Disallow non-hyphenated-identifier tag names.

lib/src/backend/platform_selector/scanner.dart

 // Copyright (c) 2015, 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 test.backend.platform_selector.scanner;
 
 import 'package:string_scanner/string_scanner.dart';
 
+import '../../utils.dart';
 import 'token.dart';
 
 /// A regular expression matching both whitespace and single-line comments.
 ///
 /// This will only match if consumes at least one character.
 final _whitespaceAndSingleLineComments =
     new RegExp(r"([ \t\n]+|//[^\n]*(\n|$))+");
 
 /// A regular expression matching the body of a multi-line comment, after `/*`
 /// but before `*/` or a nested `/*`.
 ///
 /// This will only match if it consumes at least one character.
 final _multiLineCommentBody = new RegExp(r"([^/*]|/[^*]|\*[^/])+");
 
-/// A regular expression matching an identifier.
-///
-/// Unlike standard Dart identifiers, platform selector identifiers may
-/// contain dashes for consistency with command-line arguments.
-final _identifier = new RegExp(r"[a-zA-Z_-][a-zA-Z0-9_-]*");
-
 /// A scanner that converts a platform selector string into a stream of
 /// tokens.
 class Scanner {
   /// The underlying string scanner.
   final SpanScanner _scanner;
 
   /// The next token to emit.
   Token _next;
 
   /// Whether the scanner has emitted a [TokenType.endOfFile] token.
@@ skipping 78 matching lines @@
   ///
   /// This validates that the next two characters are `&&`.
   Token _scanAnd() {
     var start = _scanner.state;
     _scanner.expect("&&");
     return new Token(TokenType.and, _scanner.spanFrom(start));
   }
 
   /// Scans and returns an identifier token.
   Token _scanIdentifier() {
-    _scanner.expect(_identifier, name: "expression");
+    _scanner.expect(hyphenatedIdentifier, name: "expression");
     return new IdentifierToken(_scanner.lastMatch[0], _scanner.lastSpan);
   }
 
   /// Consumes all whitespace and comments immediately following the cursor's
   /// current position.
   void _consumeWhitespace() {
     while (_scanner.scan(_whitespaceAndSingleLineComments) ||
         _multiLineComment()) {
       // Do nothing.
     }
   }
 
   /// Consumes a single multi-line comment.
   ///
   /// Returns whether or not a comment was consumed.
   bool _multiLineComment() {
     if (!_scanner.scan("/*")) return false;
 
     while (_scanner.scan(_multiLineCommentBody) || _multiLineComment()) {
       // Do nothing.
     }
     _scanner.expect("*/");
 
     return true;
   }
 }