/* 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_jc_object_visitor_h_

#define _include_jc_object_visitor_h_

#include "Objects.h"

#include "Types.h"

#include "FixedArray.h"

#include "Code.h"

#include "Reference.h"

#include "Modules.h"

#include "Functions.h"

#include "Array.h"

namespace jc {

// An ObjectVisitor is used for traversing object references in the heap. Since

// this pattern must be lightning fast, we avoid virtual dispatch by forcing

// visitors to compose themselves with the visiting logic.

template <typename T>

class ObjectVisitor : public T

{

  private:

    void visitField(Object *obj, size_t offset) {

        this->visit(reinterpret_cast<Object **>(Address(obj) + offset));

    }

    size_t iterateType(Object *obj) {

        visitField(obj, Type::offsetOfContained());

        visitField(obj, Type::offsetOfReturnType());

        visitField(obj, Type::offsetOfParameters());

        return sizeof(Type);

    }

    size_t iterateFixedArray(FixedArray *array) {

        unsigned length = array->length();

        Object **ptr = reinterpret_cast<Object **>(array + 1);

        for (unsigned i = 0; i < length; i++)

            this->visit(ptr + i);

        return FixedArray::SizeFor(length);

    }

    size_t iterateByteArray(ByteArray *array) {

        return ByteArray::SizeFor(array->length());

    }

    size_t iterateCode(Object *obj) {

        visitField(obj, Code::offsetOfModule());

        visitField(obj, Code::offsetOfBytecode());

        visitField(obj, Code::offsetOfLocals());

        visitField(obj, Code::offsetOfObjects());

        visitField(obj, Code::offsetOfSafepoints());

        return sizeof(Code);

    }

    size_t iterateReference(Object *obj) {

        visitField(obj, Reference::offsetOfBase());

        return sizeof(Reference);

    }

    size_t iterateModule(Object *obj) {

        visitField(obj, Module::offsetOfFunctions());

        return sizeof(Module);

    }

    size_t iterateFunction(Object *obj) {

        visitField(obj, Function::offsetOfModule());

        visitField(obj, Function::offsetOfCode());

        visitField(obj, Function::offsetOfType());

        return sizeof(Function);

    }

    size_t iterateArray(Array *array, ArrayMap *map) {

        if (map->type()->isArray()) {

            unsigned length = array->nelements();

            Object **vec = array->objVec();

            for (unsigned i = 0; i < length; i++)

                this->visit(vec + i);

        }

        return Array::SizeOf(array);

    }

    size_t iterateArrayMap(ArrayMap *map) {

        visitField(map, ArrayMap::offsetOfType());

        visitField(map, ArrayMap::offsetOfContained());

        return sizeof(ArrayMap);

    }

  public:

    size_t iterate(Object *obj) {

        visitField(obj, Object::offsetOfMap());

        return iterate(obj, obj->map());

    }

    size_t iterate(Object *obj, Map *map) {

        switch (map->kind()) {

          case MapKind_Type:

            return iterateType(obj);

          case MapKind_FixedArray:

            return iterateFixedArray(FixedArray::cast(obj));

          case MapKind_ByteArray:

            return Align(iterateByteArray(ByteArray::cast(obj)), kObjectAlignment);

          case MapKind_Code:

            return iterateCode(obj);

          case MapKind_Reference:

            return iterateReference(obj);

          case MapKind_Module:

            return iterateModule(obj);

          case MapKind_Function:

            return iterateFunction(obj);

          case MapKind_Array:

            return Align(iterateArray(Array::cast(obj), ArrayMap::cast(map)), kObjectAlignment);

          case MapKind_MetaArray:

            return iterateArrayMap(ArrayMap::cast(obj));

          default:

            assert(map->kind() == MapKind_Meta);

            return sizeof(Map);

        }

    }

};

static inline size_t

SizeOfObject(Object *obj, Map *map)

{

    switch (map->kind()) {

      case MapKind_Type:

        return sizeof(Type);

      case MapKind_FixedArray:

        return FixedArray::SizeFor(FixedArray::cast(obj)->length());

      case MapKind_ByteArray:

        return Align(ByteArray::SizeFor(ByteArray::cast(obj)->length()), kObjectAlignment);

      case MapKind_Code:

        return sizeof(Code);

      case MapKind_Reference:

        return sizeof(Reference);

      case MapKind_Module:

        return sizeof(Module);

      case MapKind_Function:

        return sizeof(Function);

      case MapKind_Array:

        return Align(Array::SizeOf(Array::cast(obj)), kObjectAlignment);

      case MapKind_MetaArray:

        return sizeof(ArrayMap);

      case MapKind_FreeRegion:

        return *reinterpret_cast<size_t *>(reinterpret_cast<Address>(obj + 1));

      default:

        assert(map->kind() == MapKind_Meta);

        return sizeof(Map);

    }

}

class ObjectSizeEvaluator

{

  public:

    size_t operator()(Object *obj, Map *map) {

        return SizeOfObject(obj, map);

    }

};

}

#endif // _include_jc_object_visitor_h_