Nuclex.Support/Source/PathHelper.cs
2017-01-21 21:33:55 +00:00

96 lines
3.6 KiB
C#

#region CPL License
/*
Nuclex Framework
Copyright (C) 2002-2017 Nuclex Development Labs
This library is free software; you can redistribute it and/or
modify it under the terms of the IBM Common Public License as
published by the IBM Corporation; either version 1.0 of the
License, or (at your option) any later version.
This library 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
IBM Common Public License for more details.
You should have received a copy of the IBM Common Public
License along with this library
*/
#endregion
using System;
using System.Text;
using System.IO;
namespace Nuclex.Support {
/// <summary>Utility class for path operations</summary>
public static class PathHelper {
/// <summary>Converts an absolute path into a relative one</summary>
/// <param name="basePath">Base directory the new path should be relative to</param>
/// <param name="absolutePath">Absolute path that will be made relative</param>
/// <returns>
/// A path relative to the indicated base directory that matches the
/// absolute path given.
/// </returns>
public static string MakeRelative(string basePath, string absolutePath) {
string[] baseDirectories = basePath.Split(Path.DirectorySeparatorChar);
string[] absoluteDirectories = absolutePath.Split(Path.DirectorySeparatorChar);
// Find the common root path of both paths so we know from which point on
// the two paths will differ
int lastCommonRoot = -1;
int commonLength = Math.Min(baseDirectories.Length, absoluteDirectories.Length);
for(int index = 0; index < commonLength; ++index) {
if(absoluteDirectories[index] == baseDirectories[index]) {
lastCommonRoot = index;
} else {
break;
}
}
// If the paths don't share a common root, we have to use an absolute path.
// Should the absolutePath parameter actually be a relative path, this will
// also trigger the return of the absolutePath as-is.
if(lastCommonRoot == -1) {
return absolutePath;
}
// Calculate the required length for the StringBuilder in order to be slightly
// more friendly in terms of memory usage.
int requiredLength = (baseDirectories.Length - (lastCommonRoot + 1)) * 3;
for(int index = lastCommonRoot + 1; index < absoluteDirectories.Length; ++index) {
requiredLength += absoluteDirectories[index].Length + 1;
}
StringBuilder relativePath = new StringBuilder(requiredLength);
// Go to the common path by adding .. until we're where we want to be
for(int index = lastCommonRoot + 1; index < baseDirectories.Length; ++index) {
if(baseDirectories[index].Length > 0) {
if(relativePath.Length > 0) { // We don't want the path to start with a slash
relativePath.Append(Path.DirectorySeparatorChar);
}
relativePath.Append("..");
}
}
// Now that we're in the common root folder, enter the folders that
// the absolute target path has in addition to the root folder.
for(int index = lastCommonRoot + 1; index < absoluteDirectories.Length; index++) {
if(relativePath.Length > 0) { // We don't want the path to start with a slash
relativePath.Append(Path.DirectorySeparatorChar);
}
relativePath.Append(absoluteDirectories[index]);
}
return relativePath.ToString();
}
}
} // namespace Nuclex.Support