From 9056842af727457299d600dea9a2eb6674830496 Mon Sep 17 00:00:00 2001
From: Mitch Capper <mitch.capper@gmail.com>
Date: Thu, 14 Mar 2024 15:28:30 -0700
Subject: [PATCH] Added Subtype Analyzer

Find classes/interfaces that directly subtype the analyzed class
---
 .../dnSpy.Analyzer.Resources.Designer.cs      | 11 ++-
 .../Properties/dnSpy.Analyzer.Resources.resx  |  3 +
 .../TreeNodes/SubtypesByNode.cs               | 67 +++++++++++++++++++
 .../dnSpy.Analyzer/TreeNodes/TypeNode.cs      |  3 +
 4 files changed, 83 insertions(+), 1 deletion(-)
 create mode 100644 Extensions/dnSpy.Analyzer/TreeNodes/SubtypesByNode.cs

diff --git a/Extensions/dnSpy.Analyzer/Properties/dnSpy.Analyzer.Resources.Designer.cs b/Extensions/dnSpy.Analyzer/Properties/dnSpy.Analyzer.Resources.Designer.cs
index a0f3a10aa0..45bb054de8 100644
--- a/Extensions/dnSpy.Analyzer/Properties/dnSpy.Analyzer.Resources.Designer.cs
+++ b/Extensions/dnSpy.Analyzer/Properties/dnSpy.Analyzer.Resources.Designer.cs
@@ -1,4 +1,4 @@
-//------------------------------------------------------------------------------
+//------------------------------------------------------------------------------
 // <auto-generated>
 //     This code was generated by a tool.
 //     Runtime Version:4.0.30319.42000
@@ -195,6 +195,15 @@ public static string InstantiatedByTreeNode {
             }
         }
         
+        /// <summary>
+        ///   Looks up a localized string similar to Subtypes.
+        /// </summary>
+        public static string SubtypesByTreeNode {
+            get {
+                return ResourceManager.GetString("SubtypesByTreeNode", resourceCulture);
+            }
+        }
+        
         /// <summary>
         ///   Looks up a localized string similar to Overridden By.
         /// </summary>
diff --git a/Extensions/dnSpy.Analyzer/Properties/dnSpy.Analyzer.Resources.resx b/Extensions/dnSpy.Analyzer/Properties/dnSpy.Analyzer.Resources.resx
index b621766877..c869329d04 100644
--- a/Extensions/dnSpy.Analyzer/Properties/dnSpy.Analyzer.Resources.resx
+++ b/Extensions/dnSpy.Analyzer/Properties/dnSpy.Analyzer.Resources.resx
@@ -159,6 +159,9 @@
   <data name="ImplementedByTreeNode" xml:space="preserve">
     <value>Implemented By</value>
   </data>
+  <data name="SubtypesByTreeNode" xml:space="preserve">
+    <value>Subtypes</value>
+  </data>
   <data name="InstantiatedByTreeNode" xml:space="preserve">
     <value>Instantiated By</value>
   </data>
diff --git a/Extensions/dnSpy.Analyzer/TreeNodes/SubtypesByNode.cs b/Extensions/dnSpy.Analyzer/TreeNodes/SubtypesByNode.cs
new file mode 100644
index 0000000000..99cca34dfb
--- /dev/null
+++ b/Extensions/dnSpy.Analyzer/TreeNodes/SubtypesByNode.cs
@@ -0,0 +1,67 @@
+/*
+    Copyright (C) 2024 mitch.capper+dns@gmail.com
+
+    This file is part of dnSpy
+
+    dnSpy is free software: you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation, either version 3 of the License, or
+    (at your option) any later version.
+
+    dnSpy 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
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with dnSpy.  If not, see <http://www.gnu.org/licenses/>.
+*/
+
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Threading;
+using dnlib.DotNet;
+using dnSpy.Analyzer.Properties;
+using dnSpy.Contracts.Decompiler;
+using dnSpy.Contracts.Text;
+
+namespace dnSpy.Analyzer.TreeNodes {
+	sealed class SubtypesByNode : SearchNode {
+		readonly TypeDef analyzedType;
+
+		public SubtypesByNode(TypeDef analyzedType) =>
+			this.analyzedType = analyzedType ?? throw new ArgumentNullException(nameof(analyzedType));
+
+		protected override void Write(ITextColorWriter output, IDecompiler decompiler) =>
+			output.Write(BoxedTextColor.Text, dnSpy_Analyzer_Resources.SubtypesByTreeNode);
+
+		protected override IEnumerable<AnalyzerTreeNodeData> FetchChildren(CancellationToken ct) {
+			var analyzer = new ScopedWhereUsedAnalyzer<AnalyzerTreeNodeData>(Context.DocumentService, analyzedType, FindReferencesInType);
+			return analyzer.PerformAnalysis(ct);
+		}
+
+		IEnumerable<AnalyzerTreeNodeData> FindReferencesInType(TypeDef type) {
+			if (analyzedType.IsInterface && type.HasInterfaces) {
+				for (int i = 0; i < type.Interfaces.Count; i++) {
+					if (IsEqual(type.Interfaces[i].Interface)) {
+						yield return new TypeNode(type) { Context = Context };
+						break;
+					}
+				}
+
+				yield break;
+			}
+
+			if (type.IsEnum || !type.IsClass)
+				yield break;
+
+			if (IsEqual(type.BaseType))
+				yield return new TypeNode(type) { Context = Context };
+		}
+
+		private bool IsEqual(ITypeDefOrRef itm) => CheckEquals(analyzedType, itm.GetScopeType());
+
+		public static bool CanShow(TypeDef type) => (type.IsClass || type.IsInterface) && !type.IsEnum && !type.IsSealed;
+	}
+}
diff --git a/Extensions/dnSpy.Analyzer/TreeNodes/TypeNode.cs b/Extensions/dnSpy.Analyzer/TreeNodes/TypeNode.cs
index 51d0f96920..c7f12ad201 100644
--- a/Extensions/dnSpy.Analyzer/TreeNodes/TypeNode.cs
+++ b/Extensions/dnSpy.Analyzer/TreeNodes/TypeNode.cs
@@ -49,6 +49,9 @@ public override IEnumerable<TreeNodeData> CreateChildren() {
 			if (TypeExposedByNode.CanShow(analyzedType))
 				yield return new TypeExposedByNode(analyzedType);
 
+			if (SubtypesByNode.CanShow(analyzedType))
+				yield return new SubtypesByNode(analyzedType);
+
 			if (TypeExtensionMethodsNode.CanShow(analyzedType))
 				yield return new TypeExtensionMethodsNode(analyzedType);
 		}