From bf2ee2d111c48699dcf41290f08bdff94904ef13 Mon Sep 17 00:00:00 2001
From: Scott Carnett <798305+scarnett@users.noreply.github.com>
Date: Tue, 20 Apr 2021 13:39:50 -0500
Subject: [PATCH 1/7] nullsafety migration

---
 lib/interval_tree.dart | 54 +++++++++++++++++++++---------------------
 pubspec.yaml           |  2 +-
 2 files changed, 28 insertions(+), 28 deletions(-)

diff --git a/lib/interval_tree.dart b/lib/interval_tree.dart
index b66861e..2e9af40 100644
--- a/lib/interval_tree.dart
+++ b/lib/interval_tree.dart
@@ -150,7 +150,7 @@ class Interval extends Comparable<Interval> {
   ///     final b = Interval(3, 5);
   ///     print(b.intersection(a)); // null
   ///
-  Interval intersection(Interval other) {
+  Interval? intersection(Interval other) {
     if (!intersects(other)) return null;
     return Interval(_max(start, other.start), _min(end, other.end));
   }
@@ -177,7 +177,7 @@ class Interval extends Comparable<Interval> {
   ///     print(a.difference(b)); // [[1, 2], [4, 5]]
   ///     print(b.difference(a)); // null
   ///
-  Iterable<Interval> difference(Interval other) {
+  Iterable<Interval>? difference(Interval other) {
     if (other.contains(this)) return null;
     if (!other.intersects(this)) return [this];
     if (other.start > start && other.end >= end) {
@@ -308,7 +308,7 @@ class Interval extends Comparable<Interval> {
 ///
 ///     final interval = ivt.Interval(1, 2);
 ///
-class IntervalTree with IterableMixin<Interval> {
+class IntervalTree with IterableMixin<Interval?> {
   /// Creates a tree, optionally with an [interval].
   IntervalTree([dynamic interval]) {
     add(interval);
@@ -324,16 +324,16 @@ class IntervalTree with IterableMixin<Interval> {
   }
 
   /// Creates a tree from [intervals].
-  factory IntervalTree.of(Iterable<Interval> intervals) =>
+  factory IntervalTree.of(Iterable<Interval?> intervals) =>
       IntervalTree()..addAll(intervals);
 
   /// Adds an [interval] into this tree.
   void add(dynamic interval) {
-    Interval iv = _asInterval(interval);
+    Interval? iv = _asInterval(interval);
     if (iv == null) return;
 
     bool joined = false;
-    BidirectionalIterator<Interval> it = _tree.fromIterator(iv);
+    BidirectionalIterator<Interval?> it = _tree.fromIterator(iv);
     while (it.movePrevious()) {
       final union = _tryJoin(it.current, iv);
       if (union == null) break;
@@ -367,7 +367,7 @@ class IntervalTree with IterableMixin<Interval> {
     final iv = _asInterval(interval);
     if (iv == null) return;
 
-    BidirectionalIterator<Interval> it = _tree.fromIterator(iv);
+    BidirectionalIterator<Interval?> it = _tree.fromIterator(iv);
     while (it.movePrevious()) {
       final current = it.current;
       if (!_trySplit(it.current, iv)) break;
@@ -408,13 +408,13 @@ class IntervalTree with IterableMixin<Interval> {
     final result = IntervalTree();
     if (isEmpty || other.isEmpty) result;
     for (final iv in other) {
-      BidirectionalIterator<Interval> it = _tree.fromIterator(iv);
-      while (it.movePrevious() && iv.intersects(it.current)) {
-        result.add(iv.intersection(it.current));
+      BidirectionalIterator<Interval?> it = _tree.fromIterator(iv);
+      while (it.movePrevious() && iv!.intersects(it.current!)) {
+        result.add(iv.intersection(it.current!));
       }
       it = _tree.fromIterator(iv, inclusive: false);
-      while (it.moveNext() && iv.intersects(it.current)) {
-        result.add(iv.intersection(it.current));
+      while (it.moveNext() && iv!.intersects(it.current!)) {
+        result.add(iv.intersection(it.current!));
       }
     }
     return result;
@@ -425,13 +425,13 @@ class IntervalTree with IterableMixin<Interval> {
     final iv = _asInterval(interval);
     if (iv == null) return false;
 
-    BidirectionalIterator<Interval> it = _tree.fromIterator(iv);
-    while (it.movePrevious() && iv.intersects(it.current)) {
-      if (it.current.contains(iv)) return true;
+    BidirectionalIterator<Interval?> it = _tree.fromIterator(iv);
+    while (it.movePrevious() && iv.intersects(it.current!)) {
+      if (it.current!.contains(iv)) return true;
     }
     it = _tree.fromIterator(iv, inclusive: false);
-    while (it.moveNext() && it.current.intersects(iv)) {
-      if (it.current.contains(iv)) return true;
+    while (it.moveNext() && it.current!.intersects(iv)) {
+      if (it.current!.contains(iv)) return true;
     }
     return false;
   }
@@ -450,35 +450,35 @@ class IntervalTree with IterableMixin<Interval> {
 
   /// Returns the first interval in tree, or `null` if this tree is empty.
   @override
-  Interval get first => _tree.first;
+  Interval? get first => _tree.first;
 
   /// Returns the first interval in tree, or `null` if this tree is empty.
   @override
-  Interval get last => _tree.last;
+  Interval? get last => _tree.last;
 
   /// Checks that this tree has only one interval, and returns that interval.
   @override
-  Interval get single => _tree.single;
+  Interval? get single => _tree.single;
 
   /// Returns a bidirectional iterator that allows iterating the intervals.
   @override
-  BidirectionalIterator<Interval> get iterator => _tree.iterator;
+  BidirectionalIterator<Interval?> get iterator => _tree.iterator;
 
   /// Returns a string representation of the tree.
   @override
   String toString() => 'IntervalTree' + super.toString();
 
-  Interval _asInterval(dynamic interval) {
+  Interval? _asInterval(dynamic interval) {
     if (interval is Iterable) {
       if (interval.length != 2 || interval.first is Iterable) {
         throw ArgumentError('$interval is not an interval');
       }
       return Interval(interval.first, interval.last);
     }
-    return interval as Interval;
+    return interval as Interval?;
   }
 
-  Interval _tryJoin(Interval a, Interval b) {
+  Interval? _tryJoin(Interval? a, Interval? b) {
     if (a == null || b == null) return null;
     if (a.contains(b)) return a;
     if (!a.intersects(b)) return null;
@@ -489,7 +489,7 @@ class IntervalTree with IterableMixin<Interval> {
     return union;
   }
 
-  bool _trySplit(Interval a, Interval b) {
+  bool _trySplit(Interval? a, Interval b) {
     if (a == null || b == null) return false;
     if (!a.intersects(b)) return false;
     _tree.remove(a);
@@ -497,6 +497,6 @@ class IntervalTree with IterableMixin<Interval> {
     return true;
   }
 
-  final AvlTreeSet<Interval> _tree =
-      AvlTreeSet<Interval>(comparator: Comparable.compare);
+  final AvlTreeSet<Interval?> _tree = AvlTreeSet<Interval?>(
+      comparator: Comparable.compare as int Function(Interval?, Interval?));
 }
diff --git a/pubspec.yaml b/pubspec.yaml
index 4eedc24..f9d3d6f 100644
--- a/pubspec.yaml
+++ b/pubspec.yaml
@@ -9,7 +9,7 @@ repository: https://github.com/jpnurmi/interval_tree
 issue_tracker: https://github.com/jpnurmi/interval_tree/issues
 
 environment:
-  sdk: ">=2.7.0 <3.0.0"
+  sdk: '>=2.12.0 <3.0.0'
 dependencies:
   meta: ^1.1.8
   quiver: ^2.0.5

From 45b0f25f2b9bd25a57f4169fa7f64ffb5e9c5cbc Mon Sep 17 00:00:00 2001
From: Scott Carnett <798305+scarnett@users.noreply.github.com>
Date: Tue, 20 Apr 2021 15:18:48 -0500
Subject: [PATCH 2/7] updates

---
 lib/interval_tree.dart       | 44 +++++++++++++++---------------------
 pubspec.yaml                 |  2 +-
 test/interval_tree_test.dart |  4 ++--
 3 files changed, 21 insertions(+), 29 deletions(-)

diff --git a/lib/interval_tree.dart b/lib/interval_tree.dart
index 2e9af40..24a744c 100644
--- a/lib/interval_tree.dart
+++ b/lib/interval_tree.dart
@@ -308,10 +308,10 @@ class Interval extends Comparable<Interval> {
 ///
 ///     final interval = ivt.Interval(1, 2);
 ///
-class IntervalTree with IterableMixin<Interval?> {
+class IntervalTree with IterableMixin<Interval> {
   /// Creates a tree, optionally with an [interval].
   IntervalTree([dynamic interval]) {
-    add(interval);
+    if (interval != null) add(interval);
   }
 
   /// Creates a tree from given iterable of [intervals].
@@ -329,9 +329,7 @@ class IntervalTree with IterableMixin<Interval?> {
 
   /// Adds an [interval] into this tree.
   void add(dynamic interval) {
-    Interval? iv = _asInterval(interval);
-    if (iv == null) return;
-
+    Interval iv = _asInterval(interval);
     bool joined = false;
     BidirectionalIterator<Interval?> it = _tree.fromIterator(iv);
     while (it.movePrevious()) {
@@ -356,7 +354,6 @@ class IntervalTree with IterableMixin<Interval?> {
 
   /// Adds all [intervals] into this tree.
   void addAll(Iterable intervals) {
-    if (intervals == null) return;
     for (final interval in intervals) {
       add(interval);
     }
@@ -365,9 +362,8 @@ class IntervalTree with IterableMixin<Interval?> {
   /// Removes an [interval] from this tree.
   void remove(dynamic interval) {
     final iv = _asInterval(interval);
-    if (iv == null) return;
 
-    BidirectionalIterator<Interval?> it = _tree.fromIterator(iv);
+    BidirectionalIterator<Interval> it = _tree.fromIterator(iv);
     while (it.movePrevious()) {
       final current = it.current;
       if (!_trySplit(it.current, iv)) break;
@@ -384,7 +380,6 @@ class IntervalTree with IterableMixin<Interval?> {
 
   /// Removes all [intervals] from this tree.
   void removeAll(Iterable intervals) {
-    if (intervals == null) return;
     for (final interval in intervals) {
       remove(interval);
     }
@@ -408,13 +403,13 @@ class IntervalTree with IterableMixin<Interval?> {
     final result = IntervalTree();
     if (isEmpty || other.isEmpty) result;
     for (final iv in other) {
-      BidirectionalIterator<Interval?> it = _tree.fromIterator(iv);
-      while (it.movePrevious() && iv!.intersects(it.current!)) {
-        result.add(iv.intersection(it.current!));
+      BidirectionalIterator<Interval> it = _tree.fromIterator(iv);
+      while (it.movePrevious() && iv.intersects(it.current)) {
+        result.add(iv.intersection(it.current));
       }
       it = _tree.fromIterator(iv, inclusive: false);
-      while (it.moveNext() && iv!.intersects(it.current!)) {
-        result.add(iv.intersection(it.current!));
+      while (it.moveNext() && iv.intersects(it.current)) {
+        result.add(iv.intersection(it.current));
       }
     }
     return result;
@@ -423,8 +418,6 @@ class IntervalTree with IterableMixin<Interval?> {
   @override
   bool contains(dynamic interval) {
     final iv = _asInterval(interval);
-    if (iv == null) return false;
-
     BidirectionalIterator<Interval?> it = _tree.fromIterator(iv);
     while (it.movePrevious() && iv.intersects(it.current!)) {
       if (it.current!.contains(iv)) return true;
@@ -450,32 +443,32 @@ class IntervalTree with IterableMixin<Interval?> {
 
   /// Returns the first interval in tree, or `null` if this tree is empty.
   @override
-  Interval? get first => _tree.first;
+  Interval get first => _tree.first;
 
   /// Returns the first interval in tree, or `null` if this tree is empty.
   @override
-  Interval? get last => _tree.last;
+  Interval get last => _tree.last;
 
   /// Checks that this tree has only one interval, and returns that interval.
   @override
-  Interval? get single => _tree.single;
+  Interval get single => _tree.single;
 
   /// Returns a bidirectional iterator that allows iterating the intervals.
   @override
-  BidirectionalIterator<Interval?> get iterator => _tree.iterator;
+  BidirectionalIterator<Interval> get iterator => _tree.iterator;
 
   /// Returns a string representation of the tree.
   @override
   String toString() => 'IntervalTree' + super.toString();
 
-  Interval? _asInterval(dynamic interval) {
+  Interval _asInterval(dynamic interval) {
     if (interval is Iterable) {
       if (interval.length != 2 || interval.first is Iterable) {
         throw ArgumentError('$interval is not an interval');
       }
       return Interval(interval.first, interval.last);
     }
-    return interval as Interval?;
+    return interval;
   }
 
   Interval? _tryJoin(Interval? a, Interval? b) {
@@ -489,14 +482,13 @@ class IntervalTree with IterableMixin<Interval?> {
     return union;
   }
 
-  bool _trySplit(Interval? a, Interval b) {
-    if (a == null || b == null) return false;
+  bool _trySplit(Interval a, Interval b) {
     if (!a.intersects(b)) return false;
     _tree.remove(a);
     _tree.addAll([...?a.difference(b)]);
     return true;
   }
 
-  final AvlTreeSet<Interval?> _tree = AvlTreeSet<Interval?>(
-      comparator: Comparable.compare as int Function(Interval?, Interval?));
+  final AvlTreeSet<Interval> _tree =
+      AvlTreeSet<Interval>(comparator: Comparable.compare);
 }
diff --git a/pubspec.yaml b/pubspec.yaml
index f9d3d6f..d47d850 100644
--- a/pubspec.yaml
+++ b/pubspec.yaml
@@ -12,7 +12,7 @@ environment:
   sdk: '>=2.12.0 <3.0.0'
 dependencies:
   meta: ^1.1.8
-  quiver: ^2.0.5
+  quiver: ^3.0.1
 dev_dependencies:
   test: ^1.14.2
   test_coverage: ^0.4.1
diff --git a/test/interval_tree_test.dart b/test/interval_tree_test.dart
index 33d17e4..82c74e4 100644
--- a/test/interval_tree_test.dart
+++ b/test/interval_tree_test.dart
@@ -248,8 +248,8 @@ void main() {
     IntervalTree empty = IntervalTree();
     expect(empty.isEmpty, isTrue);
     expect(empty.isNotEmpty, isFalse);
-    expect(empty.first, isNull);
-    expect(empty.last, isNull);
+    // expect(empty.first, isNull);
+    // expect(empty.last, isNull);
     expect(empty.length, 0);
     expect(() => empty.single, throwsStateError);
 

From 3dfce1976828c457c3186bbe32f17ed5dd7e8a9d Mon Sep 17 00:00:00 2001
From: Scott Carnett <798305+scarnett@users.noreply.github.com>
Date: Wed, 21 Apr 2021 18:51:07 -0500
Subject: [PATCH 3/7] nullsafe updates

---
 lib/interval_tree.dart       | 18 ++++++++++--------
 test/interval_tree_test.dart |  4 ++--
 2 files changed, 12 insertions(+), 10 deletions(-)

diff --git a/lib/interval_tree.dart b/lib/interval_tree.dart
index 24a744c..31a64dd 100644
--- a/lib/interval_tree.dart
+++ b/lib/interval_tree.dart
@@ -311,7 +311,7 @@ class Interval extends Comparable<Interval> {
 class IntervalTree with IterableMixin<Interval> {
   /// Creates a tree, optionally with an [interval].
   IntervalTree([dynamic interval]) {
-    if (interval != null) add(interval);
+    add(interval);
   }
 
   /// Creates a tree from given iterable of [intervals].
@@ -328,8 +328,10 @@ class IntervalTree with IterableMixin<Interval> {
       IntervalTree()..addAll(intervals);
 
   /// Adds an [interval] into this tree.
-  void add(dynamic interval) {
-    Interval iv = _asInterval(interval);
+  void add(dynamic? interval) {
+    Interval? iv = _asInterval(interval);
+    if (iv == null) return;
+
     bool joined = false;
     BidirectionalIterator<Interval?> it = _tree.fromIterator(iv);
     while (it.movePrevious()) {
@@ -339,7 +341,7 @@ class IntervalTree with IterableMixin<Interval> {
       joined = true;
     }
 
-    it = _tree.fromIterator(iv, inclusive: false);
+    it = _tree.fromIterator(iv!, inclusive: false);
     while (it.moveNext()) {
       final union = _tryJoin(it.current, iv);
       if (union == null) break;
@@ -348,7 +350,7 @@ class IntervalTree with IterableMixin<Interval> {
     }
 
     if (!joined) {
-      _tree.add(iv);
+      _tree.add(iv!);
     }
   }
 
@@ -363,7 +365,7 @@ class IntervalTree with IterableMixin<Interval> {
   void remove(dynamic interval) {
     final iv = _asInterval(interval);
 
-    BidirectionalIterator<Interval> it = _tree.fromIterator(iv);
+    BidirectionalIterator<Interval> it = _tree.fromIterator(iv!);
     while (it.movePrevious()) {
       final current = it.current;
       if (!_trySplit(it.current, iv)) break;
@@ -418,7 +420,7 @@ class IntervalTree with IterableMixin<Interval> {
   @override
   bool contains(dynamic interval) {
     final iv = _asInterval(interval);
-    BidirectionalIterator<Interval?> it = _tree.fromIterator(iv);
+    BidirectionalIterator<Interval?> it = _tree.fromIterator(iv!);
     while (it.movePrevious() && iv.intersects(it.current!)) {
       if (it.current!.contains(iv)) return true;
     }
@@ -461,7 +463,7 @@ class IntervalTree with IterableMixin<Interval> {
   @override
   String toString() => 'IntervalTree' + super.toString();
 
-  Interval _asInterval(dynamic interval) {
+  Interval? _asInterval(dynamic? interval) {
     if (interval is Iterable) {
       if (interval.length != 2 || interval.first is Iterable) {
         throw ArgumentError('$interval is not an interval');
diff --git a/test/interval_tree_test.dart b/test/interval_tree_test.dart
index 82c74e4..33d17e4 100644
--- a/test/interval_tree_test.dart
+++ b/test/interval_tree_test.dart
@@ -248,8 +248,8 @@ void main() {
     IntervalTree empty = IntervalTree();
     expect(empty.isEmpty, isTrue);
     expect(empty.isNotEmpty, isFalse);
-    // expect(empty.first, isNull);
-    // expect(empty.last, isNull);
+    expect(empty.first, isNull);
+    expect(empty.last, isNull);
     expect(empty.length, 0);
     expect(() => empty.single, throwsStateError);
 

From ad7ae023d2b336d4aa59a03f3bf9dfa879cfd2fb Mon Sep 17 00:00:00 2001
From: Scott Carnett <798305+scarnett@users.noreply.github.com>
Date: Wed, 21 Apr 2021 18:51:58 -0500
Subject: [PATCH 4/7] remove 2 tests

---
 test/interval_tree_test.dart | 2 --
 1 file changed, 2 deletions(-)

diff --git a/test/interval_tree_test.dart b/test/interval_tree_test.dart
index 33d17e4..030f715 100644
--- a/test/interval_tree_test.dart
+++ b/test/interval_tree_test.dart
@@ -248,8 +248,6 @@ void main() {
     IntervalTree empty = IntervalTree();
     expect(empty.isEmpty, isTrue);
     expect(empty.isNotEmpty, isFalse);
-    expect(empty.first, isNull);
-    expect(empty.last, isNull);
     expect(empty.length, 0);
     expect(() => empty.single, throwsStateError);
 

From 0a4b7e44b0fedcd86a522cb36698dcb0210be83c Mon Sep 17 00:00:00 2001
From: Scott Carnett <798305+scarnett@users.noreply.github.com>
Date: Wed, 21 Apr 2021 19:00:52 -0500
Subject: [PATCH 5/7] test for exception

---
 lib/interval_tree.dart       | 4 ++--
 test/interval_tree_test.dart | 2 ++
 2 files changed, 4 insertions(+), 2 deletions(-)

diff --git a/lib/interval_tree.dart b/lib/interval_tree.dart
index 31a64dd..b4d3716 100644
--- a/lib/interval_tree.dart
+++ b/lib/interval_tree.dart
@@ -443,11 +443,11 @@ class IntervalTree with IterableMixin<Interval> {
   @override
   bool get isNotEmpty => _tree.isNotEmpty;
 
-  /// Returns the first interval in tree, or `null` if this tree is empty.
+  /// Returns the first interval in tree, otherwise throw StateError.
   @override
   Interval get first => _tree.first;
 
-  /// Returns the first interval in tree, or `null` if this tree is empty.
+  /// Returns the first interval in tree, otherwise throw StateError.
   @override
   Interval get last => _tree.last;
 
diff --git a/test/interval_tree_test.dart b/test/interval_tree_test.dart
index 030f715..8a564c9 100644
--- a/test/interval_tree_test.dart
+++ b/test/interval_tree_test.dart
@@ -248,6 +248,8 @@ void main() {
     IntervalTree empty = IntervalTree();
     expect(empty.isEmpty, isTrue);
     expect(empty.isNotEmpty, isFalse);
+    expect(() => empty.first, throwsA(isA<StateError>()));
+    expect(() => empty.last, throwsA(isA<StateError>()));
     expect(empty.length, 0);
     expect(() => empty.single, throwsStateError);
 

From de16edcdb217f12fcfa3b80ae240aba9767734a6 Mon Sep 17 00:00:00 2001
From: Scott Carnett <798305+scarnett@users.noreply.github.com>
Date: Wed, 21 Apr 2021 19:24:03 -0500
Subject: [PATCH 6/7] switch to test_cov

---
 pubspec.yaml | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/pubspec.yaml b/pubspec.yaml
index d47d850..949c128 100644
--- a/pubspec.yaml
+++ b/pubspec.yaml
@@ -15,4 +15,4 @@ dependencies:
   quiver: ^3.0.1
 dev_dependencies:
   test: ^1.14.2
-  test_coverage: ^0.4.1
+  test_cov: ^1.0.1

From 72ca1a356534b1b958c8d0be51eae6063993815d Mon Sep 17 00:00:00 2001
From: Scott Carnett <798305+scarnett@users.noreply.github.com>
Date: Wed, 21 Apr 2021 19:27:21 -0500
Subject: [PATCH 7/7] update workflow

---
 .github/workflows/build.yml | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/.github/workflows/build.yml b/.github/workflows/build.yml
index a179b60..1ea9a34 100644
--- a/.github/workflows/build.yml
+++ b/.github/workflows/build.yml
@@ -19,7 +19,7 @@ jobs:
     - name: Run tests
       run: pub run test
     - name: Measure coverage
-      run: pub run test_coverage
+      run: pub run test_cov
     - name: Upload coverage
       uses: codecov/codecov-action@v1.0.6
       with: