Haxe Lib Datachannel

lib/datachannel/cpp/libdatachannel/include/rtc/utils.hpp

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+/**
+ * Copyright (c) 2019-2021 Paul-Louis Ageneau
+ *
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at https://mozilla.org/MPL/2.0/.
+ */
+
+#ifndef RTC_UTILS_H
+#define RTC_UTILS_H
+
+#include <algorithm>
+#include <cctype>
+#include <functional>
+#include <memory>
+#include <mutex>
+#include <optional>
+#include <string>
+#include <tuple>
+#include <utility>
+
+namespace rtc {
+
+// overloaded helper
+template <class... Ts> struct overloaded : Ts... { using Ts::operator()...; };
+template <class... Ts> overloaded(Ts...) -> overloaded<Ts...>;
+
+// weak_ptr bind helper
+template <typename F, typename T, typename... Args> auto weak_bind(F &&f, T *t, Args &&..._args) {
+	return [bound = std::bind(f, t, _args...), weak_this = t->weak_from_this()](auto &&...args) {
+		if (auto shared_this = weak_this.lock())
+			return bound(args...);
+		else
+			return static_cast<decltype(bound(args...))>(false);
+	};
+}
+
+// scope_guard helper
+class scope_guard final {
+public:
+	scope_guard(std::function<void()> func) : function(std::move(func)) {}
+	scope_guard(scope_guard &&other) = delete;
+	scope_guard(const scope_guard &) = delete;
+	void operator=(const scope_guard &) = delete;
+
+	~scope_guard() {
+		if (function)
+			function();
+	}
+
+private:
+	std::function<void()> function;
+};
+
+// callback with built-in synchronization
+template <typename... Args> class synchronized_callback {
+public:
+	synchronized_callback() = default;
+	synchronized_callback(synchronized_callback &&cb) { *this = std::move(cb); }
+	synchronized_callback(const synchronized_callback &cb) { *this = cb; }
+	synchronized_callback(std::function<void(Args...)> func) { *this = std::move(func); }
+	virtual ~synchronized_callback() { *this = nullptr; }
+
+	synchronized_callback &operator=(synchronized_callback &&cb) {
+		std::scoped_lock lock(mutex, cb.mutex);
+		set(std::exchange(cb.callback, nullptr));
+		return *this;
+	}
+
+	synchronized_callback &operator=(const synchronized_callback &cb) {
+		std::scoped_lock lock(mutex, cb.mutex);
+		set(cb.callback);
+		return *this;
+	}
+
+	synchronized_callback &operator=(std::function<void(Args...)> func) {
+		std::lock_guard lock(mutex);
+		set(std::move(func));
+		return *this;
+	}
+
+	bool operator()(Args... args) const {
+		std::lock_guard lock(mutex);
+		return call(std::move(args)...);
+	}
+
+	operator bool() const {
+		std::lock_guard lock(mutex);
+		return callback ? true : false;
+	}
+
+protected:
+	virtual void set(std::function<void(Args...)> func) { callback = std::move(func); }
+	virtual bool call(Args... args) const {
+		if (!callback)
+			return false;
+
+		callback(std::move(args)...);
+		return true;
+	}
+
+	std::function<void(Args...)> callback;
+	mutable std::recursive_mutex mutex;
+};
+
+// callback with built-in synchronization and replay of the last missed call
+template <typename... Args>
+class synchronized_stored_callback final : public synchronized_callback<Args...> {
+public:
+	template <typename... CArgs>
+	synchronized_stored_callback(CArgs &&...cargs)
+	    : synchronized_callback<Args...>(std::forward<CArgs>(cargs)...) {}
+	~synchronized_stored_callback() {}
+
+private:
+	void set(std::function<void(Args...)> func) {
+		synchronized_callback<Args...>::set(func);
+		if (func && stored) {
+			std::apply(func, std::move(*stored));
+			stored.reset();
+		}
+	}
+
+	bool call(Args... args) const {
+		if (!synchronized_callback<Args...>::call(args...))
+			stored.emplace(std::move(args)...);
+
+		return true;
+	}
+
+	mutable std::optional<std::tuple<Args...>> stored;
+};
+
+// pimpl base class
+template <typename T> using impl_ptr = std::shared_ptr<T>;
+template <typename T> class CheshireCat {
+public:
+	CheshireCat(impl_ptr<T> impl) : mImpl(std::move(impl)) {}
+	template <typename... Args>
+	CheshireCat(Args... args) : mImpl(std::make_shared<T>(std::forward<Args>(args)...)) {}
+	CheshireCat(CheshireCat<T> &&cc) { *this = std::move(cc); }
+	CheshireCat(const CheshireCat<T> &) = delete;
+
+	virtual ~CheshireCat() = default;
+
+	CheshireCat &operator=(CheshireCat<T> &&cc) {
+		mImpl = std::move(cc.mImpl);
+		return *this;
+	};
+	CheshireCat &operator=(const CheshireCat<T> &) = delete;
+
+protected:
+	impl_ptr<T> impl() { return mImpl; }
+	impl_ptr<const T> impl() const { return mImpl; }
+
+private:
+	impl_ptr<T> mImpl;
+};
+
+// case-insensitive string comparator using std::tolower
+class case_insensitive_less : public std::less<std::string> {
+public:
+	bool operator()(const std::string &lhs, const std::string &rhs) const {
+		return std::lexicographical_compare(lhs.begin(), lhs.end(), rhs.begin(), rhs.end(),
+		                                    [](auto a, auto b) {
+			                                    return std::tolower(static_cast<unsigned char>(a)) <
+			                                           std::tolower(static_cast<unsigned char>(b));
+		                                    });
+	}
+};
+
+} // namespace rtc
+
+#endif