Add an option to show hover tooltip automatically

Introduce a new item 'autoHover' and 'delay' to Code Hover setting.

Author: yamaton

packages/jupyterlab-lsp/schema/hover.json

@@ -5,6 +5,19 @@
   "description": "LSP Hover over the code tooltip settings.",
   "type": "object",
   "properties": {
+    "autoActivate": {
+      "title": "Automatic hover",
+      "type": "boolean",
+      "default": false,
+      "description": "Automatic activation of hover without pressing a key. It will still be possible to show up tooltips with the modifier key."
+    },
+    "delay": {
+      "title": "Hover delay",
+      "type": "number",
+      "default": 300,
+      "minimum": 0,
+      "description": "Number of milliseconds after which the hover tooltip should be shown. Ignored if 'Automatic hover' is OFF."
+    },
     "modifierKey": {
       "title": "Modifier key",
       "type": "string",

packages/jupyterlab-lsp/src/features/hover.ts

@@ -143,6 +143,10 @@ export class HoverCM extends CodeMirrorIntegration {
     return this.settings.composite.modifierKey;
   }
 
+  protected get isHoverAutomatic(): boolean {
+    return this.settings.composite.autoActivate;
+  }
+
   get lab_integration() {
     return super.lab_integration as HoverLabIntegration;
   }
@@ -390,7 +394,8 @@ export class HoverCM extends CodeMirrorIntegration {
       return false;
     }
 
-    const show_tooltip = getModifierState(event, this.modifierKey);
+    const show_tooltip =
+      this.isHoverAutomatic || getModifierState(event, this.modifierKey);
 
     // currently the events are coming from notebook panel; ideally these would be connected to individual cells,
     // (only cells with code) instead, but this is more complex to implement right. In any case filtering
@@ -440,6 +445,7 @@ export class HoverCM extends CodeMirrorIntegration {
         ]);
       }
       let response_data = this.restore_from_cache(document, virtual_position);
+      let delay_ms = this.settings.composite.delay;
 
       if (response_data == null) {
         const promise = this.debounced_get_hover.invoke();
@@ -473,12 +479,21 @@ export class HoverCM extends CodeMirrorIntegration {
           };
 
           this.cache.store(response_data);
+          delay_ms = Math.max(
+            0,
+            this.settings.composite.delay -
+              this.settings.composite.throttlerDelay
+          );
         } else {
           this.remove_range_highlight();
           return false;
         }
       }
 
+      if (this.isHoverAutomatic) {
+        await new Promise(resolve => setTimeout(resolve, delay_ms));
+      }
+
       return this.handleResponse(response_data, root_position, show_tooltip);
     } else {
       return true;