/* vim: set ts=4 sw=4 tw=99 et:

 *

 * Copyright (C) 2012 David Anderson

 *

 * This file is part of JITCraft.

 *

 * JITCraft is free software: you can redistribute it and/or modify it under

 * the terms of the GNU General Public License as published by the Free

 * Software Foundation, either version 3 of the License, or (at your option)

 * any later version.

 * 

 * Foobar 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 for more details.

 *

 * You should have received a copy of the GNU General Public License along with

 * JITCraft. If not, see http://www.gnu.org/licenses/.

 */

#ifndef _include_jitcraft_objects_h_

#define _include_jitcraft_objects_h_

#include "Utility.h"

#include "Spaces.h"

#include "Barriers.h"

namespace ke {

class Zone;

// Garbage-collection objects require a header to describe their layout. This

// header is called a "map". The different kinds of maps are enumerated below.

class Map;

enum MapKind

{

    // Represents Type objects.

    MapKind_Type,

    // Represents basic data structures. When adding to this, don't forget

    // to update Zone::initialize(), or you'll get a NULL crash trying to

    // allocate, since these maps are cached.

    MapKind_FixedArray,

    MapKind_ByteArray,

    MapKind_Code,

    MapKind_Reference,

    MapKind_Module,

    MapKind_Function,

    MapKind_String,

    MapKind_Native,

    MapKind_FreeRegion,     // Special map denoting freed space.

    MapKind_EnvironmentSlotDescriptorArray,

    MapKind_Environment,

    MapKind_Descriptor,

    MapKind_Box,

    // These do not have canonical maps.

    MapKind_Array,

    MapKind_Struct,

    // These represent special Map subclasses that require special tracing.

    MapKinds_Special,

    MapKind_Meta,               // (default map class)

    MapKind_MetaArray,          // ArrayMap instances

    MapKind_MetaEnvironment,    // EnvironmentMap instances

    MapKind_MetaStruct,         // StructMap instances

    MapKinds_EndSpecial,

    MapKinds_Total

};

// All garbage collected objects must inherit from GCObject. Note that using

// virtual functions is illegal, as the |map| field would be displaced.

class Object

{

    Barriered<Map> map_;

  public:

    void init(Map *map) {

        map_ = map;

    }

    Map *map() {

        return map_;

    }

    inline bool is(MapKind map);

    inline void write(Zone *zone, Object **ptr, Object *value);

    static inline size_t offsetOfMap() {

        // Clang doesn't accept offsetof here and it's not clear why...

        return reinterpret_cast<size_t>(&((Object *)NULL)->map_);

    }

};

// Maps describe the layout of GCObjects. Every GCObject requires a map.

class Map : public Object

{

    MapKind kind_;

  public:

    void setKind(MapKind kind) {

        kind_ = kind;

    }

    MapKind kind() {

        return kind_;

    }

    static inline Map *cast(Object *obj) {

        // Note that ArrayMap is a map, but a special one: since it is non-

        assert(obj->map()->kind() > MapKinds_Special &&

               obj->map()->kind() < MapKinds_EndSpecial);

        return reinterpret_cast<Map *>(obj);

    }

};

inline bool

Object::is(MapKind kind)

{

    return map()->kind() == kind;

}

}

#endif //_include_jitcraft_objects_h_