1 files changed, 177 insertions, 0 deletions
diff --git a/src/lib/nfs/Cancellable.hxx b/src/lib/nfs/Cancellable.hxx
new file mode 100644
index 000000000..50762b582
--- /dev/null
+++ b/src/lib/nfs/Cancellable.hxx
@@ -0,0 +1,177 @@
+/*
+ * Copyright (C) 2003-2014 The Music Player Daemon Project
+ * http://www.musicpd.org
+ *
+ * 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 of the License, 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; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#ifndef MPD_NFS_CANCELLABLE_HXX
+#define MPD_NFS_CANCELLABLE_HXX
+
+#include "Compiler.h"
+
+#include <list>
+#include <algorithm>
+
+#include <assert.h>
+
+template<typename T>
+class CancellablePointer {
+public:
+	typedef T *pointer_type;
+	typedef T &reference_type;
+	typedef const T &const_reference_type;
+
+private:
+	pointer_type p;
+
+public:
+	explicit constexpr CancellablePointer(reference_type _p):p(&_p) {}
+
+	CancellablePointer(const CancellablePointer &) = delete;
+
+	constexpr bool IsCancelled() const {
+		return p == nullptr;
+	}
+
+	void Cancel() {
+		assert(!IsCancelled());
+
+		p = nullptr;
+	}
+
+	reference_type Get() {
+		assert(p != nullptr);
+
+		return *p;
+	}
+
+	constexpr bool Is(const_reference_type other) const {
+		return p == &other;
+	}
+};
+
+template<typename T, typename CT=CancellablePointer<T>>
+class CancellableList {
+public:
+	typedef typename CT::reference_type reference_type;
+	typedef typename CT::const_reference_type const_reference_type;
+
+private:
+	typedef std::list<CT> List;
+	typedef typename List::iterator iterator;
+	typedef typename List::const_iterator const_iterator;
+	List list;
+
+	class MatchPointer {
+		const_reference_type p;
+
+	public:
+		explicit constexpr MatchPointer(const_reference_type _p)
+			:p(_p) {}
+
+		constexpr bool operator()(const CT &a) const {
+			return a.Is(p);
+		}
+	};
+
+	gcc_pure
+	iterator Find(reference_type p) {
+		return std::find_if(list.begin(), list.end(), MatchPointer(p));
+	}
+
+	gcc_pure
+	const_iterator Find(const_reference_type p) const {
+		return std::find_if(list.begin(), list.end(), MatchPointer(p));
+	}
+
+	class MatchReference {
+		const CT &c;
+
+	public:
+		constexpr explicit MatchReference(const CT &_c):c(_c) {}
+
+		gcc_pure
+		bool operator()(const CT &a) const {
+			return &a == &c;
+		}
+	};
+
+	gcc_pure
+	iterator Find(CT &c) {
+		return std::find_if(list.begin(), list.end(),
+				    MatchReference(c));
+	}
+
+	gcc_pure
+	const_iterator Find(const CT &c) const {
+		return std::find_if(list.begin(), list.end(),
+				    MatchReference(c));
+	}
+
+public:
+#ifndef NDEBUG
+	gcc_pure
+	bool IsEmpty() const {
+		for (const auto &c : list)
+			if (!c.IsCancelled())
+				return false;
+
+		return true;
+	}
+#endif
+
+	gcc_pure
+	bool Contains(const_reference_type p) const {
+		return Find(p) != list.end();
+	}
+
+	template<typename... Args>
+	CT &Add(reference_type p, Args&&... args) {
+		assert(Find(p) == list.end());
+
+		list.emplace_back(p, std::forward<Args>(args)...);
+		return list.back();
+	}
+
+	void RemoveLast() {
+		list.pop_back();
+	}
+
+	bool RemoveOptional(CT &ct) {
+		auto i = Find(ct);
+		if (i == list.end())
+			return false;
+
+		list.erase(i);
+		return true;
+	}
+
+	void Remove(CT &ct) {
+		auto i = Find(ct);
+		assert(i != list.end());
+
+		list.erase(i);
+	}
+
+	void Cancel(reference_type p) {
+		auto i = Find(p);
+		assert(i != list.end());
+
+		i->Cancel();
+	}
+};
+
+#endif