Merge pull request #14 from rokon-uddin/heap

{{cookiecutter.app_name}}/Common/Sources/Common/Heap.swift

@@ -0,0 +1,60 @@
+//
+//  Heap.swift
+//  Common
+//
+//  Created by {{ cookiecutter.creator }} on {% now 'utc', '%d/%m/%Y' %}.
+//  Copyright © {% now 'utc', '%Y' %} {{cookiecutter.company_name}}. All rights reserved.
+//
+
+private final class Reference<T: Equatable>: Equatable {
+    var value: T
+    init(_ value: T) {
+        self.value = value
+    }
+    static func == (lhs: Reference<T>, rhs: Reference<T>) -> Bool {
+        lhs.value == rhs.value
+    }
+}
+
+@propertyWrapper public struct Heap<T: Equatable>: Equatable {
+    private var reference: Reference<T>
+
+    public init(_ value: T) {
+        reference = .init(value)
+    }
+
+    public var wrappedValue: T {
+        get { reference.value }
+        set {
+            if !isKnownUniquelyReferenced(&reference) {
+                reference = .init(newValue)
+                return
+            }
+            reference.value = newValue
+        }
+    }
+    public var projectedValue: Heap<T> {
+        self
+    }
+}
+
+extension Heap: Hashable where T: Hashable {
+  public func hash(into hasher: inout Hasher) {
+    hasher.combine(wrappedValue)
+  }
+}
+
+extension Heap: Decodable where T: Decodable {
+  public init(from decoder: Decoder) throws {
+    let container = try decoder.singleValueContainer()
+    let value = try container.decode(T.self)
+    self = Heap(value)
+  }
+}
+
+extension Heap: Encodable where T: Encodable {
+  public func encode(to encoder: Encoder) throws {
+    var container = encoder.singleValueContainer()
+    try container.encode(wrappedValue)
+  }
+}