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1 /* |
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2 * Copyright (C) 2003, 2008, 2009 Apple Inc. All rights reserved. |
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3 * |
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4 * This library is free software; you can redistribute it and/or |
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5 * modify it under the terms of the GNU Library General Public |
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6 * License as published by the Free Software Foundation; either |
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7 * version 2 of the License, or (at your option) any later version. |
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8 * |
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9 * This library is distributed in the hope that it will be useful, |
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10 * but WITHOUT ANY WARRANTY; without even the implied warranty of |
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11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
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12 * Library General Public License for more details. |
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13 * |
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14 * You should have received a copy of the GNU Library General Public License |
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15 * along with this library; see the file COPYING.LIB. If not, write to |
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16 * the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, |
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17 * Boston, MA 02110-1301, USA. |
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18 * |
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19 */ |
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20 |
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21 #ifndef ScopeChain_h |
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22 #define ScopeChain_h |
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23 |
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24 #include "FastAllocBase.h" |
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25 |
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26 namespace JSC { |
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27 |
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28 class JSGlobalData; |
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29 class JSGlobalObject; |
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30 class JSObject; |
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31 class MarkStack; |
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32 class ScopeChainIterator; |
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33 |
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34 class ScopeChainNode : public FastAllocBase { |
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35 public: |
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36 ScopeChainNode(ScopeChainNode* next, JSObject* object, JSGlobalData* globalData, JSGlobalObject* globalObject, JSObject* globalThis) |
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37 : next(next) |
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38 , object(object) |
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39 , globalData(globalData) |
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40 , globalObject(globalObject) |
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41 , globalThis(globalThis) |
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42 , refCount(1) |
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43 { |
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44 ASSERT(globalData); |
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45 ASSERT(globalObject); |
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46 } |
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47 #ifndef NDEBUG |
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48 // Due to the number of subtle and timing dependent bugs that have occurred due |
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49 // to deleted but still "valid" ScopeChainNodes we now deliberately clobber the |
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50 // contents in debug builds. |
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51 ~ScopeChainNode() |
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52 { |
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53 next = 0; |
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54 object = 0; |
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55 globalData = 0; |
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56 globalObject = 0; |
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57 globalThis = 0; |
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58 } |
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59 #endif |
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60 |
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61 ScopeChainNode* next; |
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62 JSObject* object; |
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63 JSGlobalData* globalData; |
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64 JSGlobalObject* globalObject; |
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65 JSObject* globalThis; |
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66 int refCount; |
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67 |
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68 void deref() { ASSERT(refCount); if (--refCount == 0) { release();} } |
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69 void ref() { ASSERT(refCount); ++refCount; } |
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70 void release(); |
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71 |
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72 // Before calling "push" on a bare ScopeChainNode, a client should |
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73 // logically "copy" the node. Later, the client can "deref" the head |
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74 // of its chain of ScopeChainNodes to reclaim all the nodes it added |
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75 // after the logical copy, leaving nodes added before the logical copy |
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76 // (nodes shared with other clients) untouched. |
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77 ScopeChainNode* copy() |
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78 { |
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79 ref(); |
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80 return this; |
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81 } |
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82 |
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83 ScopeChainNode* push(JSObject*); |
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84 ScopeChainNode* pop(); |
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85 |
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86 ScopeChainIterator begin() const; |
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87 ScopeChainIterator end() const; |
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88 |
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89 #ifndef NDEBUG |
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90 void print() const; |
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91 #endif |
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92 }; |
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93 |
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94 inline ScopeChainNode* ScopeChainNode::push(JSObject* o) |
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95 { |
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96 ASSERT(o); |
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97 return new ScopeChainNode(this, o, globalData, globalObject, globalThis); |
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98 } |
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99 |
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100 inline ScopeChainNode* ScopeChainNode::pop() |
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101 { |
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102 ASSERT(next); |
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103 ScopeChainNode* result = next; |
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104 |
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105 if (--refCount != 0) |
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106 ++result->refCount; |
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107 else |
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108 delete this; |
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109 |
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110 return result; |
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111 } |
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112 |
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113 inline void ScopeChainNode::release() |
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114 { |
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115 // This function is only called by deref(), |
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116 // Deref ensures these conditions are true. |
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117 ASSERT(refCount == 0); |
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118 ScopeChainNode* n = this; |
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119 do { |
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120 ScopeChainNode* next = n->next; |
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121 delete n; |
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122 n = next; |
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123 } while (n && --n->refCount == 0); |
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124 } |
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125 |
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126 class ScopeChainIterator { |
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127 public: |
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128 ScopeChainIterator(const ScopeChainNode* node) |
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129 : m_node(node) |
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130 { |
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131 } |
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132 |
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133 JSObject* const & operator*() const { return m_node->object; } |
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134 JSObject* const * operator->() const { return &(operator*()); } |
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135 |
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136 ScopeChainIterator& operator++() { m_node = m_node->next; return *this; } |
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137 |
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138 // postfix ++ intentionally omitted |
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139 |
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140 bool operator==(const ScopeChainIterator& other) const { return m_node == other.m_node; } |
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141 bool operator!=(const ScopeChainIterator& other) const { return m_node != other.m_node; } |
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142 |
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143 private: |
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144 const ScopeChainNode* m_node; |
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145 }; |
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146 |
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147 inline ScopeChainIterator ScopeChainNode::begin() const |
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148 { |
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149 return ScopeChainIterator(this); |
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150 } |
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151 |
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152 inline ScopeChainIterator ScopeChainNode::end() const |
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153 { |
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154 return ScopeChainIterator(0); |
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155 } |
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156 |
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157 class NoScopeChain {}; |
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158 |
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159 class ScopeChain { |
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160 friend class JIT; |
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161 public: |
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162 ScopeChain(NoScopeChain) |
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163 : m_node(0) |
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164 { |
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165 } |
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166 |
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167 ScopeChain(JSObject* o, JSGlobalData* globalData, JSGlobalObject* globalObject, JSObject* globalThis) |
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168 : m_node(new ScopeChainNode(0, o, globalData, globalObject, globalThis)) |
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169 { |
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170 } |
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171 |
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172 ScopeChain(const ScopeChain& c) |
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173 : m_node(c.m_node->copy()) |
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174 { |
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175 } |
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176 |
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177 ScopeChain& operator=(const ScopeChain& c); |
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178 |
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179 explicit ScopeChain(ScopeChainNode* node) |
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180 : m_node(node->copy()) |
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181 { |
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182 } |
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183 |
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184 ~ScopeChain() |
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185 { |
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186 if (m_node) |
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187 m_node->deref(); |
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188 #ifndef NDEBUG |
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189 m_node = 0; |
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190 #endif |
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191 } |
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192 |
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193 void swap(ScopeChain&); |
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194 |
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195 ScopeChainNode* node() const { return m_node; } |
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196 |
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197 JSObject* top() const { return m_node->object; } |
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198 |
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199 ScopeChainIterator begin() const { return m_node->begin(); } |
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200 ScopeChainIterator end() const { return m_node->end(); } |
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201 |
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202 void push(JSObject* o) { m_node = m_node->push(o); } |
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203 |
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204 void pop() { m_node = m_node->pop(); } |
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205 void clear() { m_node->deref(); m_node = 0; } |
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206 |
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207 JSGlobalObject* globalObject() const { return m_node->globalObject; } |
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208 |
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209 void markAggregate(MarkStack&) const; |
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210 |
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211 // Caution: this should only be used if the codeblock this is being used |
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212 // with needs a full scope chain, otherwise this returns the depth of |
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213 // the preceeding call frame |
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214 // |
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215 // Returns the depth of the current call frame's scope chain |
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216 int localDepth() const; |
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217 |
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218 #ifndef NDEBUG |
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219 void print() const { m_node->print(); } |
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220 #endif |
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221 |
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222 private: |
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223 ScopeChainNode* m_node; |
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224 }; |
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225 |
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226 inline void ScopeChain::swap(ScopeChain& o) |
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227 { |
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228 ScopeChainNode* tmp = m_node; |
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229 m_node = o.m_node; |
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230 o.m_node = tmp; |
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231 } |
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232 |
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233 inline ScopeChain& ScopeChain::operator=(const ScopeChain& c) |
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234 { |
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235 ScopeChain tmp(c); |
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236 swap(tmp); |
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237 return *this; |
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238 } |
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239 |
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240 } // namespace JSC |
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241 |
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242 #endif // ScopeChain_h |