1 // Copyright 2012 the V8 project authors. All rights reserved.
2 // Use of this source code is governed by a BSD-style license that can be
3 // found in the LICENSE file.
14 class CompilationInfo;
17 // A hash map to support fast variable declaration and lookup.
18 class VariableMap: public ZoneHashMap {
20 explicit VariableMap(Zone* zone);
22 virtual ~VariableMap();
24 Variable* Declare(Scope* scope, const AstRawString* name, VariableMode mode,
25 bool is_valid_lhs, Variable::Kind kind,
26 InitializationFlag initialization_flag,
27 MaybeAssignedFlag maybe_assigned_flag = kNotAssigned,
28 Interface* interface = Interface::NewValue());
30 Variable* Lookup(const AstRawString* name);
32 Zone* zone() const { return zone_; }
39 // The dynamic scope part holds hash maps for the variables that will
40 // be looked up dynamically from within eval and with scopes. The objects
41 // are allocated on-demand from Scope::NonLocal to avoid wasting memory
42 // and setup time for scopes that don't need them.
43 class DynamicScopePart : public ZoneObject {
45 explicit DynamicScopePart(Zone* zone) {
46 for (int i = 0; i < 3; i++)
47 maps_[i] = new(zone->New(sizeof(VariableMap))) VariableMap(zone);
50 VariableMap* GetMap(VariableMode mode) {
51 int index = mode - DYNAMIC;
52 DCHECK(index >= 0 && index < 3);
57 VariableMap *maps_[3];
61 // Global invariants after AST construction: Each reference (i.e. identifier)
62 // to a JavaScript variable (including global properties) is represented by a
63 // VariableProxy node. Immediately after AST construction and before variable
64 // allocation, most VariableProxy nodes are "unresolved", i.e. not bound to a
65 // corresponding variable (though some are bound during parse time). Variable
66 // allocation binds each unresolved VariableProxy to one Variable and assigns
67 // a location. Note that many VariableProxy nodes may refer to the same Java-
70 class Scope: public ZoneObject {
72 // ---------------------------------------------------------------------------
75 Scope(Scope* outer_scope, ScopeType scope_type,
76 AstValueFactory* value_factory, Zone* zone);
78 // Compute top scope and allocate variables. For lazy compilation the top
79 // scope only contains the single lazily compiled function, so this
80 // doesn't re-allocate variables repeatedly.
81 static bool Analyze(CompilationInfo* info);
83 static Scope* DeserializeScopeChain(Context* context, Scope* script_scope,
86 // The scope name is only used for printing/debugging.
87 void SetScopeName(const AstRawString* scope_name) {
88 scope_name_ = scope_name;
93 // Checks if the block scope is redundant, i.e. it does not contain any
94 // block scoped declarations. In that case it is removed from the scope
95 // tree and its children are reparented.
96 Scope* FinalizeBlockScope();
98 Zone* zone() const { return zone_; }
100 // ---------------------------------------------------------------------------
103 // Lookup a variable in this scope. Returns the variable or NULL if not found.
104 Variable* LookupLocal(const AstRawString* name);
106 // This lookup corresponds to a lookup in the "intermediate" scope sitting
107 // between this scope and the outer scope. (ECMA-262, 3rd., requires that
108 // the name of named function literal is kept in an intermediate scope
109 // in between this scope and the next outer scope.)
110 Variable* LookupFunctionVar(const AstRawString* name,
111 AstNodeFactory* factory);
113 // Lookup a variable in this scope or outer scopes.
114 // Returns the variable or NULL if not found.
115 Variable* Lookup(const AstRawString* name);
117 // Declare the function variable for a function literal. This variable
118 // is in an intermediate scope between this function scope and the the
119 // outer scope. Only possible for function scopes; at most one variable.
120 void DeclareFunctionVar(VariableDeclaration* declaration) {
121 DCHECK(is_function_scope());
122 function_ = declaration;
125 // Declare a parameter in this scope. When there are duplicated
126 // parameters the rightmost one 'wins'. However, the implementation
127 // expects all parameters to be declared and from left to right.
128 Variable* DeclareParameter(const AstRawString* name, VariableMode mode);
130 // Declare a local variable in this scope. If the variable has been
131 // declared before, the previously declared variable is returned.
132 Variable* DeclareLocal(const AstRawString* name, VariableMode mode,
133 InitializationFlag init_flag,
134 MaybeAssignedFlag maybe_assigned_flag = kNotAssigned,
135 Interface* interface = Interface::NewValue());
137 // Declare an implicit global variable in this scope which must be a
138 // script scope. The variable was introduced (possibly from an inner
139 // scope) by a reference to an unresolved variable with no intervening
140 // with statements or eval calls.
141 Variable* DeclareDynamicGlobal(const AstRawString* name);
143 // Create a new unresolved variable.
144 VariableProxy* NewUnresolved(AstNodeFactory* factory,
145 const AstRawString* name,
146 Interface* interface = Interface::NewValue(),
147 int position = RelocInfo::kNoPosition) {
148 // Note that we must not share the unresolved variables with
149 // the same name because they may be removed selectively via
150 // RemoveUnresolved().
151 DCHECK(!already_resolved());
152 VariableProxy* proxy =
153 factory->NewVariableProxy(name, false, interface, position);
154 unresolved_.Add(proxy, zone_);
158 // Remove a unresolved variable. During parsing, an unresolved variable
159 // may have been added optimistically, but then only the variable name
160 // was used (typically for labels). If the variable was not declared, the
161 // addition introduced a new unresolved variable which may end up being
162 // allocated globally as a "ghost" variable. RemoveUnresolved removes
163 // such a variable again if it was added; otherwise this is a no-op.
164 void RemoveUnresolved(VariableProxy* var);
166 // Creates a new internal variable in this scope. The name is only used
167 // for printing and cannot be used to find the variable. In particular,
168 // the only way to get hold of the temporary is by keeping the Variable*
170 Variable* NewInternal(const AstRawString* name);
172 // Creates a new temporary variable in this scope. The name is only used
173 // for printing and cannot be used to find the variable. In particular,
174 // the only way to get hold of the temporary is by keeping the Variable*
175 // around. The name should not clash with a legitimate variable names.
176 Variable* NewTemporary(const AstRawString* name);
178 // Adds the specific declaration node to the list of declarations in
179 // this scope. The declarations are processed as part of entering
180 // the scope; see codegen.cc:ProcessDeclarations.
181 void AddDeclaration(Declaration* declaration);
183 // ---------------------------------------------------------------------------
184 // Illegal redeclaration support.
186 // Set an expression node that will be executed when the scope is
187 // entered. We only keep track of one illegal redeclaration node per
188 // scope - the first one - so if you try to set it multiple times
189 // the additional requests will be silently ignored.
190 void SetIllegalRedeclaration(Expression* expression);
192 // Visit the illegal redeclaration expression. Do not call if the
193 // scope doesn't have an illegal redeclaration node.
194 void VisitIllegalRedeclaration(AstVisitor* visitor);
196 // Check if the scope has (at least) one illegal redeclaration.
197 bool HasIllegalRedeclaration() const { return illegal_redecl_ != NULL; }
199 // For harmony block scoping mode: Check if the scope has conflicting var
200 // declarations, i.e. a var declaration that has been hoisted from a nested
201 // scope over a let binding of the same name.
202 Declaration* CheckConflictingVarDeclarations();
204 // ---------------------------------------------------------------------------
205 // Scope-specific info.
207 // Inform the scope that the corresponding code contains a with statement.
208 void RecordWithStatement() { scope_contains_with_ = true; }
210 // Inform the scope that the corresponding code contains an eval call.
211 void RecordEvalCall() { if (!is_script_scope()) scope_calls_eval_ = true; }
213 // Inform the scope that the corresponding code uses "arguments".
214 void RecordArgumentsUsage() { scope_uses_arguments_ = true; }
216 // Inform the scope that the corresponding code uses "super".
217 void RecordSuperPropertyUsage() { scope_uses_super_property_ = true; }
219 // Inform the scope that the corresponding code invokes "super" constructor.
220 void RecordSuperConstructorCallUsage() {
221 scope_uses_super_constructor_call_ = true;
224 // Inform the scope that the corresponding code uses "this".
225 void RecordThisUsage() { scope_uses_this_ = true; }
227 // Set the strict mode flag (unless disabled by a global flag).
228 void SetStrictMode(StrictMode strict_mode) { strict_mode_ = strict_mode; }
230 // Set the ASM module flag.
231 void SetAsmModule() { asm_module_ = true; }
233 // Position in the source where this scope begins and ends.
235 // * For the scope of a with statement
237 // start position: start position of first token of 'stmt'
238 // end position: end position of last token of 'stmt'
239 // * For the scope of a block
241 // start position: start position of '{'
242 // end position: end position of '}'
243 // * For the scope of a function literal or decalaration
244 // function fun(a,b) { stmts }
245 // start position: start position of '('
246 // end position: end position of '}'
247 // * For the scope of a catch block
248 // try { stms } catch(e) { stmts }
249 // start position: start position of '('
250 // end position: end position of ')'
251 // * For the scope of a for-statement
252 // for (let x ...) stmt
253 // start position: start position of '('
254 // end position: end position of last token of 'stmt'
255 int start_position() const { return start_position_; }
256 void set_start_position(int statement_pos) {
257 start_position_ = statement_pos;
259 int end_position() const { return end_position_; }
260 void set_end_position(int statement_pos) {
261 end_position_ = statement_pos;
264 // In some cases we want to force context allocation for a whole scope.
265 void ForceContextAllocation() {
266 DCHECK(!already_resolved());
267 force_context_allocation_ = true;
269 bool has_forced_context_allocation() const {
270 return force_context_allocation_;
273 // ---------------------------------------------------------------------------
276 // Specific scope types.
277 bool is_eval_scope() const { return scope_type_ == EVAL_SCOPE; }
278 bool is_function_scope() const {
279 return scope_type_ == FUNCTION_SCOPE || scope_type_ == ARROW_SCOPE;
281 bool is_module_scope() const { return scope_type_ == MODULE_SCOPE; }
282 bool is_script_scope() const { return scope_type_ == SCRIPT_SCOPE; }
283 bool is_catch_scope() const { return scope_type_ == CATCH_SCOPE; }
284 bool is_block_scope() const { return scope_type_ == BLOCK_SCOPE; }
285 bool is_with_scope() const { return scope_type_ == WITH_SCOPE; }
286 bool is_arrow_scope() const { return scope_type_ == ARROW_SCOPE; }
287 bool is_declaration_scope() const {
288 return is_eval_scope() || is_function_scope() ||
289 is_module_scope() || is_script_scope();
291 bool is_strict_eval_scope() const {
292 return is_eval_scope() && strict_mode_ == STRICT;
295 // Information about which scopes calls eval.
296 bool calls_eval() const { return scope_calls_eval_; }
297 bool calls_sloppy_eval() {
298 return scope_calls_eval_ && strict_mode_ == SLOPPY;
300 bool outer_scope_calls_sloppy_eval() const {
301 return outer_scope_calls_sloppy_eval_;
303 bool asm_module() const { return asm_module_; }
304 bool asm_function() const { return asm_function_; }
306 // Is this scope inside a with statement.
307 bool inside_with() const { return scope_inside_with_; }
308 // Does this scope contain a with statement.
309 bool contains_with() const { return scope_contains_with_; }
311 // Does this scope access "arguments".
312 bool uses_arguments() const { return scope_uses_arguments_; }
313 // Does any inner scope access "arguments".
314 bool inner_uses_arguments() const { return inner_scope_uses_arguments_; }
315 // Does this scope access "super" property (super.foo).
316 bool uses_super_property() const { return scope_uses_super_property_; }
317 // Does any inner scope access "super" property.
318 bool inner_uses_super_property() const {
319 return inner_scope_uses_super_property_;
321 // Does this scope calls "super" constructor.
322 bool uses_super_constructor_call() const {
323 return scope_uses_super_constructor_call_;
325 // Does any inner scope calls "super" constructor.
326 bool inner_uses_super_constructor_call() const {
327 return inner_scope_uses_super_constructor_call_;
329 // Does this scope access "this".
330 bool uses_this() const { return scope_uses_this_; }
331 // Does any inner scope access "this".
332 bool inner_uses_this() const { return inner_scope_uses_this_; }
334 // ---------------------------------------------------------------------------
337 // The type of this scope.
338 ScopeType scope_type() const { return scope_type_; }
340 // The language mode of this scope.
341 StrictMode strict_mode() const { return strict_mode_; }
343 // The variable corresponding the 'this' value.
344 Variable* receiver() { return receiver_; }
346 // The variable holding the function literal for named function
347 // literals, or NULL. Only valid for function scopes.
348 VariableDeclaration* function() const {
349 DCHECK(is_function_scope());
353 // Parameters. The left-most parameter has index 0.
354 // Only valid for function scopes.
355 Variable* parameter(int index) const {
356 DCHECK(is_function_scope());
357 return params_[index];
360 int num_parameters() const { return params_.length(); }
362 // The local variable 'arguments' if we need to allocate it; NULL otherwise.
363 Variable* arguments() const { return arguments_; }
365 // Declarations list.
366 ZoneList<Declaration*>* declarations() { return &decls_; }
369 ZoneList<Scope*>* inner_scopes() { return &inner_scopes_; }
371 // The scope immediately surrounding this scope, or NULL.
372 Scope* outer_scope() const { return outer_scope_; }
374 // The interface as inferred so far; only for module scopes.
375 Interface* interface() const { return interface_; }
377 // ---------------------------------------------------------------------------
378 // Variable allocation.
380 // Collect stack and context allocated local variables in this scope. Note
381 // that the function variable - if present - is not collected and should be
382 // handled separately.
383 void CollectStackAndContextLocals(ZoneList<Variable*>* stack_locals,
384 ZoneList<Variable*>* context_locals);
386 // Current number of var or const locals.
387 int num_var_or_const() { return num_var_or_const_; }
389 // Result of variable allocation.
390 int num_stack_slots() const { return num_stack_slots_; }
391 int num_heap_slots() const { return num_heap_slots_; }
393 int StackLocalCount() const;
394 int ContextLocalCount() const;
396 // For script scopes, the number of module literals (including nested ones).
397 int num_modules() const { return num_modules_; }
399 // For module scopes, the host scope's internal variable binding this module.
400 Variable* module_var() const { return module_var_; }
402 // Make sure this scope and all outer scopes are eagerly compiled.
403 void ForceEagerCompilation() { force_eager_compilation_ = true; }
405 // Determine if we can use lazy compilation for this scope.
406 bool AllowsLazyCompilation() const;
408 // Determine if we can use lazy compilation for this scope without a context.
409 bool AllowsLazyCompilationWithoutContext() const;
411 // True if the outer context of this scope is always the native context.
412 bool HasTrivialOuterContext() const;
414 // True if the outer context allows lazy compilation of this scope.
415 bool HasLazyCompilableOuterContext() const;
417 // The number of contexts between this and scope; zero if this == scope.
418 int ContextChainLength(Scope* scope);
420 // Find the script scope.
421 // Used in modules implemenetation to find hosting scope.
422 // TODO(rossberg): is this needed?
423 Scope* ScriptScope();
425 // Find the first function, global, or eval scope. This is the scope
426 // where var declarations will be hoisted to in the implementation.
427 Scope* DeclarationScope();
429 Handle<ScopeInfo> GetScopeInfo();
431 // Get the chain of nested scopes within this scope for the source statement
432 // position. The scopes will be added to the list from the outermost scope to
433 // the innermost scope. Only nested block, catch or with scopes are tracked
434 // and will be returned, but no inner function scopes.
435 void GetNestedScopeChain(List<Handle<ScopeInfo> >* chain,
436 int statement_position);
438 // ---------------------------------------------------------------------------
439 // Strict mode support.
440 bool IsDeclared(const AstRawString* name) {
441 // During formal parameter list parsing the scope only contains
442 // two variables inserted at initialization: "this" and "arguments".
443 // "this" is an invalid parameter name and "arguments" is invalid parameter
444 // name in strict mode. Therefore looking up with the map which includes
445 // "this" and "arguments" in addition to all formal parameters is safe.
446 return variables_.Lookup(name) != NULL;
449 // ---------------------------------------------------------------------------
453 void Print(int n = 0); // n = indentation; n < 0 => don't print recursively
456 // ---------------------------------------------------------------------------
459 friend class ParserFactory;
461 Isolate* const isolate_;
464 Scope* outer_scope_; // the immediately enclosing outer scope, or NULL
465 ZoneList<Scope*> inner_scopes_; // the immediately enclosed inner scopes
468 ScopeType scope_type_;
470 // Debugging support.
471 const AstRawString* scope_name_;
473 // The variables declared in this scope:
475 // All user-declared variables (incl. parameters). For script scopes
476 // variables may be implicitly 'declared' by being used (possibly in
477 // an inner scope) with no intervening with statements or eval calls.
478 VariableMap variables_;
479 // Compiler-allocated (user-invisible) internals.
480 ZoneList<Variable*> internals_;
481 // Compiler-allocated (user-invisible) temporaries.
482 ZoneList<Variable*> temps_;
483 // Parameter list in source order.
484 ZoneList<Variable*> params_;
485 // Variables that must be looked up dynamically.
486 DynamicScopePart* dynamics_;
487 // Unresolved variables referred to from this scope.
488 ZoneList<VariableProxy*> unresolved_;
490 ZoneList<Declaration*> decls_;
491 // Convenience variable.
493 // Function variable, if any; function scopes only.
494 VariableDeclaration* function_;
495 // Convenience variable; function scopes only.
496 Variable* arguments_;
497 // Interface; module scopes only.
498 Interface* interface_;
500 // Illegal redeclaration.
501 Expression* illegal_redecl_;
503 // Scope-specific information computed during parsing.
505 // This scope is inside a 'with' of some outer scope.
506 bool scope_inside_with_;
507 // This scope contains a 'with' statement.
508 bool scope_contains_with_;
509 // This scope or a nested catch scope or with scope contain an 'eval' call. At
510 // the 'eval' call site this scope is the declaration scope.
511 bool scope_calls_eval_;
512 // This scope uses "arguments".
513 bool scope_uses_arguments_;
514 // This scope uses "super" property ('super.foo').
515 bool scope_uses_super_property_;
516 // This scope uses "super" constructor ('super(..)').
517 bool scope_uses_super_constructor_call_;
518 // This scope uses "this".
519 bool scope_uses_this_;
520 // This scope contains an "use asm" annotation.
522 // This scope's outer context is an asm module.
524 // The strict mode of this scope.
525 StrictMode strict_mode_;
530 // Computed via PropagateScopeInfo.
531 bool outer_scope_calls_sloppy_eval_;
532 bool inner_scope_calls_eval_;
533 bool inner_scope_uses_arguments_;
534 bool inner_scope_uses_super_property_;
535 bool inner_scope_uses_super_constructor_call_;
536 bool inner_scope_uses_this_;
537 bool force_eager_compilation_;
538 bool force_context_allocation_;
540 // True if it doesn't need scope resolution (e.g., if the scope was
541 // constructed based on a serialized scope info or a catch context).
542 bool already_resolved_;
544 // Computed as variables are declared.
545 int num_var_or_const_;
547 // Computed via AllocateVariables; function, block and catch scopes only.
548 int num_stack_slots_;
551 // The number of modules (including nested ones).
554 // For module scopes, the host scope's internal variable binding this module.
555 Variable* module_var_;
557 // Serialized scope info support.
558 Handle<ScopeInfo> scope_info_;
559 bool already_resolved() { return already_resolved_; }
561 // Create a non-local variable with a given name.
562 // These variables are looked up dynamically at runtime.
563 Variable* NonLocal(const AstRawString* name, VariableMode mode);
565 // Variable resolution.
566 // Possible results of a recursive variable lookup telling if and how a
567 // variable is bound. These are returned in the output parameter *binding_kind
568 // of the LookupRecursive function.
570 // The variable reference could be statically resolved to a variable binding
571 // which is returned. There is no 'with' statement between the reference and
572 // the binding and no scope between the reference scope (inclusive) and
573 // binding scope (exclusive) makes a sloppy 'eval' call.
576 // The variable reference could be statically resolved to a variable binding
577 // which is returned. There is no 'with' statement between the reference and
578 // the binding, but some scope between the reference scope (inclusive) and
579 // binding scope (exclusive) makes a sloppy 'eval' call, that might
580 // possibly introduce variable bindings shadowing the found one. Thus the
581 // found variable binding is just a guess.
584 // The variable reference could not be statically resolved to any binding
585 // and thus should be considered referencing a global variable. NULL is
586 // returned. The variable reference is not inside any 'with' statement and
587 // no scope between the reference scope (inclusive) and script scope
588 // (exclusive) makes a sloppy 'eval' call.
591 // The variable reference could not be statically resolved to any binding
592 // NULL is returned. The variable reference is not inside any 'with'
593 // statement, but some scope between the reference scope (inclusive) and
594 // script scope (exclusive) makes a sloppy 'eval' call, that might
595 // possibly introduce a variable binding. Thus the reference should be
596 // considered referencing a global variable unless it is shadowed by an
597 // 'eval' introduced binding.
598 UNBOUND_EVAL_SHADOWED,
600 // The variable could not be statically resolved and needs to be looked up
601 // dynamically. NULL is returned. There are two possible reasons:
602 // * A 'with' statement has been encountered and there is no variable
603 // binding for the name between the variable reference and the 'with'.
604 // The variable potentially references a property of the 'with' object.
605 // * The code is being executed as part of a call to 'eval' and the calling
606 // context chain contains either a variable binding for the name or it
607 // contains a 'with' context.
611 // Lookup a variable reference given by name recursively starting with this
612 // scope. If the code is executed because of a call to 'eval', the context
613 // parameter should be set to the calling context of 'eval'.
614 Variable* LookupRecursive(VariableProxy* proxy, BindingKind* binding_kind,
615 AstNodeFactory* factory);
617 bool ResolveVariable(CompilationInfo* info, VariableProxy* proxy,
618 AstNodeFactory* factory);
620 bool ResolveVariablesRecursively(CompilationInfo* info,
621 AstNodeFactory* factory);
624 void PropagateScopeInfo(bool outer_scope_calls_sloppy_eval);
625 bool HasTrivialContext() const;
628 bool MustAllocate(Variable* var);
629 bool MustAllocateInContext(Variable* var);
630 bool HasArgumentsParameter();
632 // Variable allocation.
633 void AllocateStackSlot(Variable* var);
634 void AllocateHeapSlot(Variable* var);
635 void AllocateParameterLocals();
636 void AllocateNonParameterLocal(Variable* var);
637 void AllocateNonParameterLocals();
638 void AllocateVariablesRecursively();
639 void AllocateModulesRecursively(Scope* host_scope);
641 // Resolve and fill in the allocation information for all variables
642 // in this scopes. Must be called *after* all scopes have been
643 // processed (parsed) to ensure that unresolved variables can be
644 // resolved properly.
646 // In the case of code compiled and run using 'eval', the context
647 // parameter is the context in which eval was called. In all other
648 // cases the context parameter is an empty handle.
650 bool AllocateVariables(CompilationInfo* info, AstNodeFactory* factory);
653 // Construct a scope based on the scope info.
654 Scope(Scope* inner_scope, ScopeType type, Handle<ScopeInfo> scope_info,
655 AstValueFactory* value_factory, Zone* zone);
657 // Construct a catch scope with a binding for the name.
658 Scope(Scope* inner_scope,
659 const AstRawString* catch_variable_name,
660 AstValueFactory* value_factory, Zone* zone);
662 void AddInnerScope(Scope* inner_scope) {
663 if (inner_scope != NULL) {
664 inner_scopes_.Add(inner_scope, zone_);
665 inner_scope->outer_scope_ = this;
669 void SetDefaults(ScopeType type,
671 Handle<ScopeInfo> scope_info);
673 AstValueFactory* ast_value_factory_;
677 } } // namespace v8::internal
679 #endif // V8_SCOPES_H_