Support TextEdit in completion responses (#4073)

This is the vscode side of OmniSharp/omnisharp-roslyn#1941. This is written in such a fashion as to be mergeable now, as it will fall back to InsertText if TextEdit is not present in the completion response. After some appropriate period of time, we can remove the InsertText component.

Author: 333fred

src/features/completionProvider.ts

@@ -60,20 +60,26 @@ export default class OmnisharpCompletionProvider extends AbstractProvider implem
     }
 
     private _convertToVscodeCompletionItem(omnisharpCompletion: protocol.OmnisharpCompletionItem): CompletionItem {
-        let docs: MarkdownString | undefined = omnisharpCompletion.Documentation ? new MarkdownString(omnisharpCompletion.Documentation, false) : undefined;
+        const docs: MarkdownString | undefined = omnisharpCompletion.Documentation ? new MarkdownString(omnisharpCompletion.Documentation, false) : undefined;
 
-        const mapTextEdit = function (edit: protocol.LinePositionSpanTextChange): TextEdit {
+        const mapRange = function (edit: protocol.LinePositionSpanTextChange): Range {
             const newStart = new Position(edit.StartLine - 1, edit.StartColumn - 1);
             const newEnd = new Position(edit.EndLine - 1, edit.EndColumn - 1);
-            const newRange = new Range(newStart, newEnd);
-            return new TextEdit(newRange, edit.NewText);
+            return new Range(newStart, newEnd);
+        };
+
+        const mapTextEdit = function (edit: protocol.LinePositionSpanTextChange): TextEdit {
+            return new TextEdit(mapRange(edit), edit.NewText);
         };
 
         const additionalTextEdits = omnisharpCompletion.AdditionalTextEdits?.map(mapTextEdit);
 
+        const newText = omnisharpCompletion.TextEdit?.NewText ?? omnisharpCompletion.InsertText;
         const insertText = omnisharpCompletion.InsertTextFormat === InsertTextFormat.Snippet
-            ? new SnippetString(omnisharpCompletion.InsertText)
-            : omnisharpCompletion.InsertText;
+            ? new SnippetString(newText)
+            : newText;
+
+        const insertRange = omnisharpCompletion.TextEdit ? mapRange(omnisharpCompletion.TextEdit) : undefined;
 
         return {
             label: omnisharpCompletion.Label,
@@ -84,6 +90,7 @@ export default class OmnisharpCompletionProvider extends AbstractProvider implem
             preselect: omnisharpCompletion.Preselect,
             filterText: omnisharpCompletion.FilterText,
             insertText: insertText,
+            range: insertRange,
             tags: omnisharpCompletion.Tags,
             sortText: omnisharpCompletion.SortText,
             additionalTextEdits: additionalTextEdits,

src/omnisharp/protocol.ts

@@ -523,6 +523,7 @@ export interface OmnisharpCompletionItem {
     FilterText?: string;
     InsertText?: string;
     InsertTextFormat?: InsertTextFormat;
+    TextEdit?: LinePositionSpanTextChange;
     CommitCharacters?: string[];
     AdditionalTextEdits?: LinePositionSpanTextChange[];
     Data: any;