thinfunc

2 files changed, 173 insertions, 0 deletions

diff --git a/thinfunc-example.cc b/thinfunc-example.cc
new file mode 100644
index 0000000..1cf12d6
--- /dev/null
+++ b/thinfunc-example.cc
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+/* Heap-allocation free & small memory footprint
+ *   std::function alternative with limited capabilities.
+ */ // example
+
+/* Copyright (c) 2026 dyknon
+ * 
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the " Software"),
+ * to deal in the Software without restriction, including without limitation
+ * the rights to use, copy, modify, merge, publish, distribute, sublicense,
+ * and/or sell copies of the Software, and to permit persons to whom
+ * the Software is furnished to do so, subject to the following conditions:
+ * 
+ * The above copyright notice and this permission notice
+ * (including the next paragraph) shall be included in all copies
+ * or substantial portions of the Software.
+ * 
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
+ * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+#include "thinfunc.h"
+
+#include <print>
+#include <string>
+#include <ctime>
+
+using namespace tf;
+
+struct test{
+    std::string name;
+    test(std::string name): name(name){}
+
+    anchor<test, void()> m1;
+    func<void()>& get_m1(){
+        return m1.bind<&test::m1, &test::message1>();
+    }
+    anchor<test, void(std::string)> m2;
+    func<void(std::string)>& get_m2(){
+        return m2.bind<&test::m2, &test::message2>();
+    }
+    anchor<test, std::string()> t;
+    func<std::string()>& get_t(){
+        return t.bind<&test::t, &test::time>();
+    }
+
+    void message1(){
+        std::println("hello! I'm {}.", name);
+    }
+    void message2(std::string time){
+        std::println("Good {}! I'm {}.", time, name);
+    }
+    std::string time(){
+        auto t = std::time(nullptr);
+        t /= 60 * 60;
+        t %= 24;
+        if(t < 5){
+            return "night";
+        }else if(t < 12){
+            return "morning";
+        }else if(t < 18){
+            return "afternoon";
+        }else if(t < 20){
+            return "evening";
+        }else{
+            return "night";
+        }
+    }
+};
+
+int main(){
+    test o("a test object");
+    func<void()>& m1 = o.get_m1();
+    func<void(std::string)>& m2 = o.get_m2();
+    o.get_t();
+    func<std::string()>& t = o.t.assume_bound<&test::t, &test::time>();
+
+    m1();
+    m2(t());
+
+    return 0;
+}
diff --git a/thinfunc.h b/thinfunc.h
new file mode 100644
index 0000000..c75c33a
--- /dev/null
+++ b/thinfunc.h
@@ -0,0 +1,87 @@
+/* Heap-allocation free & small memory footprint
+ *   std::function alternative with limited capabilities.
+ */ // single-header library
+
+/* Copyright (c) 2026 dyknon
+ * 
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the " Software"),
+ * to deal in the Software without restriction, including without limitation
+ * the rights to use, copy, modify, merge, publish, distribute, sublicense,
+ * and/or sell copies of the Software, and to permit persons to whom
+ * the Software is furnished to do so, subject to the following conditions:
+ * 
+ * The above copyright notice and this permission notice
+ * (including the next paragraph) shall be included in all copies
+ * or substantial portions of the Software.
+ * 
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
+ * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+
+#ifndef INC_THINFUNC_H
+#define INC_THINFUNC_H
+
+namespace tf{
+
+template<class F>
+struct func;
+template<class R, class... Args>
+struct func<R(Args...)>{
+    virtual R operator()(Args...) = 0;
+};
+
+template<class T, class F>
+class anchor;
+template<class T, class AT, class MT, AT AV, MT MV>
+class bound_anchor;
+
+template<class T, class R, class... Args>
+class anchor<T, R(Args...)>{
+public:
+    template<anchor<T, R(Args...)> (T::*Self), R (T::*Method)(Args...)>
+    using bound_type = bound_anchor<T,
+        anchor<T, R(Args...)> (T::*), R (T::*)(Args...), Self, Method>;
+private:
+    alignas(bound_type<nullptr, nullptr>)
+    char body[sizeof(bound_type<nullptr, nullptr>)];
+public:
+    template<anchor<T, R(Args...)> (T::*Self), R (T::*Method)(Args...)>
+    auto& bind(){
+        return *(new (this->body) bound_type<Self, Method>());
+    }
+    template<anchor<T, R(Args...)> (T::*Self), R (T::*Method)(Args...)>
+    auto& assume_bound() const{
+        return *(bound_type<Self, Method> *)this->body;
+    }
+};
+
+template<
+    class T, class R, class... Args,
+    anchor<T, R(Args...)> (T::*Self), R (T::*Method)(Args...)
+>
+class bound_anchor<T,
+        anchor<T, R(Args...)> (T::*), R (T::*)(Args...),
+        Self, Method
+    >: public func<R(Args...)>{
+public:
+    bound_anchor(){}
+    bound_anchor(const bound_anchor&) = delete;
+    bound_anchor(const bound_anchor&&) = delete;
+    bound_anchor& operator=(const bound_anchor&) = delete;
+    bound_anchor& operator=(const bound_anchor&&) = delete;
+    virtual R operator()(Args... args){
+        auto offset = (char *)&(((T *)0)->*Self) - (char *)0;
+        T *container = (T *)((char *)this - offset);
+        return (container->*Method)(args...);
+    }
+};
+
+}   // namespace rf
+
+#endif  //INC_THINFUNC_H