C# doesn't support Tail Recursion Optimization. So time to bring out F#.

HarryCordewener · Jan 4, 2024 · 3bfae1c · 3bfae1c
1 parent 6c177ec
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Showing 7 changed files with 79 additions and 67 deletions.
diff --git a/TelnetNegotiationCore.Functional/MSDPLibrary.fs b/TelnetNegotiationCore.Functional/MSDPLibrary.fs
@@ -0,0 +1,49 @@
+namespace TelnetNegotiationCore.Functional
+
+open System.Text
+
+type Trigger =
+    | NULL = 0uy
+    | MSDP_VAR = 1uy
+    | MSDP_VAL = 2uy
+    | MSDP_TABLE_OPEN = 3uy
+    | MSDP_TABLE_CLOSE = 4uy
+    | MSDP_ARRAY_OPEN = 5uy
+    | MSDP_ARRAY_CLOSE = 6uy
+
+module MSDPLibrary =
+  let rec MSDPScan (root: obj, array: seq<byte>, type_: Trigger, encoding : Encoding) =
+      if Seq.length(array) = 0 then root
+      else
+          match type_ with
+          | Trigger.MSDP_VAR ->
+              (root :?> Map<string, obj>).Add(encoding.GetString(array |> Seq.takeWhile(fun x -> x <> byte Trigger.MSDP_VAL) |> Array.ofSeq), MSDPScan(root, array |> Seq.skipWhile(fun x -> x <> byte Trigger.MSDP_VAL) |> Seq.skip(1), Trigger.MSDP_VAL,encoding))
+          | Trigger.MSDP_VAL ->
+              let nextType = 
+                try
+                  array |> Seq.find(fun x ->  
+                  x = byte Trigger.MSDP_ARRAY_OPEN || 
+                  x = byte Trigger.MSDP_TABLE_OPEN || 
+                  x = byte Trigger.MSDP_ARRAY_CLOSE || 
+                  x = byte Trigger.MSDP_TABLE_CLOSE || 
+                  x = byte Trigger.MSDP_VAL)
+                with
+                | :? System.Collections.Generic.KeyNotFoundException -> 0uy
+
+              match LanguagePrimitives.EnumOfValue nextType : Trigger with
+              | Trigger.NULL -> 
+                  encoding.GetString(array |> Array.ofSeq)
+              | Trigger.MSDP_VAL ->
+                  MSDPScan((root :?> List<obj>) @ [encoding.GetString(array |> Seq.takeWhile(fun x -> x <> nextType) |> Array.ofSeq)], array |> Seq.skipWhile(fun x -> x <> byte Trigger.MSDP_VAL) |> Seq.skip(1), Trigger.MSDP_VAL, encoding)
+              | Trigger.MSDP_TABLE_CLOSE -> 
+                  (root :?> List<obj>) @ [encoding.GetString(array |> Seq.takeWhile(fun x -> x <> nextType) |> Array.ofSeq)]
+              | Trigger.MSDP_ARRAY_OPEN ->
+                  MSDPScan(root, array |> Seq.skipWhile(fun x -> x <> byte Trigger.MSDP_ARRAY_OPEN) |> Seq.skip(1), Trigger.MSDP_ARRAY_OPEN,encoding)
+              | Trigger.MSDP_TABLE_OPEN ->
+                  MSDPScan(root, array |> Seq.skipWhile(fun x -> x <> byte Trigger.MSDP_TABLE_OPEN) |> Seq.skip(1), Trigger.MSDP_TABLE_OPEN,encoding)
+              | _ ->  root
+          | Trigger.MSDP_ARRAY_OPEN ->
+              MSDPScan(List.Empty, array |> Seq.skip(1), Trigger.MSDP_VAL, encoding)
+          | Trigger.MSDP_TABLE_OPEN ->
+              MSDPScan(Map<string, obj> [], array |> Seq.skip(1), Trigger.MSDP_VAR, encoding)
+          | _ -> failwith "Failure in MSDPScan."
diff --git a/TelnetNegotiationCore.Functional/TelnetNegotiationCore.Functional.fsproj b/TelnetNegotiationCore.Functional/TelnetNegotiationCore.Functional.fsproj
@@ -0,0 +1,12 @@
+<Project Sdk="Microsoft.NET.Sdk">
+
+  <PropertyGroup>
+    <TargetFramework>net8.0</TargetFramework>
+    <GenerateDocumentationFile>true</GenerateDocumentationFile>
+  </PropertyGroup>
+
+  <ItemGroup>
+    <Compile Include="MSDPLibrary.fs" />
+  </ItemGroup>
+
+</Project>
diff --git a/TelnetNegotiationCore.UnitTests/CreateDotGraph.cs b/TelnetNegotiationCore.UnitTests/CreateDotGraph.cs
@@ -3,6 +3,7 @@
 using Stateless.Graph;
 using System.Collections.Generic;
 using System.IO;
+using System.Numerics;
 using System.Text;
 using System.Threading.Tasks;
 using TelnetNegotiationCore.Interpreters;

diff --git a/TelnetNegotiationCore.UnitTests/TelnetNegotiationCore.UnitTests.csproj b/TelnetNegotiationCore.UnitTests/TelnetNegotiationCore.UnitTests.csproj
@@ -4,6 +4,8 @@
     <TargetFramework>net8.0</TargetFramework>
 
     <IsPackable>false</IsPackable>
+
+    <PlatformTarget>AnyCPU</PlatformTarget>
   </PropertyGroup>
 
   <PropertyGroup Condition="'$(Configuration)|$(Platform)'=='Debug|AnyCPU'">

diff --git a/TelnetNegotiationCore.sln b/TelnetNegotiationCore.sln
@@ -19,6 +19,8 @@ Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "TelnetNegotiationCore.UnitT
 EndProject
 Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "TelnetNegotiationCore.TestClient", "TelnetNegotiationCore.TestClient\TelnetNegotiationCore.TestClient.csproj", "{E1A76C78-8246-472F-824E-9F7F9B3778B7}"
 EndProject
+Project("{F2A71F9B-5D33-465A-A702-920D77279786}") = "TelnetNegotiationCore.Functional", "TelnetNegotiationCore.Functional\TelnetNegotiationCore.Functional.fsproj", "{0307D0B8-AAA7-40C8-9E3E-34BE64F93BB7}"
+EndProject
 Global
 	GlobalSection(SolutionConfigurationPlatforms) = preSolution
 		Debug|Any CPU = Debug|Any CPU
@@ -41,6 +43,10 @@ Global
 		{E1A76C78-8246-472F-824E-9F7F9B3778B7}.Debug|Any CPU.Build.0 = Debug|Any CPU
 		{E1A76C78-8246-472F-824E-9F7F9B3778B7}.Release|Any CPU.ActiveCfg = Release|Any CPU
 		{E1A76C78-8246-472F-824E-9F7F9B3778B7}.Release|Any CPU.Build.0 = Release|Any CPU
+		{0307D0B8-AAA7-40C8-9E3E-34BE64F93BB7}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
+		{0307D0B8-AAA7-40C8-9E3E-34BE64F93BB7}.Debug|Any CPU.Build.0 = Debug|Any CPU
+		{0307D0B8-AAA7-40C8-9E3E-34BE64F93BB7}.Release|Any CPU.ActiveCfg = Release|Any CPU
+		{0307D0B8-AAA7-40C8-9E3E-34BE64F93BB7}.Release|Any CPU.Build.0 = Release|Any CPU
 	EndGlobalSection
 	GlobalSection(SolutionProperties) = preSolution
 		HideSolutionNode = FALSE

diff --git a/TelnetNegotiationCore/Interpreters/TelnetMSDPInterpreter.cs b/TelnetNegotiationCore/Interpreters/TelnetMSDPInterpreter.cs
@@ -5,6 +5,7 @@
 using System.Linq;
 using System.Reflection;
 using System.Threading.Tasks;
+using Microsoft.FSharp.Collections;
 using MoreLinq;
 using OneOf;
 using Stateless;
@@ -105,76 +106,13 @@ private void CaptureMSDPValue(OneOf<byte, Trigger> b)
 
 		private async Task ReadMSDPValues()
 		{
-			dynamic root = new ExpandoObject();
-			var array = _currentMSDPInfo.Skip(1).ToImmutableArray();
-
-			MSDPScan(root, array, Trigger.MSDP_VAR);
+			Functional.MSDPLibrary.MSDPScan(new FSharpMap<string, dynamic>(Enumerable.Empty<Tuple<string,dynamic>>()), 
+				_currentMSDPInfo.Skip(1), 
+				Functional.Trigger.MSDP_VAL, 
+				CurrentEncoding);
 			await Task.CompletedTask;
 		}
 
-		private dynamic MSDPScan(dynamic root, ImmutableArray<byte> array, Trigger type)
-		{
-			if (array.Length == 0) return root;
-
-			if (type == Trigger.MSDP_VAR)
-			{
-				var variableName = array.TakeUntil(x => x is (byte)Trigger.MSDP_VAL).ToArray();
-				((IDictionary<string, object>)root).Add(CurrentEncoding.GetString(variableName),
-					MSDPScan(root, array.SkipUntil(x => x is (byte)Trigger.MSDP_VAL).ToImmutableArray(), Trigger.MSDP_VAL));
-			}
-			else if (type == Trigger.MSDP_VAL)
-			{
-				var nextType = array.FirstOrDefault(x => x is
-					(byte)Trigger.MSDP_ARRAY_OPEN or
-					(byte)Trigger.MSDP_TABLE_OPEN or
-					(byte)Trigger.MSDP_ARRAY_CLOSE or
-					(byte)Trigger.MSDP_TABLE_CLOSE or
-					(byte)Trigger.MSDP_VAL);
-				dynamic result = root;
-
-				if (nextType == default) // We have hit the end.
-				{
-					result = CurrentEncoding.GetString(array.ToArray());
-				}
-				else if (nextType is (byte)Trigger.MSDP_VAL)
-				{
-					var value = array.TakeWhile(x => x != nextType);
-					var startOfRest = array.SkipUntil(x => x is (byte)Trigger.MSDP_VAL).ToImmutableArray();
-					result = MSDPScan(((ImmutableList<dynamic>)root).Add(CurrentEncoding.GetString(value.ToArray())), startOfRest, Trigger.MSDP_VAL);
-				}
-				else if (nextType is (byte)Trigger.MSDP_ARRAY_OPEN)
-				{
-					var startOfArray = array.SkipUntil(x => x is (byte)Trigger.MSDP_ARRAY_OPEN).ToImmutableArray();
-					result = MSDPScan(root, startOfArray, Trigger.MSDP_ARRAY_OPEN);
-				}
-				else if (nextType is (byte)Trigger.MSDP_TABLE_OPEN)
-				{
-					var startOfTable = array.SkipUntil(x => x is (byte)Trigger.MSDP_TABLE_OPEN).ToImmutableArray();
-					result = MSDPScan(root, startOfTable, Trigger.MSDP_ARRAY_OPEN);
-				}
-				else if (nextType is (byte)Trigger.MSDP_ARRAY_CLOSE)
-				{
-					result = root;
-				}
-				else if (nextType is (byte)Trigger.MSDP_TABLE_CLOSE)
-				{
-					result = root;
-				}
-
-				return result;
-			}
-			else if (type == Trigger.MSDP_ARRAY_OPEN)
-			{
-				return MSDPScan(ImmutableList<dynamic>.Empty, array.Skip(1).ToImmutableArray(), Trigger.MSDP_VAL);
-			}
-			else if (type == Trigger.MSDP_TABLE_OPEN)
-			{
-				return MSDPScan(new ExpandoObject(), array.Skip(1).ToImmutableArray(), Trigger.MSDP_VAR);
-			}
-
-			return root;
-		}
-
 		/// <summary>
 		/// Announce we do MSDP negotiation to the client.
 		/// </summary>

diff --git a/TelnetNegotiationCore/TelnetNegotiationCore.csproj b/TelnetNegotiationCore/TelnetNegotiationCore.csproj
@@ -53,4 +53,8 @@
 		<PackageReference Include="System.Collections.Immutable" Version="8.0.0" />
 	</ItemGroup>
 
+	<ItemGroup>
+	  <ProjectReference Include="..\TelnetNegotiationCore.Functional\TelnetNegotiationCore.Functional.fsproj" />
+	</ItemGroup>
+
 </Project>