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Merged
imurashka merged 1 commit into from
Sep 6, 2025
Merged

Flexible struct layout #22

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5 changes: 4 additions & 1 deletion Appegy.Union.Generator~/Appegy.Union.Generator.Shapes/Shapes/Shape.cs
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Original file line number Diff line number Diff line change
@@ -1,4 +1,6 @@
namespace Appegy.Union.Generator.Shapes;
using System.Runtime.InteropServices;

namespace Appegy.Union.Generator.Shapes;

public interface IShape
{
Expand All @@ -7,4 +9,5 @@ public interface IShape

[Union(typeof(Circle), typeof(Rectangle), typeof(Hexagon))]
[Expose(typeof(IShape))]
[StructLayout(LayoutKind.Explicit, Pack = 1)]
public partial struct Shape;
3 changes: 2 additions & 1 deletion Appegy.Union.Generator~/Appegy.Union.Generator/Union/Parts/UnionComparisonPart.cs
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Expand Up @@ -6,7 +6,8 @@ public class UnionComparisonPart : GeneratorPart<UnionAttributePartInput>
{
public override void Generate(IndentedTextWriter codeWriter, UnionAttributePartInput input)
{
var (syntax, types) = input;
var syntax = input.Syntax;
var types = input.Types;

codeWriter.Write("public static bool operator ==(");
codeWriter.Write(syntax.Identifier.Text);
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3 changes: 2 additions & 1 deletion Appegy.Union.Generator~/Appegy.Union.Generator/Union/Parts/UnionConstructorsPart.cs
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Expand Up @@ -7,7 +7,8 @@ public class UnionConstructorsPart : GeneratorPart<UnionAttributePartInput>
{
public override void Generate(IndentedTextWriter codeWriter, UnionAttributePartInput input)
{
var (syntax, types) = input;
var syntax = input.Syntax;
var types = input.Types;

for (var i = 0; i < types.Count; i++)
{
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4 changes: 2 additions & 2 deletions Appegy.Union.Generator~/Appegy.Union.Generator/Union/Parts/UnionDeclarationPart.cs
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Expand Up @@ -6,10 +6,10 @@ public class UnionDeclarationPart : GeneratorPart<UnionAttributePartInput>
{
public override void Generate(IndentedTextWriter codeWriter, UnionAttributePartInput input)
{
var (syntax, types) = input;
var syntax = input.Syntax;
var types = input.Types;

codeWriter.WriteLine(AttributesNames.GeneratedCodeAttribute);
codeWriter.WriteLine("[global::System.Runtime.InteropServices.StructLayout(global::System.Runtime.InteropServices.LayoutKind.Explicit, Pack = 1)]");
codeWriter.Write("partial struct ");
codeWriter.WriteLine(syntax.Identifier.Text);

Expand Down
3 changes: 2 additions & 1 deletion Appegy.Union.Generator~/Appegy.Union.Generator/Union/Parts/UnionEqualsPart.cs
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Expand Up @@ -6,7 +6,8 @@ public class UnionEqualsPart : GeneratorPart<UnionAttributePartInput>
{
public override void Generate(IndentedTextWriter codeWriter, UnionAttributePartInput input)
{
var (syntax, types) = input;
var syntax = input.Syntax;
var types = input.Types;

codeWriter.WriteLine("public override bool Equals(object boxed) => boxed switch");
codeWriter.WriteLine('{');
Expand Down
13 changes: 10 additions & 3 deletions Appegy.Union.Generator~/Appegy.Union.Generator/Union/Parts/UnionFieldsPart.cs
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Expand Up @@ -6,14 +6,21 @@ public class UnionFieldsPart : GeneratorPart<UnionAttributePartInput>
{
public override void Generate(IndentedTextWriter codeWriter, UnionAttributePartInput input)
{
var (_, types) = input;
var types = input.Types;
var explicitLayout = input.ExplicitLayout;

codeWriter.WriteLine("[global::System.Runtime.InteropServices.FieldOffset(0)]");
if (explicitLayout)
{
codeWriter.WriteLine("[global::System.Runtime.InteropServices.FieldOffset(0)]");
}
codeWriter.WriteLine("private Kind _type;");

foreach (var type in types)
{
codeWriter.WriteLine("[global::System.Runtime.InteropServices.FieldOffset(1)]");
if (explicitLayout)
{
codeWriter.WriteLine("[global::System.Runtime.InteropServices.FieldOffset(1)]");
}
codeWriter.Write("private ");
codeWriter.Write(type.FullName);
codeWriter.Write(' ');
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2 changes: 1 addition & 1 deletion Appegy.Union.Generator~/Appegy.Union.Generator/Union/Parts/UnionGetHashCodePart.cs
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Expand Up @@ -6,7 +6,7 @@ public class UnionGetHashCodePart : GeneratorPart<UnionAttributePartInput>
{
public override void Generate(IndentedTextWriter codeWriter, UnionAttributePartInput input)
{
var (_, types) = input;
var types = input.Types;

codeWriter.WriteLine("public override int GetHashCode() => _type switch");
codeWriter.WriteLine('{');
Expand Down
3 changes: 2 additions & 1 deletion Appegy.Union.Generator~/Appegy.Union.Generator/Union/Parts/UnionOperatorsPart.cs
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Expand Up @@ -6,7 +6,8 @@ public class UnionOperatorsPart : GeneratorPart<UnionAttributePartInput>
{
public override void Generate(IndentedTextWriter codeWriter, UnionAttributePartInput input)
{
var (syntax, types) = input;
var syntax = input.Syntax;
var types = input.Types;

for (var i = 0; i < types.Count; i++)
{
Expand Down
3 changes: 1 addition & 2 deletions Appegy.Union.Generator~/Appegy.Union.Generator/Union/Parts/UnionPropertiesPart.cs
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@@ -1,13 +1,12 @@
using System.CodeDom.Compiler;
using SymbolDisplayFormat = Microsoft.CodeAnalysis.SymbolDisplayFormat;

namespace Appegy.Union.Generator;

public class UnionPropertiesPart : GeneratorPart<UnionAttributePartInput>
{
public override void Generate(IndentedTextWriter codeWriter, UnionAttributePartInput input)
{
var (_, types) = input;
var types = input.Types;

codeWriter.WriteLine("public Kind Type => _type;");
codeWriter.WriteLine();
Expand Down
2 changes: 1 addition & 1 deletion Appegy.Union.Generator~/Appegy.Union.Generator/Union/Parts/UnionToStringPart.cs
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Expand Up @@ -6,7 +6,7 @@ public class UnionToStringPart : GeneratorPart<UnionAttributePartInput>
{
public override void Generate(IndentedTextWriter codeWriter, UnionAttributePartInput input)
{
var (_, types) = input;
var types = input.Types;

codeWriter.WriteLine("public override string ToString() => _type switch");
codeWriter.WriteLine('{');
Expand Down
2 changes: 1 addition & 1 deletion Appegy.Union.Generator~/Appegy.Union.Generator/Union/Parts/UnionTypeEnumPart.cs
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Expand Up @@ -6,7 +6,7 @@ public class UnionTypeEnumPart : GeneratorPart<UnionAttributePartInput>
{
public override void Generate(IndentedTextWriter codeWriter, UnionAttributePartInput input)
{
var (_, types) = input;
var types = input.Types;

codeWriter.WriteLine("[global::System.Serializable]");
codeWriter.WriteLine("public enum Kind : global::System.Byte");
Expand Down
36 changes: 33 additions & 3 deletions Appegy.Union.Generator~/Appegy.Union.Generator/Union/UnionAttributeGenerator.cs
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Expand Up @@ -44,17 +44,21 @@ public void Initialize(IncrementalGeneratorInitializationContext context)
transform: static (ctx, _) =>
{
var syntax = (StructDeclarationSyntax)ctx.TargetNode;
var symbol = ctx.SemanticModel.GetDeclaredSymbol(syntax);
var attribute = ctx.Attributes.First();
var types = attribute
.GetTypesFromConstructor(TypeKind.Struct)
.Select(c => new UnionTypeInfo(c))
.ToImmutableList();
return (syntax, types);

var explicitLayout = HasExplicitStructLayoutAttribute(symbol);

return (syntax, types, explicitLayout);
});

context.RegisterSourceOutput(sources, static (ctx, input) =>
{
var (syntax, types) = input;
var (syntax, types, explicitLayout) = input;

if (!syntax.Modifiers.Any(SyntaxKind.PartialKeyword)) return;
if (types.Count == 0) return;
Expand All @@ -63,10 +67,36 @@ public void Initialize(IncrementalGeneratorInitializationContext context)
using var streamWriter = new StreamWriter(memoryStream, Encoding.UTF8);
using var codeWriter = new IndentedTextWriter(streamWriter, " ");

codeWriter.AppendParts(Parts, new UnionAttributePartInput(syntax, types));
codeWriter.AppendParts(Parts, new UnionAttributePartInput(syntax, types, explicitLayout));

streamWriter.Flush();
ctx.AddSource($"{syntax.Identifier.Text}_Union.g.cs", SourceText.From(memoryStream, Encoding.UTF8, canBeEmbedded: true));
});
}

private static bool HasExplicitStructLayoutAttribute(INamedTypeSymbol? symbol)
{
if (symbol == null) return false;

return symbol.GetAttributes().Any(attr =>
{
if (attr.AttributeClass?.Name != "StructLayoutAttribute" ||
attr.AttributeClass.ContainingNamespace?.ToDisplayString() != "System.Runtime.InteropServices")
{
return false;
}

if (attr.ConstructorArguments.Length > 0)
{
var layoutKindArg = attr.ConstructorArguments[0];

if (layoutKindArg.Type?.Name == "LayoutKind" && layoutKindArg.Type.ContainingNamespace?.ToDisplayString() == "System.Runtime.InteropServices")
{
return layoutKindArg.Value is 2;
}
}

return false;
});
}
}
2 changes: 1 addition & 1 deletion Appegy.Union.Generator~/Appegy.Union.Generator/Union/UnionAttributePartInput.cs
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Expand Up @@ -4,7 +4,7 @@

namespace Appegy.Union.Generator;

public record struct UnionAttributePartInput(StructDeclarationSyntax Syntax, IReadOnlyList<UnionTypeInfo> Types);
public record struct UnionAttributePartInput(StructDeclarationSyntax Syntax, IReadOnlyList<UnionTypeInfo> Types, bool ExplicitLayout);

public readonly struct UnionTypeInfo(INamedTypeSymbol symbol)
{
Expand Down
4 changes: 2 additions & 2 deletions Runtime/Appegy.Union.Generator.dll
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Binary file modified Runtime/Appegy.Union.Generator.pdb
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