dvander@29: /* vim: set ts=4 sw=4 tw=99 et:
dvander@29:  *
dvander@29:  * Copyright (C) 2012 David Anderson
dvander@29:  *
dvander@29:  * This file is part of JITCraft.
dvander@29:  *
dvander@29:  * JITCraft is free software: you can redistribute it and/or modify it under
dvander@29:  * the terms of the GNU General Public License as published by the Free
dvander@29:  * Software Foundation, either version 3 of the License, or (at your option)
dvander@29:  * any later version.
dvander@29:  * 
dvander@29:  * Foobar is distributed in the hope that it will be useful, but WITHOUT ANY
dvander@29:  * WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
dvander@29:  * FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.
dvander@29:  *
dvander@29:  * You should have received a copy of the GNU General Public License along with
dvander@29:  * JITCraft. If not, see http://www.gnu.org/licenses/.
dvander@29:  */
dvander@29: #ifndef _include_jc_root_scopes_h_
dvander@29: #define _include_jc_root_scopes_h_
dvander@29: 
dvander@60: #include "../include/keima.h"
dvander@29: #include "Objects.h"
dvander@45: #include "VirtualObjectVisitor.h"
dvander@29: 
dvander@59: namespace ke {
dvander@29: 
dvander@29: class RootScope;
dvander@29: 
dvander@29: // A RootScopeManager is essentially a specialized PoolAllocator that can
dvander@29: // only allocate Object ** entries. It is used to allow huge, temporary
dvander@29: // heap data structures like ASTs to hold safe references to objects. When
dvander@29: // the data structures is no longer needed, all of the roots are removed
dvander@29: // at once.
dvander@29: class RootScopeManager
dvander@29: {
dvander@29:     static const size_t kObjectsPerBlock = 4096;
dvander@29: 
dvander@29:     struct Block {
dvander@29:         Object *objects[kObjectsPerBlock];
dvander@29:         Object **cur;
dvander@29:         Object **end;
dvander@29:         Block *prev;
dvander@29: 
dvander@29:         Block(Block *prev)
dvander@29:           : cur(objects),
dvander@29:             end(objects + kObjectsPerBlock),
dvander@29:             prev(prev)
dvander@29:         {
dvander@29:         }
dvander@29:     };
dvander@29: 
dvander@29:   private:
dvander@29:     bool grow();
dvander@29:     void unwindSlow(Object **position);
dvander@29: 
dvander@29:   public:
dvander@29:     RootScopeManager();
dvander@29:     ~RootScopeManager();
dvander@29: 
dvander@29:     Object **position() const {
dvander@29:         return blocks_->cur;
dvander@29:     }
dvander@29: 
dvander@29:     void unwind(Object **position) {
dvander@29:         if (position >= blocks_->cur && position <= blocks_->end) {
dvander@29:             blocks_->cur = position;
dvander@29:             return;
dvander@29:         }
dvander@29:         unwindSlow(position);
dvander@29:     }
dvander@29: 
dvander@29:     Object **make(Object *obj) {
dvander@29:         assert(scope_);
dvander@29:         if (blocks_->cur + 1 > blocks_->end) {
dvander@29:             if (!grow())
dvander@29:                 return NULL;
dvander@29:         }
dvander@29:         Object **ptr = blocks_->cur;
dvander@29:         blocks_->cur++;
dvander@29:         *ptr = obj;
dvander@29:         return ptr;
dvander@29:     }
dvander@29: 
dvander@60:     Ke::HandleScope **scope() {
dvander@29:         return &scope_;
dvander@29:     }
dvander@29: 
dvander@45:     void accept(VirtualObjectVisitor *visitor);
dvander@45: 
dvander@29:   private:
dvander@29:     Block *blocks_;
dvander@29:     Block first_;
dvander@60:     Ke::HandleScope *scope_;
dvander@29: };
dvander@29: 
dvander@60: class RootScope : public Ke::HandleScope
dvander@29: {
dvander@29:   public:
dvander@29:     // These are implemented in Zone.h.
dvander@29:     inline RootScope(Zone *zone);
dvander@29: };
dvander@29: 
dvander@29: }
dvander@29: 
dvander@29: #endif // _include_jc_root_scope_h_