/*

  * 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_