Fix stale hover reuse for unchanged regions

org.eclipse.lsp4e.test/src/org/eclipse/lsp4e/test/hover/HoverTest.java

@@ -1,5 +1,5 @@
 /*******************************************************************************
- * Copyright (c) 2016 Rogue Wave Software Inc. and others.
+ * Copyright (c) 2016, 2026 Rogue Wave Software Inc. and others.
  * This program and the accompanying materials are made
  * available under the terms of the Eclipse Public License 2.0
  * which is available at https://www.eclipse.org/legal/epl-2.0/
@@ -235,4 +235,55 @@ public void completed(ProgressEvent event) {
 			shell.dispose();
 		}
 	}
+
+	@Test
+	public void testHoverRegionRefreshesForSameOffsetAfterCompletedRequest() throws Exception {
+		// Test for https://github.com/eclipse-lsp4e/lsp4e/issues/1514
+		// Verifies that getHoverRegion refreshes for the same offset after a completed
+		// request, instead of reusing the previous completed hover range indefinitely.
+		final var firstHover = new Hover(List.of(Either.forLeft("FirstValue")),
+				new Range(new Position(0, 0), new Position(0, 5)));
+		final var secondHover = new Hover(List.of(Either.forLeft("SecondValue")),
+				new Range(new Position(0, 6), new Position(0, 10)));
+
+		IFile file = TestUtils.createUniqueTestFile(project, "HoverRange Other Text");
+		ITextViewer viewer = TestUtils.openTextViewer(file);
+
+		MockLanguageServer.INSTANCE.setHover(firstHover);
+		assertEquals(new Region(0, 5), hover.getHoverRegion(viewer, 2));
+
+		MockLanguageServer.INSTANCE.setHover(secondHover);
+		assertEquals(new Region(6, 4), hover.getHoverRegion(viewer, 2));
+	}
+
+	@Test
+	public void testHoverInfoRefreshesForSameOffsetAfterCompletedRequest() throws Exception {
+		// Test for https://github.com/eclipse-lsp4e/lsp4e/issues/1514
+		// Verifies that a second hover at the same offset recomputes the hover region
+		// and refreshes the hover content after the previous request completed.
+		final var firstHover = new Hover(List.of(Either.forLeft("FirstValue")),
+				new Range(new Position(0, 0), new Position(0, 5)));
+		final var secondHover = new Hover(List.of(Either.forLeft("SecondValue")),
+				new Range(new Position(0, 6), new Position(0, 10)));
+
+		IFile file = TestUtils.createUniqueTestFile(project, "HoverRange Other Text");
+		ITextViewer viewer = TestUtils.openTextViewer(file);
+
+		MockLanguageServer.INSTANCE.setHover(firstHover);
+		Region firstRegion = (Region) hover.getHoverRegion(viewer, 2);
+		assertEquals(new Region(0, 5), firstRegion);
+
+		String firstHtml = hover.getHoverInfoFuture(viewer, firstRegion).get(2, TimeUnit.SECONDS);
+		assertNotNull(firstHtml);
+		assertTrue(firstHtml.contains("FirstValue"));
+
+		MockLanguageServer.INSTANCE.setHover(secondHover);
+		Region secondRegion = (Region) hover.getHoverRegion(viewer, 2);
+		assertEquals(new Region(6, 4), secondRegion);
+
+		String secondHtml = hover.getHoverInfoFuture(viewer, secondRegion).get(2, TimeUnit.SECONDS);
+		assertNotNull(secondHtml);
+		assertTrue(secondHtml.contains("SecondValue"));
+		assertTrue(!secondHtml.contains("FirstValue"));
+	}
 }

org.eclipse.lsp4e/src/org/eclipse/lsp4e/operations/hover/LSPTextHover.java

@@ -1,5 +1,5 @@
 /*******************************************************************************
- * Copyright (c) 2016, 2023 Red Hat Inc. and others.
+ * Copyright (c) 2016, 2026 Red Hat Inc. and others.
  * This program and the accompanying materials are made
  * available under the terms of the Eclipse Public License 2.0
  * which is available at https://www.eclipse.org/legal/epl-2.0/
@@ -16,8 +16,6 @@
  *******************************************************************************/
 package org.eclipse.lsp4e.operations.hover;
 
-import static org.eclipse.lsp4e.internal.NullSafetyHelper.castNonNull;
-
 import java.util.List;
 import java.util.NoSuchElementException;
 import java.util.Objects;
@@ -98,10 +96,18 @@ public class LSPTextHover implements ITextHover, ITextHoverExtension, ITextHover
 	}
 
 	public CompletableFuture<@Nullable String> getHoverInfoFuture(ITextViewer textViewer, IRegion hoverRegion) {
-		if (this.request == null || !textViewer.equals(this.lastViewer) || !hoverRegion.equals(this.lastRegion)) {
+		CompletableFuture<List<Hover>> locRequest = this.request;
+		if (locRequest == null || locRequest.isDone() || !textViewer.equals(this.lastViewer)
+				|| !hoverRegion.equals(this.lastRegion)) {
 			initiateHoverRequest(textViewer, hoverRegion.getOffset());
+			locRequest = this.request;
+		}
+
+		if (locRequest == null) {
+			return CompletableFuture.completedFuture(null);
 		}
-		return castNonNull(request).thenApply(hoversList -> {
+
+		return locRequest.thenApply(hoversList -> {
 			String result = hoversList.stream() //
 					.filter(Objects::nonNull) //
 					.map(LSPTextHover::getHoverString) //
@@ -110,9 +116,8 @@ public class LSPTextHover implements ITextHover, ITextHoverExtension, ITextHover
 					.trim();
 			if (!result.isEmpty()) {
 				return MarkdownUtil.renderToHtml(result);
-			} else {
-				return null;
 			}
+			return null;
 		});
 	}
 
@@ -149,28 +154,40 @@ public class LSPTextHover implements ITextHover, ITextHoverExtension, ITextHover
 	@Override
 	public @Nullable IRegion getHoverRegion(ITextViewer textViewer, int offset) {
 		final var lastRegion = this.lastRegion;
-		if (this.request == null || lastRegion == null || !textViewer.equals(this.lastViewer)
-				|| offset < lastRegion.getOffset() || offset > lastRegion.getOffset() + lastRegion.getLength()) {
+
+		CompletableFuture<List<Hover>> locRequest = this.request;
+		if (locRequest == null || locRequest.isDone() || lastRegion == null || !textViewer.equals(this.lastViewer)
+				|| offset < lastRegion.getOffset() || offset >= lastRegion.getOffset() + lastRegion.getLength()) {
 			initiateHoverRequest(textViewer, offset);
+			locRequest = this.request;
 		}
 
 		final IDocument document = textViewer.getDocument();
 		if (document == null) {
 			return null;
 		}
 
+		if (locRequest == null) {
+			return this.lastRegion = computeHeuristicRegion(document, offset);
+		}
+
 		try {
 			// Wait shortly for hover region result, fallback to heuristics if LS is laggy
-			Range range = castNonNull(this.request).get(GET_HOVER_REGION_TIMEOUT_MS, TimeUnit.MILLISECONDS).stream() //
+			List<Hover> hovers = locRequest.get(GET_HOVER_REGION_TIMEOUT_MS, TimeUnit.MILLISECONDS);
+
+			Range range = hovers.stream() //
 					.filter(Objects::nonNull) //
 					.map(Hover::getRange) //
 					.filter(Objects::nonNull) //
 					.reduce((first, second) -> second) //
-					.get();
-			int regionStartOffset = Math.max(0,
-					LSPEclipseUtils.toOffset(range.getStart(), document));
-			int regionEndOffset = Math.min(document.getLength(),
-					LSPEclipseUtils.toOffset(range.getEnd(), document));
+					.orElse(null);
+
+			if (range == null) {
+				return this.lastRegion = computeHeuristicRegion(document, offset);
+			}
+
+			int regionStartOffset = Math.max(0, LSPEclipseUtils.toOffset(range.getStart(), document));
+			int regionEndOffset = Math.min(document.getLength(), LSPEclipseUtils.toOffset(range.getEnd(), document));
 			return this.lastRegion = new Region(regionStartOffset, regionEndOffset - regionStartOffset);
 		} catch (ExecutionException | BadLocationException e) {
 			if (!CancellationUtil.isRequestCancelledException(e)) {