Merge branch 'v8'

Author: Shane32

src/GraphQLParser.ApiTests/GraphQLParser.approved.txt

@@ -840,6 +840,10 @@ namespace GraphQLParser.Visitors
         public int MaxDepth { get; set; }
         public System.Collections.Generic.Stack<GraphQLParser.AST.ASTNode> Parents { get; set; }
     }
+    public struct DefaultVisitorContext : GraphQLParser.Visitors.IASTVisitorContext
+    {
+        public System.Threading.CancellationToken CancellationToken { get; set; }
+    }
     public interface IASTVisitorContext
     {
         System.Threading.CancellationToken CancellationToken { get; }
@@ -871,6 +875,10 @@ namespace GraphQLParser.Visitors
         public MaxDepthVisitor() { }
         public override System.Threading.Tasks.ValueTask VisitAsync(GraphQLParser.AST.ASTNode? node, TContext context) { }
     }
+    public struct NullVisitorContext : GraphQLParser.Visitors.IASTVisitorContext
+    {
+        public System.Threading.CancellationToken CancellationToken { get; }
+    }
     public static class PrintContextExtensions
     {
         public static System.Threading.Tasks.ValueTask WriteAsync<TContext>(this TContext context, GraphQLParser.ROM value)

src/GraphQLParser.Tests/Visitors/ASTVisitorTests.cs

@@ -33,12 +33,13 @@ public void ASTVisitor_Should_Throw_On_Unknown_Node()
     }
 
     [Fact]
-    public void ASTVisitor_Should_Respect_CancellationToken()
+    public void ASTVisitor_Should_Pass_CancellationToken()
     {
         var document = "scalar JSON".Parse();
         var visitor = new MyVisitor();
         using var cts = new CancellationTokenSource(500);
         var context = new Context { CancellationToken = cts.Token };
+        context.CancellationToken.ThrowIfCancellationRequested();
 
         Should.Throw<OperationCanceledException>(() => visitor.VisitAsync(document, context).GetAwaiter().GetResult());
     }
@@ -48,6 +49,7 @@ private sealed class MyVisitor : ASTVisitor<Context>
         protected override async ValueTask VisitScalarTypeDefinitionAsync(GraphQLScalarTypeDefinition scalarTypeDefinition, Context context)
         {
             await Task.Delay(700);
+            context.CancellationToken.ThrowIfCancellationRequested();
             await base.VisitScalarTypeDefinitionAsync(scalarTypeDefinition, context);
         }
     }

src/GraphQLParser/Visitors/ASTVisitor.cs

@@ -597,8 +597,6 @@ protected virtual async ValueTask VisitInputObjectTypeExtensionAsync(GraphQLInpu
     /// <param name="context">Context passed into all INodeVisitor.VisitXXX methods.</param>
     public virtual ValueTask VisitAsync(ASTNode? node, TContext context)
     {
-        context.CancellationToken.ThrowIfCancellationRequested();
-
         return node == null
             ? default
             : node switch

src/GraphQLParser/Visitors/DefaultVisitorContext.cs

@@ -0,0 +1,11 @@
+namespace GraphQLParser.Visitors;
+
+/// <summary>
+/// An implementation of <see cref="IASTVisitorContext"/> that only contains a <see cref="CancellationToken"/>.
+/// Ideal for use in cases where there is no context variables.
+/// </summary>
+public struct DefaultVisitorContext : IASTVisitorContext
+{
+    /// <inheritdoc/>
+    public CancellationToken CancellationToken { get; set; }
+}

src/GraphQLParser/Visitors/NullVisitorContext.cs

@@ -0,0 +1,12 @@
+namespace GraphQLParser.Visitors;
+
+/// <summary>
+/// An implementation of <see cref="IASTVisitorContext"/> that does nothing.
+/// Ideal for use in cases where the visitor runs synchronously, there is no context
+/// variables, and cancellation is not required.
+/// </summary>
+public struct NullVisitorContext : IASTVisitorContext
+{
+    /// <inheritdoc/>
+    public readonly CancellationToken CancellationToken => default;
+}