fix: Abort completion computations when encountering a BadLocationException

Author: FlorianKroiss

org.eclipse.lsp4e/src/org/eclipse/lsp4e/LSPEclipseUtils.java

@@ -245,18 +245,15 @@ public static CompletionParams toCompletionParams(URI fileUri, int offset, IDocu
 		Position start = toPosition(offset, document);
 		final var param = new CompletionParams();
 		if (document.getLength() > 0) {
-			try {
-				int positionCharacterOffset = offset > 0 ? offset-1 : offset;
-				String positionCharacter = document.get(positionCharacterOffset, 1);
-				if (Chars.contains(completionTriggerChars, positionCharacter.charAt(0))) {
-					param.setContext(new CompletionContext(CompletionTriggerKind.TriggerCharacter, positionCharacter));
-				} else {
-					// According to LSP 3.17 specification: the triggerCharacter in CompletionContext is undefined if
-					// triggerKind != CompletionTriggerKind.TriggerCharacter
-					param.setContext(new CompletionContext(CompletionTriggerKind.Invoked));
-				}
-			} catch (BadLocationException e) {
-				LanguageServerPlugin.logError(e);
+			int positionCharacterOffset = offset > 0 ? offset - 1 : offset;
+			String positionCharacter = document.get(positionCharacterOffset, 1);
+			if (Chars.contains(completionTriggerChars, positionCharacter.charAt(0))) {
+				param.setContext(new CompletionContext(CompletionTriggerKind.TriggerCharacter, positionCharacter));
+			} else {
+				// According to LSP 3.17 specification: the triggerCharacter in
+				// CompletionContext is undefined if
+				// triggerKind != CompletionTriggerKind.TriggerCharacter
+				param.setContext(new CompletionContext(CompletionTriggerKind.Invoked));
 			}
 		}
 		param.setPosition(start);

org.eclipse.lsp4e/src/org/eclipse/lsp4e/operations/completion/LSCompletionProposal.java

@@ -234,7 +234,9 @@ public int getRankScore() {
 			rankScore = CompletionProposalTools.getScoreOfFilterMatch(getDocumentFilter(),
 					getFilterString());
 		} catch (BadLocationException e) {
-			LanguageServerPlugin.logError(e);
+			// Document was changed while we computed completion proposals, which made the
+			// offset invalid. We can stop any further computation as the result will be
+			// discarded anyway.
 			rankScore = -1;
 		}
 		this.rankScore = rankScore;
@@ -257,7 +259,9 @@ public int getRankCategory() {
 			rankCategory = CompletionProposalTools.getCategoryOfFilterMatch(getDocumentFilter(),
 					getFilterString());
 		} catch (BadLocationException e) {
-			LanguageServerPlugin.logError(e);
+			// Document was changed while we computed completion proposals, which made the
+			// offset invalid. We can stop any further computation as the result will be
+			// discarded anyway.
 			rankCategory = CompletionProposalTools.CATEGORY_NO_MATCH;
 		}
 		this.rankCategory = rankCategory;
@@ -442,27 +446,25 @@ private void updateCompletionItem(@Nullable CompletionItem resolvedItem) {
 
 	@Override
 	public int getPrefixCompletionStart(IDocument document, int completionOffset) {
-		Either<TextEdit, InsertReplaceEdit> textEdit = item.getTextEdit();
-		if (textEdit != null) {
-			try {
+		try {
+			Either<TextEdit, InsertReplaceEdit> textEdit = item.getTextEdit();
+			if (textEdit != null) {
 				return LSPEclipseUtils.toOffset(getTextEditRange().getStart(), document);
-			} catch (BadLocationException e) {
-				LanguageServerPlugin.logError(e);
 			}
-		}
-		final String insertText = getInsertText();
-		final int insertTextLength = insertText.length();
-		try {
-			String subDoc = document.get(
-					Math.max(0, completionOffset - insertTextLength),
+
+			final String insertText = getInsertText();
+			final int insertTextLength = insertText.length();
+			String subDoc = document.get(Math.max(0, completionOffset - insertTextLength),
 					Math.min(insertTextLength, completionOffset));
 			for (int i = 0; i < insertTextLength && i < completionOffset; i++) {
 				if (insertText.regionMatches(true, 0, subDoc, i, subDoc.length() - i)) {
 					return completionOffset - subDoc.substring(i).length();
 				}
 			}
 		} catch (BadLocationException e) {
-			LanguageServerPlugin.logError(e);
+			// Document was changed while we computed completion proposals, which made the
+			// offset invalid. We can stop any further computation as the result will be
+			// discarded anyway.
 		}
 		return completionOffset;
 	}

org.eclipse.lsp4e/src/org/eclipse/lsp4e/operations/completion/LSContentAssistProcessor.java

@@ -127,7 +127,12 @@ public ICompletionProposal[] computeCompletionProposals(ITextViewer viewer, int
 		try {
 			param = LSPEclipseUtils.toCompletionParams(uri, offset, document, this.completionTriggerChars);
 		} catch (BadLocationException e) {
-			LanguageServerPlugin.logError(e);
+			// Document was changed while we computed completion proposals, which made the
+			// offset invalid. We can stop any further computation as the result will be
+			// discarded anyway.
+
+			// TODO don't even create error proposal and just return NO_COMPLETION_PROPOSALS,
+			// because the result will be discarded anyway?
 			this.errorMessage = createErrorMessage(offset, e);
 			return createErrorProposal(offset, e);
 		}