implement MountPoint interface

engine/core/filesystem/MountPoint.h

@@ -0,0 +1,108 @@
+/*
+Copyright (c) 2013 Daniele Bartolini, Michele Rossi
+Copyright (c) 2012 Daniele Bartolini, Simone Boscaratto
+
+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 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.
+*/
+
+#pragma once
+
+#include "OS.h"
+#include "File.h"
+
+
+namespace crown
+{
+
+/// Hashed values for supported MountPoint types
+const char* const DISK_MOUNT_POINT		= "disk";
+const char* const ASSET_FILE_POINT		= "asset";
+
+const uint32_t DISK_TYPE 				= 0x7BCBC5EE;
+const uint32_t ASSET_TYPE				= 0xE2AB7F68;
+
+/// Represent single entity in MountPoint
+struct MountPointEntry
+{
+	enum Type
+	{
+		DIRECTORY = 0,		/// The entry is a directory
+		FILE,				/// The entry is a file
+		MEMORY,				/// The entry is a memory file (i.e. does not exist on the disk)
+		UNKNOWN				/// The entry type is unknown
+	};
+
+	MountPointEntry() : type(UNKNOWN) {}
+
+	Type			type;								/// Type of the entry
+	char			os_path[MAX_PATH_LENGTH];			/// OS-specific path (use only for debug)
+	char			relative_path[MAX_PATH_LENGTH];		/// Relative path of the entry
+};
+
+
+/// Interface which provides a platform-independent way to access files and directories.
+/// Each MountPoint are managed by FileSystem.
+/// There may be several types of MountPoint:
+///
+/// - DiskMountPoint 	- provides interaction with HDD, DVD, BlueRay...
+/// - ZipMountPoint  	- provides interaction with compressed archives
+/// - NetworkMountPoint	- provides interaction with network
+///
+/// Accessing files:
+/// Every file and every directory must be accessed through the Filesystem's MountPoints.
+/// Not a single C/C++ std file io call or other similar facilities
+/// should be used in any other part of the engine in order to maintain
+/// absolute platform independence.
+///
+/// MountPoint maintains a root path which acts as base directory for every
+/// file operation; access to files outside the root path is not allowed. If
+/// you really need it, instantiate another filesystem whith the appropriate
+/// root path (e.g.)
+///
+/// The MountPoint will take care of the necessary path conversions.
+/// The root path must be an absolute path for the underlying operating system.
+class MountPoint
+{
+public:
+	inline				MountPoint(uint32_t type) : m_type(type) {}
+
+	/// Opens a file and returns a specific instance
+	virtual File*		open(const char* path, FileOpenMode mode) = 0;
+
+	/// Close file
+	virtual void		close(File* file) = 0;
+
+	/// Returns whether the @a relative_path exists
+	virtual bool		exists(const char* relative_path) = 0;
+
+	uint32_t			type() const { return m_type; }
+
+protected:
+
+	MountPoint*			m_next;
+
+	uint32_t			m_type;
+
+	friend class Filesystem;
+};
+
+} // namespace crown