Invalidate signature on cell blur, change and some cursor moves

Author: krassowski

atest/05_Features/Signature.robot

@@ -16,3 +16,12 @@ Triggers Signature Help After A Keystroke
     Wait Until Keyword Succeeds    20x    0.5s    Page Should Contain Element    ${SIGNATURE_BOX}
     Element Should Contain    ${SIGNATURE_BOX}    Important docstring of abc()
     [Teardown]    Clean Up After Working With File    Signature.ipynb
+
+Invalidates On Cell Change
+    Setup Notebook    Python    Signature.ipynb
+    Enter Cell Editor    1    line=6
+    Press Keys    None    (
+    Enter Cell Editor    2
+    # just to increase chances of caching this on CI (which is slow)
+    Sleep    5s
+    Page Should Not Contain Element    ${SIGNATURE_BOX}

packages/jupyterlab-lsp/src/features/completion/completion_handler.ts

@@ -619,7 +619,9 @@ export class LSPConnector
     cursor_at_request: CodeEditor.IPosition
   ) {
     if (!this._editor.hasFocus()) {
-      this.console.debug('Ignoring completion response: the corresponding editor lost focus')
+      this.console.debug(
+        'Ignoring completion response: the corresponding editor lost focus'
+      );
       return {
         start: reply.start,
         end: reply.end,
@@ -635,7 +637,9 @@ export class LSPConnector
       cursor_at_request.line != cursor_now.line ||
       cursor_now.column < cursor_at_request.column
     ) {
-      this.console.debug('Ignoring completion response: cursor has receded or changed line')
+      this.console.debug(
+        'Ignoring completion response: cursor has receded or changed line'
+      );
       return {
         start: reply.start,
         end: reply.end,

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

@@ -92,16 +92,41 @@ export class SignatureCM extends CodeMirrorIntegration {
     return markdown;
   }
 
-  private handleSignature(response: lsProtocol.SignatureHelp) {
+  private handleSignature(
+    response: lsProtocol.SignatureHelp,
+    position_at_request: IRootPosition
+  ) {
     this.lab_integration.tooltip.remove();
 
     this.console.log('Signature received', response);
+
     if (!this.signature_character || !response || !response.signatures.length) {
+      this.console.debug(
+        'Ignoring signature response: cursor lost or response empty'
+      );
       return;
     }
 
-    let root_position = this.signature_character;
+    let root_position = position_at_request;
+
+    // if the cursor advanced in the same line, the previously retrieved completions may still be useful
+    // if the line changed or cursor moved backwards then no reason to keep the suggestions
+    if (
+      position_at_request.line != root_position.line ||
+      root_position.ch < position_at_request.ch
+    ) {
+      this.console.debug(
+        'Ignoring signature response: cursor has receded or changed line'
+      );
+    }
+
     let cm_editor = this.get_cm_editor(root_position);
+    if (!cm_editor.hasFocus()) {
+      this.console.debug(
+        'Ignoring signature response: the corresponding editor lost focus'
+      );
+      return;
+    }
     let editor_position = this.virtual_editor.root_position_to_editor(
       root_position
     );
@@ -152,7 +177,7 @@ export class SignatureCM extends CodeMirrorIntegration {
         this.virtual_document.document_info,
         false
       )
-      .then(help => this.handleSignature(help))
+      .then(help => this.handleSignature(help, root_position))
       .catch(this.console.warn);
   }
 }