public IEnumerable <StatementSyntax> GenerateGuaranteedUnmarshalStatements(TypePositionInfo info, StubCodeContext context)
{
if (!_shape.HasFlag(MarshallerShape.GuaranteedUnmarshal))
{
yield break;
}
(string managedIdentifier, string nativeIdentifier) = context.GetIdentifiers(info);
string numElementsIdentifier = MarshallerHelpers.GetNumElementsIdentifier(info, context);
yield return(ExpressionStatement(
AssignmentExpression(
SyntaxKind.SimpleAssignmentExpression,
IdentifierName(numElementsIdentifier),
_numElementsExpression)));
// <managedIdentifier> = <marshallerType>.AllocateContainerForManagedElementsFinally(<nativeIdentifier>, <numElements>);
yield return(ExpressionStatement(
AssignmentExpression(
SyntaxKind.SimpleAssignmentExpression,
IdentifierName(managedIdentifier),
InvocationExpression(
MemberAccessExpression(SyntaxKind.SimpleMemberAccessExpression,
_marshallerTypeSyntax,
IdentifierName(ShapeMemberNames.LinearCollection.Stateless.AllocateContainerForManagedElementsFinally)),
ArgumentList(SeparatedList(new ArgumentSyntax[]
{
Argument(IdentifierName(nativeIdentifier)),
Argument(IdentifierName(numElementsIdentifier))
}))))));
}
public IEnumerable <StatementSyntax> GenerateUnmarshalStatements(TypePositionInfo info, StubCodeContext context)
{
if (!_shape.HasFlag(MarshallerShape.ToManaged))
{
yield break;
}
if (!info.IsByRef && info.ByValueContentsMarshalKind.HasFlag(ByValueContentsMarshalKind.Out))
{
yield return(GenerateByValueOutUnmarshalStatement(info, context));
}
else
{
// int <numElements> = <numElementExpression>
string numElementsIdentifier = MarshallerHelpers.GetNumElementsIdentifier(info, context);
yield return(LocalDeclarationStatement(
VariableDeclaration(
PredefinedType(Token(SyntaxKind.IntKeyword)),
SingletonSeparatedList(
VariableDeclarator(numElementsIdentifier)
.WithInitializer(EqualsValueClause(_numElementsExpression))))));
yield return(GenerateUnmarshalStatement(info, context));
}
foreach (StatementSyntax statement in _innerMarshaller.GenerateUnmarshalStatements(info, context))
{
yield return(statement);
}
}
public StatementSyntax GenerateUnmarshalStatement(TypePositionInfo info, StubCodeContext context)
{
string managedSpanIdentifier = MarshallerHelpers.GetManagedSpanIdentifier(info, context);
string nativeSpanIdentifier = MarshallerHelpers.GetNativeSpanIdentifier(info, context);
string numElementsIdentifier = MarshallerHelpers.GetNumElementsIdentifier(info, context);
// ReadOnlySpan<TUnmanagedElement> <nativeSpan> = <GetUnmanagedValuesSource>
// Span<T> <managedSpan> = <GetManagedValuesDestination>
// << unmarshal contents >>
return(Block(
LocalDeclarationStatement(VariableDeclaration(
GenericName(
Identifier(TypeNames.System_ReadOnlySpan),
TypeArgumentList(SingletonSeparatedList(_unmanagedElementType))),
SingletonSeparatedList(
VariableDeclarator(
Identifier(nativeSpanIdentifier))
.WithInitializer(EqualsValueClause(
GetUnmanagedValuesSource(info, context)))))),
LocalDeclarationStatement(VariableDeclaration(
GenericName(
Identifier(TypeNames.System_Span),
TypeArgumentList(SingletonSeparatedList(_elementInfo.ManagedType.Syntax))),
SingletonSeparatedList(
VariableDeclarator(
Identifier(managedSpanIdentifier))
.WithInitializer(EqualsValueClause(
GetManagedValuesDestination(info, context)))))),
GenerateContentsMarshallingStatement(
info,
context,
IdentifierName(numElementsIdentifier),
StubCodeContext.Stage.UnmarshalCapture,
StubCodeContext.Stage.Unmarshal)));
}
public IEnumerable <StatementSyntax> GenerateSetupStatements(TypePositionInfo info, StubCodeContext context)
{
yield return(MarshallerHelpers.Declare(
_marshallerTypeSyntax,
context.GetAdditionalIdentifier(info, MarshallerIdentifier),
ImplicitObjectCreationExpression(ArgumentList(), initializer: null)));
}
public IEnumerable <StatementSyntax> GenerateMarshalStatements(TypePositionInfo info, StubCodeContext context)
{
if (MarshallerHelpers.CanUseCallerAllocatedBuffer(info, context))
{
return(GenerateCallerAllocatedBufferMarshalStatements());
}
return(_innerMarshaller.GenerateMarshalStatements(info, context));
IEnumerable <StatementSyntax> GenerateCallerAllocatedBufferMarshalStatements()
{
// TODO: Update once we can consume the scoped keword. We should be able to simplify this once we get that API.
string stackPtrIdentifier = context.GetAdditionalIdentifier(info, "stackptr");
// <bufferElementType>* <managedIdentifier>__stackptr = stackalloc <bufferElementType>[<_bufferSize>];
yield return(LocalDeclarationStatement(
VariableDeclaration(
PointerType(_bufferElementType),
SingletonSeparatedList(
VariableDeclarator(stackPtrIdentifier)
.WithInitializer(EqualsValueClause(
StackAllocArrayCreationExpression(
ArrayType(
_bufferElementType,
SingletonList(ArrayRankSpecifier(SingletonSeparatedList <ExpressionSyntax>(
MemberAccessExpression(SyntaxKind.SimpleMemberAccessExpression,
_marshallerType,
IdentifierName(ShapeMemberNames.BufferSize))
)))))))))));
(string managedIdentifier, _) = context.GetIdentifiers(info);
// <marshaller>.FromManaged(<managedIdentifier>, new Span<bufferElementType>(<stackPtrIdentifier>, <marshallerType>.BufferSize));
yield return(ExpressionStatement(
InvocationExpression(
MemberAccessExpression(SyntaxKind.SimpleMemberAccessExpression,
IdentifierName(context.GetAdditionalIdentifier(info, StatefulValueMarshalling.MarshallerIdentifier)),
IdentifierName(ShapeMemberNames.Value.Stateful.FromManaged)),
ArgumentList(SeparatedList(
new[]
{
Argument(IdentifierName(managedIdentifier)),
Argument(
ObjectCreationExpression(
GenericName(Identifier(TypeNames.System_Span),
TypeArgumentList(SingletonSeparatedList(
_bufferElementType))))
.WithArgumentList(
ArgumentList(SeparatedList(new ArgumentSyntax[]
{
Argument(IdentifierName(stackPtrIdentifier)),
Argument(MemberAccessExpression(SyntaxKind.SimpleMemberAccessExpression,
_marshallerType,
IdentifierName(ShapeMemberNames.BufferSize)))
}))))
})))));
}
}
public IEnumerable <StatementSyntax> GenerateSetupStatements(TypePositionInfo info, StubCodeContext context)
{
yield return(LocalDeclarationStatement(
VariableDeclaration(
PredefinedType(Token(SyntaxKind.IntKeyword)),
SingletonSeparatedList(
VariableDeclarator(MarshallerHelpers.GetNumElementsIdentifier(info, context))))));
}
static IEnumerable <int> GetInfoDependencies(TypePositionInfo info)
{
// A parameter without a managed index cannot have any dependencies.
if (info.ManagedIndex == TypePositionInfo.UnsetIndex)
{
return(Array.Empty <int>());
}
return(MarshallerHelpers.GetDependentElementsOfMarshallingInfo(info.MarshallingAttributeInfo)
.Select(static info => GetInfoIndex(info)).ToImmutableArray());
public IEnumerable <StatementSyntax> GenerateUnmarshalStatements(TypePositionInfo info, StubCodeContext context)
{
(string managedIdentifier, string nativeIdentifier) = context.GetIdentifiers(info);
string numElementsIdentifier = MarshallerHelpers.GetNumElementsIdentifier(info, context);
if (!info.IsByRef && info.ByValueContentsMarshalKind.HasFlag(ByValueContentsMarshalKind.Out))
{
// <numElements> = <GetManagedValuesSource.Length;
yield return(ExpressionStatement(
AssignmentExpression(
SyntaxKind.SimpleAssignmentExpression,
IdentifierName(numElementsIdentifier),
MemberAccessExpression(
SyntaxKind.SimpleMemberAccessExpression,
GetManagedValuesSource(info, context),
IdentifierName("Length")))));
yield return(GenerateByValueOutUnmarshalStatement(info, context));
}
if (!_shape.HasFlag(MarshallerShape.ToManaged))
{
yield break;
}
else
{
// <numElements> = <numElementsExpression>;
yield return(ExpressionStatement(
AssignmentExpression(
SyntaxKind.SimpleAssignmentExpression,
IdentifierName(numElementsIdentifier),
_numElementsExpression)));
// <managedIdentifier> = <marshallerType>.AllocateContainerForManagedElements(<nativeIdentifier>, <numElements>);
yield return(ExpressionStatement(
AssignmentExpression(
SyntaxKind.SimpleAssignmentExpression,
IdentifierName(managedIdentifier),
InvocationExpression(
MemberAccessExpression(SyntaxKind.SimpleMemberAccessExpression,
_marshallerTypeSyntax,
IdentifierName(ShapeMemberNames.LinearCollection.Stateless.AllocateContainerForManagedElements)),
ArgumentList(SeparatedList(new ArgumentSyntax[]
{
Argument(IdentifierName(nativeIdentifier)),
Argument(IdentifierName(numElementsIdentifier))
}))))));
// ReadOnlySpan<TUnmanagedElement> <nativeSpan> = <marshallerType>.GetUnmanagedValuesSource(<nativeIdentifier>, <numElements>)
// Span<T> <managedSpan> = <marshallerType>.GetManagedValuesDestination(<managedIdentifier>)
// << unmarshal contents >>
yield return(GenerateUnmarshalStatement(info, context));
}
}
protected StatementSyntax GenerateContentsMarshallingStatement(
TypePositionInfo info,
StubCodeContext context,
ExpressionSyntax lengthExpression,
params StubCodeContext.Stage[] stagesToGeneratePerElement)
{
string managedSpanIdentifier = MarshallerHelpers.GetManagedSpanIdentifier(info, context);
string nativeSpanIdentifier = MarshallerHelpers.GetNativeSpanIdentifier(info, context);
var elementSetupSubContext = new LinearCollectionElementMarshallingCodeContext(
StubCodeContext.Stage.Setup,
managedSpanIdentifier,
nativeSpanIdentifier,
context);
TypePositionInfo localElementInfo = _elementInfo with
{
InstanceIdentifier = info.InstanceIdentifier,
RefKind = info.IsByRef ? info.RefKind : info.ByValueContentsMarshalKind.GetRefKindForByValueContentsKind(),
ManagedIndex = info.ManagedIndex,
NativeIndex = info.NativeIndex
};
List <StatementSyntax> elementStatements = new();
foreach (StubCodeContext.Stage stage in stagesToGeneratePerElement)
{
var elementSubContext = elementSetupSubContext with {
CurrentStage = stage
};
elementStatements.AddRange(_elementMarshaller.Generate(localElementInfo, elementSubContext));
}
if (elementStatements.Any())
{
StatementSyntax marshallingStatement = Block(
List(_elementMarshaller.Generate(localElementInfo, elementSetupSubContext)
.Concat(elementStatements)));
if (_elementMarshaller.AsNativeType(_elementInfo) is PointerTypeSyntax elementNativeType)
{
PointerNativeTypeAssignmentRewriter rewriter = new(elementSetupSubContext.GetIdentifiers(localElementInfo).native, elementNativeType);
marshallingStatement = (StatementSyntax)rewriter.Visit(marshallingStatement);
}
// Iterate through the elements of the native collection to marshal them
return(MarshallerHelpers.GetForLoop(lengthExpression, elementSetupSubContext.IndexerIdentifier)
.WithStatement(marshallingStatement));
}
return(EmptyStatement());
}
protected override InvocationExpressionSyntax GetManagedValuesDestination(TypePositionInfo info, StubCodeContext context)
{
string marshaller = StatefulValueMarshalling.GetMarshallerIdentifier(info, context);
string numElementsIdentifier = MarshallerHelpers.GetNumElementsIdentifier(info, context);
// <marshaller>.GetManagedValuesDestination(<numElements>)
return(InvocationExpression(
MemberAccessExpression(
SyntaxKind.SimpleMemberAccessExpression,
IdentifierName(marshaller),
IdentifierName(ShapeMemberNames.LinearCollection.Stateless.GetManagedValuesDestination)),
ArgumentList(SingletonSeparatedList(
Argument(IdentifierName(numElementsIdentifier))))));
}
public IEnumerable <StatementSyntax> GenerateUnmarshalStatements(TypePositionInfo info, StubCodeContext context)
{
string numElementsIdentifier = MarshallerHelpers.GetNumElementsIdentifier(info, context);
if (!info.IsByRef && info.ByValueContentsMarshalKind.HasFlag(ByValueContentsMarshalKind.Out))
{
// int <numElements> = <GetManagedValuesSource>.Length;
yield return(LocalDeclarationStatement(
VariableDeclaration(
PredefinedType(Token(SyntaxKind.IntKeyword)),
SingletonSeparatedList(
VariableDeclarator(numElementsIdentifier)
.WithInitializer(EqualsValueClause(
MemberAccessExpression(
SyntaxKind.SimpleMemberAccessExpression,
GetManagedValuesSource(info, context),
IdentifierName("Length"))))))));
yield return(GenerateByValueOutUnmarshalStatement(info, context));
}
if (!_shape.HasFlag(MarshallerShape.ToManaged))
{
yield break;
}
else
{
// int <numElements> = <numElementsExpression>;
yield return(LocalDeclarationStatement(
VariableDeclaration(
PredefinedType(Token(SyntaxKind.IntKeyword)),
SingletonSeparatedList(
VariableDeclarator(numElementsIdentifier)
.WithInitializer(EqualsValueClause(_numElementsExpression))))));
// ReadOnlySpan<TUnmanagedElement> <nativeSpan> = <marshaller>.GetUnmanagedValuesSource(<nativeIdentifier>, <numElements>)
// Span<T> <managedSpan> = <marshaller>.GetManagedValuesDestination(<managedIdentifier>)
// << unmarshal contents >>
yield return(GenerateUnmarshalStatement(info, context));
}
foreach (StatementSyntax statement in _innerMarshaller.GenerateUnmarshalStatements(info, context))
{
yield return(statement);
}
}
public IEnumerable <StatementSyntax> GenerateSetupStatements(TypePositionInfo info, StubCodeContext context)
{
// <marshaller> = new();
LocalDeclarationStatementSyntax declaration = MarshallerHelpers.Declare(
_marshallerType.Syntax,
context.GetAdditionalIdentifier(info, MarshallerIdentifier),
ImplicitObjectCreationExpression(ArgumentList(), initializer: null));
// For byref-like marshaller types, we'll mark them as scoped.
// Byref-like types can capture references, so by default the compiler has to worry that
// they could enable those references to escape the current stack frame.
// In particular, this can interact poorly with the caller-allocated-buffer marshalling
// support and make the simple `marshaller.FromManaged(managed, stackalloc X[i])` expression
// illegal. Mark the marshaller type as scoped so the compiler knows that it won't escape.
if (_marshallerType is ValueTypeInfo {
IsByRefLike : true
})
protected override InvocationExpressionSyntax GetUnmanagedValuesSource(TypePositionInfo info, StubCodeContext context)
{
string numElementsIdentifier = MarshallerHelpers.GetNumElementsIdentifier(info, context);
string nativeIdentifier = context.GetIdentifiers(info).native;
// <marshallerType>.GetUnmanagedValuesSource(<nativeIdentifier>, <numElements>)
return(InvocationExpression(
MemberAccessExpression(
SyntaxKind.SimpleMemberAccessExpression,
_marshallerTypeSyntax,
IdentifierName(ShapeMemberNames.LinearCollection.Stateless.GetUnmanagedValuesSource)),
ArgumentList(SeparatedList(new ArgumentSyntax[]
{
Argument(IdentifierName(nativeIdentifier)),
Argument(IdentifierName(numElementsIdentifier))
}))));
}
public IEnumerable <StatementSyntax> GenerateMarshalStatements(TypePositionInfo info, StubCodeContext context)
{
if (!_shape.HasFlag(MarshallerShape.ToUnmanaged) && !_shape.HasFlag(MarshallerShape.CallerAllocatedBuffer))
{
yield break;
}
if (_shape.HasFlag(MarshallerShape.ToUnmanaged) &&
!(_shape.HasFlag(MarshallerShape.CallerAllocatedBuffer) &&
MarshallerHelpers.CanUseCallerAllocatedBuffer(info, context)))
{
(string managedIdentifier, string nativeIdentifier) = context.GetIdentifiers(info);
string numElementsIdentifier = MarshallerHelpers.GetNumElementsIdentifier(info, context);
// <nativeIdentifier> = <marshallerType>.AllocateContainerForUnmanagedElements(<managedIdentifier>, out <numElements>);
yield return(ExpressionStatement(
AssignmentExpression(
SyntaxKind.SimpleAssignmentExpression,
IdentifierName(nativeIdentifier),
InvocationExpression(
MemberAccessExpression(SyntaxKind.SimpleMemberAccessExpression,
_marshallerTypeSyntax,
IdentifierName(ShapeMemberNames.LinearCollection.Stateless.AllocateContainerForUnmanagedElements)),
ArgumentList(SeparatedList(new ArgumentSyntax[]
{
Argument(IdentifierName(managedIdentifier)),
Argument(IdentifierName(numElementsIdentifier))
.WithRefOrOutKeyword(Token(SyntaxKind.OutKeyword))
}))))));
}
if (!info.IsByRef && info.ByValueContentsMarshalKind == ByValueContentsMarshalKind.Out)
{
yield return(GenerateByValueOutMarshalStatement(info, context));
}
else
{
yield return(GenerateMarshalStatement(info, context));
}
}
/// <summary>
/// Generate the method body of the p/invoke stub.
/// </summary>
/// <param name="dllImportName">Name of the target DllImport function to invoke</param>
/// <returns>Method body of the p/invoke stub</returns>
/// <remarks>
/// The generated code assumes it will be in an unsafe context.
/// </remarks>
public BlockSyntax GeneratePInvokeBody(string dllImportName)
{
GeneratedStatements statements = GeneratedStatements.Create(_marshallers, _context, IdentifierName(dllImportName));
bool shouldInitializeVariables = !statements.GuaranteedUnmarshal.IsEmpty || !statements.Cleanup.IsEmpty;
VariableDeclarations declarations = VariableDeclarations.GenerateDeclarationsForManagedToNative(_marshallers, _context, shouldInitializeVariables);
var setupStatements = new List <StatementSyntax>();
if (_setLastError)
{
// Declare variable for last error
setupStatements.Add(MarshallerHelpers.Declare(
PredefinedType(Token(SyntaxKind.IntKeyword)),
LastErrorIdentifier,
initializeToDefault: false));
}
if (!statements.GuaranteedUnmarshal.IsEmpty)
{
setupStatements.Add(MarshallerHelpers.Declare(PredefinedType(Token(SyntaxKind.BoolKeyword)), InvokeSucceededIdentifier, initializeToDefault: true));
}
setupStatements.AddRange(declarations.Initializations);
setupStatements.AddRange(declarations.Variables);
setupStatements.AddRange(statements.Setup);
var tryStatements = new List <StatementSyntax>();
tryStatements.AddRange(statements.Marshal);
BlockSyntax fixedBlock = Block(statements.PinnedMarshal);
if (_setLastError)
{
StatementSyntax clearLastError = MarshallerHelpers.CreateClearLastSystemErrorStatement(SuccessErrorCode);
StatementSyntax getLastError = MarshallerHelpers.CreateGetLastSystemErrorStatement(LastErrorIdentifier);
fixedBlock = fixedBlock.AddStatements(clearLastError, statements.InvokeStatement, getLastError);
}
else
{
fixedBlock = fixedBlock.AddStatements(statements.InvokeStatement);
}
tryStatements.Add(statements.Pin.NestFixedStatements(fixedBlock));
// <invokeSucceeded> = true;
if (!statements.GuaranteedUnmarshal.IsEmpty)
{
tryStatements.Add(ExpressionStatement(AssignmentExpression(SyntaxKind.SimpleAssignmentExpression,
IdentifierName(InvokeSucceededIdentifier),
LiteralExpression(SyntaxKind.TrueLiteralExpression))));
}
tryStatements.AddRange(statements.NotifyForSuccessfulInvoke);
tryStatements.AddRange(statements.Unmarshal);
List <StatementSyntax> allStatements = setupStatements;
List <StatementSyntax> finallyStatements = new List <StatementSyntax>();
if (!statements.GuaranteedUnmarshal.IsEmpty)
{
finallyStatements.Add(IfStatement(IdentifierName(InvokeSucceededIdentifier), Block(statements.GuaranteedUnmarshal)));
}
finallyStatements.AddRange(statements.Cleanup);
if (finallyStatements.Count > 0)
{
// Add try-finally block if there are any statements in the finally block
allStatements.Add(
TryStatement(Block(tryStatements), default, FinallyClause(Block(finallyStatements))));
public IEnumerable <StatementSyntax> GenerateMarshalStatements(TypePositionInfo info, StubCodeContext context)
{
if (MarshallerHelpers.CanUseCallerAllocatedBuffer(info, context))
{
return(GenerateCallerAllocatedBufferMarshalStatements());
}
return(_innerMarshaller.GenerateMarshalStatements(info, context));
IEnumerable <StatementSyntax> GenerateCallerAllocatedBufferMarshalStatements()
{
string bufferIdentifier = context.GetAdditionalIdentifier(info, "buffer");
// Span<bufferElementType> <bufferIdentifier> = stackalloc <bufferElementType>[<marshallerType>.BufferSize];
yield return(LocalDeclarationStatement(
VariableDeclaration(
GenericName(
Identifier(TypeNames.System_Span),
TypeArgumentList(
SingletonSeparatedList(_bufferElementType))),
SingletonSeparatedList(
VariableDeclarator(bufferIdentifier)
.WithInitializer(EqualsValueClause(
StackAllocArrayCreationExpression(
ArrayType(
_bufferElementType,
SingletonList(ArrayRankSpecifier(SingletonSeparatedList <ExpressionSyntax>(
MemberAccessExpression(SyntaxKind.SimpleMemberAccessExpression,
_marshallerType,
IdentifierName(ShapeMemberNames.BufferSize))
)))))))))));
(string managedIdentifier, string nativeIdentifier) = context.GetIdentifiers(info);
if (_isLinearCollectionMarshalling)
{
string numElementsIdentifier = MarshallerHelpers.GetNumElementsIdentifier(info, context);
// <nativeIdentifier> = <marshallerType>.AllocateContainerForUnmanagedElements(<managedIdentifier>, <bufferIdentifier>, out <numElements>);
yield return(ExpressionStatement(
AssignmentExpression(
SyntaxKind.SimpleAssignmentExpression,
IdentifierName(nativeIdentifier),
InvocationExpression(
MemberAccessExpression(SyntaxKind.SimpleMemberAccessExpression,
_marshallerType,
IdentifierName(ShapeMemberNames.LinearCollection.Stateless.AllocateContainerForUnmanagedElements)),
ArgumentList(SeparatedList(new ArgumentSyntax[]
{
Argument(IdentifierName(managedIdentifier)),
Argument(IdentifierName(bufferIdentifier)),
Argument(IdentifierName(numElementsIdentifier))
.WithRefOrOutKeyword(Token(SyntaxKind.OutKeyword))
}))))));
// Linear collections have additional marshalling required using the inner marshaller
foreach (StatementSyntax statement in _innerMarshaller.GenerateMarshalStatements(info, context))
{
yield return(statement);
}
}
else
{
// <nativeIdentifier> = <marshallerType>.ConvertToUnmanaged(<managedIdentifier>, <nativeIdentifier>__buffer);
yield return(ExpressionStatement(
AssignmentExpression(
SyntaxKind.SimpleAssignmentExpression,
IdentifierName(nativeIdentifier),
InvocationExpression(
MemberAccessExpression(SyntaxKind.SimpleMemberAccessExpression,
_marshallerType,
IdentifierName(ShapeMemberNames.Value.Stateless.ConvertToUnmanaged)),
ArgumentList(SeparatedList(new ArgumentSyntax[]
{
Argument(IdentifierName(managedIdentifier)),
Argument(IdentifierName(bufferIdentifier))
}))))));
}
}
}
protected StatementSyntax GenerateByValueOutUnmarshalStatement(TypePositionInfo info, StubCodeContext context)
{
// Use ManagedSource and NativeDestination spans for by-value marshalling since we're just marshalling back the contents,
// not the array itself.
// This code is ugly since we're now enforcing readonly safety with ReadOnlySpan for all other scenarios,
// but this is an uncommon case so we don't want to design the API around enabling just it.
string numElementsIdentifier = MarshallerHelpers.GetNumElementsIdentifier(info, context);
string managedSpanIdentifier = MarshallerHelpers.GetManagedSpanIdentifier(info, context);
// Span<TElement> <managedSpan> = MemoryMarshal.CreateSpan(ref Unsafe.AsRef(in <GetManagedValuesSource>.GetPinnableReference(), <numElements>));
LocalDeclarationStatementSyntax managedValuesDeclaration = LocalDeclarationStatement(VariableDeclaration(
GenericName(
Identifier(TypeNames.System_Span),
TypeArgumentList(
SingletonSeparatedList(_elementInfo.ManagedType.Syntax))
),
SingletonSeparatedList(VariableDeclarator(managedSpanIdentifier).WithInitializer(EqualsValueClause(
InvocationExpression(
MemberAccessExpression(
SyntaxKind.SimpleMemberAccessExpression,
ParseName(TypeNames.System_Runtime_InteropServices_MemoryMarshal),
IdentifierName("CreateSpan")))
.WithArgumentList(
ArgumentList(
SeparatedList(
new[]
{
Argument(
InvocationExpression(
MemberAccessExpression(SyntaxKind.SimpleMemberAccessExpression,
ParseName(TypeNames.System_Runtime_CompilerServices_Unsafe),
IdentifierName("AsRef")),
ArgumentList(SingletonSeparatedList(
Argument(
InvocationExpression(
MemberAccessExpression(
SyntaxKind.SimpleMemberAccessExpression,
GetManagedValuesSource(info, context),
IdentifierName("GetPinnableReference")),
ArgumentList()))
.WithRefKindKeyword(
Token(SyntaxKind.InKeyword))))))
.WithRefKindKeyword(
Token(SyntaxKind.RefKeyword)),
Argument(
IdentifierName(numElementsIdentifier))
}))))))));
// Span<TUnmanagedElement> <nativeSpan> = <GetUnmanagedValuesDestination>
string nativeSpanIdentifier = MarshallerHelpers.GetNativeSpanIdentifier(info, context);
LocalDeclarationStatementSyntax unmanagedValuesDeclaration = LocalDeclarationStatement(VariableDeclaration(
GenericName(
Identifier(TypeNames.System_Span),
TypeArgumentList(SingletonSeparatedList(_unmanagedElementType))),
SingletonSeparatedList(
VariableDeclarator(
Identifier(nativeSpanIdentifier))
.WithInitializer(EqualsValueClause(
GetUnmanagedValuesDestination(info, context))))));
return(Block(
managedValuesDeclaration,
unmanagedValuesDeclaration,
GenerateContentsMarshallingStatement(
info,
context,
IdentifierName(numElementsIdentifier),
StubCodeContext.Stage.UnmarshalCapture,
StubCodeContext.Stage.Unmarshal)));
}