Use packages dart_parser, dart_scanner, and compiler_util.

pkg/compiler/lib/src/scanner/scanner.dart

Index: pkg/compiler/lib/src/scanner/scanner.dart
diff --git a/pkg/compiler/lib/src/scanner/scanner.dart b/pkg/compiler/lib/src/scanner/scanner.dart
deleted file mode 100644
index f0698611482b302293d982b6bccd4f5b91af214a..0000000000000000000000000000000000000000
--- a/pkg/compiler/lib/src/scanner/scanner.dart
+++ /dev/null
@@ -1,1187 +0,0 @@
-// Copyright (c) 2012, 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 license that can be found in the LICENSE file.
-
-library dart2js.scanner;
-
-import '../io/source_file.dart' show SourceFile, Utf8BytesSourceFile;
-import '../tokens/keyword.dart' show Keyword, KeywordState;
-import '../tokens/precedence.dart';
-import '../tokens/precedence_constants.dart';
-import '../tokens/token.dart';
-import '../tokens/token_constants.dart';
-import '../util/characters.dart';
-import 'string_scanner.dart' show StringScanner;
-import 'utf8_bytes_scanner.dart' show Utf8BytesScanner;
-
-abstract class Scanner {
-  Token tokenize();
-
-  factory Scanner(SourceFile file, {bool includeComments: false}) {
-    if (file is Utf8BytesSourceFile) {
-      return new Utf8BytesScanner(file, includeComments: includeComments);
-    } else {
-      return new StringScanner(file, includeComments: includeComments);
-    }
-  }
-}
-
-abstract class AbstractScanner implements Scanner {
-  // TODO(ahe): Move this class to implementation.
-
-  final bool includeComments;
-
-  /**
-   * The string offset for the next token that will be created.
-   *
-   * Note that in the [Utf8BytesScanner], [stringOffset] and [scanOffset] values
-   * are different. One string character can be encoded using multiple UTF-8
-   * bytes.
-   */
-  int tokenStart = -1;
-
-  /**
-   * A pointer to the token stream created by this scanner. The first token
-   * is a special token and not part of the source file. This is an
-   * implementation detail to avoids special cases in the scanner. This token
-   * is not exposed to clients of the scanner, which are expected to invoke
-   * [firstToken] to access the token stream.
-   */
-  final Token tokens = new SymbolToken(EOF_INFO, -1);
-
-  /**
-   * A pointer to the last scanned token.
-   */
-  Token tail;
-
-  /**
-   * The source file that is being scanned. This field can be [:null:].
-   * If the source file is available, the scanner assigns its [:lineStarts:] and
-   * [:length:] fields at the end of [tokenize].
-   */
-  final SourceFile file;
-
-  final List<int> lineStarts = <int>[0];
-
-  AbstractScanner(this.file, this.includeComments) {
-    this.tail = this.tokens;
-  }
-
-  /**
-   * Advances and returns the next character.
-   *
-   * If the next character is non-ASCII, then the returned value depends on the
-   * scanner implementation. The [Utf8BytesScanner] returns a UTF-8 byte, while
-   * the [StringScanner] returns a UTF-16 code unit.
-   *
-   * The scanner ensures that [advance] is not invoked after it returned [$EOF].
-   * This allows implementations to omit bound checks if the data structure ends
-   * with '0'.
-   */
-  int advance();
-
-  /**
-   * Returns the current unicode character.
-   *
-   * If the current character is ASCII, then it is returned unchanged.
-   *
-   * The [Utf8BytesScanner] decodes the next unicode code point starting at the
-   * current position. Note that every unicode character is returned as a single
-   * code point, that is, for '\u{1d11e}' it returns 119070, and the following
-   * [advance] returns the next character.
-   *
-   * The [StringScanner] returns the current character unchanged, which might
-   * be a surrogate character. In the case of '\u{1d11e}', it returns the first
-   * code unit 55348, and the following [advance] returns the second code unit
-   * 56606.
-   *
-   * Invoking [currentAsUnicode] multiple times is safe, i.e.,
-   * [:currentAsUnicode(next) == currentAsUnicode(currentAsUnicode(next)):].
-   */
-  int currentAsUnicode(int next);
-
-  /**
-   * Returns the character at the next poisition. Like in [advance], the
-   * [Utf8BytesScanner] returns a UTF-8 byte, while the [StringScanner] returns
-   * a UTF-16 code unit.
-   */
-  int peek();
-
-  /**
-   * Notifies the scanner that unicode characters were detected in either a
-   * comment or a string literal between [startScanOffset] and the current
-   * scan offset.
-   */
-  void handleUnicode(int startScanOffset);
-
-  /**
-   * Returns the current scan offset.
-   *
-   * In the [Utf8BytesScanner] this is the offset into the byte list, in the
-   * [StringScanner] the offset in the source string.
-   */
-  int get scanOffset;
-
-  /**
-   * Returns the current string offset.
-   *
-   * In the [StringScanner] this is identical to the [scanOffset]. In the
-   * [Utf8BytesScanner] it is computed based on encountered UTF-8 characters.
-   */
-  int get stringOffset;
-
-  /**
-   * Returns the first token scanned by this [Scanner].
-   */
-  Token firstToken();
-
-  /**
-   * Returns the last token scanned by this [Scanner].
-   */
-  Token previousToken();
-
-  /**
-   * Notifies that a new token starts at current offset.
-   */
-  void beginToken() {
-    tokenStart = stringOffset;
-  }
-
-  /**
-   * Appends a substring from the scan offset [:start:] to the current
-   * [:scanOffset:] plus the [:extraOffset:]. For example, if the current
-   * scanOffset is 10, then [:appendSubstringToken(5, -1):] will append the
-   * substring string [5,9).
-   *
-   * Note that [extraOffset] can only be used if the covered character(s) are
-   * known to be ASCII.
-   */
-  void appendSubstringToken(PrecedenceInfo info, int start, bool asciiOnly,
-      [int extraOffset]);
-
-  /** Documentation in subclass [ArrayBasedScanner]. */
-  void appendPrecedenceToken(PrecedenceInfo info);
-
-  /** Documentation in subclass [ArrayBasedScanner]. */
-  int select(int choice, PrecedenceInfo yes, PrecedenceInfo no);
-
-  /** Documentation in subclass [ArrayBasedScanner]. */
-  void appendKeywordToken(Keyword keyword);
-
-  /** Documentation in subclass [ArrayBasedScanner]. */
-  void appendEofToken();
-
-  /** Documentation in subclass [ArrayBasedScanner]. */
-  void appendWhiteSpace(int next);
-
-  /** Documentation in subclass [ArrayBasedScanner]. */
-  void lineFeedInMultiline();
-
-  /** Documentation in subclass [ArrayBasedScanner]. */
-  void appendBeginGroup(PrecedenceInfo info);
-
-  /** Documentation in subclass [ArrayBasedScanner]. */
-  int appendEndGroup(PrecedenceInfo info, int openKind);
-
-  /** Documentation in subclass [ArrayBasedScanner]. */
-  void appendGt(PrecedenceInfo info);
-
-  /** Documentation in subclass [ArrayBasedScanner]. */
-  void appendGtGt(PrecedenceInfo info);
-
-  /** Documentation in subclass [ArrayBasedScanner]. */
-  void appendComment(start, bool asciiOnly);
-
-  /// Append [token] to the token stream.
-  void appendErrorToken(ErrorToken token);
-
-  /** Documentation in subclass [ArrayBasedScanner]. */
-  void discardOpenLt();
-
-  /// Return true when at EOF.
-  bool atEndOfFile();
-
-  Token tokenize() {
-    while (!atEndOfFile()) {
-      int next = advance();
-      while (!identical(next, $EOF)) {
-        next = bigSwitch(next);
-      }
-      if (atEndOfFile()) {
-        appendEofToken();
-      } else {
-        unexpected($EOF);
-      }
-    }
-
-    if (file != null) {
-      file.length = stringOffset;
-      // One additional line start at the end, see [SourceFile.lineStarts].
-      lineStarts.add(stringOffset + 1);
-      file.lineStarts = lineStarts;
-    }
-
-    return firstToken();
-  }
-
-  int bigSwitch(int next) {
-    beginToken();
-    if (identical(next, $SPACE) ||
-        identical(next, $TAB) ||
-        identical(next, $LF) ||
-        identical(next, $CR)) {
-      appendWhiteSpace(next);
-      next = advance();
-      // Sequences of spaces are common, so advance through them fast.
-      while (identical(next, $SPACE)) {
-        // We don't invoke [:appendWhiteSpace(next):] here for efficiency,
-        // assuming that it does not do anything for space characters.
-        next = advance();
-      }
-      return next;
-    }
-
-    if ($a <= next && next <= $z) {
-      if (identical($r, next)) {
-        return tokenizeRawStringKeywordOrIdentifier(next);
-      }
-      return tokenizeKeywordOrIdentifier(next, true);
-    }
-
-    if (($A <= next && next <= $Z) ||
-        identical(next, $_) ||
-        identical(next, $$)) {
-      return tokenizeIdentifier(next, scanOffset, true);
-    }
-
-    if (identical(next, $LT)) {
-      return tokenizeLessThan(next);
-    }
-
-    if (identical(next, $GT)) {
-      return tokenizeGreaterThan(next);
-    }
-
-    if (identical(next, $EQ)) {
-      return tokenizeEquals(next);
-    }
-
-    if (identical(next, $BANG)) {
-      return tokenizeExclamation(next);
-    }
-
-    if (identical(next, $PLUS)) {
-      return tokenizePlus(next);
-    }
-
-    if (identical(next, $MINUS)) {
-      return tokenizeMinus(next);
-    }
-
-    if (identical(next, $STAR)) {
-      return tokenizeMultiply(next);
-    }
-
-    if (identical(next, $PERCENT)) {
-      return tokenizePercent(next);
-    }
-
-    if (identical(next, $AMPERSAND)) {
-      return tokenizeAmpersand(next);
-    }
-
-    if (identical(next, $BAR)) {
-      return tokenizeBar(next);
-    }
-
-    if (identical(next, $CARET)) {
-      return tokenizeCaret(next);
-    }
-
-    if (identical(next, $OPEN_SQUARE_BRACKET)) {
-      return tokenizeOpenSquareBracket(next);
-    }
-
-    if (identical(next, $TILDE)) {
-      return tokenizeTilde(next);
-    }
-
-    if (identical(next, $BACKSLASH)) {
-      appendPrecedenceToken(BACKSLASH_INFO);
-      return advance();
-    }
-
-    if (identical(next, $HASH)) {
-      return tokenizeTag(next);
-    }
-
-    if (identical(next, $OPEN_PAREN)) {
-      appendBeginGroup(OPEN_PAREN_INFO);
-      return advance();
-    }
-
-    if (identical(next, $CLOSE_PAREN)) {
-      return appendEndGroup(CLOSE_PAREN_INFO, OPEN_PAREN_TOKEN);
-    }
-
-    if (identical(next, $COMMA)) {
-      appendPrecedenceToken(COMMA_INFO);
-      return advance();
-    }
-
-    if (identical(next, $COLON)) {
-      appendPrecedenceToken(COLON_INFO);
-      return advance();
-    }
-
-    if (identical(next, $SEMICOLON)) {
-      appendPrecedenceToken(SEMICOLON_INFO);
-      // Type parameters and arguments cannot contain semicolon.
-      discardOpenLt();
-      return advance();
-    }
-
-    if (identical(next, $QUESTION)) {
-      return tokenizeQuestion(next);
-    }
-
-    if (identical(next, $CLOSE_SQUARE_BRACKET)) {
-      return appendEndGroup(
-          CLOSE_SQUARE_BRACKET_INFO, OPEN_SQUARE_BRACKET_TOKEN);
-    }
-
-    if (identical(next, $BACKPING)) {
-      appendPrecedenceToken(BACKPING_INFO);
-      return advance();
-    }
-
-    if (identical(next, $OPEN_CURLY_BRACKET)) {
-      appendBeginGroup(OPEN_CURLY_BRACKET_INFO);
-      return advance();
-    }
-
-    if (identical(next, $CLOSE_CURLY_BRACKET)) {
-      return appendEndGroup(CLOSE_CURLY_BRACKET_INFO, OPEN_CURLY_BRACKET_TOKEN);
-    }
-
-    if (identical(next, $SLASH)) {
-      return tokenizeSlashOrComment(next);
-    }
-
-    if (identical(next, $AT)) {
-      return tokenizeAt(next);
-    }
-
-    if (identical(next, $DQ) || identical(next, $SQ)) {
-      return tokenizeString(next, scanOffset, false);
-    }
-
-    if (identical(next, $PERIOD)) {
-      return tokenizeDotsOrNumber(next);
-    }
-
-    if (identical(next, $0)) {
-      return tokenizeHexOrNumber(next);
-    }
-
-    // TODO(ahe): Would a range check be faster?
-    if (identical(next, $1) ||
-        identical(next, $2) ||
-        identical(next, $3) ||
-        identical(next, $4) ||
-        identical(next, $5) ||
-        identical(next, $6) ||
-        identical(next, $7) ||
-        identical(next, $8) ||
-        identical(next, $9)) {
-      return tokenizeNumber(next);
-    }
-
-    if (identical(next, $EOF)) {
-      return $EOF;
-    }
-    if (next < 0x1f) {
-      return unexpected(next);
-    }
-
-    next = currentAsUnicode(next);
-
-    // The following are non-ASCII characters.
-
-    if (identical(next, $NBSP)) {
-      appendWhiteSpace(next);
-      return advance();
-    }
-
-    return unexpected(next);
-  }
-
-  int tokenizeTag(int next) {
-    // # or #!.*[\n\r]
-    if (scanOffset == 0) {
-      if (identical(peek(), $BANG)) {
-        int start = scanOffset + 1;
-        bool asciiOnly = true;
-        do {
-          next = advance();
-          if (next > 127) asciiOnly = false;
-        } while (!identical(next, $LF) &&
-            !identical(next, $CR) &&
-            !identical(next, $EOF));
-        if (!asciiOnly) handleUnicode(start);
-        return next;
-      }
-    }
-    appendPrecedenceToken(HASH_INFO);
-    return advance();
-  }
-
-  int tokenizeTilde(int next) {
-    // ~ ~/ ~/=
-    next = advance();
-    if (identical(next, $SLASH)) {
-      return select($EQ, TILDE_SLASH_EQ_INFO, TILDE_SLASH_INFO);
-    } else {
-      appendPrecedenceToken(TILDE_INFO);
-      return next;
-    }
-  }
-
-  int tokenizeOpenSquareBracket(int next) {
-    // [ [] []=
-    next = advance();
-    if (identical(next, $CLOSE_SQUARE_BRACKET)) {
-      Token token = previousToken();
-      if (token is KeywordToken && token.keyword.syntax == 'operator' ||
-          token is SymbolToken && token.info == HASH_INFO) {
-        return select($EQ, INDEX_EQ_INFO, INDEX_INFO);
-      }
-    }
-    appendBeginGroup(OPEN_SQUARE_BRACKET_INFO);
-    return next;
-  }
-
-  int tokenizeCaret(int next) {
-    // ^ ^=
-    return select($EQ, CARET_EQ_INFO, CARET_INFO);
-  }
-
-  int tokenizeQuestion(int next) {
-    // ? ?. ?? ??=
-    next = advance();
-    if (identical(next, $QUESTION)) {
-      return select($EQ, QUESTION_QUESTION_EQ_INFO, QUESTION_QUESTION_INFO);
-    } else if (identical(next, $PERIOD)) {
-      appendPrecedenceToken(QUESTION_PERIOD_INFO);
-      return advance();
-    } else {
-      appendPrecedenceToken(QUESTION_INFO);
-      return next;
-    }
-  }
-
-  int tokenizeBar(int next) {
-    // | || |=
-    next = advance();
-    if (identical(next, $BAR)) {
-      appendPrecedenceToken(BAR_BAR_INFO);
-      return advance();
-    } else if (identical(next, $EQ)) {
-      appendPrecedenceToken(BAR_EQ_INFO);
-      return advance();
-    } else {
-      appendPrecedenceToken(BAR_INFO);
-      return next;
-    }
-  }
-
-  int tokenizeAmpersand(int next) {
-    // && &= &
-    next = advance();
-    if (identical(next, $AMPERSAND)) {
-      appendPrecedenceToken(AMPERSAND_AMPERSAND_INFO);
-      return advance();
-    } else if (identical(next, $EQ)) {
-      appendPrecedenceToken(AMPERSAND_EQ_INFO);
-      return advance();
-    } else {
-      appendPrecedenceToken(AMPERSAND_INFO);
-      return next;
-    }
-  }
-
-  int tokenizePercent(int next) {
-    // % %=
-    return select($EQ, PERCENT_EQ_INFO, PERCENT_INFO);
-  }
-
-  int tokenizeMultiply(int next) {
-    // * *=
-    return select($EQ, STAR_EQ_INFO, STAR_INFO);
-  }
-
-  int tokenizeMinus(int next) {
-    // - -- -=
-    next = advance();
-    if (identical(next, $MINUS)) {
-      appendPrecedenceToken(MINUS_MINUS_INFO);
-      return advance();
-    } else if (identical(next, $EQ)) {
-      appendPrecedenceToken(MINUS_EQ_INFO);
-      return advance();
-    } else {
-      appendPrecedenceToken(MINUS_INFO);
-      return next;
-    }
-  }
-
-  int tokenizePlus(int next) {
-    // + ++ +=
-    next = advance();
-    if (identical($PLUS, next)) {
-      appendPrecedenceToken(PLUS_PLUS_INFO);
-      return advance();
-    } else if (identical($EQ, next)) {
-      appendPrecedenceToken(PLUS_EQ_INFO);
-      return advance();
-    } else {
-      appendPrecedenceToken(PLUS_INFO);
-      return next;
-    }
-  }
-
-  int tokenizeExclamation(int next) {
-    // ! !=
-    // !== is kept for user-friendly error reporting.
-
-    next = advance();
-    if (identical(next, $EQ)) {
-      return select($EQ, BANG_EQ_EQ_INFO, BANG_EQ_INFO);
-    }
-    appendPrecedenceToken(BANG_INFO);
-    return next;
-  }
-
-  int tokenizeEquals(int next) {
-    // = == =>
-    // === is kept for user-friendly error reporting.
-
-    // Type parameters and arguments cannot contain any token that
-    // starts with '='.
-    discardOpenLt();
-
-    next = advance();
-    if (identical(next, $EQ)) {
-      return select($EQ, EQ_EQ_EQ_INFO, EQ_EQ_INFO);
-    } else if (identical(next, $GT)) {
-      appendPrecedenceToken(FUNCTION_INFO);
-      return advance();
-    }
-    appendPrecedenceToken(EQ_INFO);
-    return next;
-  }
-
-  int tokenizeGreaterThan(int next) {
-    // > >= >> >>=
-    next = advance();
-    if (identical($EQ, next)) {
-      appendPrecedenceToken(GT_EQ_INFO);
-      return advance();
-    } else if (identical($GT, next)) {
-      next = advance();
-      if (identical($EQ, next)) {
-        appendPrecedenceToken(GT_GT_EQ_INFO);
-        return advance();
-      } else {
-        appendGtGt(GT_GT_INFO);
-        return next;
-      }
-    } else {
-      appendGt(GT_INFO);
-      return next;
-    }
-  }
-
-  int tokenizeLessThan(int next) {
-    // < <= << <<=
-    next = advance();
-    if (identical($EQ, next)) {
-      appendPrecedenceToken(LT_EQ_INFO);
-      return advance();
-    } else if (identical($LT, next)) {
-      return select($EQ, LT_LT_EQ_INFO, LT_LT_INFO);
-    } else {
-      appendBeginGroup(LT_INFO);
-      return next;
-    }
-  }
-
-  int tokenizeNumber(int next) {
-    int start = scanOffset;
-    while (true) {
-      next = advance();
-      if ($0 <= next && next <= $9) {
-        continue;
-      } else if (identical(next, $e) || identical(next, $E)) {
-        return tokenizeFractionPart(next, start);
-      } else {
-        if (identical(next, $PERIOD)) {
-          int nextnext = peek();
-          if ($0 <= nextnext && nextnext <= $9) {
-            return tokenizeFractionPart(advance(), start);
-          }
-        }
-        appendSubstringToken(INT_INFO, start, true);
-        return next;
-      }
-    }
-    return null;
-  }
-
-  int tokenizeHexOrNumber(int next) {
-    int x = peek();
-    if (identical(x, $x) || identical(x, $X)) {
-      return tokenizeHex(next);
-    }
-    return tokenizeNumber(next);
-  }
-
-  int tokenizeHex(int next) {
-    int start = scanOffset;
-    next = advance(); // Advance past the $x or $X.
-    bool hasDigits = false;
-    while (true) {
-      next = advance();
-      if (($0 <= next && next <= $9) ||
-          ($A <= next && next <= $F) ||
-          ($a <= next && next <= $f)) {
-        hasDigits = true;
-      } else {
-        if (!hasDigits) {
-          unterminated('0x', shouldAdvance: false);
-          return next;
-        }
-        appendSubstringToken(HEXADECIMAL_INFO, start, true);
-        return next;
-      }
-    }
-    return null;
-  }
-
-  int tokenizeDotsOrNumber(int next) {
-    int start = scanOffset;
-    next = advance();
-    if (($0 <= next && next <= $9)) {
-      return tokenizeFractionPart(next, start);
-    } else if (identical($PERIOD, next)) {
-      return select($PERIOD, PERIOD_PERIOD_PERIOD_INFO, PERIOD_PERIOD_INFO);
-    } else {
-      appendPrecedenceToken(PERIOD_INFO);
-      return next;
-    }
-  }
-
-  int tokenizeFractionPart(int next, int start) {
-    bool done = false;
-    bool hasDigit = false;
-    LOOP:
-    while (!done) {
-      if ($0 <= next && next <= $9) {
-        hasDigit = true;
-      } else if (identical($e, next) || identical($E, next)) {
-        hasDigit = true;
-        next = advance();
-        if (identical(next, $PLUS) || identical(next, $MINUS)) {
-          next = advance();
-        }
-        bool hasExponentDigits = false;
-        while (true) {
-          if ($0 <= next && next <= $9) {
-            hasExponentDigits = true;
-          } else {
-            if (!hasExponentDigits) {
-              unterminated('1e', shouldAdvance: false);
-              return next;
-            }
-            break;
-          }
-          next = advance();
-        }
-
-        done = true;
-        continue LOOP;
-      } else {
-        done = true;
-        continue LOOP;
-      }
-      next = advance();
-    }
-    if (!hasDigit) {
-      // Reduce offset, we already advanced to the token past the period.
-      appendSubstringToken(INT_INFO, start, true, -1);
-
-      // TODO(ahe): Wrong offset for the period. Cannot call beginToken because
-      // the scanner already advanced past the period.
-      if (identical($PERIOD, next)) {
-        return select($PERIOD, PERIOD_PERIOD_PERIOD_INFO, PERIOD_PERIOD_INFO);
-      }
-      appendPrecedenceToken(PERIOD_INFO);
-      return next;
-    }
-    appendSubstringToken(DOUBLE_INFO, start, true);
-    return next;
-  }
-
-  int tokenizeSlashOrComment(int next) {
-    int start = scanOffset;
-    next = advance();
-    if (identical($STAR, next)) {
-      return tokenizeMultiLineComment(next, start);
-    } else if (identical($SLASH, next)) {
-      return tokenizeSingleLineComment(next, start);
-    } else if (identical($EQ, next)) {
-      appendPrecedenceToken(SLASH_EQ_INFO);
-      return advance();
-    } else {
-      appendPrecedenceToken(SLASH_INFO);
-      return next;
-    }
-  }
-
-  int tokenizeSingleLineComment(int next, int start) {
-    bool asciiOnly = true;
-    while (true) {
-      next = advance();
-      if (next > 127) asciiOnly = false;
-      if (identical($LF, next) ||
-          identical($CR, next) ||
-          identical($EOF, next)) {
-        if (!asciiOnly) handleUnicode(start);
-        appendComment(start, asciiOnly);
-        return next;
-      }
-    }
-    return null;
-  }
-
-  int tokenizeMultiLineComment(int next, int start) {
-    bool asciiOnlyComment = true; // Track if the entire comment is ASCII.
-    bool asciiOnlyLines = true; // Track ASCII since the last handleUnicode.
-    int unicodeStart = start;
-    int nesting = 1;
-    next = advance();
-    while (true) {
-      if (identical($EOF, next)) {
-        if (!asciiOnlyLines) handleUnicode(unicodeStart);
-        unterminated('/*');
-        break;
-      } else if (identical($STAR, next)) {
-        next = advance();
-        if (identical($SLASH, next)) {
-          --nesting;
-          if (0 == nesting) {
-            if (!asciiOnlyLines) handleUnicode(unicodeStart);
-            next = advance();
-            appendComment(start, asciiOnlyComment);
-            break;
-          } else {
-            next = advance();
-          }
-        }
-      } else if (identical($SLASH, next)) {
-        next = advance();
-        if (identical($STAR, next)) {
-          next = advance();
-          ++nesting;
-        }
-      } else if (identical(next, $LF)) {
-        if (!asciiOnlyLines) {
-          // Synchronize the string offset in the utf8 scanner.
-          handleUnicode(unicodeStart);
-          asciiOnlyLines = true;
-          unicodeStart = scanOffset;
-        }
-        lineFeedInMultiline();
-        next = advance();
-      } else {
-        if (next > 127) {
-          asciiOnlyLines = false;
-          asciiOnlyComment = false;
-        }
-        next = advance();
-      }
-    }
-    return next;
-  }
-
-  int tokenizeRawStringKeywordOrIdentifier(int next) {
-    // [next] is $r.
-    int nextnext = peek();
-    if (identical(nextnext, $DQ) || identical(nextnext, $SQ)) {
-      int start = scanOffset;
-      next = advance();
-      return tokenizeString(next, start, true);
-    }
-    return tokenizeKeywordOrIdentifier(next, true);
-  }
-
-  int tokenizeKeywordOrIdentifier(int next, bool allowDollar) {
-    KeywordState state = KeywordState.KEYWORD_STATE;
-    int start = scanOffset;
-    while (state != null && $a <= next && next <= $z) {
-      state = state.next(next);
-      next = advance();
-    }
-    if (state == null || state.keyword == null) {
-      return tokenizeIdentifier(next, start, allowDollar);
-    }
-    if (($A <= next && next <= $Z) ||
-        ($0 <= next && next <= $9) ||
-        identical(next, $_) ||
-        identical(next, $$)) {
-      return tokenizeIdentifier(next, start, allowDollar);
-    } else {
-      appendKeywordToken(state.keyword);
-      return next;
-    }
-  }
-
-  /**
-   * [allowDollar] can exclude '$', which is not allowed as part of a string
-   * interpolation identifier.
-   */
-  int tokenizeIdentifier(int next, int start, bool allowDollar) {
-    while (true) {
-      if (($a <= next && next <= $z) ||
-          ($A <= next && next <= $Z) ||
-          ($0 <= next && next <= $9) ||
-          identical(next, $_) ||
-          (identical(next, $$) && allowDollar)) {
-        next = advance();
-      } else {
-        // Identifier ends here.
-        if (start == scanOffset) {
-          return unexpected(next);
-        } else {
-          appendSubstringToken(IDENTIFIER_INFO, start, true);
-        }
-        break;
-      }
-    }
-    return next;
-  }
-
-  int tokenizeAt(int next) {
-    appendPrecedenceToken(AT_INFO);
-    return advance();
-  }
-
-  int tokenizeString(int next, int start, bool raw) {
-    int quoteChar = next;
-    next = advance();
-    if (identical(quoteChar, next)) {
-      next = advance();
-      if (identical(quoteChar, next)) {
-        // Multiline string.
-        return tokenizeMultiLineString(quoteChar, start, raw);
-      } else {
-        // Empty string.
-        appendSubstringToken(STRING_INFO, start, true);
-        return next;
-      }
-    }
-    if (raw) {
-      return tokenizeSingleLineRawString(next, quoteChar, start);
-    } else {
-      return tokenizeSingleLineString(next, quoteChar, start);
-    }
-  }
-
-  /**
-   * [next] is the first character after the quote.
-   * [start] is the scanOffset of the quote.
-   *
-   * The token contains a substring of the source file, including the
-   * string quotes, backslashes for escaping. For interpolated strings,
-   * the parts before and after are separate tokens.
-   *
-   *   "a $b c"
-   *
-   * gives StringToken("a $), StringToken(b) and StringToken( c").
-   */
-  int tokenizeSingleLineString(int next, int quoteChar, int start) {
-    bool asciiOnly = true;
-    while (!identical(next, quoteChar)) {
-      if (identical(next, $BACKSLASH)) {
-        next = advance();
-      } else if (identical(next, $$)) {
-        if (!asciiOnly) handleUnicode(start);
-        next = tokenizeStringInterpolation(start, asciiOnly);
-        start = scanOffset;
-        asciiOnly = true;
-        continue;
-      }
-      if (next <= $CR &&
-          (identical(next, $LF) ||
-              identical(next, $CR) ||
-              identical(next, $EOF))) {
-        if (!asciiOnly) handleUnicode(start);
-        return unterminatedString(quoteChar);
-      }
-      if (next > 127) asciiOnly = false;
-      next = advance();
-    }
-    if (!asciiOnly) handleUnicode(start);
-    // Advance past the quote character.
-    next = advance();
-    appendSubstringToken(STRING_INFO, start, asciiOnly);
-    return next;
-  }
-
-  int tokenizeStringInterpolation(int start, bool asciiOnly) {
-    appendSubstringToken(STRING_INFO, start, asciiOnly);
-    beginToken(); // $ starts here.
-    int next = advance();
-    if (identical(next, $OPEN_CURLY_BRACKET)) {
-      return tokenizeInterpolatedExpression(next);
-    } else {
-      return tokenizeInterpolatedIdentifier(next);
-    }
-  }
-
-  int tokenizeInterpolatedExpression(int next) {
-    appendBeginGroup(STRING_INTERPOLATION_INFO);
-    beginToken(); // The expression starts here.
-    next = advance(); // Move past the curly bracket.
-    while (!identical(next, $EOF) && !identical(next, $STX)) {
-      next = bigSwitch(next);
-    }
-    if (identical(next, $EOF)) return next;
-    next = advance(); // Move past the $STX.
-    beginToken(); // The string interpolation suffix starts here.
-    return next;
-  }
-
-  int tokenizeInterpolatedIdentifier(int next) {
-    appendPrecedenceToken(STRING_INTERPOLATION_IDENTIFIER_INFO);
-
-    if ($a <= next && next <= $z) {
-      beginToken(); // The identifier starts here.
-      next = tokenizeKeywordOrIdentifier(next, false);
-    } else if (($A <= next && next <= $Z) || identical(next, $_)) {
-      beginToken(); // The identifier starts here.
-      next = tokenizeIdentifier(next, scanOffset, false);
-    } else {
-      unterminated(r'$', shouldAdvance: false);
-    }
-    beginToken(); // The string interpolation suffix starts here.
-    return next;
-  }
-
-  int tokenizeSingleLineRawString(int next, int quoteChar, int start) {
-    bool asciiOnly = true;
-    while (next != $EOF) {
-      if (identical(next, quoteChar)) {
-        if (!asciiOnly) handleUnicode(start);
-        next = advance();
-        appendSubstringToken(STRING_INFO, start, asciiOnly);
-        return next;
-      } else if (identical(next, $LF) || identical(next, $CR)) {
-        if (!asciiOnly) handleUnicode(start);
-        return unterminatedRawString(quoteChar);
-      } else if (next > 127) {
-        asciiOnly = false;
-      }
-      next = advance();
-    }
-    if (!asciiOnly) handleUnicode(start);
-    return unterminatedRawString(quoteChar);
-  }
-
-  int tokenizeMultiLineRawString(int quoteChar, int start) {
-    bool asciiOnlyString = true;
-    bool asciiOnlyLine = true;
-    int unicodeStart = start;
-    int next = advance(); // Advance past the (last) quote (of three).
-    outer:
-    while (!identical(next, $EOF)) {
-      while (!identical(next, quoteChar)) {
-        if (identical(next, $LF)) {
-          if (!asciiOnlyLine) {
-            // Synchronize the string offset in the utf8 scanner.
-            handleUnicode(unicodeStart);
-            asciiOnlyLine = true;
-            unicodeStart = scanOffset;
-          }
-          lineFeedInMultiline();
-        } else if (next > 127) {
-          asciiOnlyLine = false;
-          asciiOnlyString = false;
-        }
-        next = advance();
-        if (identical(next, $EOF)) break outer;
-      }
-      next = advance();
-      if (identical(next, quoteChar)) {
-        next = advance();
-        if (identical(next, quoteChar)) {
-          if (!asciiOnlyLine) handleUnicode(unicodeStart);
-          next = advance();
-          appendSubstringToken(STRING_INFO, start, asciiOnlyString);
-          return next;
-        }
-      }
-    }
-    if (!asciiOnlyLine) handleUnicode(unicodeStart);
-    return unterminatedRawMultiLineString(quoteChar);
-  }
-
-  int tokenizeMultiLineString(int quoteChar, int start, bool raw) {
-    if (raw) return tokenizeMultiLineRawString(quoteChar, start);
-    bool asciiOnlyString = true;
-    bool asciiOnlyLine = true;
-    int unicodeStart = start;
-    int next = advance(); // Advance past the (last) quote (of three).
-    while (!identical(next, $EOF)) {
-      if (identical(next, $$)) {
-        if (!asciiOnlyLine) handleUnicode(unicodeStart);
-        next = tokenizeStringInterpolation(start, asciiOnlyString);
-        start = scanOffset;
-        unicodeStart = start;
-        asciiOnlyString = true; // A new string token is created for the rest.
-        asciiOnlyLine = true;
-        continue;
-      }
-      if (identical(next, quoteChar)) {
-        next = advance();
-        if (identical(next, quoteChar)) {
-          next = advance();
-          if (identical(next, quoteChar)) {
-            if (!asciiOnlyLine) handleUnicode(unicodeStart);
-            next = advance();
-            appendSubstringToken(STRING_INFO, start, asciiOnlyString);
-            return next;
-          }
-        }
-        continue;
-      }
-      if (identical(next, $BACKSLASH)) {
-        next = advance();
-        if (identical(next, $EOF)) break;
-      }
-      if (identical(next, $LF)) {
-        if (!asciiOnlyLine) {
-          // Synchronize the string offset in the utf8 scanner.
-          handleUnicode(unicodeStart);
-          asciiOnlyLine = true;
-          unicodeStart = scanOffset;
-        }
-        lineFeedInMultiline();
-      } else if (next > 127) {
-        asciiOnlyString = false;
-        asciiOnlyLine = false;
-      }
-      next = advance();
-    }
-    if (!asciiOnlyLine) handleUnicode(unicodeStart);
-    return unterminatedMultiLineString(quoteChar);
-  }
-
-  int unexpected(int character) {
-    appendErrorToken(new BadInputToken(character, tokenStart));
-    return advanceAfterError(true);
-  }
-
-  int unterminated(String prefix, {bool shouldAdvance: true}) {
-    appendErrorToken(new UnterminatedToken(prefix, tokenStart, stringOffset));
-    return advanceAfterError(shouldAdvance);
-  }
-
-  int unterminatedString(int quoteChar) {
-    return unterminated(new String.fromCharCodes([quoteChar]));
-  }
-
-  int unterminatedRawString(int quoteChar) {
-    return unterminated('r${new String.fromCharCodes([quoteChar])}');
-  }
-
-  int unterminatedMultiLineString(int quoteChar) {
-    return unterminated(
-        new String.fromCharCodes([quoteChar, quoteChar, quoteChar]));
-  }
-
-  int unterminatedRawMultiLineString(int quoteChar) {
-    return unterminated(
-        'r${new String.fromCharCodes([quoteChar, quoteChar, quoteChar])}');
-  }
-
-  int advanceAfterError(bool shouldAdvance) {
-    if (atEndOfFile()) return $EOF;
-    if (shouldAdvance) {
-      return advance(); // Ensure progress.
-    } else {
-      return -1;
-    }
-  }
-
-  void unmatchedBeginGroup(BeginGroupToken begin) {
-    // We want to ensure that unmatched BeginGroupTokens are reported as
-    // errors.  However, the diet parser assumes that groups are well-balanced
-    // and will never look at the endGroup token.  This is a nice property that
-    // allows us to skip quickly over correct code. By inserting an additional
-    // synthetic token in the stream, we can keep ignoring endGroup tokens.
-    //
-    // [begin] --next--> [tail]
-    // [begin] --endG--> [synthetic] --next--> [next] --next--> [tail]
-    //
-    // This allows the diet parser to skip from [begin] via endGroup to
-    // [synthetic] and ignore the [synthetic] token (assuming it's correct),
-    // then the error will be reported when parsing the [next] token.
-    //
-    // For example, tokenize("{[1};") produces:
-    //
-    // SymbolToken({) --endGroup-----+
-    //      |                        |
-    //     next                      |
-    //      v                        |
-    // SymbolToken([) --endGroup--+  |
-    //      |                     |  |
-    //     next                   |  |
-    //      v                     |  |
-    // StringToken(1)             |  |
-    //      |                     v  |
-    //     next       SymbolToken(]) | <- Synthetic token.
-    //      |                     |  |
-    //      |                   next |
-    //      v                     |  |
-    // UnmatchedToken([)<---------+  |
-    //      |                        |
-    //     next                      |
-    //      v                        |
-    // SymbolToken(})<---------------+
-    //      |
-    //     next
-    //      v
-    // SymbolToken(;)
-    //      |
-    //     next
-    //      v
-    //     EOF
-    Token synthetic =
-        new SymbolToken(closeBraceInfoFor(begin), begin.charOffset);
-    UnmatchedToken next = new UnmatchedToken(begin);
-    begin.endGroup = synthetic;
-    synthetic.next = next;
-    appendErrorToken(next);
-  }
-}
-
-PrecedenceInfo closeBraceInfoFor(BeginGroupToken begin) {
-  return const {
-    '(': CLOSE_PAREN_INFO,
-    '[': CLOSE_SQUARE_BRACKET_INFO,
-    '{': CLOSE_CURLY_BRACKET_INFO,
-    '<': GT_INFO,
-    r'${': CLOSE_CURLY_BRACKET_INFO,
-  }[begin.value];
-}