Merge the null_safety branch into master (#22)

Author: jakemac53

.travis.yml

@@ -2,7 +2,6 @@ language: dart
 
 dart:
   - dev
-  - 2.0.0
 
 dart_task:
   - test: --platform vm,chrome
@@ -15,13 +14,10 @@ matrix:
     - dart: dev
       dart_task:
         dartanalyzer: --fatal-warnings --fatal-hints .
-    - dart: 2.0.0
-      dart_task:
-        dartanalyzer: --fatal-warnings .
 
 # Only building master means that we don't run two builds for each pull request.
 branches:
-  only: [master]
+  only: [master, null_safety]
 
 cache:
  directories:

CHANGELOG.md

@@ -1,3 +1,7 @@
+## 1.1.0-nullsafety
+
+- Migrate to null safety.
+
 ## 1.0.5
 
 - Added an example.

analysis_options.yaml

@@ -4,6 +4,9 @@ analyzer:
   strong-mode:
     implicit-casts: false
 
+  enable-experiment:
+  - non-nullable
+
 linter:
   rules:
     - avoid_bool_literals_in_conditional_expressions

example/example.dart

@@ -24,11 +24,11 @@ num parseNumber(String source) {
 
   // [Scanner.lastMatch] holds the [MatchData] for the most recent call to
   // [Scanner.scan], [Scanner.expect], or [Scanner.matches].
-  var number = num.parse(scanner.lastMatch[0]);
+  var number = num.parse((scanner.lastMatch![0])!);
 
   if (scanner.scan('.')) {
     scanner.expect(RegExp(r'\d+'));
-    final decimal = scanner.lastMatch[0];
+    final decimal = scanner.lastMatch![0]!;
     number += int.parse(decimal) / math.pow(10, decimal.length);
   }
 

lib/src/eager_span_scanner.dart

@@ -31,8 +31,7 @@ class EagerSpanScanner extends SpanScanner {
 
   @override
   set state(LineScannerState state) {
-    if (state is! _EagerSpanScannerState ||
-        !identical((state as _EagerSpanScannerState)._scanner, this)) {
+    if (state is! _EagerSpanScannerState || !identical(state._scanner, this)) {
       throw ArgumentError('The given LineScannerState was not returned by '
           'this LineScanner.');
     }
@@ -69,7 +68,7 @@ class EagerSpanScanner extends SpanScanner {
     }
   }
 
-  EagerSpanScanner(String string, {sourceUrl, int position})
+  EagerSpanScanner(String string, {sourceUrl, int? position})
       : super(string, sourceUrl: sourceUrl, position: position);
 
   @override
@@ -99,13 +98,14 @@ class EagerSpanScanner extends SpanScanner {
   @override
   bool scan(Pattern pattern) {
     if (!super.scan(pattern)) return false;
+    final firstMatch = (lastMatch![0])!;
 
-    final newlines = _newlinesIn(lastMatch[0]);
+    final newlines = _newlinesIn(firstMatch);
     _line += newlines.length;
     if (newlines.isEmpty) {
-      _column += lastMatch[0].length;
+      _column += firstMatch.length;
     } else {
-      _column = lastMatch[0].length - newlines.last.end;
+      _column = firstMatch.length - newlines.last.end;
     }
 
     return true;

lib/src/exception.dart

@@ -14,7 +14,7 @@ class StringScannerException extends SourceSpanFormatException {
   /// The URL of the source file being parsed.
   ///
   /// This may be `null`, indicating that the source URL is unknown.
-  Uri get sourceUrl => span.sourceUrl;
+  Uri? get sourceUrl => span?.sourceUrl;
 
   StringScannerException(String message, SourceSpan span, String source)
       : super(message, span, source);

lib/src/line_scanner.dart

@@ -73,7 +73,7 @@ class LineScanner extends StringScanner {
     }
   }
 
-  LineScanner(String string, {sourceUrl, int position})
+  LineScanner(String string, {sourceUrl, int? position})
       : super(string, sourceUrl: sourceUrl, position: position);
 
   @override
@@ -104,12 +104,12 @@ class LineScanner extends StringScanner {
   bool scan(Pattern pattern) {
     if (!super.scan(pattern)) return false;
 
-    final newlines = _newlinesIn(lastMatch[0]);
+    final newlines = _newlinesIn(lastMatch![0]!);
     _line += newlines.length;
     if (newlines.isEmpty) {
-      _column += lastMatch[0].length;
+      _column += (lastMatch![0])!.length;
     } else {
-      _column = lastMatch[0].length - newlines.last.end;
+      _column = (lastMatch![0])!.length - newlines.last.end;
     }
 
     return true;

lib/src/relative_span_scanner.dart

@@ -47,8 +47,7 @@ class RelativeSpanScanner extends StringScanner implements SpanScanner {
 
   @override
   set state(LineScannerState state) {
-    if (state is! _SpanScannerState ||
-        !identical((state as _SpanScannerState)._scanner, this)) {
+    if (state is! _SpanScannerState || !identical(state._scanner, this)) {
       throw ArgumentError('The given LineScannerState was not returned by '
           'this LineScanner.');
     }
@@ -57,8 +56,8 @@ class RelativeSpanScanner extends StringScanner implements SpanScanner {
   }
 
   @override
-  FileSpan get lastSpan => _lastSpan;
-  FileSpan _lastSpan;
+  FileSpan? get lastSpan => _lastSpan;
+  FileSpan? _lastSpan;
 
   @override
   FileLocation get location =>
@@ -73,7 +72,7 @@ class RelativeSpanScanner extends StringScanner implements SpanScanner {
         super(span.text, sourceUrl: span.sourceUrl);
 
   @override
-  FileSpan spanFrom(LineScannerState startState, [LineScannerState endState]) {
+  FileSpan spanFrom(LineScannerState startState, [LineScannerState? endState]) {
     final endPosition = endState == null ? position : endState.position;
     return _sourceFile.span(_startLocation.offset + startState.position,
         _startLocation.offset + endPosition);
@@ -87,12 +86,12 @@ class RelativeSpanScanner extends StringScanner implements SpanScanner {
     }
 
     _lastSpan = _sourceFile.span(_startLocation.offset + position,
-        _startLocation.offset + lastMatch.end);
+        _startLocation.offset + lastMatch!.end);
     return true;
   }
 
   @override
-  void error(String message, {Match match, int position, int length}) {
+  Never error(String message, {Match? match, int? position, int? length}) {
     validateErrorArgs(string, match, position, length);
 
     if (match == null && position == null && length == null) match = lastMatch;

lib/src/span_scanner.dart

@@ -29,8 +29,7 @@ class SpanScanner extends StringScanner implements LineScanner {
 
   @override
   set state(LineScannerState state) {
-    if (state is! _SpanScannerState ||
-        !identical((state as _SpanScannerState)._scanner, this)) {
+    if (state is! _SpanScannerState || !identical(state._scanner, this)) {
       throw ArgumentError('The given LineScannerState was not returned by '
           'this LineScanner.');
     }
@@ -42,12 +41,12 @@ class SpanScanner extends StringScanner implements LineScanner {
   ///
   /// This is the span for the entire match. There's no way to get spans for
   /// subgroups since [Match] exposes no information about their positions.
-  FileSpan get lastSpan {
+  FileSpan? get lastSpan {
     if (lastMatch == null) _lastSpan = null;
     return _lastSpan;
   }
 
-  FileSpan _lastSpan;
+  FileSpan? _lastSpan;
 
   /// The current location of the scanner.
   FileLocation get location => _sourceFile.location(position);
@@ -60,7 +59,7 @@ class SpanScanner extends StringScanner implements LineScanner {
   /// [sourceUrl] is used as [SourceLocation.sourceUrl] for the returned
   /// [FileSpan]s as well as for error reporting. It can be a [String], a
   /// [Uri], or `null`.
-  SpanScanner(String string, {sourceUrl, int position})
+  SpanScanner(String string, {sourceUrl, int? position})
       : _sourceFile = SourceFile.fromString(string, url: sourceUrl),
         super(string, sourceUrl: sourceUrl, position: position);
 
@@ -75,7 +74,7 @@ class SpanScanner extends StringScanner implements LineScanner {
   /// itself and its `LineScannerState` are eagerly computed. To limit their
   /// memory footprint, returned spans and locations will still lazily compute
   /// their line and column numbers.
-  factory SpanScanner.eager(String string, {sourceUrl, int position}) =
+  factory SpanScanner.eager(String string, {sourceUrl, int? position}) =
       EagerSpanScanner;
 
   /// Creates a new [SpanScanner] that scans within [span].
@@ -88,7 +87,7 @@ class SpanScanner extends StringScanner implements LineScanner {
 
   /// Creates a [FileSpan] representing the source range between [startState]
   /// and the current position.
-  FileSpan spanFrom(LineScannerState startState, [LineScannerState endState]) {
+  FileSpan spanFrom(LineScannerState startState, [LineScannerState? endState]) {
     final endPosition = endState == null ? position : endState.position;
     return _sourceFile.span(startState.position, endPosition);
   }
@@ -100,12 +99,12 @@ class SpanScanner extends StringScanner implements LineScanner {
       return false;
     }
 
-    _lastSpan = _sourceFile.span(position, lastMatch.end);
+    _lastSpan = _sourceFile.span(position, lastMatch!.end);
     return true;
   }
 
   @override
-  void error(String message, {Match match, int position, int length}) {
+  Never error(String message, {Match? match, int? position, int? length}) {
     validateErrorArgs(string, match, position, length);
 
     if (match == null && position == null && length == null) match = lastMatch;

lib/src/string_scanner.dart

@@ -3,7 +3,6 @@
 // BSD-style license that can be found in the LICENSE file.
 
 import 'package:charcode/charcode.dart';
-import 'package:meta/meta.dart';
 import 'package:source_span/source_span.dart';
 
 import 'exception.dart';
@@ -15,7 +14,7 @@ class StringScanner {
   ///
   /// This is used for error reporting. It may be `null`, indicating that the
   /// source URL is unknown or unavailable.
-  final Uri sourceUrl;
+  final Uri? sourceUrl;
 
   /// The string being scanned through.
   final String string;
@@ -36,15 +35,15 @@ class StringScanner {
   /// The data about the previous match made by the scanner.
   ///
   /// If the last match failed, this will be `null`.
-  Match get lastMatch {
+  Match? get lastMatch {
     // Lazily unset [_lastMatch] so that we avoid extra assignments in
     // character-by-character methods that are used in core loops.
     if (_position != _lastMatchPosition) _lastMatch = null;
     return _lastMatch;
   }
 
-  Match _lastMatch;
-  int _lastMatchPosition;
+  Match? _lastMatch;
+  int? _lastMatchPosition;
 
   /// The portion of the string that hasn't yet been scanned.
   String get rest => string.substring(position);
@@ -57,9 +56,10 @@ class StringScanner {
   /// [position] defaults to 0, the beginning of the string. [sourceUrl] is the
   /// URL of the source of the string being scanned, if available. It can be
   /// a [String], a [Uri], or `null`.
-  StringScanner(this.string, {sourceUrl, int position})
-      : sourceUrl =
-            sourceUrl is String ? Uri.parse(sourceUrl) : sourceUrl as Uri {
+  StringScanner(this.string, {sourceUrl, int? position})
+      : sourceUrl = sourceUrl == null
+            ? null
+            : sourceUrl is String ? Uri.parse(sourceUrl) : sourceUrl as Uri {
     if (position != null) this.position = position;
   }
 
@@ -79,7 +79,7 @@ class StringScanner {
   ///
   /// This returns `null` if [offset] points outside the string. It doesn't
   /// affect [lastMatch].
-  int peekChar([int offset]) {
+  int? peekChar([int? offset]) {
     offset ??= 0;
     final index = position + offset;
     if (index < 0 || index >= string.length) return null;
@@ -102,7 +102,7 @@ class StringScanner {
   /// describing the position of the failure. [name] is used in this error as
   /// the expected name of the character being matched; if it's `null`, the
   /// character itself is used instead.
-  void expectChar(int character, {String name}) {
+  void expectChar(int character, {String? name}) {
     if (scanChar(character)) return;
 
     if (name == null) {
@@ -125,7 +125,7 @@ class StringScanner {
   bool scan(Pattern pattern) {
     final success = matches(pattern);
     if (success) {
-      _position = _lastMatch.end;
+      _position = _lastMatch!.end;
       _lastMatchPosition = _position;
     }
     return success;
@@ -138,7 +138,7 @@ class StringScanner {
   /// position of the failure. [name] is used in this error as the expected name
   /// of the pattern being matched; if it's `null`, the pattern itself is used
   /// instead.
-  void expect(Pattern pattern, {String name}) {
+  void expect(Pattern pattern, {String? name}) {
     if (scan(pattern)) return;
 
     if (name == null) {
@@ -175,7 +175,7 @@ class StringScanner {
   ///
   /// Unlike [String.substring], [end] defaults to [position] rather than the
   /// end of the string.
-  String substring(int start, [int end]) {
+  String substring(int start, [int? end]) {
     end ??= position;
     return string.substring(start, end);
   }
@@ -193,8 +193,7 @@ class StringScanner {
   /// position; if only [position] is passed, [length] defaults to 0.
   ///
   /// It's an error to pass [match] at the same time as [position] or [length].
-  @alwaysThrows
-  void error(String message, {Match match, int position, int length}) {
+  Never error(String message, {Match? match, int? position, int? length}) {
     validateErrorArgs(string, match, position, length);
 
     if (match == null && position == null && length == null) match = lastMatch;
@@ -209,7 +208,7 @@ class StringScanner {
   // TODO(nweiz): Make this handle long lines more gracefully.
   /// Throws a [FormatException] describing that [name] is expected at the
   /// current position in the string.
-  void _fail(String name) {
+  Never _fail(String name) {
     error('expected $name.', position: position, length: 0);
   }
 }