identify root file as file:///.; link top-level directory to root

SFI/Analyzers/PathObjectAnalyzer.cs

@@ -21,9 +21,12 @@ public async override ValueTask<AnalysisResult> Analyze(PathObject path, Analysi
         {
             if(context.Node is not ILinkedNode node)
             {
-                if(path.IsRootDirectory)
+                if(path.IsRoot)
                 {
-                    node = context.NodeFactory.Create(RootDirectoryUri.Instance, default);
+                    node = context.NodeFactory.Create(RootFileUri.Instance, default);
+                }else if(path.IsRootDirectory)
+                {
+                    node = context.NodeFactory.Create(Vocabularies.File, "");
                 }else{
                     var local = UriTools.EscapePathString(path.Value.Value ?? "");
                     node = context.NodeFactory.Create(Vocabularies.File, local);
@@ -47,15 +50,15 @@ public async override ValueTask<AnalysisResult> Analyze(PathObject path, Analysi
 
         /// <summary>
         /// This class is used to provide a fake URI with the value of
-        /// <see cref="RootDirectoryUri.Value"/> when .NET would like to change it.
+        /// <see cref="RootFileUri.Value"/> when .NET would like to change it.
         /// </summary>
-        class RootDirectoryUri : Uri, IIndividualUriFormatter<ValueTuple>
+        class RootFileUri : Uri, IIndividualUriFormatter<ValueTuple>
         {
-            public const string Value = "file:///./";
+            public const string Value = "file:///.";
 
-            public static readonly RootDirectoryUri Instance = new();
+            public static readonly RootFileUri Instance = new();
 
-            private RootDirectoryUri() : base(Value, UriKind.Absolute)
+            private RootFileUri() : base(Value, UriKind.Absolute)
             {
 
             }

SFI/Services/PathObject.cs

@@ -3,19 +3,61 @@
 
 namespace IS4.SFI.Services
 {
+    /// <summary>
+    /// Represents a path in any file system.
+    /// </summary>
+    /// <param name="Value">The textual value of the path.</param>
     public readonly record struct PathObject(StringSegment Value) : IIdentityKey
     {
+        /// <summary>
+        /// The less specific path contained within this path, if existing.
+        /// </summary>
+        /// <remarks>
+        /// The path is obtained by splitting the value at the first <c>/</c>
+        /// and retrieving the second segment.
+        /// </remarks>
         public PathObject? Broader {
             get {
                 var slash = Value.IndexOf('/');
-                if(slash != -1 && slash != Value.Length - 1)
+                if(slash != -1 && !(slash == 0 && Value.Length == 1))
                 {
-                    return new(Value.Subsegment(slash + 1));
+                    if(slash == Value.Length - 1)
+                    {
+                        return new(Value.Subsegment(slash));
+                    }else{
+                        return new(Value.Subsegment(slash + 1));
+                    }
+                }
+                return null;
+            }
+        }
+
+        /// <summary>
+        /// The parent path, as a directory containing this path.
+        /// </summary>
+        /// <remarks>
+        /// The path is obtained by splitting the value at the last <c>/</c>
+        /// and retrieving the first segment.
+        /// </remarks>
+        public PathObject? Parent {
+            get {
+                var slash = Value.LastIndexOf('/');
+                if(slash != -1)
+                {
+                    if(slash == Value.Length - 1)
+                    {
+                        return new(Value.Subsegment(0, slash));
+                    }else{
+                        return new(Value.Subsegment(0, slash + 1));
+                    }
                 }
                 return null;
             }
         }
 
+        /// <summary>
+        /// The extension indicated by the path, if any.
+        /// </summary>
         public ExtensionObject? Extension {
             get {
                 var dot = Value.LastIndexOf('.');
@@ -30,8 +72,16 @@ public ExtensionObject? Extension {
             }
         }
 
+        /// <summary>
+        /// Whether the path is equal to <c>/</c>, indicating the root directory.
+        /// </summary>
         public bool IsRootDirectory => Value.Length == 1 && Value[0] == '/';
 
+        /// <summary>
+        /// Whether the path is equal to the empty string, indicating the root.
+        /// </summary>
+        public bool IsRoot => Value.Length == 0;
+
         /// <inheritdoc/>
         public override string ToString() => $"/{Value}";