Emulate suggestion mode in LSP completion by always soft-select

dibarbet · Aug 2, 2023 · 12cc813 · 12cc813
1 parent 5024f3e
commit 12cc813
Show file tree

Hide file tree

Showing 2 changed files with 55 additions and 12 deletions.
diff --git a/.../LanguageServer/Protocol/Handler/Completion/AbstractLspCompletionResultCreationService.cs b/.../LanguageServer/Protocol/Handler/Completion/AbstractLspCompletionResultCreationService.cs
@@ -36,14 +36,15 @@ internal abstract class AbstractLspCompletionResultCreationService : ILspComplet
             CompletionList list, bool isIncomplete, long resultId,
             CancellationToken cancellationToken)
         {
+            var isSuggestionMode = list.SuggestionModeItem is not null;
             if (list.ItemsList.Count == 0)
             {
                 return new LSP.VSInternalCompletionList
                 {
                     Items = Array.Empty<LSP.CompletionItem>(),
                     // If we have a suggestion mode item, we just need to keep the list in suggestion mode.
                     // We don't need to return the fake suggestion mode item.
-                    SuggestionMode = list.SuggestionModeItem is not null,
+                    SuggestionMode = isSuggestionMode,
                     IsIncomplete = isIncomplete,
                 };
             }
@@ -132,18 +133,24 @@ internal abstract class AbstractLspCompletionResultCreationService : ILspComplet
                 lspItem.Kind = GetCompletionKind(item.Tags, capabilityHelper.SupportedItemKinds);
                 lspItem.Preselect = item.Rules.MatchPriority == MatchPriority.Preselect;
 
-                if (!lspItem.Preselect &&
-                    !lspVSClientCapability &&
-                    typedText.Length == 0 &&
-                    item.Rules.SelectionBehavior != CompletionItemSelectionBehavior.HardSelection)
+                if (lspVSClientCapability)
                 {
-                    // VSCode does not have the concept of soft selection, the list is always hard selected.
-                    // In order to emulate soft selection behavior for things like argument completion, regex completion,
-                    // datetime completion, etc. we create a completion item without any specific commit characters.
-                    // This means only tab / enter will commit. VS supports soft selection, so we only do this for non-VS clients.
-                    //
-                    // Note this only applies when user hasn't actually typed anything and completion provider does not request the item
-                    // to be hard-selected. Otherwise, we set its commit characters as normal. This also means we'd need to set IsIncomplete to true
+                    lspItem.CommitCharacters = GetCommitCharacters(item, commitCharactersRuleCache);
+                    return lspItem;
+                }
+
+                // VSCode does not have the concept of soft selection, the list is always hard selected.
+                // In order to emulate soft selection behavior for things like suggestion mode, argument completion, regex completion,
+                // datetime completion, etc. we create a completion item without any specific commit characters.
+                // This means only tab / enter will commit. VS supports soft selection, so we only do this for non-VS clients.
+                if (isSuggestionMode)
+                {
+                    lspItem.CommitCharacters = Array.Empty<string>();
+                }
+                else if (!lspItem.Preselect && typedText.Length == 0 && item.Rules.SelectionBehavior != CompletionItemSelectionBehavior.HardSelection)
+                {
+                    // Note this also applies when user hasn't actually typed anything and completion provider does not request the item
+                    // to be hard-selected. Otherwise, we set its commit characters as normal. This means we'd need to set IsIncomplete to true
                     // to make sure the client will ask us again when user starts typing so we can provide items with proper commit characters.
                     lspItem.CommitCharacters = Array.Empty<string>();
                     isIncomplete = true;

diff --git a/src/Features/LanguageServer/ProtocolUnitTests/Completion/CompletionFeaturesTests.cs b/src/Features/LanguageServer/ProtocolUnitTests/Completion/CompletionFeaturesTests.cs
@@ -20,6 +20,7 @@
 using Microsoft.CodeAnalysis.Text;
 using Microsoft.VisualStudio.LanguageServer.Protocol;
 using Roslyn.Test.Utilities;
+using Roslyn.Utilities;
 using Xunit;
 using Xunit.Abstractions;
 using LSP = Microsoft.VisualStudio.LanguageServer.Protocol;
@@ -555,4 +556,39 @@ void M()
         var expectedAdditionalEdit2 = new TextEdit() { NewText = "using Namespace2;\r\n\r\n", Range = new() { Start = new(1, 0), End = new(1, 0) } };
         AssertJsonEquals(new[] { expectedAdditionalEdit2 }, resolvedItem2.AdditionalTextEdits);
     }
+
+    [Theory, CombinatorialData, WorkItem("https://github.com/dotnet/vscode-csharp/issues/5732")]
+    public async Task TestEmptyCommitCharsInSuggestionMode(bool mutatingLspWorkspace)
+    {
+        var markup =
+@"
+using System.Collections.Generic;
+using System.Linq;
+public class C
+{
+    public Foo(List<int> myList)
+    {
+        var foo = myList.Where(i{|caret:|})
+    }
+}";
+        await using var testLspServer = await CreateTestLspServerAsync(markup, mutatingLspWorkspace, DefaultClientCapabilities);
+        var caret = testLspServer.GetLocations("caret").Single();
+        var completionParams = new LSP.CompletionParams()
+        {
+            TextDocument = CreateTextDocumentIdentifier(caret.Uri),
+            Position = caret.Range.Start,
+            Context = new LSP.CompletionContext()
+            {
+                TriggerKind = LSP.CompletionTriggerKind.Invoked,
+            }
+        };
+
+        var document = testLspServer.GetCurrentSolution().Projects.First().Documents.First();
+
+        var results = await testLspServer.ExecuteRequestAsync<LSP.CompletionParams, LSP.CompletionList>(LSP.Methods.TextDocumentCompletionName, completionParams, CancellationToken.None);
+        AssertEx.NotNull(results);
+        Assert.NotEmpty(results.Items);
+        Assert.Empty(results.ItemDefaults.CommitCharacters);
+        Assert.True(results.Items.All(item => item.CommitCharacters is null));
+    }
 }