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packages/string_scanner/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.
+
+library string_scanner.line_scanner_test;
+
+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', () {
+    expect(scanner.line, equals(0));
+    expect(scanner.column, equals(0));
+  });
+
+  group("scan()", () {
+    test("consuming no newlines increases the column but not the line", () {
+      scanner.scan('foo');
+      expect(scanner.line, equals(0));
+      expect(scanner.column, equals(3));
+    });
+
+    test("consuming a newline resets the column and increases the line", () {
+      scanner.expect('foo\nba');
+      expect(scanner.line, equals(1));
+      expect(scanner.column, equals(2));
+    });
+
+    test("consuming multiple newlines resets the column and increases the line",
+        () {
+      scanner.expect('foo\nbar\r\nb');
+      expect(scanner.line, equals(2));
+      expect(scanner.column, equals(1));
+    });
+
+    test("consuming halfway through a CR LF doesn't count as a line", () {
+      scanner.expect('foo\nbar\r');
+      expect(scanner.line, equals(1));
+      expect(scanner.column, equals(4));
+
+      scanner.expect('\nb');
+      expect(scanner.line, equals(2));
+      expect(scanner.column, equals(1));
+    });
+  });
+
+  group("readChar()", () {
+    test("on a non-newline character increases the column but not the line",
+        () {
+      scanner.readChar();
+      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.readChar();
+      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.readChar();
+      expect(scanner.line, equals(1));
+      expect(scanner.column, equals(4));
+
+      scanner.readChar();
+      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));
+      expect(scanner.column, equals(2));
+    });
+
+    test("backward through newlines sets the line and column", () {
+      scanner.scan("foo\nbar\r\nbaz");
+      scanner.position = 2; // "fo"
+      expect(scanner.line, equals(0));
+      expect(scanner.column, equals(2));
+    });
+
+    test("backward through no newlines sets the column", () {
+      scanner.scan("foo\nbar\r\nbaz");
+      scanner.position = 10; // "foo\nbar\r\nb"
+      expect(scanner.line, equals(2));
+      expect(scanner.column, equals(1));
+    });
+
+    test("forward halfway through a CR LF doesn't count as a line", () {
+      scanner.position = 8; // "foo\nbar\r"
+      expect(scanner.line, equals(1));
+      expect(scanner.column, equals(4));
+    });
+  });
+
+  test("state= restores the line, column, and position", () {
+    scanner.scan('foo\nb');
+    var state = scanner.state;
+
+    scanner.scan('ar\nba');
+    scanner.state = state;
+    expect(scanner.rest, equals('ar\r\nbaz'));
+    expect(scanner.line, equals(1));
+    expect(scanner.column, equals(1));
+  });
+
+  test("state= rejects a foreign state", () {
+    scanner.scan('foo\nb');
+
+    expect(() => new LineScanner(scanner.string).state = scanner.state,
+        throwsArgumentError);
+  });
+}