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 Local_h 27 #define Local_h 28 29 #include "Handle.h" 30 #include "JSGlobalData.h" 31 32 /* 33 A strongly referenced handle whose lifetime is temporary, limited to a given 34 LocalScope. Use Locals for local values on the stack. It is an error to 35 create a Local outside of any LocalScope. 36 */ 37 38 namespace JSC { 39 40 template <typename T> class Local : public Handle<T> { 41 friend class LocalScope; 42 using Handle<T>::slot; 43 44 public: 45 typedef typename Handle<T>::ExternalType ExternalType; 46 47 Local(JSGlobalData&, ExternalType = ExternalType()); 48 Local(JSGlobalData&, Handle<T>); 49 Local(const Local<T>&); // Adopting constructor. Used to return a Local to a calling function. 50 51 Local& operator=(ExternalType); 52 Local& operator=(Handle<T>); 53 54 private: 55 Local(HandleSlot, ExternalType); // Used by LocalScope::release() to move a Local to a containing scope. 56 void set(ExternalType); 57 }; 58 59 template <typename T> inline Local<T>::Local(JSGlobalData& globalData, ExternalType value) 60 : Handle<T>(globalData.allocateLocalHandle()) 61 { 62 set(value); 63 } 64 65 template <typename T> inline Local<T>::Local(JSGlobalData& globalData, Handle<T> other) 66 : Handle<T>(globalData.allocateLocalHandle()) 67 { 68 set(other.get()); 69 } 70 71 template <typename T> inline Local<T>::Local(const Local<T>& other) 72 : Handle<T>(other.slot()) 73 { 74 const_cast<Local<T>&>(other).setSlot(0); // Prevent accidental sharing. 75 } 76 77 template <typename T> inline Local<T>::Local(HandleSlot slot, ExternalType value) 78 : Handle<T>(slot, value) 79 { 80 } 81 82 template <typename T> inline Local<T>& Local<T>::operator=(ExternalType value) 83 { 84 set(value); 85 return *this; 86 } 87 88 template <typename T> inline Local<T>& Local<T>::operator=(Handle<T> other) 89 { 90 set(other.get()); 91 return *this; 92 } 93 94 template <typename T> inline void Local<T>::set(ExternalType externalType) 95 { 96 ASSERT(slot()); 97 ASSERT(!HandleTypes<T>::toJSValue(externalType) || !HandleTypes<T>::toJSValue(externalType).isCell() || Heap::isMarked(HandleTypes<T>::toJSValue(externalType).asCell())); 98 *slot() = externalType; 99 } 100 101 102 template <typename T, unsigned inlineCapacity = 0> class LocalStack { 103 typedef typename Handle<T>::ExternalType ExternalType; 104 public: 105 LocalStack(JSGlobalData& globalData) 106 : m_globalData(&globalData) 107 , m_count(0) 108 { 109 } 110 111 ExternalType peek() const 112 { 113 ASSERT(m_count > 0); 114 return m_stack[m_count - 1].get(); 115 } 116 117 ExternalType pop() 118 { 119 ASSERT(m_count > 0); 120 return m_stack[--m_count].get(); 121 } 122 123 void push(ExternalType value) 124 { 125 if (m_count == m_stack.size()) 126 m_stack.append(Local<T>(*m_globalData, value)); 127 else 128 m_stack[m_count] = value; 129 m_count++; 130 } 131 132 bool isEmpty() const { return !m_count; } 133 unsigned size() const { return m_count; } 134 135 private: 136 RefPtr<JSGlobalData> m_globalData; 137 Vector<Local<T>, inlineCapacity> m_stack; 138 unsigned m_count; 139 }; 140 141 } 142 143 namespace WTF { 144 145 template<typename T> struct VectorTraits<JSC::Local<T> > : SimpleClassVectorTraits { 146 static const bool needsDestruction = false; 147 static const bool canInitializeWithMemset = false; 148 static const bool canCompareWithMemcmp = false; 149 }; 150 151 } 152 153 #endif 154