is_internal(), "regular only");
      field()->set_name_index(index);
    }
    int signature_index() const {
      assert(!field()->is_internal(), "regular only");
      return field()->signature_index();
    }
    void set_signature_index(int index) {
      assert(!field()->is_internal(), "regular only");
      field()->set_signature_index(index);
    }
    int generic_signature_index() const {
      assert(!field()->is_internal(), "regular only");
      if (access_flags().field_has_generic_signature()) {
        assert(_generic_signature_slot < _fields->length(), "out of bounds");
        return _fields->at(_generic_signature_slot);
      } else {
        return 0;
      }
    }
    void set_generic_signature_index(int index) {
      assert(!field()->is_internal(), "regular only");
      if (access_flags().field_has_generic_signature()) {
        assert(_generic_signature_slot < _fields->length(), "out of bounds");
        _fields->at_put(_generic_signature_slot, index);
      }
    }
    int initval_index() const {
      assert(!field()->is_internal(), "regular only");
      return field()->initval_index();
    }
    void set_initval_index(int index) {
      assert(!field()->is_internal(), "regular only");
      return field()->set_initval_index(index);
    }
  };
  
  
  // Iterate over only the internal fields
  class InternalFieldStream : public FieldStreamBase {
   public:
    InternalFieldStream(InstanceKlass* k):      FieldStreamBase(k->fields(), k->constants(), k->java_fields_count(), 0) {}
  };
  
  
  class AllFieldStream : public FieldStreamBase {
   public:
    AllFieldStream(Array<u2>* fields, ConstantPool* constants): FieldStreamBase(fields, constants) {}
    AllFieldStream(InstanceKlass* k):      FieldStreamBase(k->fields(), k->constants()) {}
  };
  
  #endif // SHARE_OOPS_FIELDSTREAMS_HPP
  