Add StringScanner.scanChar() and .expectChar().

test/line_scanner_test.dart

 // Copyright (c) 2014, 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:charcode/charcode.dart';
 import 'package:string_scanner/string_scanner.dart';
 import 'package:test/test.dart';
 
 void main() {
   var scanner;
   setUp(() {
     scanner = new LineScanner('foo\nbar\r\nbaz');
   });
 
   test('begins with line and column 0', () {
@@ skipping 58 matching lines @@
       scanner.readChar();
       expect(scanner.line, equals(1));
       expect(scanner.column, equals(4));
 
       scanner.readChar();
       expect(scanner.line, equals(2));
       expect(scanner.column, equals(0));
     });
   });
 
+  group("scanChar()", () {
+    test("on a non-newline character increases the column but not the line",
+        () {
+      scanner.scanChar($f);
+      expect(scanner.line, equals(0));
+      expect(scanner.column, equals(1));
+    });
+
+    test("consuming a newline resets the column and increases the line", () {
+      scanner.expect('foo');
+      expect(scanner.line, equals(0));
+      expect(scanner.column, equals(3));
+
+      scanner.scanChar($lf);
+      expect(scanner.line, equals(1));
+      expect(scanner.column, equals(0));
+    });
+
+    test("consuming halfway through a CR LF doesn't count as a line", () {
+      scanner.expect('foo\nbar');
+      expect(scanner.line, equals(1));
+      expect(scanner.column, equals(3));
+
+      scanner.scanChar($cr);
+      expect(scanner.line, equals(1));
+      expect(scanner.column, equals(4));
+
+      scanner.scanChar($lf);
+      expect(scanner.line, equals(2));
+      expect(scanner.column, equals(0));
+    });
+  });
+
   group("position=", () {
     test("forward through newlines sets the line and column", () {
       scanner.position = 10; // "foo\nbar\r\nb"
       expect(scanner.line, equals(2));
       expect(scanner.column, equals(1));
     });
 
     test("forward through no newlines sets the column", () {
       scanner.position = 2; // "fo"
       expect(scanner.line, equals(0));
@@ skipping 32 matching lines @@
     expect(scanner.column, equals(1));
   });
 
   test("state= rejects a foreign state", () {
     scanner.scan('foo\nb');
 
     expect(() => new LineScanner(scanner.string).state = scanner.state,
         throwsArgumentError);
   });
 }