From 4af2cb62463ed9c5672d76b67f8a0c7c2c77a053 Mon Sep 17 00:00:00 2001
From: Andras Varga <andras@omnetpp.org>
Date: Thu, 4 Apr 2024 12:00:40 +0200
Subject: [PATCH] common: add Traced.h

---
 src/inet/common/Traced.h | 148 +++++++++++++++++++++++++++++++++++++++
 1 file changed, 148 insertions(+)
 create mode 100644 src/inet/common/Traced.h

diff --git a/src/inet/common/Traced.h b/src/inet/common/Traced.h
new file mode 100644
index 00000000000..dfc87cf7398
--- /dev/null
+++ b/src/inet/common/Traced.h
@@ -0,0 +1,148 @@
+//
+// Copyright (C) 2024 OpenSim Ltd.
+//
+// SPDX-License-Identifier: LGPL-3.0-or-later
+//
+
+
+#ifndef __INET_TRACED_H
+#define __INET_TRACED_H
+
+#include "inet/common/INETDefs.h"
+
+namespace inet {
+
+/**
+ * @brief A template class that wraps a variable of type T (usually an primitive type like int,
+ * double, enum, etc.), and monitors its value for changes. On each change, the callback function
+ * is called with the old and the new value. This class is particularly useful for automatic
+ * logging or recording of state variables in a module.
+ */
+template<typename T>
+class Traced {
+  private:
+    T value_;
+    std::function<void(T,T)> callback_;
+
+    void setValue(const T& newValue) {
+        T oldValue = value_;
+        value_ = newValue;
+        if (callback_)
+            callback_(oldValue, newValue);
+    }
+
+  public:
+    Traced() = default;
+
+    Traced(const T& value) : value_(value) {}
+
+    Traced(const T& value, std::function<void(T,T)> callback) : value_(value), callback_(callback) {}
+
+    // Set callback function
+    void addCallback(std::function<void(T,T)> callback) {
+        if (!callback_)
+            callback_ = callback;
+        else
+            // chaining
+            callback_ = [=](T oldValue, T newValue) {
+                callback_(oldValue, newValue);
+                callback(oldValue, newValue);
+            };
+    }
+
+    // Set up to emit signal on changes
+    void addEmitCallback(cComponent *component, simsignal_t signal) {
+        auto callback = [=](T oldValue, T newValue) {
+            if (oldValue != newValue)
+                component->emit(signal, newValue);
+        };
+        addCallback(callback);
+    }
+
+    void removeCallbacks() {
+        callback_ = nullptr;
+    }
+
+    // Overload assignment operator
+    Traced& operator=(const T& value) {
+        setValue(value);
+        return *this;
+    }
+
+    // Overload for += operator
+    Traced& operator+=(const T& rhs) {
+        setValue(value_ + rhs);
+        return *this;
+    }
+
+    // Overload for -= operator
+    Traced& operator-=(const T& rhs) {
+        setValue(value_ - rhs);
+        return *this;
+    }
+
+    // Overload for *= operator
+    Traced& operator*=(const T& rhs) {
+        setValue(value_ * rhs);
+        return *this;
+    }
+
+    // Overload for /= operator
+    Traced& operator/=(const T& rhs) {
+        setValue(value_ / rhs);
+        return *this;
+    }
+
+    // Overload for %= operator (only for integral types)
+    template<typename U = T>
+    typename std::enable_if<std::is_integral<U>::value, Traced&>::type operator%=(const T& rhs) {
+        setValue(value_ % rhs);
+        return *this;
+    }
+
+    // Overload for &= operator (only for integral types)
+    template<typename U = T>
+    typename std::enable_if<std::is_integral<U>::value, Traced&>::type operator&=(const T& rhs) {
+        setValue(value_ & rhs);
+        return *this;
+    }
+
+    // Overload for |= operator (only for integral types)
+    template<typename U = T>
+    typename std::enable_if<std::is_integral<U>::value, Traced&>::type operator|=(const T& rhs) {
+        setValue(value_ | rhs);
+        return *this;
+    }
+
+    // Overload for ^= operator (only for integral types)
+    template<typename U = T>
+    typename std::enable_if<std::is_integral<U>::value, Traced&>::type operator^=(const T& rhs) {
+        setValue(value_ ^ rhs);
+        return *this;
+    }
+
+    // Overload for <<= operator (only for integral types)
+    template<typename U = T>
+    typename std::enable_if<std::is_integral<U>::value, Traced&>::type operator<<=(const T& rhs) {
+        setValue(value_ << rhs);
+        return *this;
+    }
+
+    // Overload for >>= operator (only for integral types)
+    template<typename U = T>
+    typename std::enable_if<std::is_integral<U>::value, Traced&>::type operator>>=(const T& rhs) {
+        setValue(value_ >> rhs);
+        return *this;
+    }
+
+    // Overload type conversion operator to allow transparent use as T
+    operator T() const {
+        return value_;
+    }
+
+};
+
+} // namespace inet
+
+#endif
+