mono/mcs/class/corlib/System.IO/Path.cs

//------------------------------------------------------------------------------
// 
// System.IO.Path.cs 
//
// Copyright (C) 2001 Moonlight Enterprises, All Rights Reserved
// 
// Author:         Jim Richardson, [email protected]
// Created:        Saturday, August 11, 2001 
//
//------------------------------------------------------------------------------

using System;

namespace System.IO
{
	public class Path : Object
	{
		public static readonly char AltDirectorySeparatorChar = '\\'; // TODO: verify this
		public static readonly char DirectorySeparatorChar = '/';
		public static readonly char[] InvalidPathChars = { '\0' };	//  TODO: research invalid chars
		public static readonly char PathSeparator = ';';	// might be a space for unix/linux
		public static readonly char VolumeSeparatorChar = '/';

		private static readonly char[] PathSeparatorChars = {	DirectorySeparatorChar, 
																AltDirectorySeparatorChar,
																VolumeSeparatorChar };

		// class methods
		public static string ChangeExtension(string path, string extension)
		{
			if(path == null)
			{
				return null;
			}

			int iExt = findExtension(path);
			
			if(iExt < 0)
			{
				return extension == null ? path : path + extension;
			}
			else if(iExt > 0)
			{
				string temp = path.Substring(0, iExt);
				if(extension != null)
				{
					return temp + extension;
				}
				return  temp;
			}

			return extension;
		}

		public static string Combine(string path1, string path2)
		{
			if(path1 == null || path2 == null)
			{
				return null;
			}

			throwEmptyIf(path2);

			// TODO: Check for invalid DirectoryInfo characters
			//       although I don't think it is necesary for linux

			// TODO: Verify functionality further after NUnit tests written
			//		 since the documentation was rather sketchy

			if(IsPathRooted(path2))
			{
				if(path1.Equals(string.Empty))
				{
					return path2;
				}
				throw new ArgumentException("Rooted path");
			}
			
			string dirSep = new string(DirectorySeparatorChar, 1);
			string altSep = new string(AltDirectorySeparatorChar, 1);
			
			bool b1 = path1.EndsWith(dirSep) || path1.EndsWith(dirSep);
			bool b2 = path2.StartsWith(dirSep) || path2.StartsWith(altSep);
			if(b1 && b2)
			{
				throw new ArgumentException("Invalid combination");
			}
			
			if(!b1 && !b2)
			{
				return path1 + dirSep + path2;
			}

			return path1 + path2;
		}

		public static string GetDirectoryName(string path)
		{
			if(path == null)
			{
				return null;
			}
			throwEmptyIf(path);
			throwWhiteSpaceOnlyIf(path);
			throwInvalidPathCharsIf(path);

			if(path.Length > 2)
			{
				int nLast = path.LastIndexOfAny(PathSeparatorChars, path.Length - 2);

				if(nLast > 0)
				{
					return path.Substring(0, nLast);
				}
			}
			return path;
		}

		public static string GetExtension(string path)
		{
			if(path == null)
			{
				return string.Empty;
			}

			throwEmptyIf(path);
			throwWhiteSpaceOnlyIf(path);
			
			int iExt = findExtension(path);
			int iLastSep = path.LastIndexOfAny( PathSeparatorChars );

			if(iExt > -1)
			{	// okay it has an extension
				return path.Substring(iExt);
			}
			return string.Empty;
		}

		public static string GetFileName(string path)
		{
			if(path == null)
			{
				return string.Empty;
			}

			throwEmptyIf(path);
			throwWhiteSpaceOnlyIf(path);

			int nLast = path.LastIndexOfAny(PathSeparatorChars);

			if(nLast > 0)
			{
				return path.Substring(nLast + 1);
			}

			return nLast == 0 ? null : path;
		}

		public static string GetFileNameWithoutExtension(string path)
		{
			return ChangeExtension(GetFileName(path), null);
		}

		public static string GetFullPath(string path)
		{
			if(path != null)
			{
				//TODO: figure out what the equivilent linux api to
				//      windoze ::GetCurrentDirectory() is and PInvoke it
				return path;
			}
			return null;
		}

		public static string GetPathRoot(string path)
		{
			if(path != null || 
				(path.StartsWith(new string(DirectorySeparatorChar, 1)) ||
					path.StartsWith(new string(AltDirectorySeparatorChar, 1))))
			{
				return path.Substring(0, 1);
			}
			return null;
		}

		public static string GetTempFileName()
		{
			//TODO: Implement method
			return string.Empty;
		}

		/// <summary>
		/// Returns the path of the current systems temp directory
		/// </summary>
		public static string GetTempPath()
		{	// TODO: This might vary with distribution and there
			//       might be an api to provide it. Research is needed
			return "/tmp";
		}

		public static bool HasExtension(string path)
		{  
			throwNullIf(path);
			throwEmptyIf(path);
			throwWhiteSpaceOnlyIf(path);
			
			return findExtension(path) > -1;
		}

		public static bool IsPathRooted(string path)
		{
			return path.StartsWith(new string(VolumeSeparatorChar,1));
		}

		// private class methods

		private static int findExtension(string path)
		{	// method should return the index of the path extension
			// start or -1 if no valid extension
			if(path != null)
			{		
				int iLastDot = path.LastIndexOf(".");
				int iLastSep = path.LastIndexOfAny( PathSeparatorChars );

				if(iLastDot > iLastSep)
				{
					return iLastDot;
				}
			}
			return -1;
		}

		private static void throwNullIf(string path)
		{
			if(path == null)
			{
				throw new ArgumentNullException();
			}
		}

		private static void throwEmptyIf(string path)
		{
			if(path != null && path.Length == 0)
			{
				throw new ArgumentException("Empty string");
			}
		}

		private static void throwWhiteSpaceOnlyIf(string path)
		{
			if(path != null)
			{
				string temp = path;
				temp.Trim();
				if(temp.Length == 0)
				{
					throw new ArgumentException("Whitespace only string");
				}
			}
		}
		
		private static void throwInvalidPathCharsIf(string path)
		{
			if(path != null && path.IndexOfAny(InvalidPathChars) > -1)
			{
				throw new ArgumentException("Invalid path characters");
			}
		}
	}
}