hausner@google.com
5e7bc84013
Do not include captured variables in the list of local variables until the debugger knows how to get their value from the context. Fixes issue 2401 (http://code.google.com/p/dart/issues/detail?id=2401) Review URL: https://chromiumcodereview.appspot.com//9961012 git-svn-id: https://dart.googlecode.com/svn/branches/bleeding_edge/dart@6187 260f80e4-7a28-3924-810f-c04153c831b5
481 lines
16 KiB
C++
481 lines
16 KiB
C++
// Copyright (c) 2012, the Dart project authors. Please see the AUTHORS file
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// for details. All rights reserved. Use of this source code is governed by a
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// BSD-style license that can be found in the LICENSE file.
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#include "vm/scopes.h"
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#include "vm/ast.h"
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#include "vm/object.h"
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namespace dart {
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const char* SourceLabel::kDefaultLabelName = ":L";
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int SourceLabel::FunctionLevel() const {
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ASSERT(owner() != NULL);
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return owner()->function_level();
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}
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LocalScope::LocalScope(LocalScope* parent, int function_level, int loop_level)
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: parent_(parent),
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child_(NULL),
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sibling_(NULL),
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function_level_(function_level),
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loop_level_(loop_level),
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context_level_(LocalScope::kUnitializedContextLevel),
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num_context_variables_(0),
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end_token_index_(0),
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variables_(),
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labels_() {
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// Hook this node into the children of the parent, unless the parent has a
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// different function_level, since the local scope of a nested function can
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// be discarded after it has been parsed.
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if ((parent != NULL) && (parent->function_level() == function_level)) {
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sibling_ = parent->child_;
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parent->child_ = this;
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}
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}
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bool LocalScope::IsNestedWithin(LocalScope* scope) const {
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const LocalScope* current_scope = this;
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while (current_scope != NULL) {
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if (current_scope == scope) {
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return true;
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}
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current_scope = current_scope->parent();
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}
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return false;
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}
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bool LocalScope::AddVariable(LocalVariable* variable) {
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if (LocalLookupVariable(variable->name()) != NULL) {
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return false;
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}
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variables_.Add(variable);
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if (variable->owner() == NULL) {
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// Variables must be added to their owner scope first. Subsequent calls
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// to 'add' treat the variable as an alias.
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variable->set_owner(this);
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}
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return true;
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}
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bool LocalScope::AddLabel(SourceLabel* label) {
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if (LocalLookupLabel(label->name()) != NULL) {
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return false;
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}
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labels_.Add(label);
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if (label->owner() == NULL) {
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// Labels must be added to their owner scope first. Subsequent calls
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// to 'add' treat the label as an alias.
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label->set_owner(this);
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}
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return true;
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}
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void LocalScope::AllocateContextVariable(LocalVariable* variable,
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LocalScope** context_owner) {
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ASSERT(variable->is_captured());
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ASSERT(variable->owner()->loop_level() == loop_level());
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if (num_context_variables_ == 0) {
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// This scope will allocate and chain a new context.
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int new_context_level = ((*context_owner) == NULL) ?
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1 : (*context_owner)->context_level() + 1;
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// This scope becomes the current context owner.
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*context_owner = this;
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set_context_level(new_context_level);
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}
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// The context level in the owner scope of a captured variable indicates at
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// code generation time how far to walk up the context chain in order to
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// access the variable from the current context level.
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if (!variable->owner()->HasContextLevel()) {
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ASSERT(variable->owner() != this);
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variable->owner()->set_context_level(context_level());
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} else {
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ASSERT(variable->owner()->context_level() == context_level());
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}
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variable->set_index(num_context_variables_++);
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}
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int LocalScope::AllocateVariables(int first_parameter_index,
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int num_parameters,
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int first_frame_index,
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LocalScope* loop_owner,
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LocalScope** context_owner) {
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// We should not allocate variables of nested functions while compiling an
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// enclosing function.
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ASSERT(function_level() == 0);
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ASSERT(num_parameters >= 0);
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// Keep track of the current loop owner scope, that is of the highest parent
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// scope at the same loop level as this scope.
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if (loop_level() > loop_owner->loop_level()) {
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loop_owner = this;
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}
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// Parameters must be listed first and must all appear in the top scope.
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ASSERT(num_parameters <= num_variables());
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int pos = 0; // Current variable position.
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int frame_index = first_parameter_index; // Current free frame index.
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while (pos < num_parameters) {
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LocalVariable* parameter = VariableAt(pos);
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pos++;
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ASSERT(parameter->owner() == this);
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if (parameter->is_captured()) {
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// A captured parameter has a slot allocated in the frame and one in the
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// context, where it gets copied to. The parameter index reflects the
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// context allocation index.
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frame_index--;
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loop_owner->AllocateContextVariable(parameter, context_owner);
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} else {
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parameter->set_index(frame_index--);
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}
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}
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// No overlapping of parameters and locals.
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ASSERT(frame_index >= first_frame_index);
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frame_index = first_frame_index;
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while (pos < num_variables()) {
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LocalVariable* variable = VariableAt(pos);
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pos++;
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if (variable->owner() == this) {
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if (variable->is_captured()) {
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loop_owner->AllocateContextVariable(variable, context_owner);
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} else {
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variable->set_index(frame_index--);
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}
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}
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}
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// Allocate variables of all children.
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int min_frame_index = frame_index;
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LocalScope* child = this->child();
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while (child != NULL) {
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LocalScope* child_context_owner = *context_owner;
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int const dummy_parameter_index = 0; // Ignored, since no parameters.
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int const num_parameters_in_child = 0; // No parameters in children scopes.
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int child_frame_index = child->AllocateVariables(dummy_parameter_index,
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num_parameters_in_child,
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frame_index,
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loop_owner,
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&child_context_owner);
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if (child_frame_index < min_frame_index) {
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min_frame_index = child_frame_index;
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}
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// A context allocated at a deeper loop level than the current loop level is
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// not shared between children.
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if ((child_context_owner != *context_owner) &&
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(child_context_owner->loop_level() <= loop_owner->loop_level())) {
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*context_owner = child_context_owner; // Share context between siblings.
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}
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child = child->sibling();
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}
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return min_frame_index;
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}
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RawLocalVarDescriptors* LocalScope::GetVarDescriptors() {
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GrowableArray<LocalVariable*> vars(8);
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// Variables of each scope are guaranteed to be consecutive elements
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// in array vars. See CollectLocalVariables() below. The outermost
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// scope (containing the function parameters) has id 0.
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CollectLocalVariables(&vars);
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const LocalVarDescriptors& var_desc =
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LocalVarDescriptors::Handle(LocalVarDescriptors::New(vars.length()));
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intptr_t scope_id = -1;
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LocalScope* current_scope = NULL;
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for (int i = 0; i < vars.length(); i++) {
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LocalVariable* var = vars[i];
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if (current_scope != var->owner()) {
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current_scope = var->owner();
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scope_id += 1;
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}
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var_desc.SetVar(i, var->name(), var->index(),
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scope_id, var->token_index(), var->owner()->end_token_index());
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}
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return var_desc.raw();
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}
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// Add variables that are declared in this scope to vars, then collect
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// variables of children, followed by siblings.
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void LocalScope::CollectLocalVariables(GrowableArray<LocalVariable*>* vars) {
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for (int i = 0; i < this->variables_.length(); i++) {
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LocalVariable* var = variables_[i];
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// TODO(hausner): Remove the is_captured() condition once the debugger
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// can handle getting values of captured variables.
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if (!var->is_captured() && (var->owner() == this) &&
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Scanner::IsIdent(var->name())) {
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vars->Add(this->variables_[i]);
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}
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}
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if (child() != NULL) {
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child()->CollectLocalVariables(vars);
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}
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if (sibling() != NULL) {
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sibling()->CollectLocalVariables(vars);
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}
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}
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SourceLabel* LocalScope::LocalLookupLabel(const String& name) const {
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for (intptr_t i = 0; i < labels_.length(); i++) {
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SourceLabel* label = labels_[i];
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if (label->name().Equals(name)) {
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return label;
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}
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}
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return NULL;
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}
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LocalVariable* LocalScope::LocalLookupVariable(const String& name) const {
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for (intptr_t i = 0; i < variables_.length(); i++) {
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LocalVariable* var = variables_[i];
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if (var->name().Equals(name) && !var->is_invisible_) {
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return var;
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}
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}
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return NULL;
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}
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LocalVariable* LocalScope::LookupVariable(const String& name, bool test_only) {
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LocalScope* current_scope = this;
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while (current_scope != NULL) {
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LocalVariable* var = current_scope->LocalLookupVariable(name);
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if (var != NULL) {
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if (!test_only) {
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if (var->owner()->function_level() != function_level()) {
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var->set_is_captured();
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}
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// Insert aliases of the variable in intermediate scopes.
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LocalScope* intermediate_scope = this;
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while (intermediate_scope != current_scope) {
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intermediate_scope->variables_.Add(var);
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ASSERT(var->owner() != intermediate_scope); // Item is an alias.
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intermediate_scope = intermediate_scope->parent();
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}
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}
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return var;
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}
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current_scope = current_scope->parent();
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}
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return NULL;
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}
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SourceLabel* LocalScope::LookupLabel(const String& name) {
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LocalScope* current_scope = this;
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while (current_scope != NULL) {
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SourceLabel* label = current_scope->LocalLookupLabel(name);
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if (label != NULL) {
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return label;
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}
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current_scope = current_scope->parent();
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}
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return NULL;
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}
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SourceLabel* LocalScope::LookupInnermostLabel(Token::Kind jump_kind) {
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ASSERT((jump_kind == Token::kCONTINUE) || (jump_kind == Token::kBREAK));
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LocalScope* current_scope = this;
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while (current_scope != NULL) {
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for (intptr_t i = 0; i < current_scope->labels_.length(); i++) {
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SourceLabel* label = current_scope->labels_[i];
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if ((label->kind() == SourceLabel::kWhile) ||
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(label->kind() == SourceLabel::kFor) ||
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(label->kind() == SourceLabel::kDoWhile) ||
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((jump_kind == Token::kBREAK) &&
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(label->kind() == SourceLabel::kSwitch))) {
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return label;
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}
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}
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current_scope = current_scope->parent();
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}
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return NULL;
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}
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SourceLabel* LocalScope::LookupInnermostCatchLabel() {
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LocalScope* current_scope = this;
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while (current_scope != NULL) {
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for (intptr_t i = 0; i < current_scope->labels_.length(); i++) {
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SourceLabel* label = current_scope->labels_[i];
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if (label->kind() == SourceLabel::kCatch) {
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return label;
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}
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}
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current_scope = current_scope->parent();
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}
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return NULL;
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}
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LocalScope* LocalScope::LookupSwitchScope() {
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LocalScope* current_scope = this->parent();
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int this_level = this->function_level();
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while (current_scope != NULL &&
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current_scope->function_level() == this_level) {
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for (int i = 0; i < current_scope->labels_.length(); i++) {
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SourceLabel* label = current_scope->labels_[i];
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if (label->kind() == SourceLabel::kSwitch) {
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// This scope contains a label that is bound to a switch statement,
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// so it is the scope of the a statement body.
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return current_scope;
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}
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}
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current_scope = current_scope->parent();
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}
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// We did not find a switch statement scope at the same function level.
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return NULL;
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}
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SourceLabel* LocalScope::CheckUnresolvedLabels() {
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for (int i = 0; i < this->labels_.length(); i++) {
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SourceLabel* label = this->labels_[i];
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if (label->kind() == SourceLabel::kForward) {
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LocalScope* outer_switch = LookupSwitchScope();
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if (outer_switch == NULL) {
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return label;
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} else {
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outer_switch->AddLabel(label);
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}
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}
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}
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return NULL;
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}
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int LocalScope::NumCapturedVariables() const {
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// It is not necessary to traverse parent scopes, since we are only interested
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// in the captured variables referenced in this scope. If this scope
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// references a captured variable declared in a parent scope, it will contain
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// an alias for that variable.
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// Since code generation for nested functions is postponed until first
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// invocation, the function level of the closure scope can only be 1.
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ASSERT(function_level() == 1);
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int num_captured = 0;
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for (int i = 0; i < num_variables(); i++) {
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LocalVariable* variable = VariableAt(i);
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// Count the aliases of captured variables belonging to outer scopes.
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if (variable->owner()->function_level() != 1) {
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ASSERT(variable->is_captured());
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ASSERT(variable->owner()->function_level() == 0);
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num_captured++;
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}
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}
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return num_captured;
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}
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RawContextScope* LocalScope::PreserveOuterScope(int current_context_level)
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const {
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// Since code generation for nested functions is postponed until first
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// invocation, the function level of the closure scope can only be 1.
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ASSERT(function_level() == 1);
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// Count the number of referenced captured variables.
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intptr_t num_captured_vars = NumCapturedVariables();
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// Create a ContextScope with space for num_captured_vars descriptors.
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const ContextScope& context_scope =
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ContextScope::Handle(ContextScope::New(num_captured_vars));
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// Create a descriptor for each referenced captured variable of enclosing
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// functions to preserve its name and its context allocation information.
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int captured_idx = 0;
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for (int i = 0; i < num_variables(); i++) {
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LocalVariable* variable = VariableAt(i);
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// Preserve the aliases of captured variables belonging to outer scopes.
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if (variable->owner()->function_level() != 1) {
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context_scope.SetTokenIndexAt(captured_idx, variable->token_index());
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context_scope.SetNameAt(captured_idx, variable->name());
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context_scope.SetIsFinalAt(captured_idx, variable->is_final());
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context_scope.SetTypeAt(captured_idx, variable->type());
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context_scope.SetContextIndexAt(captured_idx, variable->index());
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// Adjust the context level relative to the current context level,
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// since the context of the current scope will be at level 0 when
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// compiling the nested function.
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int adjusted_context_level =
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variable->owner()->context_level() - current_context_level;
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context_scope.SetContextLevelAt(captured_idx, adjusted_context_level);
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captured_idx++;
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}
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}
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ASSERT(context_scope.num_variables() == captured_idx); // Verify count.
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return context_scope.raw();
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}
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LocalScope* LocalScope::RestoreOuterScope(const ContextScope& context_scope) {
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LocalScope* outer_scope = new LocalScope(NULL, 0, 0);
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// Add all variables as aliases to the outer scope.
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for (int i = 0; i < context_scope.num_variables(); i++) {
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LocalVariable* variable =
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new LocalVariable(context_scope.TokenIndexAt(i),
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String::ZoneHandle(context_scope.NameAt(i)),
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AbstractType::ZoneHandle(context_scope.TypeAt(i)));
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variable->set_is_captured();
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variable->set_index(context_scope.ContextIndexAt(i));
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if (context_scope.IsFinalAt(i)) {
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variable->set_is_final();
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}
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// Create a fake owner scope describing the index and context level of the
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// variable. Function level and loop level are unused (set to 0), since
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// context level has already been assigned.
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LocalScope* owner_scope = new LocalScope(NULL, 0, 0);
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owner_scope->set_context_level(context_scope.ContextLevelAt(i));
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owner_scope->AddVariable(variable);
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outer_scope->AddVariable(variable); // As alias.
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ASSERT(variable->owner() == owner_scope);
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}
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return outer_scope;
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}
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RawContextScope* LocalScope::CreateImplicitClosureScope(const Function& func) {
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static const intptr_t kNumCapturedVars = 1;
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// Create a ContextScope with space for kNumCapturedVars descriptors.
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const ContextScope& context_scope =
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ContextScope::Handle(ContextScope::New(kNumCapturedVars));
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// Create a descriptor for 'this' variable.
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const String& name = String::Handle(String::NewSymbol("this"));
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context_scope.SetTokenIndexAt(0, func.token_index());
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context_scope.SetNameAt(0, name);
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context_scope.SetIsFinalAt(0, true);
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const AbstractType& type = AbstractType::Handle(func.ParameterTypeAt(0));
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context_scope.SetTypeAt(0, type);
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context_scope.SetContextIndexAt(0, 0);
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context_scope.SetContextLevelAt(0, 0);
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ASSERT(context_scope.num_variables() == kNumCapturedVars); // Verify count.
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return context_scope.raw();
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}
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bool LocalVariable::Equals(const LocalVariable& other) const {
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if (HasIndex() && other.HasIndex() && (index() == other.index())) {
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if (is_captured() == other.is_captured()) {
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if (!is_captured()) {
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return true;
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}
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if (owner()->context_level() == other.owner()->context_level()) {
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return true;
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}
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}
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}
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return false;
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}
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} // namespace dart
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