Introduce with scope and rework variable resolution.

src/scopes.h

 // Copyright 2011 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 76 matching lines @@
 class Scope: public ZoneObject {
  public:
   // ---------------------------------------------------------------------------
   // Construction
 
   enum Type {
     EVAL_SCOPE,      // The top-level scope for an eval source.
     FUNCTION_SCOPE,  // The top-level scope for a function.
     GLOBAL_SCOPE,    // The top-level scope for a program or a top-level eval.
     CATCH_SCOPE,     // The scope introduced by catch.
-    BLOCK_SCOPE      // The scope introduced by a new block.
+    BLOCK_SCOPE,     // The scope introduced by a new block.
+    WITH_SCOPE       // The scope introduced by with.
   };
 
   Scope(Scope* outer_scope, Type type);
 
   // Compute top scope and allocate variables. For lazy compilation the top
   // scope only contains the single lazily compiled function, so this
   // doesn't re-allocate variables repeatedly.
   static bool Analyze(CompilationInfo* info);
 
   static Scope* DeserializeScopeChain(CompilationInfo* info,
                                       Scope* innermost_scope);
 
   // The scope name is only used for printing/debugging.
   void SetScopeName(Handle<String> scope_name) { scope_name_ = scope_name; }
 
-  void Initialize(bool inside_with);
+  void Initialize();
 
   // Checks if the block scope is redundant, i.e. it does not contain any
   // block scoped declarations. In that case it is removed from the scope
   // tree and its children are reparented.
   Scope* FinalizeBlockScope();
 
   // ---------------------------------------------------------------------------
   // Declarations
 
   // Lookup a variable in this scope. Returns the variable or NULL if not found.
@@ skipping 18 matching lines @@
   Variable* DeclareLocal(Handle<String> name, Variable::Mode mode);
 
   // Declare an implicit global variable in this scope which must be a
   // global scope.  The variable was introduced (possibly from an inner
   // scope) by a reference to an unresolved variable with no intervening
   // with statements or eval calls.
   Variable* DeclareGlobal(Handle<String> name);
 
   // Create a new unresolved variable.
   VariableProxy* NewUnresolved(Handle<String> name,
-                               bool inside_with,
                                int position = RelocInfo::kNoPosition);
 
   // Remove a unresolved variable. During parsing, an unresolved variable
   // may have been added optimistically, but then only the variable name
   // was used (typically for labels). If the variable was not declared, the
   // addition introduced a new unresolved variable which may end up being
   // allocated globally as a "ghost" variable. RemoveUnresolved removes
   // such a variable again if it was added; otherwise this is a no-op.
   void RemoveUnresolved(VariableProxy* var);
 
@@ skipping 29 matching lines @@
   // scope over a let binding of the same name.
   Declaration* CheckConflictingVarDeclarations();
 
   // ---------------------------------------------------------------------------
   // Scope-specific info.
 
   // Inform the scope that the corresponding code contains a with statement.
   void RecordWithStatement() { scope_contains_with_ = true; }
 
   // Inform the scope that the corresponding code contains an eval call.
-  void RecordEvalCall() { scope_calls_eval_ = true; }
+  void RecordEvalCall() { if (!is_global_scope()) scope_calls_eval_ = true; }
 
   // Enable strict mode for the scope (unless disabled by a global flag).
   void EnableStrictMode() {
     strict_mode_ = FLAG_strict_mode;
   }
 
   // ---------------------------------------------------------------------------
   // Predicates.
 
   // Specific scope types.
   bool is_eval_scope() const { return type_ == EVAL_SCOPE; }
   bool is_function_scope() const { return type_ == FUNCTION_SCOPE; }
   bool is_global_scope() const { return type_ == GLOBAL_SCOPE; }
   bool is_catch_scope() const { return type_ == CATCH_SCOPE; }
   bool is_block_scope() const { return type_ == BLOCK_SCOPE; }
+  bool is_with_scope() const { return type_ == WITH_SCOPE; }
+  bool is_declaration_scope() const {
+    return is_eval_scope() || is_function_scope() || is_global_scope();
+  }
   bool is_strict_mode() const { return strict_mode_; }
   bool is_strict_mode_eval_scope() const {
     return is_eval_scope() && is_strict_mode();
   }
 
   // Information about which scopes calls eval.
   bool calls_eval() const { return scope_calls_eval_; }
-  bool outer_scope_calls_eval() const { return outer_scope_calls_eval_; }
+  bool calls_non_strict_eval() {
+    return scope_calls_eval_ && !is_strict_mode();
+  }
   bool outer_scope_calls_non_strict_eval() const {
     return outer_scope_calls_non_strict_eval_;
   }
 
   // Is this scope inside a with statement.
   bool inside_with() const { return scope_inside_with_; }
   // Does this scope contain a with statement.
   bool contains_with() const { return scope_contains_with_; }
 
   // The scope immediately surrounding this scope, or NULL.
@@ skipping 140 matching lines @@
   bool scope_inside_with_;
   // This scope contains a 'with' statement.
   bool scope_contains_with_;
   // This scope or a nested catch scope or with scope contain an 'eval' call. At
   // the 'eval' call site this scope is the declaration scope.
   bool scope_calls_eval_;
   // This scope is a strict mode scope.
   bool strict_mode_;
 
   // Computed via PropagateScopeInfo.
-  bool outer_scope_calls_eval_;
   bool outer_scope_calls_non_strict_eval_;
   bool inner_scope_calls_eval_;
-  bool outer_scope_is_eval_scope_;
   bool force_eager_compilation_;
 
   // True if it doesn't need scope resolution (e.g., if the scope was
   // constructed based on a serialized scope info or a catch context).
   bool already_resolved_;
 
   // Computed as variables are declared.
   int num_var_or_const_;
 
-  // Computed via AllocateVariables; function scopes only.
+  // Computed via AllocateVariables; function, block and catch scopes only.
   int num_stack_slots_;
   int num_heap_slots_;
 
   // Serialized scopes support.
   Handle<SerializedScopeInfo> scope_info_;
   bool already_resolved() { return already_resolved_; }
 
   // Create a non-local variable with a given name.
   // These variables are looked up dynamically at runtime.
   Variable* NonLocal(Handle<String> name, Variable::Mode mode);
 
   // Variable resolution.
-  Variable* LookupRecursive(Handle<String> name,
-                            bool from_inner_function,
-                            Variable** invalidated_local);
+  // Possible results of a recursive variable lookup.
+  enum LookupResult {

[Kevin Millikin (Chromium), 2011/09/16 12:58:19]

This sounds like a silly request, but: we already have a type LookupResult (for
property lookups) that's used extensively.  Since C++ tools generally stink, it
might be easiest to choose some different name so it's easy to find each of
them.

BindingKind?  Something else?

[Steven, 2011/09/16 18:29:52]

Used BindingKind for lack of a better name.
On 2011/09/16 12:58:19, Kevin Millikin wrote:

+    // The variable reference could be statically resolved to a variable
+    // binding which is return in the output parameter *var. There is no
+    // 'with' statement between the reference and the binding and no scope
+    // between the reference scope (inclusive) and binding scope (exclusive)
+    // makes a non-strict 'eval' call.
+    BOUND,
+
+    // The variable reference could be statically resolved to a variable
+    // binding which is return in the output parameter *var. There is no
+    // 'with' statement between the reference and the binding, but some scope
+    // between the reference scope (inclusive) and binding scope (exclusive)
+    // makes a non-strict 'eval' call, that might possibly introduce variable
+    // bindings shadowing the found one. Thus the found variable binding is
+    // just a guess.
+    BOUND_EVAL_SHADOWED,
+
+    // The variable reference could not be statically resolved to any binding
+    // and thus should be considered referencing a global variable. No variable
+    // binding is returned in the output parameter *var. The variable reference
+    // is not inside any 'with' statement and no scope between the reference
+    // scope (inclusive) and global scope (exclusive) makes a non-strict 'eval'
+    // call.
+    UNBOUND,
+
+    // The variable reference could not be statically resolved to any binding.
+    // No variable binding is returned in the output parameter *var. The
+    // variable reference is not inside any 'with' statement, but some scope
+    // between the reference scope (inclusive) and global scope (exclusive)
+    // makes a non-strict 'eval' call, that might possibly introduce a variable
+    // binding. Thus the reference should be considered referencing a global
+    // variable unless it is shadowed by an 'eval' introduced binding.
+    UNBOUND_EVAL_SHADOWED,
+
+    // The variable could not be statically resolved and needs to be looked up
+    // dynamically. There are two possible reasons:
+    // * A 'with' statement has been encountered and there is no variable
+    //   binding for the name between the variable reference and the 'with'.
+    //   The variable potentially references a property of the 'with' object.
+    // * The code is being executed as part of a call to 'eval' and the calling
+    //   context chain contains either a variable binding for the name or it
+    //   contains a 'with' context.
+    DYNAMIC_LOOKUP
+  };
+
+  // Lookup a variable reference given by name recursively starting with this
+  // scope. If the code is executed because of a call to 'eval', the context
+  // parameter should be set to the calling context of 'eval'.
+  LookupResult LookupRecursive(Handle<String> name,
+                               Handle<Context> context,
+                               Variable** var);
   void ResolveVariable(Scope* global_scope,
                        Handle<Context> context,
                        VariableProxy* proxy);
   void ResolveVariablesRecursively(Scope* global_scope,
                                    Handle<Context> context);
 
   // Scope analysis.
-  bool PropagateScopeInfo(bool outer_scope_calls_eval,
-                          bool outer_scope_calls_non_strict_eval,
-                          bool outer_scope_is_eval_scope);
+  bool PropagateScopeInfo(bool outer_scope_calls_non_strict_eval);
   bool HasTrivialContext() const;
 
   // Predicates.
   bool MustAllocate(Variable* var);
   bool MustAllocateInContext(Variable* var);
   bool HasArgumentsParameter();
 
   // Variable allocation.
   void AllocateStackSlot(Variable* var);
   void AllocateHeapSlot(Variable* var);
   void AllocateParameterLocals();
   void AllocateNonParameterLocal(Variable* var);
   void AllocateNonParameterLocals();
   void AllocateVariablesRecursively();
 
  private:
-  // Construct a function or block scope based on the scope info.
+  // Construct a scope based on the scope info.
   Scope(Scope* inner_scope, Type type, Handle<SerializedScopeInfo> scope_info);
 
   // Construct a catch scope with a binding for the name.
   Scope(Scope* inner_scope, Handle<String> catch_variable_name);
 
   void AddInnerScope(Scope* inner_scope) {
     if (inner_scope != NULL) {
       inner_scopes_.Add(inner_scope);
       inner_scope->outer_scope_ = this;
     }
   }
 
   void SetDefaults(Type type,
                    Scope* outer_scope,
                    Handle<SerializedScopeInfo> scope_info);
 };
 
 } }  // namespace v8::internal
 
 #endif  // V8_SCOPES_H_