/// <summary>
/// Returns the position and the kind of the closest specialization preceding the given position,
/// and the name of the callable it belongs to as well as its position as Nullable.
/// Returns null if the given file or position is null, or if no preceding callable can be found (e.g. because the callable name is invalid).
/// If a callable name but no specializations (preceding or otherwise) within that callable can be found,
/// assumes that the correct specialization is an auto-inserted default body,
/// and returns QsBody as well as the start position of the callable declaration along with the callable name and its position.
/// If a callable name as well as existing specializations can be found, but no specialization precedes the given position,
/// returns null for the specialization kind as well as for its position.
/// </summary>
public static ((string, Position), (QsSpecializationKind?, Position?))? TryGetClosestSpecialization(
this FileContentManager file, Position pos)
{
QsSpecializationKind?GetSpecializationKind(CodeFragment fragment)
{
var specDecl = fragment.Kind.DeclaredSpecialization();
if (specDecl.IsNull)
{
return(null);
}
var((kind, gen), typeArgs) = specDecl.Item; // note: if we want to support type specializations we need to compute the signature of the spec to find the right one
return(kind);
}
if (file == null || pos == null || !file.ContainsPosition(pos))
{
return(null);
}
file.SyncRoot.EnterReadLock();
try
{
var declarations = file.CallableDeclarationTokens();
var precedingDecl = declarations.TakeWhile(tIndex => tIndex.GetFragment().Range.Start < pos);
if (!precedingDecl.Any())
{
return(null);
}
var closestCallable = precedingDecl.Last();
var callablePosition = closestCallable.GetFragment().Range.Start;
var callableName = closestCallable.GetFragment().Kind.DeclaredCallableName(null);
if (callableName == null)
{
return(null);
}
var specializations = FileHeader.FilterCallableSpecializations(closestCallable.GetChildren(deep: false).Select(tIndex => tIndex.GetFragment()));
var precedingSpec = specializations.TakeWhile(fragment => fragment.Range.Start < pos);
var lastPreceding = precedingSpec.Any() ? precedingSpec.Last() : null;
if (specializations.Any() && lastPreceding == null)
{
// the given position is within a callable declaration
return((callableName, callablePosition), (null, null));
}
return(lastPreceding == null
? ((callableName, callablePosition), (QsSpecializationKind.QsBody, callablePosition))
: ((callableName, callablePosition), (GetSpecializationKind(lastPreceding), lastPreceding.Range.Start)));
}
finally
{
file.SyncRoot.ExitReadLock();
}
}
