Extract syntax tree generator emit helpers

Reduce nested generation routines by moving constructor, child-dispatch, slot, and slot-kind emission into focused helpers. This keeps generator behavior intact while making the source-generator control flow easier to review and maintain.

Assisted-by: OpenCode:openai/gpt-5.5:OpenCode

ICSharpCode.Decompiler.Generators/DecompilerSyntaxTreeGenerator.cs

@@ -220,6 +220,32 @@ internal class DecompilerSyntaxTreeGenerator : IIncrementalGenerator
 	{
 		var builder = new StringBuilder();
 
+		WriteGeneratedMembersHeader(builder, source);
+		WritePatternPlaceholder(builder, source);
+		WriteVisitorOverrides(builder, source);
+		WriteDoMatch(builder, source);
+
+		if (source.Slots is { } slotsArray)
+		{
+			var slots = slotsArray.ToList();
+			WriteSlotProperties(builder, slots);
+			WriteNameAccessors(builder, source.NameAccessors);
+			WriteConstructors(builder, source, slots);
+			WriteChildAccessors(builder, slots);
+			WriteSlotInfoFields(builder, slots);
+			WriteChildSlotInfo(builder, slots);
+			WriteCollectionLookup(builder, slots);
+			WriteCloneChildrenInto(builder, source, slots);
+		}
+
+		// Close the class, trimming the blank line the per-member spacer leaves before the brace.
+		string body = builder.ToString().TrimEnd() + "\n}\n";
+
+		context.AddSource(source.NodeName + ".g.cs", SourceText.From(body.Replace("\r\n", "\n"), Encoding.UTF8));
+	}
+
+	static void WriteGeneratedMembersHeader(StringBuilder builder, AstNodeAdditions source)
+	{
 		builder.AppendLine("// <auto-generated/>");
 		builder.AppendLine("#nullable enable");
 		builder.AppendLine();
@@ -237,9 +263,13 @@ internal class DecompilerSyntaxTreeGenerator : IIncrementalGenerator
 
 		builder.AppendLine($"partial class {source.NodeName}");
 		builder.AppendLine("{");
+	}
 
-		if (source.NeedsPatternPlaceholder)
+	static void WritePatternPlaceholder(StringBuilder builder, AstNodeAdditions source)
 	{
+		if (!source.NeedsPatternPlaceholder)
+			return;
+
 		// The placeholder conversion is part of the pattern-construction DSL, where a non-null
 		// pattern is the invariant; the result is therefore non-nullable for the specific node
 		// types. AstNode (the base) and ParameterDeclaration keep the nullable contract, and only
@@ -292,8 +322,11 @@ internal class DecompilerSyntaxTreeGenerator : IIncrementalGenerator
 		);
 	}
 
-		if (source.NeedsVisitor)
+	static void WriteVisitorOverrides(StringBuilder builder, AstNodeAdditions source)
 	{
+		if (!source.NeedsVisitor)
+			return;
+
 		builder.Append($@"	public override void AcceptVisitor(IAstVisitor visitor)
 	{{
 		visitor.Visit{source.VisitMethodName}(this);
@@ -312,40 +345,17 @@ internal class DecompilerSyntaxTreeGenerator : IIncrementalGenerator
 ");
 	}
 
-		if (source.MembersToMatch != null)
+	static void WriteDoMatch(StringBuilder builder, AstNodeAdditions source)
 	{
+		if (source.MembersToMatch == null)
+			return;
+
 		builder.Append($@"	protected internal override bool DoMatch(AstNode? other, PatternMatching.Match match)
 	{{
 		return other is {source.NodeName} o");
 
 		foreach (var (member, typeName, recursive, hasAny, nullable) in source.MembersToMatch)
-			{
-				if (member == "MatchAttributesAndModifiers")
-				{
-					builder.Append($"\r\n\t\t\t&& this.MatchAttributesAndModifiers(o, match)");
-				}
-				else if (recursive && nullable && typeName != "AstNodeCollection")
-				{
-					// An optional single-value child is null when absent; match null-safely.
-					builder.Append($"\r\n\t\t\t&& MatchOptional(this.{member}, o.{member}, match)");
-				}
-				else if (recursive)
-				{
-					builder.Append($"\r\n\t\t\t&& this.{member}.DoMatch(o.{member}, match)");
-				}
-				else if (hasAny)
-				{
-					builder.Append($"\r\n\t\t\t&& (this.{member} == {typeName}.Any || this.{member} == o.{member})");
-				}
-				else if (typeName == "String")
-				{
-					builder.Append($"\r\n\t\t\t&& MatchString(this.{member}, o.{member})");
-				}
-				else
-				{
-					builder.Append($"\r\n\t\t\t&& this.{member} == o.{member}");
-				}
-			}
+			builder.Append(DoMatchTerm(member, typeName, recursive, hasAny, nullable));
 
 		builder.Append(@";
 	}
@@ -353,10 +363,24 @@ internal class DecompilerSyntaxTreeGenerator : IIncrementalGenerator
 ");
 	}
 
-		if (source.Slots is { } slotsArray)
+	static string DoMatchTerm(string member, string typeName, bool recursive, bool hasAny, bool nullable)
 	{
-			var slots = slotsArray.ToList();
+		if (member == "MatchAttributesAndModifiers")
+			return $"\r\n\t\t\t&& this.MatchAttributesAndModifiers(o, match)";
+		// An optional single-value child is null when absent; match null-safely.
+		if (recursive && nullable && typeName != "AstNodeCollection")
+			return $"\r\n\t\t\t&& MatchOptional(this.{member}, o.{member}, match)";
+		if (recursive)
+			return $"\r\n\t\t\t&& this.{member}.DoMatch(o.{member}, match)";
+		if (hasAny)
+			return $"\r\n\t\t\t&& (this.{member} == {typeName}.Any || this.{member} == o.{member})";
+		if (typeName == "String")
+			return $"\r\n\t\t\t&& MatchString(this.{member}, o.{member})";
+		return $"\r\n\t\t\t&& this.{member} == o.{member}";
+	}
 
+	static void WriteSlotProperties(StringBuilder builder, List<SlotInfo> slots)
+	{
 		// Backing fields and the partial-property bodies. A single slot stores a nullable backing
 		// field (returned null-forgiving for a required child, nullable for an optional one); a
 		// collection slot owns a lazily created AstNodeCollection bound to this node. A slot re-declared from an inherited contract
@@ -367,6 +391,10 @@ internal class DecompilerSyntaxTreeGenerator : IIncrementalGenerator
 		// preceding slots are single children, one index each).
 		int collectionCount = slots.Count(s => s.IsCollection);
 		for (int slotIndex = 0; slotIndex < slots.Count; slotIndex++)
+			WriteSlotProperty(builder, slots, slotIndex, collectionCount);
+	}
+
+	static void WriteSlotProperty(StringBuilder builder, List<SlotInfo> slots, int slotIndex, int collectionCount)
 	{
 		var (isCollection, name, type, elementType, isOverride, isNullable, kindName, isPartial) = slots[slotIndex];
 		string field = FieldName(name);
@@ -397,10 +425,17 @@ internal class DecompilerSyntaxTreeGenerator : IIncrementalGenerator
 		builder.AppendLine();
 	}
 
-			// A string [Slot] is a convenience accessor over its generated Identifier token slot.
-			if (source.NameAccessors is { } nameAccessorsArray)
+	static void WriteNameAccessors(StringBuilder builder, EquatableArray<NameAccessor>? nameAccessors)
 	{
+		// A string [Slot] is a convenience accessor over its generated Identifier token slot.
+		if (nameAccessors is not { } nameAccessorsArray)
+			return;
+
 		foreach (var (stringName, tokenName, isOptional) in nameAccessorsArray)
+			WriteNameAccessor(builder, stringName, tokenName, isOptional);
+	}
+
+	static void WriteNameAccessor(StringBuilder builder, string stringName, string tokenName, bool isOptional)
 	{
 		// The token factory is the type 'Identifier'. A [Slot] string property literally named
 		// "Identifier" (e.g. SimpleType.Identifier) shadows that type inside its own setter, so the
@@ -425,8 +460,9 @@ internal class DecompilerSyntaxTreeGenerator : IIncrementalGenerator
 		builder.AppendLine("\t}");
 		builder.AppendLine();
 	}
-			}
 
+	static void WriteConstructors(StringBuilder builder, AstNodeAdditions source, List<SlotInfo> slots)
+	{
 		// Constructors. Parameters follow member source order and cover single/collection [Slot] children,
 		// the string [Slot], and settable enum scalars (Operator, FieldDirection, ...); a collection is
 		// an IEnumerable<T> param in its declared position. We emit the empty ctor (for object-initializer
@@ -434,56 +470,94 @@ internal class DecompilerSyntaxTreeGenerator : IIncrementalGenerator
 		// each collection, and one with all params. A params T[] overload is added when a ctor's last param
 		// is the collection. Pure-scalar nodes (no [Slot], e.g. PrimitiveExpression) are excluded
 		// because their non-enum state (a literal value) is invisible here; those keep hand-written ctors.
-			if (!source.IsAbstract && source.BaseHasDefaultConstructor && slots.Count > 0 && source.CtorParams is { } ctorParamsArray)
-			{
-				var cp = ctorParamsArray.ToList();
-				string ParamName(string n)
-				{
-					string p = char.ToLowerInvariant(n[0]) + n.Substring(1);
-					return SyntaxFacts.GetKeywordKind(p) != SyntaxKind.None ? "@" + p : p;
-				}
-				string ParamType(int i) => cp[i].IsCollection
-					? $"IEnumerable<{cp[i].ElementType}>"
-					: cp[i].ParamType;
+		if (source.IsAbstract || !source.BaseHasDefaultConstructor || slots.Count == 0 || source.CtorParams is not { } ctorParamsArray)
+			return;
 
+		var cp = ctorParamsArray.ToList();
 		builder.AppendLine($"\tpublic {source.NodeName}()");
 		builder.AppendLine("\t{");
 		builder.AppendLine("\t}");
 		builder.AppendLine();
 
+		int reqLen = RequiredConstructorPrefixLength(cp);
+		int prev = 0;
+		foreach (int len in ConstructorPrefixLengths(cp, reqLen))
+		{
+			if (len <= 0)
+				continue;
+			WriteConstructorPrefix(builder, source.NodeName, cp, len, prev, paramsForm: false);
+			if (cp[len - 1].IsCollection)
+				WriteConstructorPrefix(builder, source.NodeName, cp, len, len, paramsForm: true);
+			prev = len;
+		}
+	}
+
+	static int RequiredConstructorPrefixLength(List<CtorParam> cp)
+	{
 		// Required prefix: through the last non-optional param (an optional param before it is still
 		// positionally included so the required param after it can be passed).
 		int reqLen = 0;
 		for (int i = 0; i < cp.Count; i++)
 			if (!cp[i].IsOptional)
 				reqLen = i + 1;
+		return reqLen;
+	}
+
+	static SortedSet<int> ConstructorPrefixLengths(List<CtorParam> cp, int reqLen)
+	{
+		var lengths = new SortedSet<int>();
+		if (reqLen > 0)
+			lengths.Add(reqLen);
+		for (int i = 0; i < cp.Count; i++)
+			if (cp[i].IsCollection && i + 1 >= reqLen)
+				lengths.Add(i + 1);
+		lengths.Add(cp.Count);
+		return lengths;
+	}
 
+	static void WriteConstructorPrefix(StringBuilder builder, string nodeName, List<CtorParam> cp, int len, int chainLen, bool paramsForm)
+	{
 		// A normal prefix ctor forwards to the previous (shorter) emitted prefix via : this(...) and only
 		// sets the params between them; the shortest sets its params directly. A params T[] overload
 		// forwards to the IEnumerable overload of the same length.
-				void EmitPrefix(int len, int chainLen, bool paramsForm)
+		builder.AppendLine($"\tpublic {nodeName}({string.Join(", ", ConstructorParameterDeclarations(cp, len, paramsForm))})");
+		if (paramsForm)
+			WriteParamsConstructorBody(builder, cp, len);
+		else
+			WriteNormalConstructorBody(builder, cp, len, chainLen);
+		builder.AppendLine();
+	}
+
+	static IEnumerable<string> ConstructorParameterDeclarations(List<CtorParam> cp, int len, bool paramsForm)
 	{
-					var decls = new List<string>();
 		for (int i = 0; i < len; i++)
 		{
 			if (paramsForm && i == len - 1)
-							decls.Add($"params {cp[i].ElementType}[] {ParamName(cp[i].PropertyName)}");
+				yield return $"params {cp[i].ElementType}[] {ParamName(cp[i].PropertyName)}";
 			else
-							decls.Add($"{ParamType(i)} {ParamName(cp[i].PropertyName)}");
+				yield return $"{ParamType(cp[i])} {ParamName(cp[i].PropertyName)}";
 		}
-					builder.AppendLine($"\tpublic {source.NodeName}({string.Join(", ", decls)})");
-					if (paramsForm)
+	}
+
+	static void WriteParamsConstructorBody(StringBuilder builder, List<CtorParam> cp, int len)
 	{
-						var args = new List<string>();
-						for (int i = 0; i < len; i++)
-							args.Add(i == len - 1
-								? $"(IEnumerable<{cp[i].ElementType}>){ParamName(cp[i].PropertyName)}"
-								: ParamName(cp[i].PropertyName));
-						builder.AppendLine($"\t\t: this({string.Join(", ", args)})");
+		builder.AppendLine($"\t\t: this({string.Join(", ", ParamsConstructorArguments(cp, len))})");
 		builder.AppendLine("\t{");
 		builder.AppendLine("\t}");
 	}
+
+	static IEnumerable<string> ParamsConstructorArguments(List<CtorParam> cp, int len)
+	{
+		for (int i = 0; i < len; i++)
+		{
+			if (i == len - 1)
+				yield return $"(IEnumerable<{cp[i].ElementType}>){ParamName(cp[i].PropertyName)}";
 			else
+				yield return ParamName(cp[i].PropertyName);
+		}
+	}
+
+	static void WriteNormalConstructorBody(StringBuilder builder, List<CtorParam> cp, int len, int chainLen)
 	{
 		if (chainLen > 0)
 			builder.AppendLine($"\t\t: this({string.Join(", ", Enumerable.Range(0, chainLen).Select(i => ParamName(cp[i].PropertyName)))})");
@@ -497,28 +571,17 @@ internal class DecompilerSyntaxTreeGenerator : IIncrementalGenerator
 		}
 		builder.AppendLine("\t}");
 	}
-					builder.AppendLine();
-				}
 
-				var lengths = new SortedSet<int>();
-				if (reqLen > 0)
-					lengths.Add(reqLen);
-				for (int i = 0; i < cp.Count; i++)
-					if (cp[i].IsCollection && i + 1 >= reqLen)
-						lengths.Add(i + 1);
-				lengths.Add(cp.Count);
-				int prev = 0;
-				foreach (int len in lengths)
+	static string ParamName(string n)
 	{
-					if (len <= 0)
-						continue;
-					EmitPrefix(len, prev, paramsForm: false);
-					if (cp[len - 1].IsCollection)
-						EmitPrefix(len, len, paramsForm: true);
-					prev = len;
-				}
+		string p = char.ToLowerInvariant(n[0]) + n.Substring(1);
+		return SyntaxFacts.GetKeywordKind(p) != SyntaxKind.None ? "@" + p : p;
 	}
 
+	static string ParamType(CtorParam cp) => cp.IsCollection ? $"IEnumerable<{cp.ElementType}>" : cp.ParamType;
+
+	static void WriteChildAccessors(StringBuilder builder, List<SlotInfo> slots)
+	{
 		// Flattened child-index space: slots in declaration order, a single slot occupying one index
 		// (even when empty), a collection slot a contiguous run of its current length.
 		var countTerms = new List<string>();
@@ -530,15 +593,35 @@ internal class DecompilerSyntaxTreeGenerator : IIncrementalGenerator
 		builder.AppendLine($"\tinternal override int GetChildCount() => {string.Join(" + ", countTerms)};");
 		builder.AppendLine();
 
-			bool anyCollection = slots.Any(s => s.IsCollection);
+		builder.AppendLine("\tinternal override AstNode? GetChild(int index)");
+		builder.AppendLine("\t{");
+		WriteReturnDispatch(builder, slots, k => FieldName(slots[k].PropertyName), k => $"{FieldName(slots[k].PropertyName)}![i]");
+		builder.AppendLine("\t}");
+		builder.AppendLine();
 
+		builder.AppendLine("\tinternal override void SetChild(int index, AstNode? value)");
+		builder.AppendLine("\t{");
+		if (slots.Any(s => s.IsCollection))
+			WriteSetChildWithCollections(builder, slots);
+		else
+			WriteSetChildSwitch(builder, slots);
+		builder.AppendLine("\t}");
+		builder.AppendLine();
+	}
+
+	static void WriteReturnDispatch(StringBuilder builder, List<SlotInfo> slots, Func<int, string> singleExpr, Func<int, string> collectionExpr)
+	{
 		// Emits a method body that maps a flat child index to a slot and returns an expression for it.
 		// With only single slots the index is a constant offset, so a switch reads best; once a
 		// collection slot is present the widths are dynamic, so walk the slots subtracting each one's
 		// length from a running index.
-			void EmitReturnDispatch(Func<int, string> singleExpr, Func<int, string> collectionExpr)
-			{
-				if (!anyCollection)
+		if (slots.Any(s => s.IsCollection))
+			WriteReturnDispatchWithCollections(builder, slots, singleExpr, collectionExpr);
+		else
+			WriteReturnDispatchSwitch(builder, slots, singleExpr);
+	}
+
+	static void WriteReturnDispatchSwitch(StringBuilder builder, List<SlotInfo> slots, Func<int, string> singleExpr)
 	{
 		builder.AppendLine("\t\tswitch (index)");
 		builder.AppendLine("\t\t{");
@@ -550,43 +633,43 @@ internal class DecompilerSyntaxTreeGenerator : IIncrementalGenerator
 		builder.AppendLine("\t\t\tdefault:");
 		builder.AppendLine("\t\t\t\tthrow new System.ArgumentOutOfRangeException(nameof(index));");
 		builder.AppendLine("\t\t}");
-					return;
 	}
+
+	static void WriteReturnDispatchWithCollections(StringBuilder builder, List<SlotInfo> slots, Func<int, string> singleExpr, Func<int, string> collectionExpr)
+	{
 		builder.AppendLine("\t\tint i = index;");
 		for (int k = 0; k < slots.Count; k++)
 		{
 			bool last = k == slots.Count - 1;
 			if (slots[k].IsCollection)
+				WriteCollectionReturnDispatchStep(builder, slots[k], k, collectionExpr, last);
+			else
+				WriteSingleReturnDispatchStep(builder, k, singleExpr, last);
+		}
+		builder.AppendLine("\t\tthrow new System.ArgumentOutOfRangeException(nameof(index));");
+	}
+
+	static void WriteCollectionReturnDispatchStep(StringBuilder builder, SlotInfo slot, int index, Func<int, string> collectionExpr, bool last)
 	{
-						string field = FieldName(slots[k].PropertyName);
+		string field = FieldName(slot.PropertyName);
 		builder.AppendLine("\t\t{");
 		builder.AppendLine($"\t\t\tint n = {field}?.Count ?? 0;");
 		builder.AppendLine("\t\t\tif (i < n)");
-						builder.AppendLine($"\t\t\t\treturn {collectionExpr(k)};");
+		builder.AppendLine($"\t\t\t\treturn {collectionExpr(index)};");
 		if (!last)
 			builder.AppendLine("\t\t\ti -= n;");
 		builder.AppendLine("\t\t}");
 	}
-					else
+
+	static void WriteSingleReturnDispatchStep(StringBuilder builder, int index, Func<int, string> singleExpr, bool last)
 	{
 		builder.AppendLine("\t\tif (i == 0)");
-						builder.AppendLine($"\t\t\treturn {singleExpr(k)};");
+		builder.AppendLine($"\t\t\treturn {singleExpr(index)};");
 		if (!last)
 			builder.AppendLine("\t\ti--;");
 	}
-				}
-				builder.AppendLine("\t\tthrow new System.ArgumentOutOfRangeException(nameof(index));");
-			}
 
-			builder.AppendLine("\tinternal override AstNode? GetChild(int index)");
-			builder.AppendLine("\t{");
-			EmitReturnDispatch(k => FieldName(slots[k].PropertyName), k => $"{FieldName(slots[k].PropertyName)}![i]");
-			builder.AppendLine("\t}");
-			builder.AppendLine();
-
-			builder.AppendLine("\tinternal override void SetChild(int index, AstNode? value)");
-			builder.AppendLine("\t{");
-			if (!anyCollection)
+	static void WriteSetChildSwitch(StringBuilder builder, List<SlotInfo> slots)
 	{
 		builder.AppendLine("\t\tswitch (index)");
 		builder.AppendLine("\t\t{");
@@ -600,57 +683,72 @@ internal class DecompilerSyntaxTreeGenerator : IIncrementalGenerator
 		builder.AppendLine("\t\t\t\tthrow new System.ArgumentOutOfRangeException(nameof(index));");
 		builder.AppendLine("\t\t}");
 	}
-			else
+
+	static void WriteSetChildWithCollections(StringBuilder builder, List<SlotInfo> slots)
 	{
 		builder.AppendLine("\t\tint i = index;");
 		for (int k = 0; k < slots.Count; k++)
 		{
 			bool last = k == slots.Count - 1;
 			var s = slots[k];
-					string field = FieldName(s.PropertyName);
 			if (s.IsCollection)
+				WriteSetCollectionChildStep(builder, s, last);
+			else
+				WriteSetSingleChildStep(builder, s, last);
+		}
+		builder.AppendLine("\t\tthrow new System.ArgumentOutOfRangeException(nameof(index));");
+	}
+
+	static void WriteSetCollectionChildStep(StringBuilder builder, SlotInfo slot, bool last)
 	{
+		string field = FieldName(slot.PropertyName);
 		builder.AppendLine("\t\t{");
 		builder.AppendLine($"\t\t\tint n = {field}?.Count ?? 0;");
 		builder.AppendLine("\t\t\tif (i < n)");
 		builder.AppendLine("\t\t\t{");
-						builder.AppendLine($"\t\t\t\t{field}![i] = ({s.ElementType})value!;");
+		builder.AppendLine($"\t\t\t\t{field}![i] = ({slot.ElementType})value!;");
 		builder.AppendLine("\t\t\t\treturn;");
 		builder.AppendLine("\t\t\t}");
 		if (!last)
 			builder.AppendLine("\t\t\ti -= n;");
 		builder.AppendLine("\t\t}");
 	}
-					else
+
+	static void WriteSetSingleChildStep(StringBuilder builder, SlotInfo slot, bool last)
 	{
+		string field = FieldName(slot.PropertyName);
 		builder.AppendLine("\t\tif (i == 0)");
 		builder.AppendLine("\t\t{");
-						builder.AppendLine($"\t\t\tSetChildNode(ref {field}, ({s.PropertyType}?)value, index);");
+		builder.AppendLine($"\t\t\tSetChildNode(ref {field}, ({slot.PropertyType}?)value, index);");
 		builder.AppendLine("\t\t\treturn;");
 		builder.AppendLine("\t\t}");
 		if (!last)
 			builder.AppendLine("\t\ti--;");
 	}
-				}
-				builder.AppendLine("\t\tthrow new System.ArgumentOutOfRangeException(nameof(index));");
-			}
-			builder.AppendLine("\t}");
-			builder.AppendLine();
 
+	static void WriteSlotInfoFields(StringBuilder builder, List<SlotInfo> slots)
+	{
 		// One typed CSharpSlotInfo<T> static per slot; node.Slot compares against these by object
 		// identity, and the typed child accessors infer the child type from the slot.
 		foreach (var s in slots)
 			builder.AppendLine($"\tpublic static readonly CSharpSlotInfo<{s.ElementType}> {s.PropertyName}Slot = new CSharpSlotInfo<{s.ElementType}>(\"{s.PropertyName}\", {(s.IsCollection ? "true" : "false")}, Slots.{s.KindName}, {(s.IsCollection || s.IsNullable ? "true" : "false")});");
 		builder.AppendLine();
+	}
 
+	static void WriteChildSlotInfo(StringBuilder builder, List<SlotInfo> slots)
+	{
 		builder.AppendLine("\tinternal override CSharpSlotInfo GetChildSlotInfo(int index)");
 		builder.AppendLine("\t{");
-			EmitReturnDispatch(k => $"{slots[k].PropertyName}Slot", k => $"{slots[k].PropertyName}Slot");
+		WriteReturnDispatch(builder, slots, k => $"{slots[k].PropertyName}Slot", k => $"{slots[k].PropertyName}Slot");
 		builder.AppendLine("\t}");
 		builder.AppendLine();
+	}
 
-			if (slots.Any(s => s.IsCollection))
+	static void WriteCollectionLookup(StringBuilder builder, List<SlotInfo> slots)
 	{
+		if (!slots.Any(s => s.IsCollection))
+			return;
+
 		builder.AppendLine("\tinternal override AstNodeCollection? GetCollectionByKind(CSharpSlotInfo kind)");
 		builder.AppendLine("\t{");
 		foreach (var s in slots.Where(s => s.IsCollection))
@@ -660,6 +758,8 @@ internal class DecompilerSyntaxTreeGenerator : IIncrementalGenerator
 		builder.AppendLine();
 	}
 
+	static void WriteCloneChildrenInto(StringBuilder builder, AstNodeAdditions source, List<SlotInfo> slots)
+	{
 		builder.AppendLine("\tinternal override void CloneChildrenInto(AstNode copyNode)");
 		builder.AppendLine("\t{");
 		builder.AppendLine($"\t\tvar copy = ({source.NodeName})copyNode;");
@@ -675,18 +775,14 @@ internal class DecompilerSyntaxTreeGenerator : IIncrementalGenerator
 				builder.AppendLine($"\t\t\t\tcopy.{s.PropertyName}.Add(({s.ElementType})c.Clone());");
 			}
 			else
+			{
 				builder.AppendLine($"\t\tif ({field} != null) copy.{s.PropertyName} = ({s.PropertyType}){field}.Clone();");
 			}
+		}
 		builder.AppendLine("\t}");
 		builder.AppendLine();
 	}
 
-		// Close the class, trimming the blank line the per-member spacer leaves before the brace.
-		string body = builder.ToString().TrimEnd() + "\n}\n";
-
-		context.AddSource(source.NodeName + ".g.cs", SourceText.From(body.Replace("\r\n", "\n"), Encoding.UTF8));
-	}
-
 	void WriteVisitors(SourceProductionContext context, ImmutableArray<AstNodeAdditions> source)
 	{
 		var builder = new StringBuilder();
@@ -791,6 +887,20 @@ namespace ICSharpCode.Decompiler.CSharp.Syntax
 	// back at it, and consumers compare node.Slot.Kind == Slots.X by object identity -- shared across node
 	// types, replacing the old polymorphic node.Role == Roles.X comparisons.
 	void WriteSlotKinds(SourceProductionContext context, ImmutableArray<AstNodeAdditions> source)
+	{
+		var (kindTypes, kindIsCollection) = CollectSlotKinds(source);
+
+		// A slot kind names one child position, so it maps to a single child type (DSTG001 enforces this);
+		// the typed Slots constant therefore always carries that precise type. A kind that is a collection
+		// on one node and a single (or optional) child on another keeps a single type but no single arity,
+		// so its hard-coded IsCollection/isOptional flags are not authoritative -- the precise per-position
+		// flags live on the per-node slots, which is where consumers read them; the shared constant carries
+		// identity (and the now-precise child type), not those flags.
+		ReportSlotKindTypeConflicts(context, kindTypes);
+		WriteSlotKindsSource(context, kindTypes, kindIsCollection);
+	}
+
+	static (SortedDictionary<string, SortedSet<string>> kindTypes, Dictionary<string, bool?> kindIsCollection) CollectSlotKinds(ImmutableArray<AstNodeAdditions> source)
 	{
 		// Per kind: the element types seen (to choose a typed slot's T) and whether it is a collection.
 		// kindIsCollection is null once a kind is seen as a collection on one node and a single child on
@@ -799,34 +909,42 @@ namespace ICSharpCode.Decompiler.CSharp.Syntax
 		var kindTypes = new SortedDictionary<string, SortedSet<string>>(StringComparer.Ordinal);
 		var kindIsCollection = new Dictionary<string, bool?>();
 		foreach (var node in source)
+			CollectNodeSlotKinds(node, kindTypes, kindIsCollection);
+		return (kindTypes, kindIsCollection);
+	}
+
+	static void CollectNodeSlotKinds(AstNodeAdditions node, SortedDictionary<string, SortedSet<string>> kindTypes, Dictionary<string, bool?> kindIsCollection)
 	{
-			if (node.Slots is { } slots)
-			{
+		if (node.Slots is not { } slots)
+			return;
+
 		foreach (var s in slots)
-				{
-					if (!kindTypes.TryGetValue(s.KindName, out var set))
-						kindTypes[s.KindName] = set = new SortedSet<string>(StringComparer.Ordinal);
-					set.Add(s.ElementType);
-					if (!kindIsCollection.TryGetValue(s.KindName, out var arity))
-						kindIsCollection[s.KindName] = s.IsCollection;
-					else if (arity is bool b && b != s.IsCollection)
-						kindIsCollection[s.KindName] = null;
-				}
+			CollectSlotKind(s, kindTypes, kindIsCollection);
 	}
+
+	static void CollectSlotKind(SlotInfo slot, SortedDictionary<string, SortedSet<string>> kindTypes, Dictionary<string, bool?> kindIsCollection)
+	{
+		if (!kindTypes.TryGetValue(slot.KindName, out var set))
+			kindTypes[slot.KindName] = set = new SortedSet<string>(StringComparer.Ordinal);
+		set.Add(slot.ElementType);
+
+		if (!kindIsCollection.TryGetValue(slot.KindName, out var arity))
+			kindIsCollection[slot.KindName] = slot.IsCollection;
+		else if (arity is bool b && b != slot.IsCollection)
+			kindIsCollection[slot.KindName] = null;
 	}
 
-		// A slot kind names one child position, so it maps to a single child type (DSTG001 enforces this);
-		// the typed Slots constant therefore always carries that precise type. A kind that is a collection
-		// on one node and a single (or optional) child on another keeps a single type but no single arity,
-		// so its hard-coded IsCollection/isOptional flags are not authoritative -- the precise per-position
-		// flags live on the per-node slots, which is where consumers read them; the shared constant carries
-		// identity (and the now-precise child type), not those flags.
+	void ReportSlotKindTypeConflicts(SourceProductionContext context, SortedDictionary<string, SortedSet<string>> kindTypes)
+	{
 		foreach (var kv in kindTypes)
 		{
 			if (kv.Value.Count > 1)
 				context.ReportDiagnostic(Diagnostic.Create(MultipleChildTypesForKind, Location.None, kv.Key, string.Join(", ", kv.Value)));
 		}
+	}
 
+	static void WriteSlotKindsSource(SourceProductionContext context, SortedDictionary<string, SortedSet<string>> kindTypes, Dictionary<string, bool?> kindIsCollection)
+	{
 		var builder = new StringBuilder();
 		builder.AppendLine("// <auto-generated/>");
 		builder.AppendLine();