[parser] implement error reporting for Scanner

Enables the Scanner to provide a better error message when errors occur
in escape sequences, numbers, strings, etc.

BUG=v8:4829, v8:3230
LOG=N
R=adamk@chromium.org, littledan@chromium.org

Review URL: https://codereview.chromium.org/1793913002

Cr-Commit-Position: refs/heads/master@{#34966}

src/messages.h

@@ -464,6 +464,9 @@ class CallSite {
   T(UnterminatedTemplate, "Unterminated template literal")                     \
   T(UnterminatedTemplateExpr, "Missing } in template expression")              \
   T(FoundNonCallableHasInstance, "Found non-callable @@hasInstance")           \
+  T(InvalidHexEscapeSequence, "Invalid hexadecimal escape sequence")           \
+  T(InvalidUnicodeEscapeSequence, "Invalid Unicode escape sequence")           \
+  T(UndefinedUnicodeCodePoint, "Undefined Unicode code-point")                 \
   /* EvalError */                                                              \
   T(CodeGenFromStrings, "%")                                                   \
   /* URIError */                                                               \

src/parsing/parser-base.h

@@ -586,7 +586,8 @@ class ParserBase : public Traits {
   }
 
   void GetUnexpectedTokenMessage(
-      Token::Value token, MessageTemplate::Template* message, const char** arg,
+      Token::Value token, MessageTemplate::Template* message,
+      Scanner::Location* location, const char** arg,
       MessageTemplate::Template default_ = MessageTemplate::kUnexpectedToken);
 
   void ReportUnexpectedToken(Token::Value token);
@@ -687,33 +688,34 @@ class ParserBase : public Traits {
   void ExpressionUnexpectedToken(ExpressionClassifier* classifier) {
     MessageTemplate::Template message = MessageTemplate::kUnexpectedToken;
     const char* arg;
-    GetUnexpectedTokenMessage(peek(), &message, &arg);
-    classifier->RecordExpressionError(scanner()->peek_location(), message, arg);
+    Scanner::Location location = scanner()->peek_location();
+    GetUnexpectedTokenMessage(peek(), &message, &location, &arg);
+    classifier->RecordExpressionError(location, message, arg);
   }
 
   void BindingPatternUnexpectedToken(ExpressionClassifier* classifier) {
     MessageTemplate::Template message = MessageTemplate::kUnexpectedToken;
     const char* arg;
-    GetUnexpectedTokenMessage(peek(), &message, &arg);
-    classifier->RecordBindingPatternError(scanner()->peek_location(), message,
-                                          arg);
+    Scanner::Location location = scanner()->peek_location();
+    GetUnexpectedTokenMessage(peek(), &message, &location, &arg);
+    classifier->RecordBindingPatternError(location, message, arg);
   }
 
   void ArrowFormalParametersUnexpectedToken(ExpressionClassifier* classifier) {
     MessageTemplate::Template message = MessageTemplate::kUnexpectedToken;
     const char* arg;
-    GetUnexpectedTokenMessage(peek(), &message, &arg);
-    classifier->RecordArrowFormalParametersError(scanner()->peek_location(),
-                                                 message, arg);
+    Scanner::Location location = scanner()->peek_location();
+    GetUnexpectedTokenMessage(peek(), &message, &location, &arg);
+    classifier->RecordArrowFormalParametersError(location, message, arg);
   }
 
   void FormalParameterInitializerUnexpectedToken(
       ExpressionClassifier* classifier) {
     MessageTemplate::Template message = MessageTemplate::kUnexpectedToken;
     const char* arg;
-    GetUnexpectedTokenMessage(peek(), &message, &arg);
-    classifier->RecordFormalParameterInitializerError(
-        scanner()->peek_location(), message, arg);
+    Scanner::Location location = scanner()->peek_location();
+    GetUnexpectedTokenMessage(peek(), &message, &location, &arg);
+    classifier->RecordFormalParameterInitializerError(location, message, arg);
   }
 
   // Recursive descent functions:
@@ -962,10 +964,10 @@ ParserBase<Traits>::FunctionState::~FunctionState() {
   *function_state_stack_ = outer_function_state_;
 }
 
-
 template <class Traits>
 void ParserBase<Traits>::GetUnexpectedTokenMessage(
-    Token::Value token, MessageTemplate::Template* message, const char** arg,
+    Token::Value token, MessageTemplate::Template* message,
+    Scanner::Location* location, const char** arg,
     MessageTemplate::Template default_) {
   *arg = nullptr;
   switch (token) {
@@ -1002,7 +1004,12 @@ void ParserBase<Traits>::GetUnexpectedTokenMessage(
       *message = MessageTemplate::kInvalidEscapedReservedWord;
       break;
     case Token::ILLEGAL:
+      if (scanner()->has_error()) {
+        *message = scanner()->error();
+        *location = scanner()->error_location();
+      } else {
         *message = MessageTemplate::kInvalidOrUnexpectedToken;
+      }
       break;
     default:
       const char* name = Token::String(token);
@@ -1024,7 +1031,7 @@ void ParserBase<Traits>::ReportUnexpectedTokenAt(
     Scanner::Location source_location, Token::Value token,
     MessageTemplate::Template message) {
   const char* arg;
-  GetUnexpectedTokenMessage(token, &message, &arg);
+  GetUnexpectedTokenMessage(token, &message, &source_location, &arg);
   Traits::ReportMessageAt(source_location, message, arg);
 }
 

src/parsing/scanner.cc

@@ -61,15 +61,19 @@ void Scanner::Initialize(Utf16CharacterStream* source) {
   Scan();
 }
 
-
-template <bool capture_raw>
+template <bool capture_raw, bool unicode>
 uc32 Scanner::ScanHexNumber(int expected_length) {
   DCHECK(expected_length <= 4);  // prevent overflow
 
+  int begin = source_pos() - 2;
   uc32 x = 0;
   for (int i = 0; i < expected_length; i++) {
     int d = HexValue(c0_);
     if (d < 0) {
+      ReportScannerError(Location(begin, begin + expected_length + 2),
+                         unicode
+                             ? MessageTemplate::kInvalidUnicodeEscapeSequence
+                             : MessageTemplate::kInvalidHexEscapeSequence);
       return -1;
     }
     x = x * 16 + d;
@@ -79,20 +83,23 @@ uc32 Scanner::ScanHexNumber(int expected_length) {
   return x;
 }
 
-
 template <bool capture_raw>
-uc32 Scanner::ScanUnlimitedLengthHexNumber(int max_value) {
+uc32 Scanner::ScanUnlimitedLengthHexNumber(int max_value, int beg_pos) {
   uc32 x = 0;
   int d = HexValue(c0_);
-  if (d < 0) {
-    return -1;
-  }
+  if (d < 0) return -1;
+
   while (d >= 0) {
     x = x * 16 + d;
-    if (x > max_value) return -1;
+    if (x > max_value) {
+      ReportScannerError(Location(beg_pos, source_pos() + 1),
+                         MessageTemplate::kUndefinedUnicodeCodePoint);
+      return -1;
+    }
     Advance<capture_raw>();
     d = HexValue(c0_);
   }
+
   return x;
 }
 
@@ -855,7 +862,9 @@ Token::Value Scanner::ScanString() {
     uc32 c = c0_;
     Advance();
     if (c == '\\') {
-      if (c0_ < 0 || !ScanEscape<false, false>()) return Token::ILLEGAL;
+      if (c0_ < 0 || !ScanEscape<false, false>()) {
+        return Token::ILLEGAL;
+      }
     } else {
       AddLiteralChar(c);
     }
@@ -887,7 +896,6 @@ Token::Value Scanner::ScanTemplateSpan() {
   StartRawLiteral();
   const bool capture_raw = true;
   const bool in_template_literal = true;
-
   while (true) {
     uc32 c = c0_;
     Advance<capture_raw>();
@@ -1107,18 +1115,19 @@ uc32 Scanner::ScanUnicodeEscape() {
   // Accept both \uxxxx and \u{xxxxxx}. In the latter case, the number of
   // hex digits between { } is arbitrary. \ and u have already been read.
   if (c0_ == '{') {
+    int begin = source_pos() - 2;
     Advance<capture_raw>();
-    uc32 cp = ScanUnlimitedLengthHexNumber<capture_raw>(0x10ffff);
-    if (cp < 0) {
-      return -1;
-    }
-    if (c0_ != '}') {
+    uc32 cp = ScanUnlimitedLengthHexNumber<capture_raw>(0x10ffff, begin);
+    if (cp < 0 || c0_ != '}') {
+      ReportScannerError(source_pos(),
+                         MessageTemplate::kInvalidUnicodeEscapeSequence);
       return -1;
     }
     Advance<capture_raw>();
     return cp;
   }
-  return ScanHexNumber<capture_raw>(4);
+  const bool unicode = true;
+  return ScanHexNumber<capture_raw, unicode>(4);
 }
 
 

src/parsing/scanner.h

@@ -14,6 +14,7 @@
 #include "src/globals.h"
 #include "src/hashmap.h"
 #include "src/list.h"
+#include "src/messages.h"
 #include "src/parsing/token.h"
 #include "src/unicode.h"
 #include "src/unicode-decoder.h"
@@ -354,6 +355,10 @@ class Scanner {
   // (the token last returned by Next()).
   Location location() const { return current_.location; }
 
+  bool has_error() const { return scanner_error_ != MessageTemplate::kNone; }
+  MessageTemplate::Template error() const { return scanner_error_; }
+  Location error_location() const { return scanner_error_location_; }
+
   // Similar functions for the upcoming token.
 
   // One token look-ahead (past the token returned by Next()).
@@ -482,6 +487,7 @@ class Scanner {
     current_.raw_literal_chars = NULL;
     next_next_.token = Token::UNINITIALIZED;
     found_html_comment_ = false;
+    scanner_error_ = MessageTemplate::kNone;
   }
 
   // Support BookmarkScope functionality.
@@ -492,6 +498,19 @@ class Scanner {
   void DropBookmark();
   static void CopyTokenDesc(TokenDesc* to, TokenDesc* from);
 
+  void ReportScannerError(const Location& location,
+                          MessageTemplate::Template error) {
+    if (has_error()) return;
+    scanner_error_ = error;
+    scanner_error_location_ = location;
+  }
+
+  void ReportScannerError(int pos, MessageTemplate::Template error) {
+    if (has_error()) return;
+    scanner_error_ = error;
+    scanner_error_location_ = Location(pos, pos + 1);
+  }
+
   // Literal buffer support
   inline void StartLiteral() {
     LiteralBuffer* free_buffer =
@@ -637,13 +656,13 @@ class Scanner {
     return current_.raw_literal_chars->is_one_byte();
   }
 
-  template <bool capture_raw>
+  template <bool capture_raw, bool unicode = false>
   uc32 ScanHexNumber(int expected_length);
   // Scan a number of any length but not bigger than max_value. For example, the
   // number can be 000000001, so it's very long in characters but its value is
   // small.
   template <bool capture_raw>
-  uc32 ScanUnlimitedLengthHexNumber(int max_value);
+  uc32 ScanUnlimitedLengthHexNumber(int max_value, int beg_pos);
 
   // Scans a single JavaScript token.
   void Scan();
@@ -766,6 +785,9 @@ class Scanner {
   bool found_html_comment_;
 
   bool allow_harmony_exponentiation_operator_;
+
+  MessageTemplate::Template scanner_error_;
+  Location scanner_error_location_;
 };
 
 }  // namespace internal

test/message/regress/regress-4829-1.out

@@ -2,7 +2,7 @@
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
-*%(basename)s:7: SyntaxError: Invalid or unexpected token
+*%(basename)s:7: SyntaxError: Invalid hexadecimal escape sequence
 tag(tag`\xyy`);
-       ^^^
-SyntaxError: Invalid or unexpected token
\ No newline at end of file
+        ^^^^
+SyntaxError: Invalid hexadecimal escape sequence

test/message/regress/regress-4829-2.out

@@ -2,7 +2,7 @@
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
-*%(basename)s:7: SyntaxError: Invalid or unexpected token
+*%(basename)s:7: SyntaxError: Invalid hexadecimal escape sequence
 `${tag`\xyy`}`;
-      ^^^
-SyntaxError: Invalid or unexpected token
\ No newline at end of file
+       ^^^^
+SyntaxError: Invalid hexadecimal escape sequence

test/message/unicode-escape-invalid-2.js

+// Copyright 2016 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.
+
+print("\u162P");

test/message/unicode-escape-invalid-2.out

+# Copyright 2016 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.
+
+*%(basename)s:5: SyntaxError: Invalid Unicode escape sequence
+print("\u162P");
+       ^^^^^^
+SyntaxError: Invalid Unicode escape sequence

test/message/unicode-escape-invalid.js

+// Copyright 2016 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.
+
+print("\u{FFYZ}");

test/message/unicode-escape-invalid.out

+# Copyright 2016 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.
+
+*%(basename)s:5: SyntaxError: Invalid Unicode escape sequence
+print("\u{FFYZ}");
+            ^
+SyntaxError: Invalid Unicode escape sequence

test/message/unicode-escape-undefined.js

+// Copyright 2016 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.
+
+print("\u{110000}");

test/message/unicode-escape-undefined.out

+# Copyright 2016 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.
+
+*%(basename)s:5: SyntaxError: Undefined Unicode code-point
+print("\u{110000}");
+       ^^^^^^^^^
+SyntaxError: Undefined Unicode code-point
\ No newline at end of file