page: convert to C++

1 files changed, 104 insertions, 0 deletions

diff --git a/src/Page.hxx b/src/Page.hxx
new file mode 100644
index 00000000..2bc9a6ac
--- /dev/null
+++ b/src/Page.hxx
@@ -0,0 +1,104 @@
+/*
+ * Copyright (C) 2003-2011 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.
+ */
+
+/** \file
+ *
+ * This is a library which manages reference counted buffers.
+ */
+
+#ifndef MPD_PAGE_HXX
+#define MPD_PAGE_HXX
+
+#include "util/RefCount.hxx"
+
+#include <algorithm>
+
+#include <stddef.h>
+
+/**
+ * A dynamically allocated buffer which keeps track of its reference
+ * count.  This is useful for passing buffers around, when several
+ * instances hold references to one buffer.
+ */
+class Page {
+	/**
+	 * The number of references to this buffer.  This library uses
+	 * atomic functions to access it, i.e. no locks are required.
+	 * As soon as this attribute reaches zero, the buffer is
+	 * freed.
+	 */
+	RefCount ref;
+
+public:
+	/**
+	 * The size of this buffer in bytes.
+	 */
+	const size_t size;
+
+	/**
+	 * Dynamic array containing the buffer data.
+	 */
+	unsigned char data[sizeof(long)];
+
+protected:
+	Page(size_t _size):size(_size) {}
+	~Page() = default;
+
+	/**
+	 * Allocates a new #Page object, without filling the data
+	 * element.
+	 */
+	static Page *Create(size_t size);
+
+public:
+	/**
+	 * Creates a new #page object, and copies data from the
+	 * specified buffer.  It is initialized with a reference count
+	 * of 1.
+	 *
+	 * @param data the source buffer
+	 * @param size the size of the source buffer
+	 */
+	static Page *Copy(const void *data, size_t size);
+
+	/**
+	 * Concatenates two pages to a new page.
+	 *
+	 * @param a the first page
+	 * @param b the second page, which is appended
+	 */
+	static Page *Concat(const Page &a, const Page &b);
+
+	/**
+	 * Increases the reference counter.
+	 */
+	void Ref() {
+		ref.Increment();
+	}
+
+	/**
+	 * Decreases the reference counter.  If it reaches zero, the #page is
+	 * freed.
+	 *
+	 * @return true if the #page has been freed
+	 */
+	bool Unref();
+};
+
+#endif