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      1 /*
      2  * Copyright (C) 2010 Apple Inc. All rights reserved.
      3  *
      4  * Redistribution and use in source and binary forms, with or without
      5  * modification, are permitted provided that the following conditions
      6  * are met:
      7  * 1. Redistributions of source code must retain the above copyright
      8  *    notice, this list of conditions and the following disclaimer.
      9  * 2. Redistributions in binary form must reproduce the above copyright
     10  *    notice, this list of conditions and the following disclaimer in the
     11  *    documentation and/or other materials provided with the distribution.
     12  *
     13  * THIS SOFTWARE IS PROVIDED BY APPLE INC. AND ITS CONTRIBUTORS ``AS IS''
     14  * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
     15  * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
     16  * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR ITS CONTRIBUTORS
     17  * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
     18  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
     19  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
     20  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
     21  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
     22  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
     23  * THE POSSIBILITY OF SUCH DAMAGE.
     24  */
     25 
     26 #ifndef LocalScope_h
     27 #define LocalScope_h
     28 
     29 #include "HandleStack.h"
     30 #include "Local.h"
     31 
     32 namespace JSC {
     33 /*
     34     A LocalScope is a temporary scope in which Locals are allocated. When a
     35     LocalScope goes out of scope, all the Locals created in it are destroyed.
     36 
     37     LocalScope is similar in concept to NSAutoreleasePool.
     38 */
     39 
     40 class JSGlobalData;
     41 
     42 class LocalScope {
     43 public:
     44     explicit LocalScope(JSGlobalData&);
     45     ~LocalScope();
     46 
     47     template <typename T> Local<T> release(Local<T>); // Destroys all other locals in the scope.
     48 
     49 private:
     50     HandleStack* m_handleStack;
     51     HandleStack::Frame m_lastFrame;
     52 };
     53 
     54 inline LocalScope::LocalScope(JSGlobalData& globalData)
     55     : m_handleStack(globalData.heap.handleStack())
     56 {
     57     m_handleStack->enterScope(m_lastFrame);
     58 }
     59 
     60 inline LocalScope::~LocalScope()
     61 {
     62     m_handleStack->leaveScope(m_lastFrame);
     63 }
     64 
     65 template <typename T> Local<T> LocalScope::release(Local<T> local)
     66 {
     67     typename Local<T>::ExternalType ptr = local.get();
     68 
     69     m_handleStack->leaveScope(m_lastFrame);
     70     HandleSlot slot = m_handleStack->push();
     71     m_handleStack->enterScope(m_lastFrame);
     72 
     73     return Local<T>(slot, ptr);
     74 }
     75 
     76 }
     77 
     78 #endif
     79