Added type methods.

Author: simphotonics

lib/src/extension/nullable_type_check.dart

@@ -0,0 +1,7 @@
+extension NullableTypeCheck on Object? {
+  /// Returns `true` if the object is null, and `false` otherwise.
+  bool get isNull => this == null ? true : false;
+
+  /// Returns `true` if the object is not null, and `false` otherwise.
+  bool get isNotNull => this == null ? false : true;
+}

lib/src/extension/type_methods.dart

@@ -0,0 +1,115 @@
+import 'package:analyzer/dart/constant/value.dart' show DartObject;
+import 'package:analyzer/dart/element/type.dart'
+    show DynamicType, DartType, ParameterizedType;
+
+/// Extension adding the type methods to `ConstantReader`.
+extension TypeMethods on DartObject {
+  // Returns `true` if `this` represents a constant expression
+  /// with type [double].
+  bool get isBool => type?.isDartCoreBool ?? false;
+
+  // Returns `true` if `this` represents a constant expression
+  /// with type
+  bool get isDouble => type?.isDartCoreDouble ?? false;
+
+  /// Returns `true` if `this` represents a constant expression
+  /// with type [dynamic].
+  bool get isDynamic => type is DynamicType;
+
+  // Returns `true` if `this` represents a constant expression
+  /// with type [Enum].
+  bool get isEnum => type?.isDartCoreEnum ?? false;
+
+  // Returns `true` if `this` represents a constant expression
+  /// with type [int].
+  bool get isInt => type?.isDartCoreInt ?? false;
+
+  /// Returns `true` is `this` represents a constant expression with
+  /// type exactly [Iterable]`.
+  ///
+  /// Note: Returns `false` if the static type represents `List` or `Set`.
+  bool get isIterable => type?.isDartCoreIterable ?? false;
+
+  // Returns `true` if `this` represents a constant expression
+  /// with type [List].
+  bool get isList => type?.isDartCoreList ?? false;
+
+  // Returns `true` if `this` represents a constant expression
+  /// with type that is not [List].
+  bool get isNotList => !isList;
+
+  // Returns `true` if `this` represents a constant expression
+  /// with type [Map].
+  bool get isMap => type?.isDartCoreMap ?? false;
+
+  // Returns `true` if `this` represents a constant expression
+  /// with type that is not [Map].
+  bool get isNotMap => !isMap;
+
+  // Returns `true` if `this` represents a constant expression
+  /// with type [Set].
+  bool get isSet => type?.isDartCoreSet ?? false;
+
+  // Returns `true` if `this` represents a constant expression
+  /// with a type that is not [Set].
+  bool get isNotSet => !isSet;
+
+  // Returns `true` if `this` represents a constant expression
+  /// with type [Null].
+  bool get isNull => type?.isDartCoreNull ?? false;
+
+  // Returns `true` if `this` represents a constant expression
+  /// with type [num].
+  bool get isNum => type?.isDartCoreNum ?? false;
+
+  // Returns `true` if `this` represents a constant expression
+  /// with type [Object].
+  bool get isObject => type?.isDartCoreObject ?? false;
+
+  // Returns `true` if `this` represents a constant expression
+  /// with type [Record].
+  bool get isRecord => type?.isDartCoreRecord ?? false;
+
+  // Returns `true` if `this` represents a constant expression
+  /// with type [String].
+  bool get isString => type?.isDartCoreString ?? false;
+
+  // Returns `true` if `this` represents a constant expression
+  /// with type [Symbol].
+  bool get isSymbol => type?.isDartCoreSymbol ?? false;
+
+  // Returns `true` if `this` represents a constant expression
+  /// with type [Type].
+  bool get isType => type?.isDartCoreType ?? false;
+
+  /// Returns `true` if the static type represents a
+  /// `List`, `Set`, `Map`, or `Iterable`.
+  bool get isCollection => isList || isSet || isMap || isIterable;
+
+  /// Returns `true` if the static type *and* the static type argument
+  /// represent a `List`, `Set`, `Map`, or `Iterable`
+  bool get isRecursiveCollection {
+    if (isNotCollection) return false;
+    final typeArg = dartTypeArgs[0];
+    if (typeArg.isDartCoreIterable ||
+        typeArg.isDartCoreList ||
+        typeArg.isDartCoreSet ||
+        typeArg.isDartCoreMap) {
+      return true;
+    } else {
+      return false;
+    }
+  }
+
+  /// Returns `true` if the static type does not represent
+  /// `List`, `Set`, `Map`, or `Iterable`.
+  bool get isNotCollection => !isList && !isSet && !isMap && !isIterable;
+
+  /// Returns a `List` of type arguments or an empty list.
+  List<DartType> get dartTypeArgs {
+    final dartType = type;
+    return dartType is ParameterizedType
+        ? dartType.typeArguments
+        : <DartType>[];
+  }
+}

lib/src/type/type_utils.dart

@@ -0,0 +1,20 @@
+/// Returns `true` if the derived type [D] is a subtype of base type [B],
+/// and `false` otherwise.
+bool isSubType<D, B>() => Iterable<D>.empty() is Iterable<B>;
+
+/// Returns `true` if [T] is exactly the same type as [S], and `false` otherwise.
+bool isExactly<T, S>() => isSubType<T, S>() && isSubType<S, T>();
+
+/// Returns `true` if [T] is nullable and `false` otherwise.
+bool isNullable<T>() {
+  return Iterable<T>.empty is Iterable<T?>;
+}
+
+/// Returns `true` if `T` is a Dart `enum`.
+///
+/// Note: `T` must not be `dynamic`.
+bool isEnum<T>() => isSubType<Enum, T>();
+
+/// Returns the [Type] representing [T]. Useful to get a instance [Type]
+///  representing a parameterized type.
+Type getType<T>() => T;