From d98e139d08d2d24426d75384f8789ccc7279bca4 Mon Sep 17 00:00:00 2001 From: dyknon Date: Mon, 7 Sep 2026 23:28:33 +0900 Subject: thinfunc --- thinfunc-example.cc | 86 ++++++++++++++++++++++++++++++++++++++++++++++++++++ thinfunc.h | 87 +++++++++++++++++++++++++++++++++++++++++++++++++++++ 2 files changed, 173 insertions(+) create mode 100644 thinfunc-example.cc create mode 100644 thinfunc.h diff --git a/thinfunc-example.cc b/thinfunc-example.cc new file mode 100644 index 0000000..1cf12d6 --- /dev/null +++ b/thinfunc-example.cc @@ -0,0 +1,86 @@ +/* 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 +#include +#include + +using namespace tf; + +struct test{ + std::string name; + test(std::string name): name(name){} + + anchor m1; + func& get_m1(){ + return m1.bind<&test::m1, &test::message1>(); + } + anchor m2; + func& get_m2(){ + return m2.bind<&test::m2, &test::message2>(); + } + anchor t; + func& 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& m1 = o.get_m1(); + func& m2 = o.get_m2(); + o.get_t(); + func& 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 +struct func; +template +struct func{ + virtual R operator()(Args...) = 0; +}; + +template +class anchor; +template +class bound_anchor; + +template +class anchor{ +public: + template (T::*Self), R (T::*Method)(Args...)> + using bound_type = bound_anchor (T::*), R (T::*)(Args...), Self, Method>; +private: + alignas(bound_type) + char body[sizeof(bound_type)]; +public: + template (T::*Self), R (T::*Method)(Args...)> + auto& bind(){ + return *(new (this->body) bound_type()); + } + template (T::*Self), R (T::*Method)(Args...)> + auto& assume_bound() const{ + return *(bound_type *)this->body; + } +}; + +template< + class T, class R, class... Args, + anchor (T::*Self), R (T::*Method)(Args...) +> +class bound_anchor (T::*), R (T::*)(Args...), + Self, Method + >: public func{ +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 -- cgit v1.2.3