/*

 * 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_ke_environment_h_

#define _include_ke_environment_h_

#include "Objects.h"

#include "Handles.h"

#include "Heap.h"

#include "FixedArray.h"

namespace ke {

class EnvironmentMap;

class Variable;

class ByteArray;

class Type;

// An environment represents the lexical environment of a code or function

// object. It used for variables which may be accessed outside a function's

// normal activation (i.e., upvars).

//

// A module uses an Environment to store its global variables.

class Environment : public Object

{

    template <typename T>

    inline T *pointerToSlot(unsigned slot);

  public:

    static Environment *New(Zone *zone, Handle<EnvironmentMap> map, Heap::Tenure tenure = Heap::Tenure_Default);

    inline EnvironmentMap *map();

    inline size_t objSize();

    float getFloat(unsigned slot) {

        return *pointerToSlot<float>(slot);

    }

    int getInt32(unsigned slot) {

        return *pointerToSlot<int>(slot);

    }

    Object *getObject(unsigned slot) {

        return *pointerToSlot<Object *>(slot);

    }

    void setFloat(unsigned slot, float f) {

        *pointerToSlot<float>(slot) = f;

    }

    void setInt32(unsigned slot, int i) {

        *pointerToSlot<int>(slot) = i;

    }

    void setObject(unsigned slot, Object *obj) {

        // :TODO: write barrier

        *pointerToSlot<Object *>(slot) = obj;

    }

    static inline size_t offsetOfSlotOffset(unsigned offset) {

        return sizeof(Environment) + offset;

    }

    static inline Environment *cast(Object *obj) {

        assert(!obj || obj->is(MapKind_Environment));

        return reinterpret_cast<Environment *>(obj);

    }

};

struct EnvironmentSlotDescriptor

{

    Barriered<Type> type;

    unsigned offset;

};

class EnvironmentSlotDescriptorArray : public Object

{

    unsigned length_;

  public:

    static EnvironmentSlotDescriptorArray *New(Zone *zone, unsigned length);

    EnvironmentSlotDescriptor *slots() {

        return reinterpret_cast<EnvironmentSlotDescriptor *>(this + 1);

    }

    EnvironmentSlotDescriptor &at(unsigned slot) {

        assert(slot < length_);

        return slots()[slot];

    }

    unsigned length() {

        return length_;

    }

    unsigned objSize() {

        return sizeof(*this) + length() * sizeof(EnvironmentSlotDescriptorArray);

    }

    static inline EnvironmentSlotDescriptorArray *cast(Object *obj) {

        assert(!obj || obj->is(MapKind_EnvironmentSlotDescriptorArray));

        return reinterpret_cast<EnvironmentSlotDescriptorArray *>(obj);

    }

};

class EnvironmentMap : public Map

{

    unsigned structureSize_;

    unsigned traceOffsetCount_;

    Barriered<EnvironmentSlotDescriptorArray> slots_;

  public:

    static EnvironmentMap *New(Zone *zone, unsigned nvars, Variable **vars);

    unsigned structureSize() {

        return structureSize_;

    }

    unsigned traceOffsetCount() {

        return traceOffsetCount_;

    }

    const unsigned *traceOffsets() {

        return reinterpret_cast<unsigned *>(this + 1);

    }

    size_t objSize() {

        return sizeof(EnvironmentMap) + sizeof(unsigned) * traceOffsetCount();

    }

    EnvironmentSlotDescriptor &slotDescriptor(unsigned slot) {

        return slots_->at(slot);

    }

    // Begin GC descriptors.

    static inline size_t offsetOfSlots() {

        return OFFSETOF(EnvironmentMap, slots_);

    }

    // End GC descriptors.

    static inline EnvironmentMap *cast(Object *obj) {

        assert(!obj || obj->is(MapKind_MetaEnvironment));

        return reinterpret_cast<EnvironmentMap *>(obj);

    }

};

size_t

Environment::objSize()

{

    return sizeof(Environment) + map()->structureSize();

}

EnvironmentMap *

Environment::map()

{

    return EnvironmentMap::cast(Object::map());

}

template <typename T> T *

Environment::pointerToSlot(unsigned slot)

{

    return reinterpret_cast<T *>(reinterpret_cast<char *>(this + 1) + map()->slotDescriptor(slot).offset);

}

}

#endif // _include_ke_environment_h_