Implement hashCode on objects stored in a set or used as map keys.

dart/sdk/lib/_internal/compiler/implementation/scanner/token.dart

 // Copyright (c) 2011, 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.
 
 part of scanner;
 
 const int EOF_TOKEN = 0;
 
 const int KEYWORD_TOKEN = $k;
 const int IDENTIFIER_TOKEN = $a;
@@ skipping 132 matching lines @@
    */
   int get slowCharCount {
     if (info == BAD_INPUT_INFO) {
       // This is a token that wraps around an error message. Return 1
       // instead of the size of the length of the error message.
       return 1;
     } else {
       return slowToString().length;
     }
   }
+
+  int get hashCode => computeHashCode(charOffset, info, value);
 }
 
 /**
  * A keyword token.
  */
 class KeywordToken extends Token {
   final Keyword value;
   String get stringValue => value.syntax;
 
   KeywordToken(Keyword value, int charOffset)
@@ skipping 142 matching lines @@
 bool isMinusOperator(String value) => identical(value, '-');
 
 class PrecedenceInfo {
   final SourceString value;
   final int precedence;
   final int kind;
 
   const PrecedenceInfo(this.value, this.precedence, this.kind);
 
   toString() => 'PrecedenceInfo($value, $precedence, $kind)';
+
+  int get hashCode => computeHashCode(value, precedence, kind);
 }
 
 // TODO(ahe): The following are not tokens in Dart.
 const PrecedenceInfo BACKPING_INFO =
   const PrecedenceInfo(const SourceString('`'), 0, BACKPING_TOKEN);
 const PrecedenceInfo BACKSLASH_INFO =
   const PrecedenceInfo(const SourceString('\\'), 0, BACKSLASH_TOKEN);
 const PrecedenceInfo PERIOD_PERIOD_PERIOD_INFO =
   const PrecedenceInfo(const SourceString('...'), 0,
                        PERIOD_PERIOD_PERIOD_TOKEN);
@@ skipping 196 matching lines @@
 
 const PrecedenceInfo HEXADECIMAL_INFO =
   const PrecedenceInfo(const SourceString('hexadecimal'), 0, HEXADECIMAL_TOKEN);
 
 const PrecedenceInfo COMMENT_INFO =
   const PrecedenceInfo(const SourceString('comment'), 0, COMMENT_TOKEN);
 
 // For reporting lexical errors.
 const PrecedenceInfo ERROR_INFO =
   const PrecedenceInfo(const SourceString('?'), 0, UNKNOWN_TOKEN);