Reworked the syntax rewriter and introduced a syntax navigator.

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

@@ -0,0 +1,9 @@
+namespace HotChocolate.Language.Rewriters;
+
+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 +1,40 @@
+using System.Collections.Generic;
+
+namespace HotChocolate.Language.Rewriters;
+
+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>
+    /// 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>
+    /// <returns>The parent Syntax Node or null if the current node does not have a parent.</returns>
+    ISyntaxNode? GetParent();
+}

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

@@ -0,0 +1,56 @@
+using System;
+using System.Collections.Generic;
+using static HotChocolate.Language.Rewriters.LangRewritersResources;
+
+namespace HotChocolate.Language.Rewriters;
+
+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 (_ancestors.Count == 0)
+        {
+            throw new InvalidOperationException(DefaultSyntaxNavigator_NoAncestors);
+        }
+
+        node = _ancestors[_ancestors.Count - 1];
+        _ancestors.RemoveAt(_ancestors.Count - 1);
+    }
+
+    /// <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.GetParent"/>
+    public ISyntaxNode? GetParent() => GetAncestor<ISyntaxNode>();
+}

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>

src/HotChocolate/Language/src/Language.Rewriters/Properties/LangRewritersResources.resx

@@ -0,0 +1,126 @@
+<?xml version="1.0" encoding="utf-8"?>
+<root>
+  <!-- 
+    Microsoft ResX Schema 
+
+    Version 2.0
+
+    The primary goals of this format is to allow a simple XML format 
+    that is mostly human readable. The generation and parsing of the 
+    various data types are done through the TypeConverter classes 
+    associated with the data types.
+
+    Example:
+
+    ... ado.net/XML headers & schema ...
+    <resheader name="resmimetype">text/microsoft-resx</resheader>
+    <resheader name="version">2.0</resheader>
+    <resheader name="reader">System.Resources.ResXResourceReader, System.Windows.Forms, ...</resheader>
+    <resheader name="writer">System.Resources.ResXResourceWriter, System.Windows.Forms, ...</resheader>
+    <data name="Name1"><value>this is my long string</value><comment>this is a comment</comment></data>
+    <data name="Color1" type="System.Drawing.Color, System.Drawing">Blue</data>
+    <data name="Bitmap1" mimetype="application/x-microsoft.net.object.binary.base64">
+        <value>[base64 mime encoded serialized .NET Framework object]</value>
+    </data>
+    <data name="Icon1" type="System.Drawing.Icon, System.Drawing" mimetype="application/x-microsoft.net.object.bytearray.base64">
+        <value>[base64 mime encoded string representing a byte array form of the .NET Framework object]</value>
+        <comment>This is a comment</comment>
+    </data>
+
+    There are any number of "resheader" rows that contain simple 
+    name/value pairs.
+
+    Each data row contains a name, and value. The row also contains a 
+    type or mimetype. Type corresponds to a .NET class that support 
+    text/value conversion through the TypeConverter architecture. 
+    Classes that don't support this are serialized and stored with the 
+    mimetype set.
+
+    The mimetype is used for serialized objects, and tells the 
+    ResXResourceReader how to depersist the object. This is currently not 
+    extensible. For a given mimetype the value must be set accordingly:
+
+    Note - application/x-microsoft.net.object.binary.base64 is the format 
+    that the ResXResourceWriter will generate, however the reader can 
+    read any of the formats listed below.
+
+    mimetype: application/x-microsoft.net.object.binary.base64
+    value   : The object must be serialized with 
+            : System.Runtime.Serialization.Formatters.Binary.BinaryFormatter
+            : and then encoded with base64 encoding.
+
+    mimetype: application/x-microsoft.net.object.soap.base64
+    value   : The object must be serialized with 
+            : System.Runtime.Serialization.Formatters.Soap.SoapFormatter
+            : and then encoded with base64 encoding.
+
+    mimetype: application/x-microsoft.net.object.bytearray.base64
+    value   : The object must be serialized into a byte array 
+            : using a System.ComponentModel.TypeConverter
+            : and then encoded with base64 encoding.
+    -->
+  <xsd:schema id="root" xmlns="" xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns:msdata="urn:schemas-microsoft-com:xml-msdata">
+    <xsd:import namespace="http://www.w3.org/XML/1998/namespace" />
+    <xsd:element name="root" msdata:IsDataSet="true">
+      <xsd:complexType>
+        <xsd:choice maxOccurs="unbounded">
+          <xsd:element name="metadata">
+            <xsd:complexType>
+              <xsd:sequence>
+                <xsd:element name="value" type="xsd:string" minOccurs="0" />
+              </xsd:sequence>
+              <xsd:attribute name="name" use="required" type="xsd:string" />
+              <xsd:attribute name="type" type="xsd:string" />
+              <xsd:attribute name="mimetype" type="xsd:string" />
+              <xsd:attribute ref="xml:space" />
+            </xsd:complexType>
+          </xsd:element>
+          <xsd:element name="assembly">
+            <xsd:complexType>
+              <xsd:attribute name="alias" type="xsd:string" />
+              <xsd:attribute name="name" type="xsd:string" />
+            </xsd:complexType>
+          </xsd:element>
+          <xsd:element name="data">
+            <xsd:complexType>
+              <xsd:sequence>
+                <xsd:element name="value" type="xsd:string" minOccurs="0" msdata:Ordinal="1" />
+                <xsd:element name="comment" type="xsd:string" minOccurs="0" msdata:Ordinal="2" />
+              </xsd:sequence>
+              <xsd:attribute name="name" type="xsd:string" use="required" msdata:Ordinal="1" />
+              <xsd:attribute name="type" type="xsd:string" msdata:Ordinal="3" />
+              <xsd:attribute name="mimetype" type="xsd:string" msdata:Ordinal="4" />
+              <xsd:attribute ref="xml:space" />
+            </xsd:complexType>
+          </xsd:element>
+          <xsd:element name="resheader">
+            <xsd:complexType>
+              <xsd:sequence>
+                <xsd:element name="value" type="xsd:string" minOccurs="0" msdata:Ordinal="1" />
+              </xsd:sequence>
+              <xsd:attribute name="name" type="xsd:string" use="required" />
+            </xsd:complexType>
+          </xsd:element>
+        </xsd:choice>
+      </xsd:complexType>
+    </xsd:element>
+  </xsd:schema>
+  <resheader name="resmimetype">
+    <value>text/microsoft-resx</value>
+  </resheader>
+  <resheader name="version">
+    <value>2.0</value>
+  </resheader>
+  <resheader name="reader">
+    <value>System.Resources.ResXResourceReader, System.Windows.Forms, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089</value>
+  </resheader>
+  <resheader name="writer">
+    <value>System.Resources.ResXResourceWriter, System.Windows.Forms, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089</value>
+  </resheader>
+  <data name="DefaultSyntaxNavigator_NoAncestors" xml:space="preserve">
+    <value>The navigator does not contain any ancestors</value>
+  </data>
+  <data name="QuerySyntaxRewriter_NotSupported" xml:space="preserve">
+    <value>The given syntax node is not supported by this rewriter.</value>
+  </data>
+</root>

src/HotChocolate/Language/src/Language.Rewriters/PublicAPI.Unshipped.txt

@@ -0,0 +1 @@
+#nullable enable

src/HotChocolate/Language/src/Language/Legacy/Visitors/QuerySyntaxRewriter.cs → src/HotChocolate/Language/src/Language.Rewriters/QuerySyntaxRewriter.cs

@@ -1,8 +1,8 @@
 using System;
 using System.Collections.Generic;
-using static HotChocolate.Language.Properties.LangUtf8Resources;
+using static HotChocolate.Language.Rewriters.LangRewritersResources;
 
-namespace HotChocolate.Language;
+namespace HotChocolate.Language.Rewriters;
 
 public class QuerySyntaxRewriter<TContext>
     : SyntaxRewriter<TContext>

src/HotChocolate/Language/src/Language/Legacy/Visitors/SchemaSyntaxRewriter.cs → src/HotChocolate/Language/src/Language.Rewriters/SchemaSyntaxRewriter.cs

@@ -1,7 +1,7 @@
 using System;
 using System.Collections.Generic;
 
-namespace HotChocolate.Language;
+namespace HotChocolate.Language.Rewriters;
 
 public class SchemaSyntaxRewriter<TContext>
     : SyntaxRewriter<TContext>