CodeMinings: Add support for rendering placeholder while resolving #3723

[flori-schwa]

Codemining implementations can now opt-in to rendering placeholder text while the resolve() Task is still running. The IPlaceholderCodeMining marker interface must be implemented and getLabel() must return a non-empty string, which will be used as the placeholder while the future is not done.

Fixes #3723

Example Usage:

In JavaImplementationCodeMining (JDT):

• implement the new IPlaceholderCodeMining interface:

-public class JavaImplementationCodeMining extends AbstractJavaElementLineHeaderCodeMining {
+public class JavaImplementationCodeMining extends AbstractJavaElementLineHeaderCodeMining implements IPlaceholderCodeMining {

• Add a setLabel() Call in the constructor:

	public JavaImplementationCodeMining(IJavaElement element, JavaEditor editor, IDocument document, ICodeMiningProvider provider,
			boolean showImplementationsAtLeastOne) throws JavaModelException, BadLocationException {
		super(element, document, provider, null);
		this.editor= editor;
		this.showImplementationsAtLeastOne= showImplementationsAtLeastOne;

+		if (!showImplementationsAtLeastOne) {
+			setLabel("?? implementations"); //$NON-NLS-1$
+		}
	}

[flori-schwa]

Here is a screen recording where I added a placeholder to the "Java References" and "Java Implementations" Code minings. I also added a random delay in the resolve method to simulate work.

Placeholders.mp4

[github-actions]

Test Results

   867 files  ± 0     867 suites  ±0   49m 27s ⏱️ - 10m 41s
 8 470 tests + 5   8 228 ✅ + 5  242 💤 ±0  0 ❌ ±0 
21 288 runs  +15  20 605 ✅ +15  683 💤 ±0  0 ❌ ±0 

Results for commit 05782b5. ± Comparison against base commit 3faf11c.

This pull request removes 2 and adds 7 tests. Note that renamed tests count towards both.

org.eclipse.jface.text.tests.codemining.CodeMiningLineHeaderAnnotationTest ‑ testGetHeightDoesNotReturnZero
org.eclipse.jface.text.tests.codemining.CodeMiningLineHeaderAnnotationTest ‑ testTwoLineCodeMiningHeightMatchesTextWidgetLineHeight

org.eclipse.jface.text.tests.codemining.CodeMiningLineHeaderAnnotationTest ‑ testGetHeightDoesNotReturnZero(boolean)[1] placeHolder: false
org.eclipse.jface.text.tests.codemining.CodeMiningLineHeaderAnnotationTest ‑ testGetHeightDoesNotReturnZero(boolean)[2] placeHolder: true
org.eclipse.jface.text.tests.codemining.CodeMiningLineHeaderAnnotationTest ‑ testResolvedPlaceholderDoesNotRequestRedraw
org.eclipse.jface.text.tests.codemining.CodeMiningLineHeaderAnnotationTest ‑ testTwoLineCodeMiningHeightMatchesTextWidgetLineHeight(boolean)[1] placeHolder: false
org.eclipse.jface.text.tests.codemining.CodeMiningLineHeaderAnnotationTest ‑ testTwoLineCodeMiningHeightMatchesTextWidgetLineHeight(boolean)[2] placeHolder: true
org.eclipse.jface.text.tests.codemining.CodeMiningLineHeaderAnnotationTest ‑ testUnresolvedPlaceholderRequestsRedraw
org.eclipse.jface.text.tests.codemining.CodeMiningTest ‑ testLineHeaderCodeMiningPlaceholder