IsSelected Refinements (#6957)

Author: michaelstaib

src/HotChocolate/Core/src/Execution/Processing/EmptySelectionCollection.cs

@@ -0,0 +1,39 @@
+using System;
+using System.Collections;
+using System.Collections.Generic;
+using System.Linq;
+using HotChocolate.Resolvers;
+
+namespace HotChocolate.Execution.Processing;
+
+internal sealed class EmptySelectionCollection : ISelectionCollection
+{
+    private static readonly ISelection[] _empty = Array.Empty<ISelection>();
+    
+    public static EmptySelectionCollection Instance { get; } = new();
+
+    public int Count => 0;
+
+    public ISelection this[int index] => throw new IndexOutOfRangeException();
+
+    public ISelectionCollection Select(string fieldName)
+        => Instance;
+
+    public bool IsSelected(string fieldName)
+        => false;
+
+    public bool IsSelected(string fieldName1, string fieldName2)
+        => false;
+
+    public bool IsSelected(string fieldName1, string fieldName2, string fieldName3)
+        => false;
+
+    public bool IsSelected(ISet<string> fieldNames)
+        => false;
+    
+    public IEnumerator<ISelection> GetEnumerator()
+        => _empty.AsEnumerable().GetEnumerator();
+
+    IEnumerator IEnumerable.GetEnumerator()
+        => GetEnumerator();
+}

src/HotChocolate/Core/src/Execution/Processing/MiddlewareContext.Global.cs

@@ -1,7 +1,5 @@
 using System;
 using System.Collections.Generic;
-using System.Runtime.CompilerServices;
-using System.Runtime.InteropServices;
 using System.Threading;
 using System.Threading.Tasks;
 using HotChocolate.Execution.Properties;
@@ -46,49 +44,7 @@ public IServiceProvider Services
     public CancellationToken RequestAborted { get; private set; }
 
     public bool HasCleanupTasks => _cleanupTasks.Count > 0;
-
-    public IReadOnlyList<ISelection> GetSelections(
-        IObjectType typeContext,
-        ISelection? selection = null,
-        bool allowInternals = false)
-    {
-        if (typeContext is null)
-        {
-            throw new ArgumentNullException(nameof(typeContext));
-        }
-
-        selection ??= _selection;
-
-        if (selection.SelectionSet is null)
-        {
-            return Array.Empty<ISelection>();
-        }
-
-        var selectionSet = _operationContext.CollectFields(selection, typeContext);
-
-        if (selectionSet.IsConditional)
-        {
-            var operationIncludeFlags = _operationContext.IncludeFlags;
-            var selectionCount = selectionSet.Selections.Count;
-            ref var selectionRef = ref ((SelectionSet)selectionSet).GetSelectionsReference();
-            var finalFields = new List<ISelection>();
-
-            for (var i = 0; i < selectionCount; i++)
-            {
-                var childSelection = Unsafe.Add(ref selectionRef, i);
-
-                if (childSelection.IsIncluded(operationIncludeFlags, allowInternals))
-                {
-                    finalFields.Add(childSelection);
-                }
-            }
-
-            return finalFields;
-        }
-
-        return selectionSet.Selections;
-    }
-
+    
     public void ReportError(string errorMessage)
     {
         if (string.IsNullOrEmpty(errorMessage))

src/HotChocolate/Core/src/Execution/Processing/MiddlewareContext.Selection.cs

@@ -1,4 +1,7 @@
+using System;
+using System.Collections.Generic;
 using System.Diagnostics.CodeAnalysis;
+using System.Runtime.CompilerServices;
 using HotChocolate.Resolvers;
 using HotChocolate.Types;
 
@@ -39,4 +42,54 @@ public bool TryCreatePureContext(
         context = null;
         return false;
     }
-}
+
+    public IReadOnlyList<ISelection> GetSelections(
+        IObjectType typeContext,
+        ISelection? selection = null,
+        bool allowInternals = false)
+    {
+        if (typeContext is null)
+        {
+            throw new ArgumentNullException(nameof(typeContext));
+        }
+
+        selection ??= _selection;
+
+        if (selection.SelectionSet is null)
+        {
+            return Array.Empty<ISelection>();
+        }
+
+        var selectionSet = _operationContext.CollectFields(selection, typeContext);
+
+        if (selectionSet.IsConditional)
+        {
+            var operationIncludeFlags = _operationContext.IncludeFlags;
+            var selectionCount = selectionSet.Selections.Count;
+            ref var selectionRef = ref ((SelectionSet)selectionSet).GetSelectionsReference();
+            var finalFields = new List<ISelection>();
+
+            for (var i = 0; i < selectionCount; i++)
+            {
+                var childSelection = Unsafe.Add(ref selectionRef, i);
+
+                if (childSelection.IsIncluded(operationIncludeFlags, allowInternals))
+                {
+                    finalFields.Add(childSelection);
+                }
+            }
+
+            return finalFields;
+        }
+
+        return selectionSet.Selections;
+    }
+
+    public ISelectionCollection Select(string fieldName)
+        => new SelectionCollection(
+            Schema,
+            Operation,
+            [Selection,],
+            _operationContext.IncludeFlags)
+            .Select(fieldName);
+}