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// Copyright 2006-2008 the V8 project authors. All rights reserved.
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// Redistribution and use in source and binary forms, with or without
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// modification, are permitted provided that the following conditions are
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// met:
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//
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// * Redistributions of source code must retain the above copyright
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// notice, this list of conditions and the following disclaimer.
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// * Redistributions in binary form must reproduce the above
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// copyright notice, this list of conditions and the following
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// disclaimer in the documentation and/or other materials provided
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// with the distribution.
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// * Neither the name of Google Inc. nor the names of its
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// contributors may be used to endorse or promote products derived
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// from this software without specific prior written permission.
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//
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// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
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// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
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// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
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// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
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// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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#include "v8.h"
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#include "bootstrapper.h"
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#include "debug.h"
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#include "scopeinfo.h"
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namespace v8 {
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namespace internal {
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JSBuiltinsObject* Context::builtins() {
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GlobalObject* object = global();
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if (object->IsJSGlobalObject()) {
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return JSGlobalObject::cast(object)->builtins();
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} else {
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ASSERT(object->IsJSBuiltinsObject());
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return JSBuiltinsObject::cast(object);
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}
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}
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Context* Context::global_context() {
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// Fast case: the global object for this context has been set. In
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// that case, the global object has a direct pointer to the global
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// context.
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if (global()->IsGlobalObject()) {
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return global()->global_context();
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}
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// During bootstrapping, the global object might not be set and we
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// have to search the context chain to find the global context.
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ASSERT(Bootstrapper::IsActive());
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Context* current = this;
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while (!current->IsGlobalContext()) {
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JSFunction* closure = JSFunction::cast(current->closure());
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current = Context::cast(closure->context());
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}
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return current;
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}
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JSObject* Context::global_proxy() {
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return global_context()->global_proxy_object();
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}
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void Context::set_global_proxy(JSObject* object) {
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global_context()->set_global_proxy_object(object);
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}
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Handle<Object> Context::Lookup(Handle<String> name, ContextLookupFlags flags,
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int* index_, PropertyAttributes* attributes) {
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Handle<Context> context(this);
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bool follow_context_chain = (flags & FOLLOW_CONTEXT_CHAIN) != 0;
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*index_ = -1;
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*attributes = ABSENT;
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if (FLAG_trace_contexts) {
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PrintF("Context::Lookup(");
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name->ShortPrint();
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PrintF(")\n");
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}
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do {
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if (FLAG_trace_contexts) {
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PrintF(" - looking in context %p", *context);
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if (context->IsGlobalContext()) PrintF(" (global context)");
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PrintF("\n");
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}
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// check extension/with object
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if (context->has_extension()) {
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Handle<JSObject> extension = Handle<JSObject>(context->extension());
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// Context extension objects needs to behave as if they have no
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// prototype. So even if we want to follow prototype chains, we
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// need to only do a local lookup for context extension objects.
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if ((flags & FOLLOW_PROTOTYPE_CHAIN) == 0 ||
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extension->IsJSContextExtensionObject()) {
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*attributes = extension->GetLocalPropertyAttribute(*name);
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} else {
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*attributes = extension->GetPropertyAttribute(*name);
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}
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if (*attributes != ABSENT) {
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// property found
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if (FLAG_trace_contexts) {
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PrintF("=> found property in context object %p\n", *extension);
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}
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return extension;
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}
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}
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if (context->is_function_context()) {
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// we have context-local slots
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// check non-parameter locals in context
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Handle<SerializedScopeInfo> scope_info(
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context->closure()->shared()->scope_info());
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Variable::Mode mode;
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int index = scope_info->ContextSlotIndex(*name, &mode);
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ASSERT(index < 0 || index >= MIN_CONTEXT_SLOTS);
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if (index >= 0) {
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// slot found
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if (FLAG_trace_contexts) {
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PrintF("=> found local in context slot %d (mode = %d)\n",
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index, mode);
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}
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*index_ = index;
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// Note: Fixed context slots are statically allocated by the compiler.
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// Statically allocated variables always have a statically known mode,
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// which is the mode with which they were declared when added to the
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// scope. Thus, the DYNAMIC mode (which corresponds to dynamically
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// declared variables that were introduced through declaration nodes)
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// must not appear here.
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switch (mode) {
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case Variable::INTERNAL: // fall through
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case Variable::VAR: *attributes = NONE; break;
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case Variable::CONST: *attributes = READ_ONLY; break;
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case Variable::DYNAMIC: UNREACHABLE(); break;
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case Variable::DYNAMIC_GLOBAL: UNREACHABLE(); break;
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case Variable::DYNAMIC_LOCAL: UNREACHABLE(); break;
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case Variable::TEMPORARY: UNREACHABLE(); break;
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}
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return context;
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}
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// check parameter locals in context
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int param_index = scope_info->ParameterIndex(*name);
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if (param_index >= 0) {
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// slot found.
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int index =
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scope_info->ContextSlotIndex(Heap::arguments_shadow_symbol(), NULL);
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ASSERT(index >= 0); // arguments must exist and be in the heap context
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Handle<JSObject> arguments(JSObject::cast(context->get(index)));
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ASSERT(arguments->HasLocalProperty(Heap::length_symbol()));
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if (FLAG_trace_contexts) {
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PrintF("=> found parameter %d in arguments object\n", param_index);
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}
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*index_ = param_index;
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*attributes = NONE;
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return arguments;
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}
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// check intermediate context (holding only the function name variable)
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if (follow_context_chain) {
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int index = scope_info->FunctionContextSlotIndex(*name);
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if (index >= 0) {
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// slot found
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if (FLAG_trace_contexts) {
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PrintF("=> found intermediate function in context slot %d\n",
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index);
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}
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*index_ = index;
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*attributes = READ_ONLY;
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return context;
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}
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}
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}
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// proceed with enclosing context
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if (context->IsGlobalContext()) {
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follow_context_chain = false;
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} else if (context->is_function_context()) {
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context = Handle<Context>(Context::cast(context->closure()->context()));
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} else {
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context = Handle<Context>(context->previous());
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}
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} while (follow_context_chain);
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// slot not found
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if (FLAG_trace_contexts) {
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PrintF("=> no property/slot found\n");
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}
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return Handle<Object>::null();
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}
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bool Context::GlobalIfNotShadowedByEval(Handle<String> name) {
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Context* context = this;
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// Check that there is no local with the given name in contexts
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// before the global context and check that there are no context
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// extension objects (conservative check for with statements).
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while (!context->IsGlobalContext()) {
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// Check if the context is a potentially a with context.
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if (context->has_extension()) return false;
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// Not a with context so it must be a function context.
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ASSERT(context->is_function_context());
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// Check non-parameter locals.
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Handle<SerializedScopeInfo> scope_info(
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context->closure()->shared()->scope_info());
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Variable::Mode mode;
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int index = scope_info->ContextSlotIndex(*name, &mode);
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ASSERT(index < 0 || index >= MIN_CONTEXT_SLOTS);
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if (index >= 0) return false;
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// Check parameter locals.
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int param_index = scope_info->ParameterIndex(*name);
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if (param_index >= 0) return false;
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// Check context only holding the function name variable.
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index = scope_info->FunctionContextSlotIndex(*name);
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if (index >= 0) return false;
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context = Context::cast(context->closure()->context());
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}
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// No local or potential with statement found so the variable is
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// global unless it is shadowed by an eval-introduced variable.
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return true;
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}
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#ifdef DEBUG
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bool Context::IsBootstrappingOrContext(Object* object) {
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// During bootstrapping we allow all objects to pass as
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// contexts. This is necessary to fix circular dependencies.
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return Bootstrapper::IsActive() || object->IsContext();
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}
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bool Context::IsBootstrappingOrGlobalObject(Object* object) {
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// During bootstrapping we allow all objects to pass as global
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// objects. This is necessary to fix circular dependencies.
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return Bootstrapper::IsActive() || object->IsGlobalObject();
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}
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#endif
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} } // namespace v8::internal
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