Add Signal for callbacks within a process (code executing on one core).

firmware/application/signal.hpp

@@ -0,0 +1,85 @@
+/*
+ * Copyright (C) 2015 Jared Boone, ShareBrained Technology, Inc.
+ *
+ * This file is part of PortaPack.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2, or (at your option)
+ * any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; see the file COPYING.  If not, write to
+ * the Free Software Foundation, Inc., 51 Franklin Street,
+ * Boston, MA 02110-1301, USA.
+ */
+
+#ifndef __SIGNAL_H__
+#define __SIGNAL_H__
+
+#include <cstdint>
+#include <list>
+#include <functional>
+#include <memory>
+
+#include "utility.hpp"
+
+/* Tweaked and vastly simplified implementation of Simple::Signal, from
+ * https://testbit.eu/cpp11-signal-system-performance/
+ *
+ * Original license:
+ *   CC0 Public Domain
+ *   http://creativecommons.org/publicdomain/zero/1.0/
+ */
+
+using SignalToken = uint32_t;
+
+template<class... Args>
+struct Signal {
+	using Callback = std::function<void (Args...)>;
+
+	SignalToken operator+=(const Callback& callback) {
+		const SignalToken token = next_token++;
+		entries.emplace_back(std::make_unique<CallbackEntry>(callback, token));
+		return token;
+	}
+
+	bool operator-=(const SignalToken token) {
+		entries.remove_if([token](EntryType& entry) {
+			return entry.get()->token == token;
+		});
+		return true;
+	}
+
+	void emit(Args... args) {
+		for(auto& entry : entries) {
+			entry.get()->callback(args...);
+		};
+	}
+
+private:
+	struct CallbackEntry {
+		const Callback callback;
+		const SignalToken token;
+
+		constexpr CallbackEntry(
+			const Callback& callback,
+			const SignalToken token
+		) : callback { callback },
+			token { token }
+		{
+		}
+	};
+
+	using EntryType = std::unique_ptr<CallbackEntry>;
+	
+	std::list<EntryType> entries;
+	SignalToken next_token = 1;
+};
+
+#endif/*__SIGNAL_H__*/