public async Task <SignatureHelpItems?> GetItemsAsync(Document document, int position, SignatureHelpTriggerInfo trigger, CancellationToken cancellationToken)
{
Microsoft.CodeAnalysis.SignatureHelp.SignatureHelpItems?bestItems = null;
// TODO(cyrusn): We're calling into extensions, we need to make ourselves resilient
// to the extension crashing.
foreach (var provider in _providers)
{
cancellationToken.ThrowIfCancellationRequested();
var currentItems = await provider.GetItemsAsync(document, position, trigger.Inner, cancellationToken).ConfigureAwait(false);
if (currentItems != null && currentItems.ApplicableSpan.IntersectsWith(position))
{
// If another provider provides sig help items, then only take them if they
// start after the last batch of items. i.e. we want the set of items that
// conceptually are closer to where the caret position is. This way if you have:
//
// Foo(new Bar($$
//
// Then invoking sig help will only show the items for "new Bar(" and not also
// the items for "Foo(..."
if (IsBetter(bestItems, currentItems.ApplicableSpan))
{
bestItems = currentItems;
}
}
}
if (bestItems != null)
{
var items = new SignatureHelpItems(bestItems);
if (items.SelectedItemIndex == null)
{
var selection = DefaultSignatureHelpSelector.GetSelection(items.Items, null, false, items.ArgumentIndex, items.ArgumentCount, items.ArgumentName, isCaseSensitive: true);
if (selection.SelectedItem != null)
{
items.SelectedItemIndex = items.Items.IndexOf(selection.SelectedItem);
}
}
return(items);
}
return(null);
}
SignatureHelpResult GetSignatureHelpResult(Tuple <ISignatureHelpProvider, SignatureHelpItems> res, Document document)
{
// Code is from the end of ComputeModelInBackgroundAsync()
var items = res.Item2;
if (items == null)
{
return(null);
}
var selectedItem = GetSelectedItem(items, res.Item1);
var syntaxFactsService = document?.Project?.LanguageServices?.GetService <Microsoft.CodeAnalysis.LanguageServices.ISyntaxFactsService>();
var isCaseSensitive = syntaxFactsService == null || syntaxFactsService.IsCaseSensitive;
var selection = DefaultSignatureHelpSelector.GetSelection(items.Items,
selectedItem, items.ArgumentIndex, items.ArgumentCount, items.ArgumentName, isCaseSensitive);
return(new SignatureHelpResult(items, selection.SelectedItem, selection.SelectedParameter));
}
private async Task <Model> ComputeModelInBackgroundAsync(
Model currentModel,
ImmutableArray <ISignatureHelpProvider> providers,
SnapshotPoint caretPosition,
DisconnectedBufferGraph disconnectedBufferGraph,
SignatureHelpTriggerInfo triggerInfo,
CancellationToken cancellationToken)
{
try
{
using (Logger.LogBlock(FunctionId.SignatureHelp_ModelComputation_ComputeModelInBackground, cancellationToken))
{
AssertIsBackground();
cancellationToken.ThrowIfCancellationRequested();
var document = Controller.DocumentProvider.GetDocument(caretPosition.Snapshot, cancellationToken);
if (document == null)
{
return(currentModel);
}
if (triggerInfo.TriggerReason == SignatureHelpTriggerReason.RetriggerCommand)
{
if (currentModel == null)
{
return(null);
}
if (triggerInfo.TriggerCharacter.HasValue &&
!currentModel.Provider.IsRetriggerCharacter(triggerInfo.TriggerCharacter.Value))
{
return(currentModel);
}
}
// first try to query the providers that can trigger on the specified character
var(provider, items) = await ComputeItemsAsync(
providers, caretPosition, triggerInfo,
document, cancellationToken).ConfigureAwait(false);
if (provider == null)
{
// No provider produced items. So we can't produce a model
return(null);
}
if (currentModel != null &&
currentModel.Provider == provider &&
currentModel.GetCurrentSpanInSubjectBuffer(disconnectedBufferGraph.SubjectBufferSnapshot).Span.Start == items.ApplicableSpan.Start &&
currentModel.Items.IndexOf(currentModel.SelectedItem) == items.SelectedItemIndex &&
currentModel.ArgumentIndex == items.ArgumentIndex &&
currentModel.ArgumentCount == items.ArgumentCount &&
currentModel.ArgumentName == items.ArgumentName)
{
// The new model is the same as the current model. Return the currentModel
// so we keep the active selection.
return(currentModel);
}
var selectedItem = GetSelectedItem(currentModel, items, provider, out var userSelected);
var model = new Model(disconnectedBufferGraph, items.ApplicableSpan, provider,
items.Items, selectedItem, items.ArgumentIndex, items.ArgumentCount, items.ArgumentName,
selectedParameter: 0, userSelected);
var syntaxFactsService = document.GetLanguageService <ISyntaxFactsService>();
var isCaseSensitive = syntaxFactsService == null || syntaxFactsService.IsCaseSensitive;
var selection = DefaultSignatureHelpSelector.GetSelection(model.Items,
model.SelectedItem, model.UserSelected, model.ArgumentIndex, model.ArgumentCount, model.ArgumentName, isCaseSensitive);
return(model.WithSelectedItem(selection.SelectedItem, selection.UserSelected)
.WithSelectedParameter(selection.SelectedParameter));
}
}
catch (Exception e) when(FatalError.ReportUnlessCanceled(e))
{
throw ExceptionUtilities.Unreachable;
}
}
