Added a new class PathHelper with a method that converts absolute paths into relative paths

git-svn-id: file:///srv/devel/repo-conversion/nusu@49 d2e56fa2-650e-0410-a79f-9358c0239efd

Nuclex.Support (PC).csproj

@@ -179,6 +179,10 @@
       <Name>SimpleRectanglePacker.Test</Name>
       <DependentUpon>SimpleRectanglePacker.cs</DependentUpon>
     </Compile>
+    <Compile Include="Source\PathHelper.cs">
+      <XNAUseContentPipeline>false</XNAUseContentPipeline>
+      <Name>PathHelper</Name>
+    </Compile>
     <Compile Include="Source\Scheduling\AbortedException.cs">
       <XNAUseContentPipeline>false</XNAUseContentPipeline>
       <Name>AbortedException</Name>
@@ -304,6 +308,7 @@
   </ItemGroup>
   <ItemGroup>
     <Folder Include="Documents\" />
+    <Folder Include="Source\Parsing\" />
   </ItemGroup>
   <Import Project="$(MSBuildBinPath)\Microsoft.CSharp.targets" />
   <Import Project="$(MSBuildExtensionsPath)\Microsoft\XNA\Game Studio Express\v1.0\Microsoft.Xna.ContentPipeline.targets" />

Source/PathHelper.cs

@@ -0,0 +1,69 @@
+using System;
+using System.Collections.Generic;
+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
+      if(lastCommonRoot == -1)
+        return absolutePath;
+
+      // Calculate the required length for the StrinBuilder 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 path has in addition to the 
+      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