Port parser and scanner fixes from rasta branch.

pkg/front_end/lib/src/fasta/scanner/error_token.dart

Index: pkg/front_end/lib/src/fasta/scanner/error_token.dart
diff --git a/pkg/front_end/lib/src/fasta/scanner/error_token.dart b/pkg/front_end/lib/src/fasta/scanner/error_token.dart
new file mode 100644
index 0000000000000000000000000000000000000000..97579b0a9be20dc12665dfef54f14d7edb5f1410
--- /dev/null
+++ b/pkg/front_end/lib/src/fasta/scanner/error_token.dart
@@ -0,0 +1,219 @@
+// Copyright (c) 2017, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style licenset hat can be found in the LICENSE file.
+
+library dart_scanner.error_token;
+
+// TODO(ahe): ErrorKind doesn't belong in dart_parser. Move to compiler_util or
+// this package?
+import '../parser/error_kind.dart' show
+    ErrorKind;
+
+import '../scanner.dart' show
+    BeginGroupToken,
+    Token,
+    unicodeReplacementCharacter;
+
+import 'precedence.dart' show
+    BAD_INPUT_INFO,
+    PrecedenceInfo;
+
+export '../parser/error_kind.dart' show
+    ErrorKind;
+
+ErrorToken buildUnexpectedCharacterToken(int character, int charOffset) {
+  if (character < 0x1f) {
+    return new AsciiControlCharacterToken(character, charOffset);
+  }
+  switch (character) {
+    case unicodeReplacementCharacter:
+      return new EncodingErrorToken(charOffset);
+
+      /// See [General Punctuation]
+      /// (http://www.unicode.org/charts/PDF/U2000.pdf).
+    case 0x00A0: // No-break space.
+    case 0x1680: // Ogham space mark.
+    case 0x180E: // Mongolian vowel separator.
+    case 0x2000: // En quad.
+    case 0x2001: // Em quad.
+    case 0x2002: // En space.
+    case 0x2003: // Em space.
+    case 0x2004: // Three-per-em space.
+    case 0x2005: // Four-per-em space.
+    case 0x2006: // Six-per-em space.
+    case 0x2007: // Figure space.
+    case 0x2008: // Punctuation space.
+    case 0x2009: // Thin space.
+    case 0x200A: // Hair space.
+    case 0x200B: // Zero width space.
+    case 0x2028: // Line separator.
+    case 0x2029: // Paragraph separator.
+    case 0x202F: // Narrow no-break space.
+    case 0x205F: // Medium mathematical space.
+    case 0x3000: // Ideographic space.
+    case 0xFEFF: // Zero width no-break space.
+      return new NonAsciiWhitespaceToken(character, charOffset);
+
+    default:
+      return new NonAsciiIdentifierToken(character, charOffset);
+  }
+}
+
+/// Common superclass for all error tokens.
+///
+/// It's considered an implementation error to access [value] of an
+/// [ErrorToken].
+abstract class ErrorToken extends Token {
+  ErrorToken(int charOffset) : super(charOffset);
+
+  PrecedenceInfo get info => BAD_INPUT_INFO;
+
+  String get value => throw assertionMessage;
+
+  String get stringValue => null;
+
+  bool isIdentifier() => false;
+
+  String get assertionMessage;
+
+  ErrorKind get errorCode;
+
+  int get character => null;
+
+  String get start => null;
+
+  int get endOffset => null;
+
+  BeginGroupToken get begin => null;
+}
+
+/// Represents an encoding error.
+class EncodingErrorToken extends ErrorToken {
+  EncodingErrorToken(int charOffset) : super(charOffset);
+
+  String toString() => "EncodingErrorToken()";
+
+  String get assertionMessage => "Unable to decode bytes as UTF-8.";
+
+  ErrorKind get errorCode => ErrorKind.Encoding;
+}
+
+/// Represents a non-ASCII character outside a string or comment.
+class NonAsciiIdentifierToken extends ErrorToken {
+  final int character;
+
+  NonAsciiIdentifierToken(this.character, int charOffset) : super(charOffset);
+
+  String toString() => "NonAsciiIdentifierToken($character)";
+
+  String get assertionMessage {
+    String c = new String.fromCharCodes([character]);
+    String hex = character.toRadixString(16);
+    String padding = "0000".substring(hex.length);
+    hex = "$padding$hex";
+    return
+        "The non-ASCII character '$c' (U+$hex) can't be used in identifiers,"
+        " only in strings and comments.\n"
+        "Try using an US-ASCII letter, a digit, '_' (an underscore),"
+        " or '\$' (a dollar sign).";
+  }
+
+  ErrorKind get errorCode => ErrorKind.NonAsciiIdentifier;
+}
+
+/// Represents a non-ASCII whitespace outside a string or comment.
+class NonAsciiWhitespaceToken extends ErrorToken {
+  final int character;
+
+  NonAsciiWhitespaceToken(this.character, int charOffset) : super(charOffset);
+
+  String toString() => "NonAsciiWhitespaceToken($character)";
+
+  String get assertionMessage {
+    String hex = character.toRadixString(16);
+    return "The non-ASCII space character U+$hex can only be used in strings "
+        "and comments.";
+  }
+
+  ErrorKind get errorCode => ErrorKind.NonAsciiWhitespace;
+}
+
+/// Represents an ASCII control character outside a string or comment.
+class AsciiControlCharacterToken extends ErrorToken {
+  final int character;
+
+  AsciiControlCharacterToken(this.character, int charOffset)
+      : super(charOffset);
+
+  String toString() => "AsciiControlCharacterToken($character)";
+
+  String get assertionMessage {
+    String hex = character.toRadixString(16);
+    return "The control character U+$hex can only be used in strings and "
+        "comments.";
+  }
+
+  ErrorKind get errorCode => ErrorKind.AsciiControlCharacter;
+}
+
+/// Represents an unterminated string.
+class UnterminatedToken extends ErrorToken {
+  final String start;
+  final int endOffset;
+
+  UnterminatedToken(this.start, int charOffset, this.endOffset)
+      : super(charOffset);
+
+  String toString() => "UnterminatedToken($start)";
+
+  String get assertionMessage => "'$start' isn't terminated.";
+
+  int get charCount => endOffset - charOffset;
+
+  ErrorKind get errorCode {
+    switch (start) {
+      case '1e':
+        return ErrorKind.MissingExponent;
+
+      case '"':
+      case "'":
+      case '"""':
+      case "'''":
+      case 'r"':
+      case "r'":
+      case 'r"""':
+      case "r'''":
+        return ErrorKind.UnterminatedString;
+
+      case '0x':
+        return ErrorKind.ExpectedHexDigit;
+
+      case r'$':
+        return ErrorKind.UnexpectedDollarInString;
+
+      case '/*':
+        return ErrorKind.UnterminatedComment;
+
+      default:
+        return ErrorKind.UnterminatedToken;
+    }
+  }
+}
+
+/// Represents an open brace without a matching close brace.
+///
+/// In this case, brace means any of `(`, `{`, `[`, and `<`, parenthesis, curly
+/// brace, square brace, and angle brace, respectively.
+class UnmatchedToken extends ErrorToken {
+  final BeginGroupToken begin;
+
+  UnmatchedToken(BeginGroupToken begin)
+      : this.begin = begin,
+        super(begin.charOffset);
+
+  String toString() => "UnmatchedToken(${begin.value})";
+
+  String get assertionMessage => "'$begin' isn't closed.";
+
+  ErrorKind get errorCode => ErrorKind.UnmatchedToken;
+}