Early draft of strict mode

src/parser.cc

 // Copyright 2010 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 265 matching lines @@
   Handle<FixedArray> this_property_assignments() {
     return this_property_assignments_;
   }
 
   void AddProperty() { expected_property_count_++; }
   int expected_property_count() { return expected_property_count_; }
 
   void AddLoop() { loop_count_++; }
   bool ContainsLoops() const { return loop_count_ > 0; }
 
+  bool StrictMode() { return strict_mode_; }
+  void EnableStrictMode() {
+    strict_mode_ = FLAG_strict_mode;
+  }
+
  private:
   // Captures the number of literals that need materialization in the
   // function.  Includes regexp literals, and boilerplate for object
   // and array literals.
   int materialized_literal_count_;
 
   // Properties count estimation.
   int expected_property_count_;
 
   // Keeps track of assignments to properties of this. Used for
   // optimizing constructors.
   bool only_simple_this_property_assignments_;
   Handle<FixedArray> this_property_assignments_;
 
   // Captures the number of loops inside the scope.
   int loop_count_;
 
+  // Parsing strict mode code.
+  bool strict_mode_;
+
   // Bookkeeping
   TemporaryScope** variable_;
   TemporaryScope* parent_;
 };
 
 
 TemporaryScope::TemporaryScope(TemporaryScope** variable)
   : materialized_literal_count_(0),
     expected_property_count_(0),
     only_simple_this_property_assignments_(false),
     this_property_assignments_(Factory::empty_fixed_array()),
     loop_count_(0),
     variable_(variable),
     parent_(*variable) {
+  // Inherit the strict mode from the parent scope.
+  strict_mode_ = (parent_ != NULL) ? parent_->strict_mode_ : false;

[Lasse Reichstein, 2011/01/18 13:40:59]

Can be written
  (parent_ != NULL) && parent_->strict_mode_
Probably doesn't make any difference, though.

[Martin Maly, 2011/01/18 16:46:38]

Done.

   *variable = this;
 }
 
 
 TemporaryScope::~TemporaryScope() {
   *variable_ = parent_;
 }
 
 
 Handle<String> Parser::LookupSymbol(int symbol_id) {
@@ skipping 227 matching lines @@
     *with_nesting_level_variable_ = prev_level_;
   }
 
  private:
   Scope** scope_variable_;
   int* with_nesting_level_variable_;
   Scope* prev_scope_;
   int prev_level_;
 };
 
-
 // ----------------------------------------------------------------------------
 // The CHECK_OK macro is a convenient macro to enforce error
 // handling for functions that may fail (by returning !*ok).
 //
 // CAUTION: This macro appends extra statements after a call,
 // thus it must never be used where only a single statement
 // is correct (e.g. an if statement branch w/o braces)!
 
 #define CHECK_OK  ok);   \
   if (!*ok) return NULL; \
@@ skipping 86 matching lines @@
           top_scope_,
           body,
           temp_scope.materialized_literal_count(),
           temp_scope.expected_property_count(),
           temp_scope.only_simple_this_property_assignments(),
           temp_scope.this_property_assignments(),
           0,
           0,
           source->length(),
           false,
-          temp_scope.ContainsLoops());
+          temp_scope.ContainsLoops(),
+          temp_scope.StrictMode());
     } else if (stack_overflow_) {
       Top::StackOverflow();
     }
   }
 
   // Make sure the target stack is empty.
   ASSERT(target_stack_ == NULL);
 
   // If there was a syntax error we have to get rid of the AST
   // and it is not safe to do so before the scope has been deleted.
@@ skipping 369 matching lines @@
 
   // Allocate a target stack to use for this set of source
   // elements. This way, all scripts and functions get their own
   // target stack thus avoiding illegal breaks and continues across
   // functions.
   TargetScope scope(&this->target_stack_);
 
   ASSERT(processor != NULL);
   InitializationBlockFinder block_finder;
   ThisNamedPropertyAssigmentFinder this_property_assignment_finder;
+  bool directive_prologue = true;     // Parsing directive prologue.
+
   while (peek() != end_token) {
+    if (directive_prologue && peek() != Token::STRING) {
+      directive_prologue = false;
+    }
+
+    Scanner::Location token_loc = scanner().peek_location();
     Statement* stat = ParseStatement(NULL, CHECK_OK);
-    if (stat == NULL || stat->IsEmpty()) continue;
+
+    if (stat == NULL || stat->IsEmpty()) {
+      directive_prologue = false;   // End of directive prologue.
+      continue;
+    }
+
+    if (directive_prologue) {
+      // A shot at a directive.
+      ExpressionStatement *e_stat;
+      Literal *literal;
+      // Still processing directive prologue?
+      if ((e_stat = stat->AsExpressionStatement()) != NULL &&
+          (literal = e_stat->expression()->AsLiteral()) != NULL &&
+          literal->handle()->IsString()) {
+        Handle<String> directive = Handle<String>::cast(literal->handle());
+
+        // Check "use strict" directive (ES5 14.1).
+        if (!temp_scope_->StrictMode() &&
+            directive->Equals(Heap::use_strict()) &&
+            token_loc.end_pos - token_loc.beg_pos ==
+              Heap::use_strict()->length() + 2) {
+          temp_scope_->EnableStrictMode();

[Lasse Reichstein, 2011/01/18 13:40:59]

You can set directive_prologue to false here, since there is no more reason to
look at the directive prologue.

On the other hand, any realistic code won't have any directive prologue except
"use strict", if any.

[Martin Maly, 2011/01/18 16:46:38]

Done.

+        }
+      } else {
+        // End of the directive prologue.
+        directive_prologue = false;
+      }
+    }
+
     // We find and mark the initialization blocks on top level code only.
     // This is because the optimization prevents reuse of the map transitions,
     // so it should be used only for code that will only be run once.
     if (top_scope_->is_global_scope()) {
       block_finder.Update(stat);
     }
     // Find and mark all assignments to named properties in this (this.x =)
     if (top_scope_->is_function_scope()) {
       this_property_assignment_finder.Update(top_scope_, stat);
     }
@@ skipping 333 matching lines @@
 Block* Parser::ParseVariableStatement(bool* ok) {
   // VariableStatement ::
   //   VariableDeclarations ';'
 
   Expression* dummy;  // to satisfy the ParseVariableDeclarations() signature
   Block* result = ParseVariableDeclarations(true, &dummy, CHECK_OK);
   ExpectSemicolon(CHECK_OK);
   return result;
 }
 
+static bool IsEvalOrArguments(Handle<String> string) {
+  return string.is_identical_to(Factory::eval_symbol()) ||
+         string.is_identical_to(Factory::arguments_symbol());
+}
 
 // If the variable declaration declares exactly one non-const
 // variable, then *var is set to that variable. In all other cases,
 // *var is untouched; in particular, it is the caller's responsibility
 // to initialize it properly. This mechanism is used for the parsing
 // of 'for-in' loops.
 Block* Parser::ParseVariableDeclarations(bool accept_IN,
                                          Expression** var,
                                          bool* ok) {
   // VariableDeclarations ::
@@ skipping 28 matching lines @@
   VariableProxy* last_var = NULL;  // the last variable declared
   int nvars = 0;  // the number of variables declared
   do {
     if (fni_ != NULL) fni_->Enter();
 
     // Parse variable name.
     if (nvars > 0) Consume(Token::COMMA);
     Handle<String> name = ParseIdentifier(CHECK_OK);
     if (fni_ != NULL) fni_->PushVariableName(name);
 
+    // Strict mode variables may not be named eval or arguments
+    if (temp_scope_->StrictMode() && IsEvalOrArguments(name)) {
+      ReportMessage("strict_var_name", Vector<const char*>::empty());
+      *ok = false;
+      return NULL;
+    }
+
     // Declare variable.
     // Note that we *always* must treat the initial value via a separate init
     // assignment for variables and constants because the value must be assigned
     // when the variable is encountered in the source. But the variable/constant
     // is declared (and set to 'undefined') upon entering the function within
     // which the variable or constant is declared. Only function variables have
     // an initial value in the declaration (because they are initialized upon
     // entering the function).
     //
     // If we have a const declaration, in an inner scope, the proxy is always
@@ skipping 332 matching lines @@
   }
   return result;
 }
 
 
 Statement* Parser::ParseWithStatement(ZoneStringList* labels, bool* ok) {
   // WithStatement ::
   //   'with' '(' Expression ')' Statement
 
   Expect(Token::WITH, CHECK_OK);
+
+  if (temp_scope_->StrictMode()) {
+    ReportMessage("strict_mode_with", Vector<const char*>::empty());
+    *ok = false;
+    return NULL;
+  }
+
   Expect(Token::LPAREN, CHECK_OK);
   Expression* expr = ParseExpression(true, CHECK_OK);
   Expect(Token::RPAREN, CHECK_OK);
 
   return WithHelper(expr, labels, false, CHECK_OK);
 }
 
 
 CaseClause* Parser::ParseCaseClause(bool* default_seen_ptr, bool* ok) {
   // CaseClause ::
@@ skipping 112 matching lines @@
   // the jump targets.
   ZoneList<BreakTarget*>* catch_target_list = new ZoneList<BreakTarget*>(0);
   TargetCollector catch_collector(catch_target_list);
   bool has_catch = false;
   if (tok == Token::CATCH) {
     has_catch = true;
     Consume(Token::CATCH);
 
     Expect(Token::LPAREN, CHECK_OK);
     Handle<String> name = ParseIdentifier(CHECK_OK);
+
+    if (temp_scope_->StrictMode() && IsEvalOrArguments(name)) {
+      ReportMessage("strict_catch_variable", Vector<const char*>::empty());
+      *ok = false;
+      return NULL;
+    }
+
     Expect(Token::RPAREN, CHECK_OK);
 
     if (peek() == Token::LBRACE) {
       // Allocate a temporary for holding the finally state while
       // executing the finally block.
       catch_var = top_scope_->NewTemporary(Factory::catch_var_symbol());
       Literal* name_literal = new Literal(name);
       VariableProxy* catch_var_use = new VariableProxy(catch_var);
       Expression* obj = new CatchExtensionObject(name_literal, catch_var_use);
       { Target target(&this->target_stack_, &catch_collector);
@@ skipping 1226 matching lines @@
         NewScope(top_scope_, Scope::FUNCTION_SCOPE, inside_with());
     LexicalScope lexical_scope(&this->top_scope_, &this->with_nesting_level_,
                                scope);
     TemporaryScope temp_scope(&this->temp_scope_);
     top_scope_->SetScopeName(name);
 
     //  FormalParameterList ::
     //    '(' (Identifier)*[','] ')'
     Expect(Token::LPAREN, CHECK_OK);
     int start_pos = scanner().location().beg_pos;
+    Scanner::Location eval_loc(RelocInfo::kNoPosition, RelocInfo::kNoPosition);
+    Scanner::Location dupe_loc(RelocInfo::kNoPosition, RelocInfo::kNoPosition);
+
     bool done = (peek() == Token::RPAREN);
     while (!done) {
       Handle<String> param_name = ParseIdentifier(CHECK_OK);
-      top_scope_->AddParameter(top_scope_->DeclareLocal(param_name,
-                                                        Variable::VAR));
+      Variable* parameter = top_scope_->DeclareLocal(param_name, Variable::VAR);
+
+      // Store locations for possible future error reports.
+      if (eval_loc.beg_pos == RelocInfo::kNoPosition &&
+          IsEvalOrArguments(param_name)) {
+        // Store location for later
+        eval_loc = scanner().location();
+      }
+      if (dupe_loc.beg_pos == RelocInfo::kNoPosition &&
+        top_scope_->IsParameterDeclared(param_name)) {
+        // Store location for later
+        dupe_loc = scanner().location();
+      }
+
+      top_scope_->AddParameter(parameter);
       num_parameters++;
       done = (peek() == Token::RPAREN);
       if (!done) Expect(Token::COMMA, CHECK_OK);
     }
     Expect(Token::RPAREN, CHECK_OK);
 
     Expect(Token::LBRACE, CHECK_OK);
     ZoneList<Statement*>* body = new ZoneList<Statement*>(8);
 
     // If we have a named function expression, we add a local variable
@@ skipping 48 matching lines @@
       materialized_literal_count = temp_scope.materialized_literal_count();
       expected_property_count = temp_scope.expected_property_count();
       only_simple_this_property_assignments =
           temp_scope.only_simple_this_property_assignments();
       this_property_assignments = temp_scope.this_property_assignments();
 
       Expect(Token::RBRACE, CHECK_OK);
       end_pos = scanner().location().end_pos;
     }
 
+    // Validate strict mode.
+    if (temp_scope_->StrictMode()) {
+      if (IsEvalOrArguments(name)) {
+        int position = function_token_position != RelocInfo::kNoPosition
+                         ? function_token_position
+                         : (start_pos > 0 ? start_pos - 1 : start_pos);
+        ReportMessageAt(Scanner::Location(position, start_pos),
+                        "strict_function_name", Vector<const char*>::empty());
+        *ok = false;
+        return NULL;
+      }
+      if (eval_loc.beg_pos != RelocInfo::kNoPosition) {
+        ReportMessageAt(eval_loc, "strict_param_name",
+                        Vector<const char*>::empty());
+        *ok = false;
+        return NULL;
+      }
+      if (dupe_loc.beg_pos != RelocInfo::kNoPosition) {
+        ReportMessageAt(dupe_loc, "strict_param_dupe",
+                        Vector<const char*>::empty());
+        *ok = false;
+        return NULL;
+      }
+      // TODO(mmaly): Check for octal escape sequence here.
+    }
+
     FunctionLiteral* function_literal =
         new FunctionLiteral(name,
                             top_scope_,
                             body,
                             materialized_literal_count,
                             expected_property_count,
                             only_simple_this_property_assignments,
                             this_property_assignments,
                             num_parameters,
                             start_pos,
                             end_pos,
                             function_name->length() > 0,
-                            temp_scope.ContainsLoops());
+                            temp_scope.ContainsLoops(),
+                            temp_scope.StrictMode());
     function_literal->set_function_token_position(function_token_position);
 
     if (fni_ != NULL && !is_named) fni_->AddFunction(function_literal);
     return function_literal;
   }
 }
 
 
 Expression* Parser::ParseV8Intrinsic(bool* ok) {
   // CallRuntime ::
@@ skipping 1404 matching lines @@
       Handle<String> source = Handle<String>(String::cast(script->source()));
       result = parser.ParseProgram(source, info->is_global());
     }
   }
 
   info->SetFunction(result);
   return (result != NULL);
 }
 
 } }  // namespace v8::internal