Steve Block | a7e24c1 | 2009-10-30 11:49:00 +0000 | [diff] [blame^] | 1 | // Copyright 2006-2008 the V8 project authors. All rights reserved. |
| 2 | // Redistribution and use in source and binary forms, with or without |
| 3 | // modification, are permitted provided that the following conditions are |
| 4 | // met: |
| 5 | // |
| 6 | // * Redistributions of source code must retain the above copyright |
| 7 | // notice, this list of conditions and the following disclaimer. |
| 8 | // * Redistributions in binary form must reproduce the above |
| 9 | // copyright notice, this list of conditions and the following |
| 10 | // disclaimer in the documentation and/or other materials provided |
| 11 | // with the distribution. |
| 12 | // * Neither the name of Google Inc. nor the names of its |
| 13 | // contributors may be used to endorse or promote products derived |
| 14 | // from this software without specific prior written permission. |
| 15 | // |
| 16 | // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS |
| 17 | // "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT |
| 18 | // LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR |
| 19 | // A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT |
| 20 | // OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, |
| 21 | // SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT |
| 22 | // LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, |
| 23 | // DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY |
| 24 | // THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT |
| 25 | // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE |
| 26 | // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. |
| 27 | |
| 28 | #include "v8.h" |
| 29 | |
| 30 | #include "bootstrapper.h" |
| 31 | #include "debug.h" |
| 32 | #include "scopeinfo.h" |
| 33 | |
| 34 | namespace v8 { |
| 35 | namespace internal { |
| 36 | |
| 37 | JSBuiltinsObject* Context::builtins() { |
| 38 | GlobalObject* object = global(); |
| 39 | if (object->IsJSGlobalObject()) { |
| 40 | return JSGlobalObject::cast(object)->builtins(); |
| 41 | } else { |
| 42 | ASSERT(object->IsJSBuiltinsObject()); |
| 43 | return JSBuiltinsObject::cast(object); |
| 44 | } |
| 45 | } |
| 46 | |
| 47 | |
| 48 | Context* Context::global_context() { |
| 49 | // Fast case: the global object for this context has been set. In |
| 50 | // that case, the global object has a direct pointer to the global |
| 51 | // context. |
| 52 | if (global()->IsGlobalObject()) { |
| 53 | return global()->global_context(); |
| 54 | } |
| 55 | // During bootstrapping, the global object might not be set and we |
| 56 | // have to search the context chain to find the global context. |
| 57 | Context* current = this; |
| 58 | while (!current->IsGlobalContext()) { |
| 59 | current = Context::cast(JSFunction::cast(current->closure())->context()); |
| 60 | } |
| 61 | return current; |
| 62 | } |
| 63 | |
| 64 | |
| 65 | JSObject* Context::global_proxy() { |
| 66 | return global_context()->global_proxy_object(); |
| 67 | } |
| 68 | |
| 69 | void Context::set_global_proxy(JSObject* object) { |
| 70 | global_context()->set_global_proxy_object(object); |
| 71 | } |
| 72 | |
| 73 | |
| 74 | Handle<Object> Context::Lookup(Handle<String> name, ContextLookupFlags flags, |
| 75 | int* index_, PropertyAttributes* attributes) { |
| 76 | Handle<Context> context(this); |
| 77 | |
| 78 | bool follow_context_chain = (flags & FOLLOW_CONTEXT_CHAIN) != 0; |
| 79 | *index_ = -1; |
| 80 | *attributes = ABSENT; |
| 81 | |
| 82 | if (FLAG_trace_contexts) { |
| 83 | PrintF("Context::Lookup("); |
| 84 | name->ShortPrint(); |
| 85 | PrintF(")\n"); |
| 86 | } |
| 87 | |
| 88 | do { |
| 89 | if (FLAG_trace_contexts) { |
| 90 | PrintF(" - looking in context %p", *context); |
| 91 | if (context->IsGlobalContext()) PrintF(" (global context)"); |
| 92 | PrintF("\n"); |
| 93 | } |
| 94 | |
| 95 | // check extension/with object |
| 96 | if (context->has_extension()) { |
| 97 | Handle<JSObject> extension = Handle<JSObject>(context->extension()); |
| 98 | // Context extension objects needs to behave as if they have no |
| 99 | // prototype. So even if we want to follow prototype chains, we |
| 100 | // need to only do a local lookup for context extension objects. |
| 101 | if ((flags & FOLLOW_PROTOTYPE_CHAIN) == 0 || |
| 102 | extension->IsJSContextExtensionObject()) { |
| 103 | *attributes = extension->GetLocalPropertyAttribute(*name); |
| 104 | } else { |
| 105 | *attributes = extension->GetPropertyAttribute(*name); |
| 106 | } |
| 107 | if (*attributes != ABSENT) { |
| 108 | // property found |
| 109 | if (FLAG_trace_contexts) { |
| 110 | PrintF("=> found property in context object %p\n", *extension); |
| 111 | } |
| 112 | return extension; |
| 113 | } |
| 114 | } |
| 115 | |
| 116 | if (context->is_function_context()) { |
| 117 | // we have context-local slots |
| 118 | |
| 119 | // check non-parameter locals in context |
| 120 | Handle<Code> code(context->closure()->code()); |
| 121 | Variable::Mode mode; |
| 122 | int index = ScopeInfo<>::ContextSlotIndex(*code, *name, &mode); |
| 123 | ASSERT(index < 0 || index >= MIN_CONTEXT_SLOTS); |
| 124 | if (index >= 0) { |
| 125 | // slot found |
| 126 | if (FLAG_trace_contexts) { |
| 127 | PrintF("=> found local in context slot %d (mode = %d)\n", |
| 128 | index, mode); |
| 129 | } |
| 130 | *index_ = index; |
| 131 | // Note: Fixed context slots are statically allocated by the compiler. |
| 132 | // Statically allocated variables always have a statically known mode, |
| 133 | // which is the mode with which they were declared when added to the |
| 134 | // scope. Thus, the DYNAMIC mode (which corresponds to dynamically |
| 135 | // declared variables that were introduced through declaration nodes) |
| 136 | // must not appear here. |
| 137 | switch (mode) { |
| 138 | case Variable::INTERNAL: // fall through |
| 139 | case Variable::VAR: *attributes = NONE; break; |
| 140 | case Variable::CONST: *attributes = READ_ONLY; break; |
| 141 | case Variable::DYNAMIC: UNREACHABLE(); break; |
| 142 | case Variable::DYNAMIC_GLOBAL: UNREACHABLE(); break; |
| 143 | case Variable::DYNAMIC_LOCAL: UNREACHABLE(); break; |
| 144 | case Variable::TEMPORARY: UNREACHABLE(); break; |
| 145 | } |
| 146 | return context; |
| 147 | } |
| 148 | |
| 149 | // check parameter locals in context |
| 150 | int param_index = ScopeInfo<>::ParameterIndex(*code, *name); |
| 151 | if (param_index >= 0) { |
| 152 | // slot found. |
| 153 | int index = |
| 154 | ScopeInfo<>::ContextSlotIndex(*code, |
| 155 | Heap::arguments_shadow_symbol(), |
| 156 | NULL); |
| 157 | ASSERT(index >= 0); // arguments must exist and be in the heap context |
| 158 | Handle<JSObject> arguments(JSObject::cast(context->get(index))); |
| 159 | ASSERT(arguments->HasLocalProperty(Heap::length_symbol())); |
| 160 | if (FLAG_trace_contexts) { |
| 161 | PrintF("=> found parameter %d in arguments object\n", param_index); |
| 162 | } |
| 163 | *index_ = param_index; |
| 164 | *attributes = NONE; |
| 165 | return arguments; |
| 166 | } |
| 167 | |
| 168 | // check intermediate context (holding only the function name variable) |
| 169 | if (follow_context_chain) { |
| 170 | int index = ScopeInfo<>::FunctionContextSlotIndex(*code, *name); |
| 171 | if (index >= 0) { |
| 172 | // slot found |
| 173 | if (FLAG_trace_contexts) { |
| 174 | PrintF("=> found intermediate function in context slot %d\n", |
| 175 | index); |
| 176 | } |
| 177 | *index_ = index; |
| 178 | *attributes = READ_ONLY; |
| 179 | return context; |
| 180 | } |
| 181 | } |
| 182 | } |
| 183 | |
| 184 | // proceed with enclosing context |
| 185 | if (context->IsGlobalContext()) { |
| 186 | follow_context_chain = false; |
| 187 | } else if (context->is_function_context()) { |
| 188 | context = Handle<Context>(Context::cast(context->closure()->context())); |
| 189 | } else { |
| 190 | context = Handle<Context>(context->previous()); |
| 191 | } |
| 192 | } while (follow_context_chain); |
| 193 | |
| 194 | // slot not found |
| 195 | if (FLAG_trace_contexts) { |
| 196 | PrintF("=> no property/slot found\n"); |
| 197 | } |
| 198 | return Handle<Object>::null(); |
| 199 | } |
| 200 | |
| 201 | |
| 202 | bool Context::GlobalIfNotShadowedByEval(Handle<String> name) { |
| 203 | Context* context = this; |
| 204 | |
| 205 | // Check that there is no local with the given name in contexts |
| 206 | // before the global context and check that there are no context |
| 207 | // extension objects (conservative check for with statements). |
| 208 | while (!context->IsGlobalContext()) { |
| 209 | // Check if the context is a potentially a with context. |
| 210 | if (context->has_extension()) return false; |
| 211 | |
| 212 | // Not a with context so it must be a function context. |
| 213 | ASSERT(context->is_function_context()); |
| 214 | |
| 215 | // Check non-parameter locals. |
| 216 | Handle<Code> code(context->closure()->code()); |
| 217 | Variable::Mode mode; |
| 218 | int index = ScopeInfo<>::ContextSlotIndex(*code, *name, &mode); |
| 219 | ASSERT(index < 0 || index >= MIN_CONTEXT_SLOTS); |
| 220 | if (index >= 0) return false; |
| 221 | |
| 222 | // Check parameter locals. |
| 223 | int param_index = ScopeInfo<>::ParameterIndex(*code, *name); |
| 224 | if (param_index >= 0) return false; |
| 225 | |
| 226 | // Check context only holding the function name variable. |
| 227 | index = ScopeInfo<>::FunctionContextSlotIndex(*code, *name); |
| 228 | if (index >= 0) return false; |
| 229 | context = Context::cast(context->closure()->context()); |
| 230 | } |
| 231 | |
| 232 | // No local or potential with statement found so the variable is |
| 233 | // global unless it is shadowed by an eval-introduced variable. |
| 234 | return true; |
| 235 | } |
| 236 | |
| 237 | |
| 238 | #ifdef DEBUG |
| 239 | bool Context::IsBootstrappingOrContext(Object* object) { |
| 240 | // During bootstrapping we allow all objects to pass as |
| 241 | // contexts. This is necessary to fix circular dependencies. |
| 242 | return Bootstrapper::IsActive() || object->IsContext(); |
| 243 | } |
| 244 | |
| 245 | |
| 246 | bool Context::IsBootstrappingOrGlobalObject(Object* object) { |
| 247 | // During bootstrapping we allow all objects to pass as global |
| 248 | // objects. This is necessary to fix circular dependencies. |
| 249 | return Bootstrapper::IsActive() || object->IsGlobalObject(); |
| 250 | } |
| 251 | #endif |
| 252 | |
| 253 | } } // namespace v8::internal |