merge null_safety branch into master (#28)

* Migrate package to Null Safety.

- Update CHANGELOG.md.
- Add unsound entry point for test, so it can be run.
- Update SDK dependency to 2.9.0-1
- Updates travis config to run nnbd tests/analysis 
- Adds dependency overrides so tests can be ran in null safety mode
- Updates package version to expected pre-release version
- Updates sdk constraints to restrict to dev sdks with the allow list

Co-authored-by @lrhn.

.travis.yml

@@ -1,14 +1,38 @@
 language: dart
 dart:
 - dev
-- stable
-# Only building master means that we don't run two builds for each pull request.
-dart_task:
-- test: --platform vm,chrome
-- dartanalyzer
-- dartfmt
+
+jobs:
+  include:
+    - stage: analyze_and_format
+      name: "Analyze lib/ (no experiment flag)"
+      dart: dev
+      os: linux
+      script: dartanalyzer --fatal-warnings --fatal-infos lib/
+    - stage: analyze_and_format
+      name: "Analyze (with experiment flag)"
+      dart: dev
+      os: linux
+      script: dartanalyzer --enable-experiment=non-nullable --fatal-warnings --fatal-infos .
+    - stage: analyze_and_format
+      name: "Format"
+      dart: dev
+      os: linux
+      script: dartfmt -n --set-exit-if-changed .
+    - stage: test
+      name: "Vm Tests"
+      dart: dev
+      os: linux
+      script: pub run --enable-experiment=non-nullable test -p vm
+    - stage: test
+      name: "Web Tests"
+      dart: dev
+      os: linux
+      script: pub run --enable-experiment=non-nullable test -p chrome
+
 branches:
-  only: [master]
+  only: [master, null_safety]
+
 cache:
   directories:
     - $HOME/.pub-cache

CHANGELOG.md

@@ -1,5 +1,9 @@
 # Changelog
 
+## 1.1.0-nullsafety
+
+* Make package null safe.
+
 ## 1.0.0
 
 * Core APIs deemed stable; package version set to 1.0.0.

analysis_options.yaml

@@ -5,3 +5,5 @@ analyzer:
     annotate_overrides: ignore
     prefer_single_quotes: ignore
     use_function_type_syntax_for_parameters: ignore
+  enable-experiment:
+    - non-nullable

lib/src/characters.dart

@@ -47,14 +47,14 @@ abstract class Characters implements Iterable<String> {
   /// as well as controlling the iteration in more detail.
   CharacterRange get iteratorAtEnd;
 
-  /// Whether [Character] is an element of this sequence of
-  /// characters.
+  /// Whether [other] is an element of this sequence of
+  /// others.
   ///
-  /// Returns false if [Character] is not a string containing
+  /// Returns false if [other] is not a string containing
   /// a single character,
   /// because then it is not a single element of this [Iterable]
   /// of characters.
-  bool contains(Object Character);
+  bool contains(Object? other);
 
   /// Whether this sequence of characters contains [other]
   /// as a subsequence.
@@ -79,13 +79,14 @@ abstract class Characters implements Iterable<String> {
   /// Returns a [CharacterRange] containing the first occurrence of
   /// [characters] in this string.
   /// Returns `null` if there is no such occurrence.
-  CharacterRange /*?*/ findFirst(Characters characters);
+  CharacterRange? findFirst(Characters characters);
 
   /// Finds the last occurrence of [characters].
   ///
   /// Returns a [CharacterRange] containing the last occurrence of
-  /// [characters]. Returns `null` if there is no such occurrence,
-  CharacterRange /*?*/ findLast(Characters characters);
+  /// [characters].
+  /// Returns `null` if there is no such occurrence,
+  CharacterRange? findLast(Characters characters);
 
   /// Eagerly selects a subset of the characters.
   ///
@@ -132,7 +133,7 @@ abstract class Characters implements Iterable<String> {
   /// of characters.
   Characters skipWhile(bool Function(String) test);
 
-  /// Eagerly selects a leading sequnce of characters.
+  /// Eagerly selects a leading sequence of characters.
   ///
   /// Checks each character, from first to last, against [test],
   /// until one is found whwere [test] returns `false`.
@@ -143,7 +144,7 @@ abstract class Characters implements Iterable<String> {
   /// is returned.
   Characters takeWhile(bool Function(String) test);
 
-  /// Eagerly selects a leading sequnce of characters.
+  /// Eagerly selects a leading sequence of characters.
   ///
   /// Checks each character, from last to first, against [test],
   /// until one is found whwere [test] returns `false`.
@@ -679,7 +680,7 @@ abstract class CharacterRange implements Iterator<String> {
   ///
   /// Returns `null` if there are no occurrences of [pattern]
   /// in the current range.
-  CharacterRange /*?*/ replaceAll(Characters pattern, Characters replacement);
+  CharacterRange? replaceAll(Characters pattern, Characters replacement);
 
   /// Splits the current range of characters at each occurrence of [pattern].
   ///
@@ -737,7 +738,7 @@ abstract class CharacterRange implements Iterator<String> {
   ///
   /// Returns `null` if there are no occurrences of [pattern]
   /// in the current range.
-  CharacterRange /*?*/ replaceFirst(Characters pattern, Characters replacement);
+  CharacterRange? replaceFirst(Characters pattern, Characters replacement);
 
   /// Whether the current range starts with [characters].
   ///

lib/src/characters_impl.dart

@@ -69,7 +69,7 @@ class StringCharacters extends Iterable<String> implements Characters {
 
   @override
   Iterable<T> whereType<T>() {
-    Iterable<Object> self = this;
+    Iterable<Object?> self = this;
     if (self is Iterable<T>) {
       return self.map<T>((x) => x);
     }
@@ -83,7 +83,7 @@ class StringCharacters extends Iterable<String> implements Characters {
   }
 
   @override
-  String lastWhere(bool test(String element), {String orElse()}) {
+  String lastWhere(bool test(String element), {String orElse()?}) {
     int cursor = string.length;
     var brk = BackBreaks(string, cursor, 0, stateEoTNoBreak);
     int next = 0;
@@ -114,7 +114,7 @@ class StringCharacters extends Iterable<String> implements Characters {
   }
 
   @override
-  bool contains(Object other) {
+  bool contains(Object? other) {
     if (other is String) {
       if (other.isEmpty) return false;
       int next = Breaks(other, 0, other.length, stateSoTNoBreak).nextBreak();
@@ -375,14 +375,14 @@ class StringCharacters extends Iterable<String> implements Characters {
   String toString() => string;
 
   @override
-  CharacterRange findFirst(Characters characters) {
+  CharacterRange? findFirst(Characters characters) {
     var range = _rangeAll;
     if (range.collapseToFirst(characters)) return range;
     return null;
   }
 
   @override
-  CharacterRange findLast(Characters characters) {
+  CharacterRange? findLast(Characters characters) {
     var range = _rangeAll;
     if (range.collapseToLast(characters)) return range;
     return null;
@@ -408,7 +408,7 @@ class StringCharacterRange implements CharacterRange {
 
   /// The [current] value is created lazily and cached to avoid repeated
   /// or unnecessary string allocation.
-  String _currentCache;
+  String? _currentCache;
 
   StringCharacterRange(String string) : this._(string, 0, 0);
   StringCharacterRange._(this._string, this._start, this._end);
@@ -778,8 +778,7 @@ class StringCharacterRange implements CharacterRange {
   }
 
   @override
-  CharacterRange /*?*/ replaceFirst(
-      Characters pattern, Characters replacement) {
+  CharacterRange? replaceFirst(Characters pattern, Characters replacement) {
     String patternString = pattern.string;
     String replacementString = replacement.string;
     String replaced;
@@ -799,7 +798,7 @@ class StringCharacterRange implements CharacterRange {
   }
 
   @override
-  CharacterRange /*?*/ replaceAll(Characters pattern, Characters replacement) {
+  CharacterRange? replaceAll(Characters pattern, Characters replacement) {
     var patternString = pattern.string;
     var replacementString = replacement.string;
     if (patternString.isEmpty) {
@@ -811,7 +810,7 @@ class StringCharacterRange implements CharacterRange {
     if (_start == _end) return null;
     int start = 0;
     int cursor = _start;
-    StringBuffer buffer;
+    StringBuffer? buffer;
     while ((cursor = _indexOf(_string, patternString, cursor, _end)) >= 0) {
       (buffer ??= StringBuffer())
         ..write(_string.substring(start, cursor))

pubspec.yaml

@@ -1,10 +1,96 @@
 name: characters
-version: 1.0.0
+version: 1.1.0-nullsafety
 description: String replacement with operations that are Unicode/grapheme cluster aware.
 homepage: https://www.github.com/dart-lang/characters
 
 environment:
-  sdk: ">=2.6.0 <3.0.0"
+  # This must remain a tight constraint (only allow dev versions) until nnbd is
+  # stable.
+  sdk: '>=2.9.0-18.0 <2.9.0'
+
 dev_dependencies:
   test: "^1.6.0"
   pedantic: ^1.9.0
+
+dependency_overrides:
+  async:
+    git:
+      url: git://github.com/dart-lang/async.git
+      ref: null_safety
+  boolean_selector:
+    git:
+      url: git://github.com/dart-lang/boolean_selector.git
+      ref: null_safety
+  charcode:
+    git:
+      url: git://github.com/dart-lang/charcode.git
+      ref: null_safety
+  collection:
+    git: git://github.com/dart-lang/collection.git
+  js:
+    git:
+      url: git://github.com/dart-lang/sdk.git
+      path: pkg/js
+  matcher:
+    git:
+      url: git://github.com/dart-lang/matcher.git
+      ref: null_safety
+  meta:
+    git:
+      url: git://github.com/dart-lang/sdk.git
+      path: pkg/meta
+  path:
+    git:
+      url: git://github.com/dart-lang/path.git
+      ref: null_safety
+  pedantic:
+    git:
+      url: git://github.com/dart-lang/pedantic.git
+      ref: null_safety
+  pool:
+    git:
+      url: git://github.com/dart-lang/pool.git
+      ref: null_safety
+  source_maps:
+    git:
+      url: git://github.com/dart-lang/source_maps.git
+      ref: null_safety
+  source_map_stack_trace:
+    git:
+      url: git://github.com/dart-lang/source_map_stack_trace.git
+      ref: null_safety
+  source_span:
+    git:
+      url: git://github.com/dart-lang/source_span.git
+      ref: null_safety
+  stack_trace:
+    git:
+      url: git://github.com/dart-lang/stack_trace.git
+      ref: null_safety
+  stream_channel:
+    git:
+      url: git://github.com/dart-lang/stream_channel.git
+      ref: null_safety
+  string_scanner:
+    git:
+      url: git://github.com/dart-lang/string_scanner.git
+      ref: null_safety
+  term_glyph:
+    git:
+      url: git://github.com/dart-lang/term_glyph.git
+      ref: null_safety
+  test_api:
+    git:
+      url: git://github.com/dart-lang/test.git
+      ref: null_safety
+      path: pkgs/test_api
+  test_core:
+    git:
+      url: git://github.com/dart-lang/test.git
+      ref: null_safety
+      path: pkgs/test_core
+  test:
+    git:
+      url: git://github.com/dart-lang/test.git
+      ref: null_safety
+      path: pkgs/test