Fix peeked editor closing without reopening when triggered again at the same position in the same file (#1019)

Author: lokesh-tr

src/sourcekit-lsp/peekDocuments.ts

@@ -16,27 +16,88 @@ import * as vscode from "vscode";
 import * as langclient from "vscode-languageclient/node";
 import { PeekDocumentsParams, PeekDocumentsRequest } from "./lspExtensions";
 
+/**
+ * Opens a peeked editor in `uri` at `position` having contents from `locations`.
+ *
+ * **NOTE**:
+ * - If the `uri` is not open in the editor, this opens the `uri` in the editor and then opens a peeked editor.
+ * - This closes any previously displayed peeked editor in `uri` and then, reopens a peeked editor in `uri` at
+ *   the given `position` with contents from the new `locations`.
+ *
+ * @param uri The uri of the file in which a peeked editor is to be opened
+ * @param position The position in the file in which a peeked editor is to be opened
+ * @param locations The locations of the contents which has to be displayed by the peeked editor
+ */
+async function openPeekedEditorIn(
+    uri: vscode.Uri,
+    position: vscode.Position,
+    locations: vscode.Location[]
+) {
+    // #### NOTE - Undocumented behaviour of invoking VS Code's built-in "editor.action.peekLocations" command:
+    // 1. If the `uri` is not open in the editor, it opens the `uri` in the editor and then opens a peeked editor.
+    // 2. It always closes the previous peeked editor (If any)
+    // 3. And after closing, It opens a new peeked editor having the contents of `locations` in `uri` **if and only
+    //    if** the previous peeked editor was displayed at a *different* `position` in `uri`.
+    // 4. If it happens to be that the previous peeked editor was displayed at the *same* `position` in `uri`, then it
+    //    doesn't open the peeked editor window having the contents of new `locations` at all.
+
+    // As (4.) says above, if we invoke "editor.action.peekLocations" on a position in which another peeked editor
+    // window is already being shown, it won't cause the new peeked editor window to show up at all. This is not the
+    // ideal behaviour.
+    //
+    // For example:
+    // If there's already a peeked editor window at the position (2, 2) in "main.swift", its impossible to close this
+    // peeked editor window and open a new peeked editor window at the same position (2, 2) in "main.swift" by invoking
+    // the "editor.action.peekLocations" command in a single call.
+    //
+    // *The ideal behaviour* is to close any previously opened peeked editor window and then open the new one without
+    // any regard to its `position` in the `uri`.
+
+    // In order to achieve *the ideal behaviour*, we manually close the peeked editor window by ourselves before
+    // opening a new peeked editor window.
+    //
+    // Since there isn't any API available to close the previous peeked editor, as a **workaround**, we open a dummy
+    // peeked editor at a different position, causing the previous one to close irrespective of where it is. After
+    // which we can invoke the command again to show the actual peeked window having the contents of the `locations`.
+    await vscode.commands.executeCommand(
+        "editor.action.peekLocations",
+        uri,
+        new vscode.Position(position.line, position.character !== 0 ? position.character - 1 : 1),
+        [new vscode.Location(vscode.Uri.parse(""), new vscode.Position(0, 0))],
+        "peek"
+    );
+
+    // Opens the actual peeked editor window
+    await vscode.commands.executeCommand(
+        "editor.action.peekLocations",
+        uri,
+        position,
+        locations,
+        "peek"
+    );
+}
+
 export function activatePeekDocuments(client: langclient.LanguageClient): vscode.Disposable {
     const peekDocuments = client.onRequest(
         PeekDocumentsRequest.method,
         async (params: PeekDocumentsParams) => {
-            const locations = params.locations.map(uri => {
-                const location = new vscode.Location(
-                    client.protocol2CodeConverter.asUri(uri),
-                    new vscode.Position(0, 0)
-                );
-
-                return location;
-            });
-
-            await vscode.commands.executeCommand(
-                "editor.action.peekLocations",
-                client.protocol2CodeConverter.asUri(params.uri),
-                new vscode.Position(params.position.line, params.position.character),
-                locations,
-                "peek"
+            const peekURI = client.protocol2CodeConverter.asUri(params.uri);
+
+            const peekPosition = new vscode.Position(
+                params.position.line,
+                params.position.character
             );
 
+            const peekLocations = params.locations.map(
+                location =>
+                    new vscode.Location(
+                        client.protocol2CodeConverter.asUri(location),
+                        new vscode.Position(0, 0)
+                    )
+            );
+
+            openPeekedEditorIn(peekURI, peekPosition, peekLocations);
+
             return { success: true };
         }
     );