Merge pull request #34 from code-shoily/migrate_to_nnbd

Migrate to nnbd

Author: code-shoily

.travis.yml

@@ -1,7 +1,7 @@
 language: dart
 
 dart:
-  - stable
+  - beta
 
 dart_task:
   - test

analysis_options.yaml

@@ -3,9 +3,77 @@ analyzer:
 #     - path/to/excluded/files/**
 
 # Lint rules and documentation, see http://dart-lang.github.io/linter/lints
-
-include: package:effective_dart/analysis_options.1.2.0.yaml
+# NOTE: The contents of `Effective Dart` have been copied over because it does not yet support NNBD
 
 linter:
   rules:
+    # STYLE
+    - camel_case_types
+    - camel_case_extensions
+    - library_names
+    - file_names
+    - library_prefixes
+    - non_constant_identifier_names
+    - constant_identifier_names # prefer
+    - directives_ordering
+    - lines_longer_than_80_chars # avoid
+    - curly_braces_in_flow_control_structures
     - prefer_single_quotes
+
+    # DOCUMENTATION
+    - slash_for_doc_comments
+    - package_api_docs # prefer
+    - public_member_api_docs # prefer
+    #- comment_references # Unused because https://github.com/dart-lang/sdk/issues/36974
+
+    # USAGE
+    - implementation_imports
+    - avoid_relative_lib_imports
+    - prefer_relative_imports
+    - prefer_adjacent_string_concatenation
+    - prefer_interpolation_to_compose_strings # prefer
+    - unnecessary_brace_in_string_interps # avoid
+    - prefer_collection_literals
+    - prefer_is_empty
+    - prefer_is_not_empty
+    - avoid_function_literals_in_foreach_calls # avoid
+    - prefer_iterable_whereType
+    - prefer_function_declarations_over_variables
+    - unnecessary_lambdas
+    - prefer_equal_for_default_values
+    - avoid_init_to_null
+    - unnecessary_getters_setters
+    #- unnecessary_getters # prefer # Disabled pending fix: https://github.com/dart-lang/linter/issues/23
+    #- prefer_expression_function_bodies # consider
+    - unnecessary_this
+    - prefer_initializing_formals
+    - type_init_formals
+    - empty_constructor_bodies
+    - unnecessary_new
+    - unnecessary_const
+    - avoid_catches_without_on_clauses # avoid
+    - avoid_catching_errors
+    - use_rethrow_when_possible
+
+    # DESIGN
+    - use_to_and_as_if_applicable # prefer
+    - one_member_abstracts # avoid
+    - avoid_classes_with_only_static_members # avoid
+    - prefer_mixin
+    - prefer_final_fields # prefer
+    - use_setters_to_change_properties
+    - avoid_setters_without_getters
+    - avoid_returning_null # avoid
+    - avoid_returning_this # avoid
+    - type_annotate_public_apis # prefer
+    #- prefer_typing_uninitialized_variables # consider
+    - omit_local_variable_types # avoid
+    #- avoid_types_on_closure_parameters # avoid
+    - avoid_return_types_on_setters
+    - prefer_generic_function_type_aliases
+    - avoid_private_typedef_functions # prefer
+    #- use_function_type_syntax_for_parameters # consider
+    - avoid_positional_boolean_parameters # avoid
+    - hash_and_equals
+    - avoid_equals_and_hash_code_on_mutable_classes # avoid
+    - avoid_null_checks_in_equality_operators

lib/graph/bellman_ford.dart

@@ -5,7 +5,7 @@ import 'vertex.dart';
 
 /// Run the Bellman Ford algorithm to get the shortest paths from [source] to
 /// all vertices.
-HashMap<Vertex, num> bellmanFord(SimpleGraph graph, Vertex source) {
+HashMap<Vertex, num>? bellmanFord(SimpleGraph graph, Vertex source) {
   var distances = HashMap<Vertex, num>();
   distances[source] = 0;
 
@@ -14,7 +14,7 @@ HashMap<Vertex, num> bellmanFord(SimpleGraph graph, Vertex source) {
 
   bool shouldUpdate(Vertex u, Vertex v, num w) {
     if (!distances.containsKey(u)) return false;
-    var uValue = distances[u];
+    var uValue = distances[u]!;
     var vValue = distances[v] ?? (uValue + w + 1);
 
     return uValue + w < vValue;
@@ -26,7 +26,7 @@ HashMap<Vertex, num> bellmanFord(SimpleGraph graph, Vertex source) {
       var v = edge[1];
       var w = edge[2];
       if (shouldUpdate(u, v, w)) {
-        distances[v] = distances[u] + w;
+        distances[v] = distances[u]! + w;
       }
     }
 

lib/graph/dijkstra.dart

@@ -36,18 +36,18 @@ bool _shouldRelax(Map path, Vertex u, Vertex v, num w) => path.containsKey(v)
 
 Vertex _minimumDistance(
     List<Vertex> vertices, Map<Vertex, int> path, Set<Vertex> pathSet) {
-  int min;
-  Vertex vertex;
+  int? min;
+  Vertex? vertex;
 
   for (var v in vertices) {
-    var updateMinimum = min == null || (path.containsKey(v) && path[v] < min);
+    var updateMinimum = min == null || (path.containsKey(v) && path[v]! < min);
     if (updateMinimum && !pathSet.contains(v)) {
       min = path[v];
       vertex = v;
     }
   }
 
-  return vertex;
+  return vertex!;
 }
 
 void _ensurePositiveWeight(SimpleGraph g) {

lib/graph/simple_graph.dart

@@ -2,7 +2,7 @@ import 'vertex.dart';
 
 /// A Graph Type
 class SimpleGraph<T> {
-  Set<Vertex<T>> _vertices;
+  final Set<Vertex<T>> _vertices;
 
   /// Vertices of this graph
   List<Vertex<T>> get vertices => List<Vertex<T>>.unmodifiable(_vertices);
@@ -12,9 +12,7 @@ class SimpleGraph<T> {
   final bool isDigraph;
 
   /// Create a new graph
-  SimpleGraph({this.isDigraph = true}) {
-    _vertices = <Vertex<T>>{};
-  }
+  SimpleGraph({this.isDigraph = true}) : _vertices = <Vertex<T>>{};
 
   /// Total number of vertices for this graph
   int get numberOfVertices => _vertices.length;
@@ -24,7 +22,7 @@ class SimpleGraph<T> {
       _vertices.map((v) => v.outDegree).fold(0, (a, b) => a + b);
 
   /// Adds an edge
-  void addEdge(Vertex src, Vertex dst, [num weight = 1]) {
+  void addEdge(Vertex<T> src, Vertex<T> dst, [num weight = 1]) {
     unlockVertices(<Vertex>{src, dst});
     if (src.key == dst.key) throw Error();
 
@@ -58,20 +56,20 @@ class SimpleGraph<T> {
   bool get isEmpty => numberOfEdges == 0;
 
   /// Adds a new vertex
-  bool addVertex(Vertex vertex) => _vertices.add(vertex);
+  bool addVertex(Vertex<T> vertex) => _vertices.add(vertex);
 
   /// Removes a vertex
   bool removeVertex(Vertex vertex) {
     var edgesRemoved = vertices.contains(vertex)
         ? [
             ...vertex.outgoingConnections.entries.map((e) => [vertex, e.key]),
             ...vertex.incomingVertices.map((e) => [e, vertex])
-          ].fold(true, (acc, v) => acc && removeEdge(v[0], v[1]))
+          ].fold(true, (bool acc, v) => acc && removeEdge(v[0], v[1]))
         : false;
     return edgesRemoved ? _vertices.remove(vertex) : edgesRemoved;
   }
 
-  Vertex<T> _getOrAddVertex(Vertex vertex) =>
+  Vertex<T> _getOrAddVertex(Vertex<T> vertex) =>
       _vertices.add(vertex) ? vertex : vertex;
 
   /// Gets an edge list for [this].

lib/graph/topological_sort.dart

@@ -4,7 +4,7 @@ import 'simple_graph.dart';
 import 'vertex.dart';
 
 /// Returns topological sort using Kahn's algorithm
-List<Vertex> topologicalSort(SimpleGraph graph) {
+List<Vertex>? topologicalSort(SimpleGraph graph) {
   var sorted = <Vertex>[];
   var inDegreeData = inDegrees(graph);
   var noInDegrees = <Vertex>{};
@@ -15,13 +15,14 @@ List<Vertex> topologicalSort(SimpleGraph graph) {
     }
   });
 
-  while (!noInDegrees.isEmpty) {
+  while (noInDegrees.isNotEmpty) {
     var vertex = noInDegrees.first;
     noInDegrees.remove(vertex);
     sorted.add(vertex);
 
     for (var connectedVertex in vertex.outgoingVertices) {
-      if (--inDegreeData[connectedVertex] == 0) {
+      inDegreeData[connectedVertex] = inDegreeData[connectedVertex]! - 1;
+      if (inDegreeData[connectedVertex] == 0) {
         noInDegrees.add(connectedVertex);
       }
     }
@@ -34,7 +35,7 @@ List<Vertex> topologicalSort(SimpleGraph graph) {
 }
 
 bool _detectCycle(HashMap<Vertex, int> inDegreeData) =>
-    inDegreeData.values.where((element) => element > 0).length > 0;
+    inDegreeData.values.where((element) => element > 0).isNotEmpty;
 
 /// Returns in degrees of all vertices of [graph]
 HashMap<Vertex, int> inDegrees(SimpleGraph graph) {

lib/graph/vertex.dart

@@ -11,7 +11,7 @@ class Vertex<T> {
   String get key => _key;
 
   /// Optional value
-  T value;
+  T? value;
 
   final LinkedHashSet<Vertex> _incomingVertices;
 
@@ -22,16 +22,14 @@ class Vertex<T> {
   final LinkedHashMap<Vertex, num> _outgoingConnections;
 
   /// Outgoing connections from this [Vertex]
-  UnmodifiableMapView<Vertex, num> get outgoingConnections =>
+  Map<Vertex, num> get outgoingConnections =>
       Map<Vertex, num>.unmodifiable(_outgoingConnections);
 
   /// Constructor
-  Vertex(this._key, [T value])
+  Vertex(this._key, [this.value])
       : _isLocked = true,
-        _incomingVertices = <Vertex>{} as LinkedHashSet,
-        _outgoingConnections = <Vertex, num>{} as LinkedHashMap {
-    this.value = value ?? key;
-  }
+        _incomingVertices = <Vertex>{} as LinkedHashSet<Vertex>,
+        _outgoingConnections = <Vertex, num>{} as LinkedHashMap<Vertex, num>;
 
   /// Lock [this] vertex, cannot modify after it is locked
   void lock() => _isLocked = true;

lib/heaps/base.dart

@@ -27,7 +27,7 @@ abstract class HeapBase<T> {
   bool get isEmpty;
 
   /// The length of this heap
-  int length;
+  int get length;
 
   /// Inserts [item] into [this]
   void insert(T item);