[flori-schwa]

Codemining implementations can now opt-in to rendering placeholder text
to prevent editor jumping. The IPlaceholderCodeMining interface must be
implemented and getPlaceholderLabel() should return a non-empty string.

If no label is set and there is no last resolved mining, the placeholder
text will be shown while the resolve() Future is still running.

Fixes #3723

Example Usage:

In JavaImplementationCodeMining (JDT):

• implement the new IPlaceholderCodeMining interface:

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

• Implement the getPlaceholderLabel() Method:

@Override
public String getPlaceholderLabel() {
  if (!showImplementationsAtLeastOne) {
    return "?? implementations"; //$NON-NLS-1$
  }
  return null;
}

[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

[Copilot]

🟡 Changes recommended

Incorrect click-target mapping, a null-label painting race, and a nondeterministic test remain unresolved.

3 open issues

• Map drawn bounds to their associated code minings · New
• Capture mining label once before null and placeholder checks · New
• Keep placeholder unresolved during incomplete draw test · New

What changed in this PR

Adds opt-in code-mining placeholders to reduce editor content shifting while labels resolve asynchronously, addressing #3723.

Changes:

• Introduces IPlaceholderCodeMining to distinguish placeholder labels from resolved labels.
• Updates header, inline, and footer rendering to support placeholders without caching them as resolved results.
• Adds placeholder rendering, height, and redraw tests.

File	Description
tests/​org.eclipse.jface.text.tests/​src/​org/​eclipse/​jface/​text/​tests/​codemining/​PlaceholderLineHeaderCodeMining.java	Adds a reusable placeholder-enabled test mining.
tests/​org.eclipse.jface.text.tests/​src/​org/​eclipse/​jface/​text/​tests/​codemining/​CodeMiningTest.java	Tests placeholder-to-resolved label rendering.
tests/​org.eclipse.jface.text.tests/​src/​org/​eclipse/​jface/​text/​tests/​codemining/​CodeMiningLineHeaderAnnotationTest.java	Tests placeholder height and resolution-triggered redraws.
bundles/​org.eclipse.jface.text/​src/​org/​eclipse/​jface/​text/​codemining/​IPlaceholderCodeMining.java	Defines the public placeholder contract.
bundles/​org.eclipse.jface.text/​src/​org/​eclipse/​jface/​internal/​text/​codemining/​CodeMiningManager.java	Adds a helper to identify unresolved placeholders.
bundles/​org.eclipse.jface.text/​src/​org/​eclipse/​jface/​internal/​text/​codemining/​CodeMiningLineHeaderAnnotation.java	Supports placeholder drawing and separates resolved-cache handling.
bundles/​org.eclipse.jface.text/​src/​org/​eclipse/​jface/​internal/​text/​codemining/​CodeMiningLineContentAnnotation.java	Supports inline placeholders and resolution-triggered redraws.
bundles/​org.eclipse.jface.text/​src/​org/​eclipse/​jface/​internal/​text/​codemining/​CodeMiningDocumentFooterAnnotation.java	Updates footer height checks and resolved-cache handling.

_{Review effort: Balanced}

[fedejeanne]

🟢 Only the (int, IDocument, ICodeMiningProvider) constructor is used; drop the other two. You could also reuse the private ResolvablePlaceholderMining from CodeMiningLineHeaderAnnotationTest (moved here) instead of having two similar helper classes.

(Created by Claude)