scope_chain.h

00001 /*
00002  *  This file is part of the KDE libraries
00003  *  Copyright (C) 2003 Apple Computer, Inc.
00004  *
00005  *  This library is free software; you can redistribute it and/or
00006  *  modify it under the terms of the GNU Library General Public
00007  *  License as published by the Free Software Foundation; either
00008  *  version 2 of the License, or (at your option) any later version.
00009  *
00010  *  This library is distributed in the hope that it will be useful,
00011  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
00012  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
00013  *  Library General Public License for more details.
00014  *
00015  *  You should have received a copy of the GNU Library General Public License
00016  *  along with this library; see the file COPYING.LIB.  If not, write to
00017  *  the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
00018  *  Boston, MA 02110-1301, USA.
00019  *
00020  */
00021 
00022 #ifndef KJS_SCOPE_CHAIN_H
00023 #define KJS_SCOPE_CHAIN_H
00024 
00025 #include "global.h"
00026 
00027 namespace KJS {
00028 
00029     class ObjectImp;
00030 
00034     class KJS_EXPORT ScopeChainNode {
00035     public:
00036         ScopeChainNode(ScopeChainNode *n, ObjectImp *o)
00037             : next(n), object(o), refCount(1) { }
00038 
00039         ScopeChainNode *next;
00040         ObjectImp *object;
00041         int refCount;
00042     };
00043 
00047     class KJS_EXPORT ScopeChain {
00048     public:
00049         ScopeChain() : _node(0) { }
00050         ~ScopeChain() { deref(); }
00051 
00052         ScopeChain(const ScopeChain &c) : _node(c._node)
00053             { if (_node) ++_node->refCount; }
00054         ScopeChain &operator=(const ScopeChain &);
00055 
00056         bool isEmpty() const { return !_node; }
00057         ObjectImp *top() const { return _node->object; }
00058         ObjectImp *bottom() const { const ScopeChainNode *n = _node;
00059                     while (n->next) n = n->next;
00060                     return n->object; }
00061 
00062         void clear() { deref(); _node = 0; }
00063         void push(ObjectImp *);
00064         void pop();
00065 
00066         void mark();
00067 
00068     private:
00069         ScopeChainNode *_node;
00070 
00071         void deref() { if (_node && --_node->refCount == 0) release(); }
00072         void ref() const;
00073 
00074         void release();
00075     };
00076 
00077 } // namespace KJS
00078 
00079 #endif // KJS_SCOPE_CHAIN_H
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