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)));
}
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 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)));
}
