public static ImmutableDictionary <CaptureId, FlowCaptureKind> CreateLValueFlowCaptures(ControlFlowGraph cfg)
{
// This method identifies flow capture reference operations that are target of an assignment
// and marks them as lvalue flow captures.
// Note that currently the control flow graph does not contain flow captures
// that are r-value captures at some point and l-values captures at other point in
// the flow graph. The debug only asserts in this method ensure this invariant.
// If these asserts fire, we should adjust this algorithm.
ImmutableDictionary <CaptureId, FlowCaptureKind> .Builder lvalueFlowCaptureIdBuilder = null;
#if DEBUG
var rvalueFlowCaptureIds = new HashSet <CaptureId>();
#endif
foreach (var flowCaptureReference in cfg.DescendantOperations <IFlowCaptureReferenceOperation>(OperationKind.FlowCaptureReference))
{
if (flowCaptureReference.Parent is IAssignmentOperation assignment &&
assignment.Target == flowCaptureReference ||
flowCaptureReference.IsInLeftOfDeconstructionAssignment(out _))
{
lvalueFlowCaptureIdBuilder = lvalueFlowCaptureIdBuilder ?? ImmutableDictionary.CreateBuilder <CaptureId, FlowCaptureKind>();
var captureKind = flowCaptureReference.Parent is ICompoundAssignmentOperation ? FlowCaptureKind.LValueAndRValueCapture : FlowCaptureKind.LValueCapture;
lvalueFlowCaptureIdBuilder.Add(flowCaptureReference.Id, captureKind);
}
public static IEnumerable <T> DescendantOperations <T>(this ControlFlowGraph cfg, OperationKind operationKind)
where T : IOperation
=> cfg.DescendantOperations().Where(d => d?.Kind == operationKind).Cast <T>();