From d98e139d08d2d24426d75384f8789ccc7279bca4 Mon Sep 17 00:00:00 2001
From: dyknon <dyknon@r5f.jp>
Date: Mon, 7 Sep 2026 23:28:33 +0900
Subject: thinfunc

---
 thinfunc.h | 87 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 87 insertions(+)
 create mode 100644 thinfunc.h

(limited to 'thinfunc.h')

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
-- 
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