Make PlatformSelector use boolean_selector.

lib/src/backend/platform_selector/scanner.dart

Index: lib/src/backend/platform_selector/scanner.dart
diff --git a/lib/src/backend/platform_selector/scanner.dart b/lib/src/backend/platform_selector/scanner.dart
deleted file mode 100644
index 44dddca43d596637f87f1224705903490077b672..0000000000000000000000000000000000000000
--- a/lib/src/backend/platform_selector/scanner.dart
+++ /dev/null
@@ -1,146 +0,0 @@
-// 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.
-
-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 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.
-  bool _endOfFileEmitted = false;
-
-  Scanner(String selector)
-      : _scanner = new SpanScanner(selector);
-
-  /// Returns the next token that will be returned by [next].
-  ///
-  /// Throws a [StateError] if a [TokenType.endOfFile] token has already been
-  /// consumed.
-  Token peek() {
-    if (_next == null) _next = _getNext();
-    return _next;
-  }
-
-  /// Consumes and returns the next token in the stream.
-  ///
-  /// Throws a [StateError] if a [TokenType.endOfFile] token has already been
-  /// consumed.
-  Token next() {
-    var token = _next == null ? _getNext() : _next;
-    _endOfFileEmitted = token.type == TokenType.endOfFile;
-    _next = null;
-    return token;
-  }
-
-  /// If the next token matches [type], consumes it and returns `true`;
-  /// otherwise, returns `false`.
-  ///
-  /// Throws a [StateError] if a [TokenType.endOfFile] token has already been
-  /// consumed.
-  bool scan(TokenType type) {
-    if (peek().type != type) return false;
-    next();
-    return true;
-  }
-
-  /// Scan and return the next token in the stream.
-  Token _getNext() {
-    if (_endOfFileEmitted) throw new StateError("No more tokens.");
-
-    _consumeWhitespace();
-    if (_scanner.isDone) {
-      return new Token(
-          TokenType.endOfFile, _scanner.spanFrom(_scanner.state));
-    }
-
-    switch (_scanner.peekChar()) {
-      case 0x28 /* ( */: return _scanOperator(TokenType.leftParen);
-      case 0x29 /* ) */: return _scanOperator(TokenType.rightParen);
-      case 0x3F /* ? */: return _scanOperator(TokenType.questionMark);
-      case 0x3A /* : */: return _scanOperator(TokenType.colon);
-      case 0x21 /* ! */: return _scanOperator(TokenType.not);
-      case 0x7C /* | */: return _scanOr();
-      case 0x26 /* & */: return _scanAnd();
-      default: return _scanIdentifier();
-    }
-  }
-
-  /// Scans a single-character operator and returns a token of type [type].
-  ///
-  /// This assumes that the caller has already verified that the next character
-  /// is correct for the given operator.
-  Token _scanOperator(TokenType type) {
-    var start = _scanner.state;
-    _scanner.readChar();
-    return new Token(type, _scanner.spanFrom(start));
-  }
-
-  /// Scans a `||` operator and returns the appropriate token.
-  ///
-  /// This validates that the next two characters are `||`.
-  Token _scanOr() {
-    var start = _scanner.state;
-    _scanner.expect("||");
-    return new Token(TokenType.or, _scanner.spanFrom(start));
-  }
-
-  /// Scans a `&&` operator and returns the appropriate token.
-  ///
-  /// 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(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;
-  }
-}