Remove blocking-wait from completoin when caret is moved.

src/EditorFeatures/Core/Implementation/IntelliSense/Completion/Controller.Session.cs

@@ -14,7 +14,7 @@ internal partial class Session : Session<Controller, Model, ICompletionPresenter
 
             // When we issue filter tasks, provide them with a (monotonically increasing) id.  That
             // way, when they run we can bail on computation if they've been superseded by another
-            // filter task.  
+            // filter task.
             private int _filterId;
 
             #endregion

src/EditorFeatures/Core/Implementation/IntelliSense/Completion/Controller.Session_FilterModel.cs

@@ -98,20 +98,9 @@ internal partial class Session
                     return null;
                 }
 
-                var filterState = model.FilterState;
-
-                // If all the filters are on, or all the filters are off then we don't actually 
-                // need to filter.
-                if (filterState != null)
-                {
-                    if (filterState.Values.All(b => b) ||
-                        filterState.Values.All(b => !b))
-                    {
-                        filterState = null;
-                    }
-                }
-
                 // We want to dismiss the session if the caret ever moved outside our bounds.
+                // Do this before we check the _filterId.  We don't want this work to not happen
+                // just becaus the user typed more text and added more filter items.
                 if (recheckCaretPosition && Controller.IsCaretOutsideAllItemBounds(model, caretPosition))
                 {
                     return null;
@@ -155,6 +144,7 @@ internal partial class Session
                     }
                 }
 
+                var filterItemState = ComputeFilterItemState(model);
                 foreach (var currentItem in model.TotalItems)
                 {
                     // Check if something new has happened and there's a later on filter operation
@@ -165,7 +155,7 @@ internal partial class Session
                         return model;
                     }
 
-                    if (ItemIsFilteredOut(currentItem, filterState))
+                    if (ItemIsFilteredOut(currentItem, filterItemState))
                     {
                         continue;
                     }
@@ -207,10 +197,28 @@ internal partial class Session
                 }
 
                 return HandleNormalFiltering(
-                    model, document, filterReason, textSnapshot,
+                    model, document, filterReason, caretPosition,
                     helper, recentItems, filterText, filterResults);
             }
 
+            private static ImmutableDictionary<CompletionItemFilter, bool> ComputeFilterItemState(Model model)
+            {
+                var filterState = model.FilterState;
+
+                // If all the filters are on, or all the filters are off then we don't actually 
+                // need to filter.
+                if (filterState != null)
+                {
+                    if (filterState.Values.All(b => b) ||
+                        filterState.Values.All(b => !b))
+                    {
+                        filterState = null;
+                    }
+                }
+
+                return filterState;
+            }
+
             private Boolean IsAfterDot(Model model, ITextSnapshot textSnapshot, Dictionary<TextSpan, string> textSpanToText)
             {
                 var span = model.OriginalList.Span;
@@ -226,7 +234,7 @@ private Boolean IsAfterDot(Model model, ITextSnapshot textSnapshot, Dictionary<T
                 Model model,
                 Document document,
                 CompletionFilterReason filterReason,
-                ITextSnapshot textSnapshot,
+                SnapshotPoint caretPosition,
                 CompletionHelper helper,
                 ImmutableArray<string> recentItems,
                 string filterText,
@@ -255,7 +263,7 @@ private Boolean IsAfterDot(Model model, ITextSnapshot textSnapshot, Dictionary<T
                 var bestOrFirstCompletionItem = bestCompletionItem ?? filterResults.First().CompletionItem;
 
                 var hardSelection = IsHardSelection(
-                    model, bestOrFirstCompletionItem, textSnapshot, helper, filterReason);
+                    model, bestOrFirstCompletionItem, caretPosition, helper, filterReason);
 
                 // Determine if we should consider this item 'unique' or not.  A unique item
                 // will be automatically committed if the user hits the 'invoke completion' 
@@ -528,7 +536,7 @@ private static bool IsAllDigits(string filterText)
             private bool IsHardSelection(
                 Model model,
                 CompletionItem bestFilterMatch,
-                ITextSnapshot textSnapshot,
+                SnapshotPoint caretPosition,
                 CompletionHelper completionHelper,
                 CompletionFilterReason reason)
             {
@@ -537,6 +545,8 @@ private static bool IsAllDigits(string filterText)
                     return false;
                 }
 
+                var textSnapshot = caretPosition.Snapshot;
+
                 // We don't have a builder and we have a best match.  Normally this will be hard
                 // selected, except for a few cases.  Specifically, if no filter text has been
                 // provided, and this is not a preselect match then we will soft select it.  This
@@ -548,8 +558,8 @@ private static bool IsAllDigits(string filterText)
                 //
                 // Completion will comes up after = with 'integer' selected (Because of MRU).  We do
                 // not want 'space' to commit this.
-                var viewSpan = model.GetViewBufferSpan(bestFilterMatch.Span);
-                var fullFilterText = model.GetCurrentTextInSnapshot(viewSpan, textSnapshot, endPoint: null);
+                var itemViewSpan = model.GetViewBufferSpan(bestFilterMatch.Span);
+                var fullFilterText = model.GetCurrentTextInSnapshot(itemViewSpan, textSnapshot, endPoint: null);
 
                 var trigger = model.Trigger;
                 var shouldSoftSelect = ShouldSoftSelectItem(bestFilterMatch, fullFilterText, trigger);
@@ -565,6 +575,18 @@ private static bool IsAllDigits(string filterText)
                     return false;
                 }
 
+                // Switch to soft selection, if user moved caret to the start of a non-empty filter span.
+                // This prevents commiting if user types a commit character at this position later, but still has the list if user types filter character
+                // i.e. blah| -> |blah -> !|blah
+                // We want the filter span non-empty because we still want completion in the following case:
+                //
+                //  A a = new |
+                if (caretPosition == itemViewSpan.TextSpan.Start && itemViewSpan.TextSpan.Length > 0)
+                {
+                    return false;
+                }
+
+
                 // There was either filter text, or this was a preselect match.  In either case, we
                 // can hard select this.
                 return true;

src/EditorFeatures/Core/Implementation/IntelliSense/Completion/Controller_CaretPositionChanged.cs

@@ -25,36 +25,23 @@ internal override void OnCaretPositionChanged(object sender, EventArgs args)
             // caret isn't within the bounds of the items, then we dismiss completion.
             var caretPoint = this.GetCaretPointInViewBuffer();
             var model = sessionOpt.Computation.InitialUnfilteredModel;
-            if (model == null ||
-                this.IsCaretOutsideAllItemBounds(model, caretPoint))
-            {
-                // Completions hadn't even been computed yet or the caret is out of bounds.
-                // Just cancel everything we're doing.
-                this.StopModelComputation();
-                return;
-            }
-
-            // TODO(cyrusn): Find a way to allow the user to cancel out of this.
-            model = sessionOpt.WaitForModel();
             if (model == null)
             {
+                // Completions hadn't even been computed yet. Just cancel everything we're doing
+                // and move to the Inactive state.
+                this.StopModelComputation();
                 return;
             }
 
-            if (model.SelectedItem != null && model.IsHardSelection)
-            {
-                // Switch to soft selection, if user moved caret to the start of a non-empty filter span.
-                // This prevents commiting if user types a commit character at this position later, but still has the list if user types filter character
-                // i.e. blah| -> |blah -> !|blah
-                // We want the filter span non-empty because we still want completion in the following case:
-                // A a = new | -> A a = new (|
-
-                var currentSpan = model.GetViewBufferSpan(model.SelectedItem.Span).TextSpan;
-                if (caretPoint == currentSpan.Start && currentSpan.Length > 0)
-                {
-                    sessionOpt.SetModelIsHardSelection(false);
-                }
-            }
+            // We're currently computing items. We'll need to make sure that the caret point
+            // hasn't moved outside all of the items.  If so, we'd want to dismiss completions.
+            // Just refilter the list, asking it to make sure that the caret is still within
+            // bounds.
+            sessionOpt.FilterModel(
+                CompletionFilterReason.CaretPositionChanged,
+                dismissIfEmptyAllowed: false,
+                recheckCaretPosition: true,
+                filterState: null);
         }
 
         internal bool IsCaretOutsideAllItemBounds(Model model, SnapshotPoint caretPoint)

src/EditorFeatures/Core/Implementation/IntelliSense/Completion/Controller_CommitUniqueCompletionListItem.cs

@@ -48,7 +48,6 @@ CommandState ICommandHandler<CommitUniqueCompletionListItemCommandArgs>.GetComma
             // with how that convoluted code worked.  So I'm not maintaining that behavior here.  If
             // we do want it through, it would be easy to get again simply by asking the model
             // computation to remove all filtering.
-
             if (model.IsUnique)
             {
                 // We had a unique item in the list.  Commit it and dismiss this session.

src/EditorFeatures/Test2/IntelliSense/CSharpCompletionCommandHandlerTests.vb

@@ -2570,5 +2570,34 @@ class C
                 Await state.AssertSelectedCompletionItem("ConfigureAwait")
             End Using
         End Function
+
+        <WpfFact, Trait(Traits.Feature, Traits.Features.Completion)>
+        Public Async Function MovingCaretToStartSoftSelects() As Task
+            Using state = TestState.CreateCSharpTestState(
+                              <Document>
+using System;
+
+class C
+{
+    void M()
+    {
+        $$
+    }
+}
+                              </Document>)
+
+                state.SendTypeChars("Conso")
+                Await state.WaitForAsynchronousOperationsAsync()
+                Await state.AssertSelectedCompletionItem(displayText:="Console", isHardSelected:=True)
+                For Each ch In "Conso"
+                    state.SendLeftKey()
+                Next
+
+                Await state.AssertSelectedCompletionItem(displayText:="Console", isHardSelected:=False)
+
+                state.SendRightKey()
+                Await state.AssertSelectedCompletionItem(displayText:="Console", isHardSelected:=True)
+            End Using
+        End Function
     End Class
 End Namespace
\ No newline at end of file

src/Features/Core/Portable/Completion/CompletionFilterReason.cs

 // Copyright (c) Microsoft.  All Rights Reserved.  Licensed under the Apache License, Version 2.0.  See License.txt in the project root for license information.
 
-
 namespace Microsoft.CodeAnalysis.Completion
 {
     internal enum CompletionFilterReason
@@ -8,6 +7,7 @@ internal enum CompletionFilterReason
         Other,
         TypeChar,
         BackspaceOrDelete,
-        ItemFiltersChanged
+        ItemFiltersChanged,
+        CaretPositionChanged,
     }
-}
+}
\ No newline at end of file