95 lines
3.5 KiB
C#
95 lines
3.5 KiB
C#
#region Apache License 2.0
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/*
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Nuclex .NET Framework
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Copyright (C) 2002-2024 Markus Ewald / Nuclex Development Labs
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Licensed under the Apache License, Version 2.0 (the "License");
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you may not use this file except in compliance with the License.
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You may obtain a copy of the License at
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http://www.apache.org/licenses/LICENSE-2.0
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Unless required by applicable law or agreed to in writing, software
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distributed under the License is distributed on an "AS IS" BASIS,
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WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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See the License for the specific language governing permissions and
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limitations under the License.
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*/
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#endregion // Apache License 2.0
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using System;
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using System.Text;
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using System.IO;
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namespace Nuclex.Support {
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/// <summary>Utility class for path operations</summary>
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public static class PathHelper {
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/// <summary>Converts an absolute path into a relative one</summary>
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/// <param name="basePath">Base directory the new path should be relative to</param>
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/// <param name="absolutePath">Absolute path that will be made relative</param>
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/// <returns>
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/// A path relative to the indicated base directory that matches the
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/// absolute path given.
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/// </returns>
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public static string MakeRelative(string basePath, string absolutePath) {
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string[] baseDirectories = basePath.Split(Path.DirectorySeparatorChar);
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string[] absoluteDirectories = absolutePath.Split(Path.DirectorySeparatorChar);
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// Find the common root path of both paths so we know from which point on
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// the two paths will differ
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int lastCommonRoot = -1;
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int commonLength = Math.Min(baseDirectories.Length, absoluteDirectories.Length);
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for(int index = 0; index < commonLength; ++index) {
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if(absoluteDirectories[index] == baseDirectories[index]) {
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lastCommonRoot = index;
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} else {
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break;
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}
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}
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// If the paths don't share a common root, we have to use an absolute path.
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// Should the absolutePath parameter actually be a relative path, this will
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// also trigger the return of the absolutePath as-is.
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if(lastCommonRoot == -1) {
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return absolutePath;
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}
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// Calculate the required length for the StringBuilder in order to be slightly
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// more friendly in terms of memory usage.
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int requiredLength = (baseDirectories.Length - (lastCommonRoot + 1)) * 3;
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for(int index = lastCommonRoot + 1; index < absoluteDirectories.Length; ++index) {
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requiredLength += absoluteDirectories[index].Length + 1;
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}
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StringBuilder relativePath = new StringBuilder(requiredLength);
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// Go to the common path by adding .. until we're where we want to be
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for(int index = lastCommonRoot + 1; index < baseDirectories.Length; ++index) {
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if(baseDirectories[index].Length > 0) {
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if(relativePath.Length > 0) { // We don't want the path to start with a slash
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relativePath.Append(Path.DirectorySeparatorChar);
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}
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relativePath.Append("..");
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}
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}
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// Now that we're in the common root folder, enter the folders that
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// the absolute target path has in addition to the root folder.
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for(int index = lastCommonRoot + 1; index < absoluteDirectories.Length; index++) {
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if(relativePath.Length > 0) { // We don't want the path to start with a slash
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relativePath.Append(Path.DirectorySeparatorChar);
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}
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relativePath.Append(absoluteDirectories[index]);
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}
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return relativePath.ToString();
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}
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}
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} // namespace Nuclex.Support
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