File indexing completed on 2024-05-12 15:43:34

 /*
  *  This file is part of the KDE libraries
  *  Copyright (C) 2003 Apple Computer, Inc.
  *            (C) 2008 Maksim Orlovich <maksim@kde.org>
  *
  *  This library is free software; you can redistribute it and/or
  *  modify it under the terms of the GNU Library General Public
  *  License as published by the Free Software Foundation; either
  *  version 2 of the License, or (at your option) any later version.
  *
  *  This library 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
  *  Library General Public License for more details.
  *
  *  You should have received a copy of the GNU Library General Public License
  *  along with this library; see the file COPYING.LIB.  If not, write to
  *  the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
  *  Boston, MA 02110-1301, USA.
  *
  */
 
 #ifndef KJS_SCOPE_CHAIN_H
 #define KJS_SCOPE_CHAIN_H
 
 #include "global.h"
 #if HAVE_STDINT_H
 #include <stdint.h>
 #endif
 #include <assert.h>
 
 namespace KJS
 {
 
 class JSObject;
 class JSVariableObject;
 class ScopeChainNode;
 
 class KJS_EXPORT ScopeChainLink
 {
 public:
     /* This class abstracts a link to a node in a scope chain. The node may be
         either a JSVariable, which stores the next pointer in one of its
         slots, or a full-blown ScopeChainNode with separate object/next field and a
         refcount.
 
         We link to variable object by storing the pointer to them; to ScopeChainNode's by
         storing the pointer with lower bit set.
     */
     uintptr_t ptr;
 
     // in lieu of constructor, for POD'ness
     void init()
     {
         ptr = 0;
     }
 
     void set(ScopeChainNode *node)
     {
         ptr = reinterpret_cast<uintptr_t>(node) | 1;
     }
 
     void set(JSVariableObject *act)
     {
         ptr = reinterpret_cast<uintptr_t>(act);
     }
 
     // these are inline in JSVariableObject.h
     JSObject      *object() const;
     ScopeChainLink next()   const;
 
     void deref();
     void ref();
 
     bool isToScopeChainNode() const
     {
         return ptr & 1;
     }
 
     JSVariableObject *asVariableObject() const
     {
         assert(!isToScopeChainNode());
         return reinterpret_cast<JSVariableObject *>(ptr);
     }
 
     ScopeChainNode *asScopeChainNode() const
     {
         assert(isToScopeChainNode());
         return reinterpret_cast<ScopeChainNode *>(ptr & ~1);
     }
 
     bool operator == (const ScopeChainLink &other) const
     {
         return other.ptr == ptr;
     }
 
     bool operator != (const ScopeChainLink &other) const
     {
         return other.ptr != ptr;
     }
 };
 
 // A ScopeChainNode is used to put things other than JSVariableObject's
 // in the scope chain.
 class KJS_EXPORT ScopeChainNode
 {
 public:
     ScopeChainNode(ScopeChainLink n, JSObject *o)
         : next(n), object(o), refCount(1)
     {
         // Note: we don't ref the next here, since its reference is
         // transferred from top pointer in ScopeChain to us
         // We ourselves are ref'd by the refCount(1)
     }
 
     ~ScopeChainNode()
     {
         // ### non-recursive?
         next.deref();
     }
 
     ScopeChainLink next;
     JSObject *object;
     int refCount;
 
     void ref()
     {
         ++refCount;
     }
     void deref()
     {
         --refCount;
         if (!refCount) {
             delete this;
         }
     }
 };
 
 class KJS_EXPORT ScopeChainIterator
 {
 public:
     ScopeChainIterator(ScopeChainLink node) : m_node(node) {}
 
     JSObject *operator*()  const
     {
         return m_node.object();
     }
 
     ScopeChainIterator &operator++()
     {
         m_node = m_node.next();
         return *this;
     }
 
     // postfix ++ intentionally omitted
 
     bool operator==(const ScopeChainIterator &other) const
     {
         return m_node == other.m_node;
     }
     bool operator!=(const ScopeChainIterator &other) const
     {
         return m_node != other.m_node;
     }
 
 private:
     ScopeChainLink m_node;
 };
 
 class KJS_EXPORT ScopeChain
 {
 public:
     ScopeChain()
     {
         m_top.init();
     }
 
     ~ScopeChain()
     {
         m_top.deref();
     }
 
     ScopeChain(const ScopeChain &c) : m_top(c.m_top)
     {
         m_top.ref();
     }
 
     ScopeChain &operator=(const ScopeChain &);
 
     JSObject *top() const
     {
         return m_top.object();
     }
     JSObject *bottom() const;
 
     ScopeChainIterator begin() const;
     ScopeChainIterator end() const;
 
     void push(JSObject *obj)
     {
         m_top.set(new ScopeChainNode(m_top, obj));
     }
 
     // inline def in JSVariableObject.h
     void pushVariableObject(JSVariableObject *act);
 
     void pop();
     void mark(); // inline in JSVariableObject.h
 
 #ifndef NDEBUG
     void print();
 #endif
 
 private:
     ScopeChainLink m_top;
 };
 
 inline void ScopeChainLink::deref()
 {
     if (isToScopeChainNode()) {
         asScopeChainNode()->deref();
     }
     ptr = 0;
 }
 
 inline void ScopeChainLink::ref()
 {
     if (isToScopeChainNode()) {
         asScopeChainNode()->ref();
     }
 }
 
 inline ScopeChainIterator ScopeChain::begin() const
 {
     return ScopeChainIterator(m_top);
 }
 
 inline ScopeChainIterator ScopeChain::end() const
 {
     ScopeChainLink empty;
     empty.init();
     return ScopeChainIterator(empty);
 }
 
 inline ScopeChain &ScopeChain::operator=(const ScopeChain &c)
 {
     ScopeChainLink newTop = c.m_top;
     newTop.ref();
     m_top.deref();
     m_top = newTop;
     return *this;
 }
 
 inline JSObject *ScopeChain::bottom() const
 {
     ScopeChainLink last;
     for (ScopeChainLink n = m_top; n.ptr; n = n.next()) {
         last = n;
     }
     return last.object();
 }
 
 inline void ScopeChain::pop()
 {
     // ### may need manual CSE, it also thrashes more that needed
     ScopeChainLink newTop = m_top.next();
     newTop.ref();
     m_top.deref();
     m_top = newTop;
 }
 
 } // namespace KJS
 
 #endif // KJS_SCOPE_CHAIN_H