dirtyvalue: Move to src/utility

src/utility/DirtyValue.h

@@ -0,0 +1,39 @@
+#pragma once
+
+namespace Pinetime {
+  namespace Utility {
+    template <class T>
+    class DirtyValue {
+    public:
+      DirtyValue() = default; // Use NSDMI
+
+      explicit DirtyValue(T const& v) : value {v} {
+      } // Use MIL and const-lvalue-ref
+
+      bool IsUpdated() {
+        if (this->isUpdated) {
+          this->isUpdated = false;
+          return true;
+        }
+        return false;
+      }
+
+      T const& Get() {
+        this->isUpdated = false;
+        return value;
+      } // never expose a non-const lvalue-ref
+
+      DirtyValue& operator=(const T& other) {
+        if (this->value != other) {
+          this->value = other;
+          this->isUpdated = true;
+        }
+        return *this;
+      }
+
+    private:
+      T value {};            // NSDMI - default initialise type
+      bool isUpdated {true}; // NSDMI - use brace initialisation
+    };
+  }
+}