[parser] Refactor of Parse*Statement*, part 1

src/parsing/parser.cc

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/parsing/parser.h"
 
 #include <memory>
 
 #include "src/api.h"
 #include "src/ast/ast-expression-rewriter.h"
@@ skipping 213 matching lines @@
   return function_literal;
 }
 
 
 // ----------------------------------------------------------------------------
 // Target is a support class to facilitate manipulation of the
 // Parser's target_stack_ (the stack of potential 'break' and
 // 'continue' statement targets). Upon construction, a new target is
 // added; it is removed upon destruction.
 
-class Target BASE_EMBEDDED {
+class ParserTarget BASE_EMBEDDED {
  public:
-  Target(Target** variable, BreakableStatement* statement)
-      : variable_(variable), statement_(statement), previous_(*variable) {
-    *variable = this;
+  ParserTarget(ParserBase<Parser>* parser, BreakableStatement* statement)
+      : variable_(&parser->impl()->target_stack_),
+        statement_(statement),
+        previous_(parser->impl()->target_stack_) {
+    parser->impl()->target_stack_ = this;
   }
 
-  ~Target() {
-    *variable_ = previous_;
-  }
+  ~ParserTarget() { *variable_ = previous_; }
 
-  Target* previous() { return previous_; }
+  ParserTarget* previous() { return previous_; }
   BreakableStatement* statement() { return statement_; }
 
  private:
-  Target** variable_;
+  ParserTarget** variable_;
   BreakableStatement* statement_;
-  Target* previous_;
+  ParserTarget* previous_;
+};
+
+class ParserTargetScope BASE_EMBEDDED {
+ public:
+  explicit ParserTargetScope(ParserBase<Parser>* parser)
+      : variable_(&parser->impl()->target_stack_),
+        previous_(parser->impl()->target_stack_) {
+    parser->impl()->target_stack_ = nullptr;
+  }
+
+  ~ParserTargetScope() { *variable_ = previous_; }
+
+ private:
+  ParserTarget** variable_;
+  ParserTarget* previous_;
 };
 
 
-class TargetScope BASE_EMBEDDED {
- public:
-  explicit TargetScope(Target** variable)
-      : variable_(variable), previous_(*variable) {
-    *variable = NULL;
-  }
-
-  ~TargetScope() {
-    *variable_ = previous_;
-  }
-
- private:
-  Target** variable_;
-  Target* previous_;
-};
-
-
 // ----------------------------------------------------------------------------
 // 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_VALUE(x) ok); \
   if (!*ok) return x;          \
@@ skipping 642 matching lines @@
     }
     // Make sure the results agree.
     DCHECK(ok == (result != nullptr));
   }
 
   // Make sure the target stack is empty.
   DCHECK_NULL(target_stack_);
   return result;
 }
 
-
-void Parser::ParseStatementList(ZoneList<Statement*>* body, int end_token,
-                                bool* ok) {
-  // StatementList ::
-  //   (StatementListItem)* <end_token>
-
-  // 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_);
-
-  DCHECK(body != NULL);
-  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 = ParseStatementListItem(CHECK_OK_VOID);
-    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->raw_value()->IsString()) {
-        // Check "use strict" directive (ES5 14.1), "use asm" directive.
-        bool use_strict_found =
-            literal->raw_value()->AsString() ==
-                ast_value_factory()->use_strict_string() &&
-            token_loc.end_pos - token_loc.beg_pos ==
-                ast_value_factory()->use_strict_string()->length() + 2;
-        if (use_strict_found) {
-          if (is_sloppy(language_mode())) {
-            RaiseLanguageMode(STRICT);
-          }
-
-          if (!this->scope()->HasSimpleParameters()) {
-            // TC39 deemed "use strict" directives to be an error when occurring
-            // in the body of a function with non-simple parameter list, on
-            // 29/7/2015. https://goo.gl/ueA7Ln
-            const AstRawString* string = literal->raw_value()->AsString();
-            ReportMessageAt(token_loc,
-                            MessageTemplate::kIllegalLanguageModeDirective,
-                            string);
-            *ok = false;
-            return;
-          }
-          // Because declarations in strict eval code don't leak into the scope
-          // of the eval call, it is likely that functions declared in strict
-          // eval code will be used within the eval code, so lazy parsing is
-          // probably not a win.
-          if (this->scope()->is_eval_scope()) mode_ = PARSE_EAGERLY;
-        } else if (literal->raw_value()->AsString() ==
-                       ast_value_factory()->use_asm_string() &&
-                   token_loc.end_pos - token_loc.beg_pos ==
-                       ast_value_factory()->use_asm_string()->length() + 2) {
-          // Store the usage count; The actual use counter on the isolate is
-          // incremented after parsing is done.
-          ++use_counts_[v8::Isolate::kUseAsm];
-          DCHECK(this->scope()->is_declaration_scope());
-          this->scope()->AsDeclarationScope()->set_asm_module();
-        } else {
-          // Should not change mode, but will increment UseCounter
-          // if appropriate. Ditto usages below.
-          RaiseLanguageMode(SLOPPY);
-        }
-      } else {
-        // End of the directive prologue.
-        directive_prologue = false;
-        RaiseLanguageMode(SLOPPY);
-      }
-    } else {
-      RaiseLanguageMode(SLOPPY);
-    }
-
-    body->Add(stat, zone());
-  }
-}
-
-
-Statement* Parser::ParseStatementListItem(bool* ok) {
-  // (Ecma 262 6th Edition, 13.1):
-  // StatementListItem:
-  //    Statement
-  //    Declaration
-  const Token::Value peeked = peek();
-  switch (peeked) {
-    case Token::FUNCTION:
-      return ParseHoistableDeclaration(NULL, false, ok);
-    case Token::CLASS:
-      Consume(Token::CLASS);
-      return ParseClassDeclaration(NULL, false, ok);
-    case Token::CONST:
-      return ParseVariableStatement(kStatementListItem, NULL, ok);
-    case Token::VAR:
-      return ParseVariableStatement(kStatementListItem, NULL, ok);
-    case Token::LET:
-      if (IsNextLetKeyword()) {
-        return ParseVariableStatement(kStatementListItem, NULL, ok);
-      }
-      break;
-    case Token::ASYNC:
-      if (allow_harmony_async_await() && PeekAhead() == Token::FUNCTION &&
-          !scanner()->HasAnyLineTerminatorAfterNext()) {
-        Consume(Token::ASYNC);
-        return ParseAsyncFunctionDeclaration(NULL, false, ok);
-      }
-    /* falls through */
-    default:
-      break;
-  }
-  return ParseStatement(NULL, kAllowLabelledFunctionStatement, ok);
-}
-
-
 Statement* Parser::ParseModuleItem(bool* ok) {
   // ecma262/#prod-ModuleItem
   // ModuleItem :
   //    ImportDeclaration
   //    ExportDeclaration
   //    StatementListItem
 
   switch (peek()) {
     case Token::IMPORT:
       ParseImportDeclaration(CHECK_OK);
@@ skipping 410 matching lines @@
   ModuleDescriptor* descriptor = module();
   for (int i = 0; i < names.length(); ++i) {
     // TODO(neis): Provide better location.
     descriptor->AddExport(names[i], names[i], scanner()->location(), zone());
   }
 
   DCHECK_NOT_NULL(result);
   return result;
 }
 
-Statement* Parser::ParseStatement(ZoneList<const AstRawString*>* labels,
-                                  AllowLabelledFunctionStatement allow_function,
-                                  bool* ok) {
-  // Statement ::
-  //   EmptyStatement
-  //   ...
-
-  if (peek() == Token::SEMICOLON) {
-    Next();
-    return factory()->NewEmptyStatement(kNoSourcePosition);
-  }
-  return ParseSubStatement(labels, allow_function, ok);
-}
-
-Statement* Parser::ParseSubStatement(
-    ZoneList<const AstRawString*>* labels,
-    AllowLabelledFunctionStatement allow_function, bool* ok) {
-  // Statement ::
-  //   Block
-  //   VariableStatement
-  //   EmptyStatement
-  //   ExpressionStatement
-  //   IfStatement
-  //   IterationStatement
-  //   ContinueStatement
-  //   BreakStatement
-  //   ReturnStatement
-  //   WithStatement
-  //   LabelledStatement
-  //   SwitchStatement
-  //   ThrowStatement
-  //   TryStatement
-  //   DebuggerStatement
-
-  // Note: Since labels can only be used by 'break' and 'continue'
-  // statements, which themselves are only valid within blocks,
-  // iterations or 'switch' statements (i.e., BreakableStatements),
-  // labels can be simply ignored in all other cases; except for
-  // trivial labeled break statements 'label: break label' which is
-  // parsed into an empty statement.
-  switch (peek()) {
-    case Token::LBRACE:
-      return ParseBlock(labels, ok);
-
-    case Token::SEMICOLON:
-      Next();
-      return factory()->NewEmptyStatement(kNoSourcePosition);
-
-    case Token::IF:
-      return ParseIfStatement(labels, ok);
-
-    case Token::DO:
-      return ParseDoWhileStatement(labels, ok);
-
-    case Token::WHILE:
-      return ParseWhileStatement(labels, ok);
-
-    case Token::FOR:
-      return ParseForStatement(labels, ok);
-
-    case Token::CONTINUE:
-    case Token::BREAK:
-    case Token::RETURN:
-    case Token::THROW:
-    case Token::TRY: {
-      // These statements must have their labels preserved in an enclosing
-      // block
-      if (labels == NULL) {
-        return ParseStatementAsUnlabelled(labels, ok);
-      } else {
-        Block* result =
-            factory()->NewBlock(labels, 1, false, kNoSourcePosition);
-        Target target(&this->target_stack_, result);
-        Statement* statement = ParseStatementAsUnlabelled(labels, CHECK_OK);
-        if (result) result->statements()->Add(statement, zone());
-        return result;
-      }
-    }
-
-    case Token::WITH:
-      return ParseWithStatement(labels, ok);
-
-    case Token::SWITCH:
-      return ParseSwitchStatement(labels, ok);
-
-    case Token::FUNCTION:
-      // FunctionDeclaration only allowed as a StatementListItem, not in
-      // an arbitrary Statement position. Exceptions such as
-      // ES#sec-functiondeclarations-in-ifstatement-statement-clauses
-      // are handled by calling ParseScopedStatement rather than
-      // ParseSubStatement directly.
-      ReportMessageAt(scanner()->peek_location(),
-                      is_strict(language_mode())
-                          ? MessageTemplate::kStrictFunction
-                          : MessageTemplate::kSloppyFunction);
-      *ok = false;
-      return nullptr;
-
-    case Token::DEBUGGER:
-      return ParseDebuggerStatement(ok);
-
-    case Token::VAR:
-      return ParseVariableStatement(kStatement, NULL, ok);
-
-    default:
-      return ParseExpressionOrLabelledStatement(labels, allow_function, ok);
-  }
-}
-
-Statement* Parser::ParseStatementAsUnlabelled(
-    ZoneList<const AstRawString*>* labels, bool* ok) {
-  switch (peek()) {
-    case Token::CONTINUE:
-      return ParseContinueStatement(ok);
-
-    case Token::BREAK:
-      return ParseBreakStatement(labels, ok);
-
-    case Token::RETURN:
-      return ParseReturnStatement(ok);
-
-    case Token::THROW:
-      return ParseThrowStatement(ok);
-
-    case Token::TRY:
-      return ParseTryStatement(ok);
-
-    default:
-      UNREACHABLE();
-      return NULL;
-  }
-}
-
 VariableProxy* Parser::NewUnresolved(const AstRawString* name, int begin_pos,
                                      int end_pos, Variable::Kind kind) {
   return scope()->NewUnresolved(factory(), name, begin_pos, end_pos, kind);
 }
 
 VariableProxy* Parser::NewUnresolved(const AstRawString* name) {
   return scope()->NewUnresolved(factory(), name, scanner()->location().beg_pos,
                                 scanner()->location().end_pos);
 }
 
@@ skipping 238 matching lines @@
   //   '{' StatementList '}'
 
   // Construct block expecting 16 statements.
   Block* body = factory()->NewBlock(labels, 16, false, kNoSourcePosition);
 
   // Parse the statements and collect escaping labels.
   Expect(Token::LBRACE, CHECK_OK);
   {
     BlockState block_state(&scope_state_);
     block_state.set_start_position(scanner()->location().beg_pos);
-    Target target(&this->target_stack_, body);
+    ParserTarget target(this, body);
 
     while (peek() != Token::RBRACE) {
       Statement* stat = ParseStatementListItem(CHECK_OK);
       if (stat && !stat->IsEmpty()) {
         body->statements()->Add(stat, zone());
       }
     }
 
     Expect(Token::RBRACE, CHECK_OK);
     block_state.set_end_position(scanner()->location().end_pos);
@@ skipping 451 matching lines @@
 
   Block* cases_block = factory()->NewBlock(NULL, 1, false, kNoSourcePosition);
 
   SwitchStatement* switch_statement =
       factory()->NewSwitchStatement(labels, switch_pos);
 
   {
     BlockState cases_block_state(&scope_state_);
     cases_block_state.set_start_position(scanner()->location().beg_pos);
     cases_block_state.SetNonlinear();
-    Target target(&this->target_stack_, switch_statement);
+    ParserTarget target(this, switch_statement);
 
     Expression* tag_read = factory()->NewVariableProxy(tag_variable);
 
     bool default_seen = false;
     ZoneList<CaseClause*>* cases =
         new (zone()) ZoneList<CaseClause*>(4, zone());
     Expect(Token::LBRACE, CHECK_OK);
     while (peek() != Token::RBRACE) {
       CaseClause* clause = ParseCaseClause(&default_seen, CHECK_OK);
       cases->Add(clause, zone());
@@ skipping 85 matching lines @@
               function_state_, &tail_call_expressions_in_catch_block);
       BlockState block_state(&scope_state_, catch_scope);
 
       catch_block = factory()->NewBlock(nullptr, 16, false, kNoSourcePosition);
 
       // Create a block scope to hold any lexical declarations created
       // as part of destructuring the catch parameter.
       {
         BlockState block_state(&scope_state_);
         block_state.set_start_position(scanner()->location().beg_pos);
-        Target target(&this->target_stack_, catch_block);
+        ParserTarget target(this, catch_block);
 
         const AstRawString* name = ast_value_factory()->dot_catch_string();
         Expression* pattern = nullptr;
         if (peek_any_identifier()) {
           name = ParseIdentifier(kDontAllowRestrictedIdentifiers, CHECK_OK);
         } else {
           ExpressionClassifier pattern_classifier(this);
           pattern = ParsePrimaryExpression(CHECK_OK);
           ValidateBindingPattern(CHECK_OK);
         }
@@ skipping 118 matching lines @@
 }
 
 
 DoWhileStatement* Parser::ParseDoWhileStatement(
     ZoneList<const AstRawString*>* labels, bool* ok) {
   // DoStatement ::
   //   'do' Statement 'while' '(' Expression ')' ';'
 
   DoWhileStatement* loop =
       factory()->NewDoWhileStatement(labels, peek_position());
-  Target target(&this->target_stack_, loop);
+  ParserTarget target(this, loop);
 
   Expect(Token::DO, CHECK_OK);
   Statement* body = ParseScopedStatement(NULL, true, CHECK_OK);
   Expect(Token::WHILE, CHECK_OK);
   Expect(Token::LPAREN, CHECK_OK);
 
   Expression* cond = ParseExpression(true, CHECK_OK);
   Expect(Token::RPAREN, CHECK_OK);
 
   // Allow do-statements to be terminated with and without
   // semi-colons. This allows code such as 'do;while(0)return' to
   // parse, which would not be the case if we had used the
   // ExpectSemicolon() functionality here.
   if (peek() == Token::SEMICOLON) Consume(Token::SEMICOLON);
 
   if (loop != NULL) loop->Initialize(cond, body);
   return loop;
 }
 
 
 WhileStatement* Parser::ParseWhileStatement(
     ZoneList<const AstRawString*>* labels, bool* ok) {
   // WhileStatement ::
   //   'while' '(' Expression ')' Statement
 
   WhileStatement* loop = factory()->NewWhileStatement(labels, peek_position());
-  Target target(&this->target_stack_, loop);
+  ParserTarget target(this, loop);
 
   Expect(Token::WHILE, CHECK_OK);
   Expect(Token::LPAREN, CHECK_OK);
   Expression* cond = ParseExpression(true, CHECK_OK);
   Expect(Token::RPAREN, CHECK_OK);
   Statement* body = ParseScopedStatement(NULL, true, CHECK_OK);
 
   if (loop != NULL) loop->Initialize(cond, body);
   return loop;
 }
@@ skipping 427 matching lines @@
   }
 
   outer_loop->Initialize(NULL, NULL, NULL, inner_block);
   return outer_block;
 }
 
 Statement* Parser::ParseScopedStatement(ZoneList<const AstRawString*>* labels,
                                         bool legacy, bool* ok) {
   if (is_strict(language_mode()) || peek() != Token::FUNCTION ||
       (legacy && allow_harmony_restrictive_declarations())) {
-    return ParseSubStatement(labels, kDisallowLabelledFunctionStatement, ok);
+    return ParseStatement(labels, kDisallowLabelledFunctionStatement, ok);
   } else {
     if (legacy) {
       ++use_counts_[v8::Isolate::kLegacyFunctionDeclaration];
     }
     // Make a block around the statement for a lexical binding
     // is introduced by a FunctionDeclaration.
     BlockState block_state(&scope_state_);
     block_state.set_start_position(scanner()->location().beg_pos);
     Block* block = factory()->NewBlock(NULL, 1, false, kNoSourcePosition);
     Statement* body = ParseFunctionDeclaration(CHECK_OK);
@@ skipping 88 matching lines @@
         //       let/const/var x;
         //       x = x';
         //       b;
         //     }
         //     let x;  // for TDZ
         //   }
 
         Variable* temp = NewTemporary(ast_value_factory()->dot_for_string());
         ForEachStatement* loop =
             factory()->NewForEachStatement(mode, labels, stmt_pos);
-        Target target(&this->target_stack_, loop);
+        ParserTarget target(this, loop);
 
         int each_keyword_position = scanner()->location().beg_pos;
 
         Expression* enumerable;
         if (mode == ForEachStatement::ITERATE) {
           ExpressionClassifier classifier(this);
           enumerable = ParseAssignmentExpression(true, CHECK_OK);
           RewriteNonPattern(CHECK_OK);
         } else {
           enumerable = ParseExpression(true, CHECK_OK);
@@ skipping 125 matching lines @@
 
       if (is_for_each) {
         if (!is_destructuring) {
           expression = CheckAndRewriteReferenceExpression(
               expression, lhs_beg_pos, lhs_end_pos,
               MessageTemplate::kInvalidLhsInFor, kSyntaxError, CHECK_OK);
         }
 
         ForEachStatement* loop =
             factory()->NewForEachStatement(mode, labels, stmt_pos);
-        Target target(&this->target_stack_, loop);
+        ParserTarget target(this, loop);
 
         int each_keyword_position = scanner()->location().beg_pos;
 
         Expression* enumerable;
         if (mode == ForEachStatement::ITERATE) {
           ExpressionClassifier classifier(this);
           enumerable = ParseAssignmentExpression(true, CHECK_OK);
           RewriteNonPattern(CHECK_OK);
         } else {
           enumerable = ParseExpression(true, CHECK_OK);
@@ skipping 11 matching lines @@
         return final_loop;
 
       } else {
         init = factory()->NewExpressionStatement(expression, lhs_beg_pos);
       }
     }
   }
 
   // Standard 'for' loop
   ForStatement* loop = factory()->NewForStatement(labels, stmt_pos);
-  Target target(&this->target_stack_, loop);
+  ParserTarget target(this, loop);
 
   // Parsed initializer at this point.
   Expect(Token::SEMICOLON, CHECK_OK);
 
   Expression* cond = NULL;
   Statement* next = NULL;
   Statement* body = NULL;
 
   // If there are let bindings, then condition and the next statement of the
   // for loop must be parsed in a new scope.
@@ skipping 1438 matching lines @@
       delegate->set_statement(statement);
     }
   }
 }
 
 
 // ----------------------------------------------------------------------------
 // Parser support
 
 bool Parser::TargetStackContainsLabel(const AstRawString* label) {
-  for (Target* t = target_stack_; t != NULL; t = t->previous()) {
+  for (ParserTarget* t = target_stack_; t != NULL; t = t->previous()) {
     if (ContainsLabel(t->statement()->labels(), label)) return true;
   }
   return false;
 }
 
 
 BreakableStatement* Parser::LookupBreakTarget(const AstRawString* label,
                                               bool* ok) {
   bool anonymous = label == NULL;
-  for (Target* t = target_stack_; t != NULL; t = t->previous()) {
+  for (ParserTarget* t = target_stack_; t != NULL; t = t->previous()) {
     BreakableStatement* stat = t->statement();
     if ((anonymous && stat->is_target_for_anonymous()) ||
         (!anonymous && ContainsLabel(stat->labels(), label))) {
       return stat;
     }
   }
   return NULL;
 }
 
 
 IterationStatement* Parser::LookupContinueTarget(const AstRawString* label,
                                                  bool* ok) {
   bool anonymous = label == NULL;
-  for (Target* t = target_stack_; t != NULL; t = t->previous()) {
+  for (ParserTarget* t = target_stack_; t != NULL; t = t->previous()) {
     IterationStatement* stat = t->statement()->AsIterationStatement();
     if (stat == NULL) continue;
 
     DCHECK(stat->is_target_for_anonymous());
     if (anonymous || ContainsLabel(stat->labels(), label)) {
       return stat;
     }
   }
   return NULL;
 }
@@ skipping 373 matching lines @@
   if (is_sloppy(mode))
     feature = v8::Isolate::kSloppyMode;
   else if (is_strict(mode))
     feature = v8::Isolate::kStrictMode;
   else
     UNREACHABLE();
   ++use_counts_[feature];
   scope->SetLanguageMode(mode);
 }
 
-
-void Parser::RaiseLanguageMode(LanguageMode mode) {
-  LanguageMode old = scope()->language_mode();
-  SetLanguageMode(scope(), old > mode ? old : mode);
+void Parser::SetAsmModule() {
+  // Store the usage count; The actual use counter on the isolate is
+  // incremented after parsing is done.
+  ++use_counts_[v8::Isolate::kUseAsm];
+  DCHECK(scope()->is_declaration_scope());
+  scope()->AsDeclarationScope()->set_asm_module();
 }
 
 void Parser::MarkCollectedTailCallExpressions() {
   const ZoneList<Expression*>& tail_call_expressions =
       function_state_->tail_call_expressions().expressions();
   for (int i = 0; i < tail_call_expressions.length(); ++i) {
     Expression* expression = tail_call_expressions[i];
     // If only FLAG_harmony_explicit_tailcalls is enabled then expression
     // must be a Call expression.
     DCHECK(FLAG_harmony_tailcalls || !FLAG_harmony_explicit_tailcalls ||
@@ skipping 1240 matching lines @@
   node->Print(Isolate::Current());
 }
 #endif  // DEBUG
 
 #undef CHECK_OK
 #undef CHECK_OK_VOID
 #undef CHECK_FAILED
 
 }  // namespace internal
 }  // namespace v8