Properly handle CR LF in LineScanner.

lib/src/line_scanner.dart

Index: lib/src/line_scanner.dart
diff --git a/lib/src/line_scanner.dart b/lib/src/line_scanner.dart
index 54ecf7bf9e62215d7a7412a760a24fb1b5dae60d..148ad6081395cae8de857049ba55400324ca30ca 100644
--- a/lib/src/line_scanner.dart
+++ b/lib/src/line_scanner.dart
@@ -4,8 +4,13 @@
 
 library string_scanner.line_scanner;
 
+import 'package:charcode/ascii.dart';
+
 import 'string_scanner.dart';
 
+/// A regular expression matching newlines across platforms.
+final _newlineRegExp = new RegExp(r"\r\n?|\n");
+
 /// A subclass of [StringScanner] that tracks line and column information.
 class LineScanner extends StringScanner {
   /// The scanner's current (zero-based) line number.
@@ -24,6 +29,10 @@ class LineScanner extends StringScanner {
   LineScannerState get state =>
       new LineScannerState._(this, position, line, column);
 
+  /// Whether the current position is between a CR character and an LF
+  /// charactet.
+  bool get _betweenCRLF => peekChar(-1) == $cr && peekChar() == $lf;
+
   set state(LineScannerState state) {
     if (!identical(state._scanner, this)) {
       throw new ArgumentError("The given LineScannerState was not returned by "
@@ -40,8 +49,10 @@ class LineScanner extends StringScanner {
     super.position = newPosition;
 
     if (newPosition > oldPosition) {
-      var newlines =
-          "\n".allMatches(string.substring(oldPosition, newPosition)).toList();
+      var newlines = _newlineRegExp
+          .allMatches(string.substring(oldPosition, newPosition)).toList();
+      if (_betweenCRLF) newlines.removeLast();

[Bob Nystrom, 2015/09/02 00:07:24]

How about hoisting this to a function:

int _newlinesIn(String text) { ... }

and reusing it below too.

[nweiz, 2015/09/02 00:10:57]

Done.

+
       _line += newlines.length;
       if (newlines.isEmpty) {
         _column += newPosition - oldPosition;
@@ -49,13 +60,16 @@ class LineScanner extends StringScanner {
         _column = newPosition - newlines.last.end;
       }
     } else {
-      var newlines =
-          "\n".allMatches(string.substring(newPosition, oldPosition)).toList();
+      var newlines = _newlineRegExp
+          .allMatches(string.substring(newPosition, oldPosition)).toList();
+      if (_betweenCRLF) newlines.removeLast();
+
       _line -= newlines.length;
       if (newlines.isEmpty) {
         _column -= oldPosition - newPosition;
       } else {
-        _column = newPosition - string.lastIndexOf("\n", newPosition) - 1;
+        _column = newPosition -
+            string.lastIndexOf(_newlineRegExp, newPosition) - 1;
       }
     }
   }
@@ -65,7 +79,7 @@ class LineScanner extends StringScanner {
 
   int readChar() {
     var char = super.readChar();
-    if (char == 0xA) {
+    if (char == $lf || (char == $cr && peekChar() != $lf)) {
       _line += 1;
       _column = 0;
     } else {
@@ -77,7 +91,8 @@ class LineScanner extends StringScanner {
   bool scan(Pattern pattern) {
     if (!super.scan(pattern)) return false;
 
-    var newlines = "\n".allMatches(lastMatch[0]).toList();
+    var newlines = _newlineRegExp.allMatches(lastMatch[0]).toList();
+    if (_betweenCRLF) newlines.removeLast();
     _line += newlines.length;

[Bob Nystrom, 2015/09/02 00:07:24]

Even here.

[nweiz, 2015/09/02 00:10:57]

Done.

     if (newlines.isEmpty) {
       _column += lastMatch[0].length;