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* global_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<AstNullVisitor>* 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 // global 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 template<class Visitor>
145 VariableProxy* NewUnresolved(AstNodeFactory<Visitor>* factory,
146 const AstRawString* name,
147 Interface* interface = Interface::NewValue(),
148 int position = RelocInfo::kNoPosition) {
149 // Note that we must not share the unresolved variables with
150 // the same name because they may be removed selectively via
151 // RemoveUnresolved().
152 DCHECK(!already_resolved());
153 VariableProxy* proxy =
154 factory->NewVariableProxy(name, false, interface, position);
155 unresolved_.Add(proxy, zone_);
159 // Remove a unresolved variable. During parsing, an unresolved variable
160 // may have been added optimistically, but then only the variable name
161 // was used (typically for labels). If the variable was not declared, the
162 // addition introduced a new unresolved variable which may end up being
163 // allocated globally as a "ghost" variable. RemoveUnresolved removes
164 // such a variable again if it was added; otherwise this is a no-op.
165 void RemoveUnresolved(VariableProxy* var);
167 // Creates a new internal variable in this scope. The name is only used
168 // for printing and cannot be used to find the variable. In particular,
169 // the only way to get hold of the temporary is by keeping the Variable*
171 Variable* NewInternal(const AstRawString* name);
173 // Creates a new temporary variable in this scope. The name is only used
174 // for printing and cannot be used to find the variable. In particular,
175 // the only way to get hold of the temporary is by keeping the Variable*
176 // around. The name should not clash with a legitimate variable names.
177 Variable* NewTemporary(const AstRawString* name);
179 // Adds the specific declaration node to the list of declarations in
180 // this scope. The declarations are processed as part of entering
181 // the scope; see codegen.cc:ProcessDeclarations.
182 void AddDeclaration(Declaration* declaration);
184 // ---------------------------------------------------------------------------
185 // Illegal redeclaration support.
187 // Set an expression node that will be executed when the scope is
188 // entered. We only keep track of one illegal redeclaration node per
189 // scope - the first one - so if you try to set it multiple times
190 // the additional requests will be silently ignored.
191 void SetIllegalRedeclaration(Expression* expression);
193 // Visit the illegal redeclaration expression. Do not call if the
194 // scope doesn't have an illegal redeclaration node.
195 void VisitIllegalRedeclaration(AstVisitor* visitor);
197 // Check if the scope has (at least) one illegal redeclaration.
198 bool HasIllegalRedeclaration() const { return illegal_redecl_ != NULL; }
200 // For harmony block scoping mode: Check if the scope has conflicting var
201 // declarations, i.e. a var declaration that has been hoisted from a nested
202 // scope over a let binding of the same name.
203 Declaration* CheckConflictingVarDeclarations();
205 // ---------------------------------------------------------------------------
206 // Scope-specific info.
208 // Inform the scope that the corresponding code contains a with statement.
209 void RecordWithStatement() { scope_contains_with_ = true; }
211 // Inform the scope that the corresponding code contains an eval call.
212 void RecordEvalCall() { if (!is_global_scope()) scope_calls_eval_ = true; }
214 // Set the strict mode flag (unless disabled by a global flag).
215 void SetStrictMode(StrictMode strict_mode) { strict_mode_ = strict_mode; }
217 // Position in the source where this scope begins and ends.
219 // * For the scope of a with statement
221 // start position: start position of first token of 'stmt'
222 // end position: end position of last token of 'stmt'
223 // * For the scope of a block
225 // start position: start position of '{'
226 // end position: end position of '}'
227 // * For the scope of a function literal or decalaration
228 // function fun(a,b) { stmts }
229 // start position: start position of '('
230 // end position: end position of '}'
231 // * For the scope of a catch block
232 // try { stms } catch(e) { stmts }
233 // start position: start position of '('
234 // end position: end position of ')'
235 // * For the scope of a for-statement
236 // for (let x ...) stmt
237 // start position: start position of '('
238 // end position: end position of last token of 'stmt'
239 int start_position() const { return start_position_; }
240 void set_start_position(int statement_pos) {
241 start_position_ = statement_pos;
243 int end_position() const { return end_position_; }
244 void set_end_position(int statement_pos) {
245 end_position_ = statement_pos;
248 // In some cases we want to force context allocation for a whole scope.
249 void ForceContextAllocation() {
250 DCHECK(!already_resolved());
251 force_context_allocation_ = true;
253 bool has_forced_context_allocation() const {
254 return force_context_allocation_;
257 // ---------------------------------------------------------------------------
260 // Specific scope types.
261 bool is_eval_scope() const { return scope_type_ == EVAL_SCOPE; }
262 bool is_function_scope() const { return scope_type_ == FUNCTION_SCOPE; }
263 bool is_module_scope() const { return scope_type_ == MODULE_SCOPE; }
264 bool is_global_scope() const { return scope_type_ == GLOBAL_SCOPE; }
265 bool is_catch_scope() const { return scope_type_ == CATCH_SCOPE; }
266 bool is_block_scope() const { return scope_type_ == BLOCK_SCOPE; }
267 bool is_with_scope() const { return scope_type_ == WITH_SCOPE; }
268 bool is_declaration_scope() const {
269 return is_eval_scope() || is_function_scope() ||
270 is_module_scope() || is_global_scope();
272 bool is_strict_eval_scope() const {
273 return is_eval_scope() && strict_mode_ == STRICT;
276 // Information about which scopes calls eval.
277 bool calls_eval() const { return scope_calls_eval_; }
278 bool calls_sloppy_eval() {
279 return scope_calls_eval_ && strict_mode_ == SLOPPY;
281 bool outer_scope_calls_sloppy_eval() const {
282 return outer_scope_calls_sloppy_eval_;
285 // Is this scope inside a with statement.
286 bool inside_with() const { return scope_inside_with_; }
287 // Does this scope contain a with statement.
288 bool contains_with() const { return scope_contains_with_; }
290 // ---------------------------------------------------------------------------
293 // The type of this scope.
294 ScopeType scope_type() const { return scope_type_; }
296 // The language mode of this scope.
297 StrictMode strict_mode() const { return strict_mode_; }
299 // The variable corresponding the 'this' value.
300 Variable* receiver() { return receiver_; }
302 // The variable holding the function literal for named function
303 // literals, or NULL. Only valid for function scopes.
304 VariableDeclaration* function() const {
305 DCHECK(is_function_scope());
309 // Parameters. The left-most parameter has index 0.
310 // Only valid for function scopes.
311 Variable* parameter(int index) const {
312 DCHECK(is_function_scope());
313 return params_[index];
316 int num_parameters() const { return params_.length(); }
318 // The local variable 'arguments' if we need to allocate it; NULL otherwise.
319 Variable* arguments() const { return arguments_; }
321 // Declarations list.
322 ZoneList<Declaration*>* declarations() { return &decls_; }
325 ZoneList<Scope*>* inner_scopes() { return &inner_scopes_; }
327 // The scope immediately surrounding this scope, or NULL.
328 Scope* outer_scope() const { return outer_scope_; }
330 // The interface as inferred so far; only for module scopes.
331 Interface* interface() const { return interface_; }
333 // ---------------------------------------------------------------------------
334 // Variable allocation.
336 // Collect stack and context allocated local variables in this scope. Note
337 // that the function variable - if present - is not collected and should be
338 // handled separately.
339 void CollectStackAndContextLocals(ZoneList<Variable*>* stack_locals,
340 ZoneList<Variable*>* context_locals);
342 // Current number of var or const locals.
343 int num_var_or_const() { return num_var_or_const_; }
345 // Result of variable allocation.
346 int num_stack_slots() const { return num_stack_slots_; }
347 int num_heap_slots() const { return num_heap_slots_; }
349 int StackLocalCount() const;
350 int ContextLocalCount() const;
352 // For global scopes, the number of module literals (including nested ones).
353 int num_modules() const { return num_modules_; }
355 // For module scopes, the host scope's internal variable binding this module.
356 Variable* module_var() const { return module_var_; }
358 // Make sure this scope and all outer scopes are eagerly compiled.
359 void ForceEagerCompilation() { force_eager_compilation_ = true; }
361 // Determine if we can use lazy compilation for this scope.
362 bool AllowsLazyCompilation() const;
364 // Determine if we can use lazy compilation for this scope without a context.
365 bool AllowsLazyCompilationWithoutContext() const;
367 // True if the outer context of this scope is always the native context.
368 bool HasTrivialOuterContext() const;
370 // True if the outer context allows lazy compilation of this scope.
371 bool HasLazyCompilableOuterContext() const;
373 // The number of contexts between this and scope; zero if this == scope.
374 int ContextChainLength(Scope* scope);
376 // Find the innermost global scope.
377 Scope* GlobalScope();
379 // Find the first function, global, or eval scope. This is the scope
380 // where var declarations will be hoisted to in the implementation.
381 Scope* DeclarationScope();
383 Handle<ScopeInfo> GetScopeInfo();
385 // Get the chain of nested scopes within this scope for the source statement
386 // position. The scopes will be added to the list from the outermost scope to
387 // the innermost scope. Only nested block, catch or with scopes are tracked
388 // and will be returned, but no inner function scopes.
389 void GetNestedScopeChain(List<Handle<ScopeInfo> >* chain,
390 int statement_position);
392 // ---------------------------------------------------------------------------
393 // Strict mode support.
394 bool IsDeclared(const AstRawString* name) {
395 // During formal parameter list parsing the scope only contains
396 // two variables inserted at initialization: "this" and "arguments".
397 // "this" is an invalid parameter name and "arguments" is invalid parameter
398 // name in strict mode. Therefore looking up with the map which includes
399 // "this" and "arguments" in addition to all formal parameters is safe.
400 return variables_.Lookup(name) != NULL;
403 // ---------------------------------------------------------------------------
407 void Print(int n = 0); // n = indentation; n < 0 => don't print recursively
410 // ---------------------------------------------------------------------------
413 friend class ParserFactory;
415 Isolate* const isolate_;
418 Scope* outer_scope_; // the immediately enclosing outer scope, or NULL
419 ZoneList<Scope*> inner_scopes_; // the immediately enclosed inner scopes
422 ScopeType scope_type_;
424 // Debugging support.
425 const AstRawString* scope_name_;
427 // The variables declared in this scope:
429 // All user-declared variables (incl. parameters). For global scopes
430 // variables may be implicitly 'declared' by being used (possibly in
431 // an inner scope) with no intervening with statements or eval calls.
432 VariableMap variables_;
433 // Compiler-allocated (user-invisible) internals.
434 ZoneList<Variable*> internals_;
435 // Compiler-allocated (user-invisible) temporaries.
436 ZoneList<Variable*> temps_;
437 // Parameter list in source order.
438 ZoneList<Variable*> params_;
439 // Variables that must be looked up dynamically.
440 DynamicScopePart* dynamics_;
441 // Unresolved variables referred to from this scope.
442 ZoneList<VariableProxy*> unresolved_;
444 ZoneList<Declaration*> decls_;
445 // Convenience variable.
447 // Function variable, if any; function scopes only.
448 VariableDeclaration* function_;
449 // Convenience variable; function scopes only.
450 Variable* arguments_;
451 // Interface; module scopes only.
452 Interface* interface_;
454 // Illegal redeclaration.
455 Expression* illegal_redecl_;
457 // Scope-specific information computed during parsing.
459 // This scope is inside a 'with' of some outer scope.
460 bool scope_inside_with_;
461 // This scope contains a 'with' statement.
462 bool scope_contains_with_;
463 // This scope or a nested catch scope or with scope contain an 'eval' call. At
464 // the 'eval' call site this scope is the declaration scope.
465 bool scope_calls_eval_;
466 // The strict mode of this scope.
467 StrictMode strict_mode_;
472 // Computed via PropagateScopeInfo.
473 bool outer_scope_calls_sloppy_eval_;
474 bool inner_scope_calls_eval_;
475 bool force_eager_compilation_;
476 bool force_context_allocation_;
478 // True if it doesn't need scope resolution (e.g., if the scope was
479 // constructed based on a serialized scope info or a catch context).
480 bool already_resolved_;
482 // Computed as variables are declared.
483 int num_var_or_const_;
485 // Computed via AllocateVariables; function, block and catch scopes only.
486 int num_stack_slots_;
489 // The number of modules (including nested ones).
492 // For module scopes, the host scope's internal variable binding this module.
493 Variable* module_var_;
495 // Serialized scope info support.
496 Handle<ScopeInfo> scope_info_;
497 bool already_resolved() { return already_resolved_; }
499 // Create a non-local variable with a given name.
500 // These variables are looked up dynamically at runtime.
501 Variable* NonLocal(const AstRawString* name, VariableMode mode);
503 // Variable resolution.
504 // Possible results of a recursive variable lookup telling if and how a
505 // variable is bound. These are returned in the output parameter *binding_kind
506 // of the LookupRecursive function.
508 // The variable reference could be statically resolved to a variable binding
509 // which is returned. There is no 'with' statement between the reference and
510 // the binding and no scope between the reference scope (inclusive) and
511 // binding scope (exclusive) makes a sloppy 'eval' call.
514 // The variable reference could be statically resolved to a variable binding
515 // which is returned. There is no 'with' statement between the reference and
516 // the binding, but some scope between the reference scope (inclusive) and
517 // binding scope (exclusive) makes a sloppy 'eval' call, that might
518 // possibly introduce variable bindings shadowing the found one. Thus the
519 // found variable binding is just a guess.
522 // The variable reference could not be statically resolved to any binding
523 // and thus should be considered referencing a global variable. NULL is
524 // returned. The variable reference is not inside any 'with' statement and
525 // no scope between the reference scope (inclusive) and global scope
526 // (exclusive) makes a sloppy 'eval' call.
529 // The variable reference could not be statically resolved to any binding
530 // NULL is returned. The variable reference is not inside any 'with'
531 // statement, but some scope between the reference scope (inclusive) and
532 // global scope (exclusive) makes a sloppy 'eval' call, that might
533 // possibly introduce a variable binding. Thus the reference should be
534 // considered referencing a global variable unless it is shadowed by an
535 // 'eval' introduced binding.
536 UNBOUND_EVAL_SHADOWED,
538 // The variable could not be statically resolved and needs to be looked up
539 // dynamically. NULL is returned. There are two possible reasons:
540 // * A 'with' statement has been encountered and there is no variable
541 // binding for the name between the variable reference and the 'with'.
542 // The variable potentially references a property of the 'with' object.
543 // * The code is being executed as part of a call to 'eval' and the calling
544 // context chain contains either a variable binding for the name or it
545 // contains a 'with' context.
549 // Lookup a variable reference given by name recursively starting with this
550 // scope. If the code is executed because of a call to 'eval', the context
551 // parameter should be set to the calling context of 'eval'.
552 Variable* LookupRecursive(VariableProxy* proxy,
553 BindingKind* binding_kind,
554 AstNodeFactory<AstNullVisitor>* factory);
556 bool ResolveVariable(CompilationInfo* info,
557 VariableProxy* proxy,
558 AstNodeFactory<AstNullVisitor>* factory);
560 bool ResolveVariablesRecursively(CompilationInfo* info,
561 AstNodeFactory<AstNullVisitor>* factory);
564 void PropagateScopeInfo(bool outer_scope_calls_sloppy_eval);
565 bool HasTrivialContext() const;
568 bool MustAllocate(Variable* var);
569 bool MustAllocateInContext(Variable* var);
570 bool HasArgumentsParameter();
572 // Variable allocation.
573 void AllocateStackSlot(Variable* var);
574 void AllocateHeapSlot(Variable* var);
575 void AllocateParameterLocals();
576 void AllocateNonParameterLocal(Variable* var);
577 void AllocateNonParameterLocals();
578 void AllocateVariablesRecursively();
579 void AllocateModulesRecursively(Scope* host_scope);
581 // Resolve and fill in the allocation information for all variables
582 // in this scopes. Must be called *after* all scopes have been
583 // processed (parsed) to ensure that unresolved variables can be
584 // resolved properly.
586 // In the case of code compiled and run using 'eval', the context
587 // parameter is the context in which eval was called. In all other
588 // cases the context parameter is an empty handle.
590 bool AllocateVariables(CompilationInfo* info,
591 AstNodeFactory<AstNullVisitor>* factory);
594 // Construct a scope based on the scope info.
595 Scope(Scope* inner_scope, ScopeType type, Handle<ScopeInfo> scope_info,
596 AstValueFactory* value_factory, Zone* zone);
598 // Construct a catch scope with a binding for the name.
599 Scope(Scope* inner_scope,
600 const AstRawString* catch_variable_name,
601 AstValueFactory* value_factory, Zone* zone);
603 void AddInnerScope(Scope* inner_scope) {
604 if (inner_scope != NULL) {
605 inner_scopes_.Add(inner_scope, zone_);
606 inner_scope->outer_scope_ = this;
610 void SetDefaults(ScopeType type,
612 Handle<ScopeInfo> scope_info);
614 AstValueFactory* ast_value_factory_;
618 } } // namespace v8::internal
620 #endif // V8_SCOPES_H_