Reworked the syntax rewriter and introduced a syntax navigator.

src/HotChocolate/Language/src/Language.Rewriters/Contracts/INavigatorContext.cs

@@ -0,0 +1,12 @@
+namespace HotChocolate.Language.Rewriters;
+
+/// <summary>
+/// A rewriter context that contains a syntax navigator.
+/// </summary>
+public interface INavigatorContext
+{
+    /// <summary>
+    /// Gets the associated <see cref="ISyntaxNavigator" /> from the current context.
+    /// </summary>
+    ISyntaxNavigator Navigator { get; }
+}

src/HotChocolate/Language/src/Language.Rewriters/Contracts/ISyntaxNavigator.cs

@@ -0,0 +1,51 @@
+using System.Collections.Generic;
+using System.Diagnostics.CodeAnalysis;
+
+namespace HotChocolate.Language.Rewriters;
+
+/// <summary>
+/// The syntax navigator keeps track of the syntax path that has been traversed and allows to access the nodes in the path in a streamlined way.
+/// </summary>
+public interface ISyntaxNavigator
+{
+    /// <summary>
+    /// Adds a syntax node to the Syntax Navigator to record the parent of the Syntax Node being visited.
+    /// </summary>
+    /// <param name="node">The parent syntax node to be added to the Syntax Navigator</param>
+    void Push(ISyntaxNode node);
+
+    /// <summary>
+    /// Removes the current parent node from the Syntax Navigator.
+    /// </summary>
+    /// <param name="node">The removed parent node.</param>
+    void Pop(out ISyntaxNode node);
+
+    /// <summary>
+    /// Attempts to remove the current parent node from the Syntax Navigator.
+    /// </summary>
+    /// <param name="node">The removed parent node.</param>
+    /// <returns>True when a syntax node was successfully removed from the Syntax Navigator.
+    /// False when a syntax node was not removed.</returns>
+    bool TryPop([NotNullWhen(true)] out ISyntaxNode? node);
+
+    /// <summary>
+    /// Returns the first ancestor of the provided <see cref="TNode" /> type.
+    /// </summary>
+    /// <typeparam name="TNode">The type of syntax node to be returned.</typeparam>
+    /// <returns>The matching first ancestor or null if no match is found.</returns>
+    TNode? GetAncestor<TNode>()
+        where TNode : ISyntaxNode;
+
+    /// <summary>
+    /// Returns all ancestors of the provided <see cref="TNode" /> type.
+    /// </summary>
+    /// <typeparam name="TNode">The type of syntax nodes to be returned.</typeparam>
+    /// <returns>A collection of Syntax Nodes of type <see cref="TNode" /></returns>
+    IEnumerable<TNode> GetAncestors<TNode>()
+        where TNode : ISyntaxNode;
+
+    /// <summary>
+    /// Returns the immediate parent of the current Syntax Node
+    /// </summary>
+    ISyntaxNode? Parent { get; }
+}

src/HotChocolate/Language/src/Language.Rewriters/DefaultSyntaxNavigator.cs

@@ -0,0 +1,82 @@
+using System;
+using System.Collections.Generic;
+using System.Diagnostics.CodeAnalysis;
+using static HotChocolate.Language.Rewriters.LangRewritersResources;
+
+namespace HotChocolate.Language.Rewriters;
+
+/// <summary>
+/// Represents the default implementation of <see cref="ISyntaxNavigator" />
+/// </summary>
+public class DefaultSyntaxNavigator : ISyntaxNavigator
+{
+    private readonly List<ISyntaxNode> _ancestors = new();
+
+    /// <inheritdoc cref="ISyntaxNavigator.Push"/>
+    public void Push(ISyntaxNode node) => _ancestors.Add(node);
+
+    /// <inheritdoc cref="ISyntaxNavigator.Pop"/>
+    public void Pop(out ISyntaxNode node)
+    {
+        if (!TryPop(out node!))
+        {
+            throw new InvalidOperationException(DefaultSyntaxNavigator_NoAncestors);
+        }
+    }
+
+    /// <inheritdoc cref="ISyntaxNavigator.TryPop"/>
+    public bool TryPop([NotNullWhen(true)] out ISyntaxNode? node)
+    {
+        if (_ancestors.Count == 0)
+        {
+            node = default;
+            return false;
+        }
+
+        node = _ancestors[_ancestors.Count - 1];
+        _ancestors.RemoveAt(_ancestors.Count - 1);
+        return true;
+    }
+
+    /// <inheritdoc cref="ISyntaxNavigator.GetAncestor{TNode}"/>
+    public TNode? GetAncestor<TNode>()
+        where TNode : ISyntaxNode
+    {
+        for (var i = _ancestors.Count - 1; i >= 0; i--)
+        {
+            if (_ancestors[i] is TNode typedNode)
+            {
+                return typedNode;
+            }
+        }
+
+        return default;
+    }
+
+    /// <inheritdoc cref="ISyntaxNavigator.GetAncestors{TNode}"/>
+    public IEnumerable<TNode> GetAncestors<TNode>()
+        where TNode : ISyntaxNode
+    {
+        for (var i = _ancestors.Count - 1; i >= 0; i--)
+        {
+            if (_ancestors[i] is TNode typedNode)
+            {
+                yield return typedNode;
+            }
+        }
+    }
+
+    /// <inheritdoc cref="ISyntaxNavigator.Parent"/>
+    public ISyntaxNode? Parent
+    {
+        get
+        {
+            if (_ancestors.Count == 0)
+            {
+                return null;
+            }
+
+            return _ancestors[_ancestors.Count - 1];
+        }
+    }
+}

src/HotChocolate/Language/test/Language.Tests/Visitors/DirectiveQuerySyntaxRewriter.cs → src/HotChocolate/Language/src/Language.Rewriters/DirectiveQuerySyntaxRewriter.cs

@@ -1,6 +1,6 @@
 using System.Collections.Generic;
 
-namespace HotChocolate.Language;
+namespace HotChocolate.Language.Rewriters;
 
 public class DirectiveQuerySyntaxRewriter
     : QuerySyntaxRewriter<DirectiveNode>

src/HotChocolate/Language/src/Language/Legacy/Visitors/DocumentRewriterExtensions.cs → src/HotChocolate/Language/src/Language.Rewriters/Extensions/DocumentRewriterExtensions.cs

@@ -1,4 +1,4 @@
-namespace HotChocolate.Language;
+namespace HotChocolate.Language.Rewriters;
 
 public static class DocumentRewriterExtensions
 {

src/HotChocolate/Language/src/Language.Rewriters/HotChocolate.Language.Rewriters.csproj

@@ -0,0 +1,34 @@
+<Project Sdk="Microsoft.NET.Sdk">
+
+  <PropertyGroup>
+    <PackageId>HotChocolate.Language.Rewriters</PackageId>
+    <AssemblyName>HotChocolate.Language.Rewriters</AssemblyName>
+    <RootNamespace>HotChocolate.Language.Rewriters</RootNamespace>
+    <Description>This package contains Syntax Rewrite primitives of Hot Chocolate.</Description>
+  </PropertyGroup>
+
+  <ItemGroup>
+    <None Remove="HotChocolate.Language.Rewriters.csproj.DotSettings" />
+  </ItemGroup>
+
+  <ItemGroup>
+   <ProjectReference Include="..\Language.SyntaxTree\HotChocolate.Language.SyntaxTree.csproj" />
+  </ItemGroup>
+
+  <ItemGroup>
+    <Compile Update="Properties\LangRewritersResources.Designer.cs">
+      <DesignTime>True</DesignTime>
+      <AutoGen>True</AutoGen>
+      <DependentUpon>LangRewritersResources.resx</DependentUpon>
+    </Compile>
+  </ItemGroup>
+
+  <ItemGroup>
+    <EmbeddedResource Update="Properties\LangRewritersResources.resx">
+      <Generator>ResXFileCodeGenerator</Generator>
+      <LastGenOutput>LangRewritersResources.Designer.cs</LastGenOutput>
+      <CustomToolNamespace>HotChocolate.Language.Rewriters</CustomToolNamespace>
+    </EmbeddedResource>
+  </ItemGroup>
+
+</Project>