org.eclipse.lsp4j.SignatureHelp Java Examples

@Test
public void testSignatureHelp_javadoc() throws JavaModelException {
	IPackageFragment pack1 = sourceFolder.createPackageFragment("test1", false, null);
	StringBuilder buf = new StringBuilder();
	buf.append("package test1;\n");
	buf.append("public class E {\n");
	buf.append("/**\n");
	buf.append(" * @see String#substring()\n");
	buf.append(" */\n");
	buf.append("   public int test() {}\n");
	buf.append("}\n");
	ICompilationUnit cu = pack1.createCompilationUnit("E.java", buf.toString(), false, null);
	SignatureHelp help = getSignatureHelp(cu, 3, 25);
	assertNotNull(help);
	assertEquals(2, help.getSignatures().size());
	assertTrue(help.getSignatures().get(help.getActiveSignature()).getLabel().matches("substring\\(\\w+ \\w+\\) : String"));
}
 

@Test
public void testSignatureHelp_constructorParameters2() throws JavaModelException {
	IPackageFragment pack1 = sourceFolder.createPackageFragment("test1", false, null);
	StringBuilder buf = new StringBuilder();
	buf.append("package test1;\n");
	buf.append("public class E {\n");
	buf.append("   public void bar() {\n");
	buf.append("     new RuntimeException(\"foo\")\n");
	buf.append("   }\n");
	buf.append("}\n");
	ICompilationUnit cu = pack1.createCompilationUnit("E.java", buf.toString(), false, null);
	SignatureHelp help = getSignatureHelp(cu, 3, 31);
	assertNotNull(help);
	assertEquals(4, help.getSignatures().size());
	assertTrue(help.getSignatures().get(help.getActiveSignature()).getLabel().matches("RuntimeException\\(String \\w+\\)"));
}
 

@Override
public SignatureHelp getSignatureHelp(final Document document, final XtextResource resource, final SignatureHelpParams params, final CancelIndicator cancelIndicator) {
  final int offset = document.getOffSet(params.getPosition());
  Preconditions.<XtextResource>checkNotNull(resource, "resource");
  Preconditions.checkArgument((offset >= 0), ("offset >= 0. Was: " + Integer.valueOf(offset)));
  final EObject object = this.offsetHelper.resolveContainedElementAt(resource, offset);
  if ((object instanceof OperationCall)) {
    final String operationName = this.getOperationName(((OperationCall)object));
    boolean _isNullOrEmpty = StringExtensions.isNullOrEmpty(operationName);
    boolean _not = (!_isNullOrEmpty);
    if (_not) {
      return this.getSignatureHelp(((OperationCall)object), operationName, offset);
    }
  }
  return ISignatureHelpService.EMPTY;
}
 

@Test
public void testSignatureHelp_constructorParameters() throws JavaModelException {
	IPackageFragment pack1 = sourceFolder.createPackageFragment("test1", false, null);
	StringBuilder buf = new StringBuilder();
	buf.append("package test1;\n");
	buf.append("public class E {\n");
	buf.append("   public void bar() {\n");
	buf.append("     new RuntimeException(\"t\", )\n");
	buf.append("   }\n");
	buf.append("}\n");
	ICompilationUnit cu = pack1.createCompilationUnit("E.java", buf.toString(), false, null);
	SignatureHelp help = getSignatureHelp(cu, 3, 31);
	assertNotNull(help);
	assertEquals(4, help.getSignatures().size());
	assertTrue(help.getSignatures().get(help.getActiveSignature()).getLabel().matches("RuntimeException\\(String \\w+, Throwable \\w+\\)"));
}
 

@Test
public void testSignatureHelp_constructor() throws JavaModelException {
	IPackageFragment pack1 = sourceFolder.createPackageFragment("test1", false, null);
	StringBuilder buf = new StringBuilder();
	buf.append("package test1;\n");
	buf.append("public class E {\n");
	buf.append("   public void bar() {\n");
	buf.append("     new RuntimeException()\n");
	buf.append("   }\n");
	buf.append("}\n");
	ICompilationUnit cu = pack1.createCompilationUnit("E.java", buf.toString(), false, null);
	SignatureHelp help = getSignatureHelp(cu, 3, 26);
	assertNotNull(help);
	assertEquals(4, help.getSignatures().size());
	assertEquals(help.getSignatures().get(help.getActiveSignature()).getLabel(), "RuntimeException()");
}
 

@Test
public void testSignatureHelp_activeSignature() throws JavaModelException {
	IPackageFragment pack1 = sourceFolder.createPackageFragment("test1", false, null);
	StringBuilder buf = new StringBuilder();
	buf.append("package test1;\n");
	buf.append("public class E {\n");
	buf.append("   public void bar() {\n");
	buf.append("     foo(\"a\",\"b\");\n");
	buf.append("   }\n");
	buf.append("   public void foo(String s) {}\n");
	buf.append("   public void foo(String s, String b) {}\n");
	buf.append("   public void foo() {}\n");
	buf.append("}\n");
	ICompilationUnit cu = pack1.createCompilationUnit("E.java", buf.toString(), false, null);
	SignatureHelp help = getSignatureHelp(cu, 3, 12);
	assertNotNull(help);
	assertEquals(3, help.getSignatures().size());
	assertEquals(help.getSignatures().get(help.getActiveSignature()).getLabel(), "foo(String s, String b) : void");
}
 

@Test
public void testSignatureHelp_parameterObject() throws JavaModelException {
	IPackageFragment pack1 = sourceFolder.createPackageFragment("test1", false, null);
	StringBuilder buf = new StringBuilder();
	buf.append("package test1;\n");
	buf.append("public class E {\n");
	buf.append("	public static void main(String[] args) {\n");
	buf.append("		 Object foo = new Object();\n");
	buf.append("		 System.err.println(foo);\n");
	buf.append("	}\n");
	buf.append("}\n");
	ICompilationUnit cu = pack1.createCompilationUnit("E.java", buf.toString(), false, null);
	SignatureHelp help = getSignatureHelp(cu, 4, 23);
	assertNotNull(help);
	assertEquals(10, help.getSignatures().size());
	assertNotNull(help.getActiveParameter());
	assertTrue(help.getSignatures().get(help.getActiveSignature()).getLabel().matches("println\\(Object \\w+\\) : void"));
}
 

@Test
public void testSignatureHelp_parameterTypes() throws JavaModelException {
	IPackageFragment pack1 = sourceFolder.createPackageFragment("test1", false, null);
	StringBuilder buf = new StringBuilder();
	buf.append("package test1;\n");
	buf.append("public class E {\n");
	buf.append("	public static void main(String[] args) {\n");
	buf.append("		 new RuntimeException(new Exception(),)\n");
	buf.append("	}\n");
	buf.append("}\n");
	ICompilationUnit cu = pack1.createCompilationUnit("E.java", buf.toString(), false, null);
	SignatureHelp help = getSignatureHelp(cu, 3, 40);
	assertNotNull(help);
	assertEquals(4, help.getSignatures().size());
	assertNull(help.getActiveParameter());
}
 

@Test
public void testSignatureHelp_parameters() throws JavaModelException {
	IPackageFragment pack1 = sourceFolder.createPackageFragment("test1", false, null);
	StringBuilder buf = new StringBuilder();
	buf.append("package test1;\n");
	buf.append("public class E {\n");
	buf.append("   public boolean bar() {\n");
	buf.append("     foo(\"\",)\n");
	buf.append("     return true;\n");
	buf.append("   }\n");
	buf.append("   public void foo(String s) {}\n");
	buf.append("   public void foo(String s, boolean bar) {}\n");
	buf.append("}\n");
	ICompilationUnit cu = pack1.createCompilationUnit("E.java", buf.toString(), false, null);
	SignatureHelp help = getSignatureHelp(cu, 3, 12);
	assertNotNull(help);
	assertEquals(2, help.getSignatures().size());
	assertEquals(help.getSignatures().get(help.getActiveSignature()).getLabel(), "foo(String s, boolean bar) : void");
}
 

public SignatureHelp getSignatureHelp(IProgressMonitor monitor) {
	SignatureHelp signatureHelp = new SignatureHelp();
	response.setProposals(proposals);
	CompletionResponses.store(response);

	List<SignatureInformation> infos = new ArrayList<>();
	for (int i = 0; i < proposals.size(); i++) {
		if (!monitor.isCanceled()) {
			CompletionProposal proposal = proposals.get(i);
			SignatureInformation signatureInformation = this.toSignatureInformation(proposal);
			infoProposals.put(signatureInformation, proposal);
			infos.add(signatureInformation);
		} else {
			return signatureHelp;
		}
	}
	infos.sort((SignatureInformation a, SignatureInformation b) -> a.getParameters().size() - b.getParameters().size());
	signatureHelp.getSignatures().addAll(infos);

	return signatureHelp;
}
 

@Test
public void testSignatureHelp_javadocOriginal() throws JavaModelException {
	IPackageFragment pack1 = sourceFolder.createPackageFragment("test1", false, null);
	StringBuilder buf = new StringBuilder();
	buf.append("package test1;\n");
	buf.append("import java.util.LinkedList;\n");
	buf.append("import org.sample.MyList;\n");
	buf.append("public class E {\n\n");
	buf.append("	void test() {\n");
	buf.append("		MyList<String> l = new LinkedList<>();\n");
	buf.append("		l.add(\n");
	buf.append("	}\n");
	buf.append("}\n");
	ICompilationUnit cu = pack1.createCompilationUnit("E.java", buf.toString(), false, null);
	int[] loc = findCompletionLocation(cu, "l.add(");
	SignatureHelp help = getSignatureHelp(cu, loc[0], loc[1]);
	assertNotNull(help);
	assertEquals(2, help.getSignatures().size());
	SignatureInformation signature = help.getSignatures().get(help.getActiveSignature());
	assertTrue(signature.getLabel().equals("add(String e) : boolean"));
	String documentation = signature.getDocumentation().getLeft();
	assertEquals(" Test ", documentation);
}
 

@Test
public void testSignatureHelp_varargs() throws JavaModelException {
	IPackageFragment pack1 = sourceFolder.createPackageFragment("test1", false, null);
	StringBuilder buf = new StringBuilder();
	buf.append("package test1;\n");
	buf.append("import java.util.Arrays;\n");
	buf.append("public class E {\n");
	buf.append("	public static void main(String[] args) {\n");
	buf.append("		Arrays.asList(1,2,3);\n");
	buf.append("		demo(\"1\", \"2\",\"3\" )\n");
	buf.append("	}\n");
	buf.append("	public static void demo (String s, String... s2) {\n");
	buf.append("	}\n");
	buf.append("}\n");
	ICompilationUnit cu = pack1.createCompilationUnit("E.java", buf.toString(), false, null);
	SignatureHelp help = getSignatureHelp(cu, 4, 21);
	assertNotNull(help);
	assertEquals(1, help.getSignatures().size());
	assertTrue(help.getSignatures().get(help.getActiveSignature()).getLabel().startsWith("asList(T... "));
	help = getSignatureHelp(cu, 5, 19);
	assertNotNull(help);
	assertEquals(1, help.getSignatures().size());
	assertTrue(help.getSignatures().get(help.getActiveSignature()).getLabel().equals("demo(String s, String... s2) : void"));
}
 

@Test
public void testSignatureHelp_singleMethod() throws JavaModelException {
	IPackageFragment pack1 = sourceFolder.createPackageFragment("test1", false, null);
	StringBuilder buf = new StringBuilder();
	buf.append("package test1;\n");
	buf.append("public class E {\n");
	buf.append("   /** This is a method */\n");
	buf.append("   public int foo(String s) { }\n");
	buf.append("   public int bar(String s) { this.foo() }\n");
	buf.append("}\n");
	ICompilationUnit cu = pack1.createCompilationUnit("E.java", buf.toString(), false, null);

	SignatureHelp help = getSignatureHelp(cu, 4, 39);
	assertNotNull(help);
	assertEquals(1, help.getSignatures().size());
	assertEquals("foo(String s) : int", help.getSignatures().get(0).getLabel());
	assertTrue(help.getSignatures().get(0).getDocumentation().getLeft().length() > 0);
	assertEquals((Integer) 0, help.getActiveParameter());
}
 

@Test
public void testSignatureHelp_multipeMethod() throws JavaModelException {
	IPackageFragment pack1 = sourceFolder.createPackageFragment("test1", false, null);
	StringBuilder buf = new StringBuilder();
	buf.append("package test1;\n");
	buf.append("public class E {\n");
	buf.append("   public int foo(String s) { }\n");
	buf.append("   public int foo(int s) { }\n");
	buf.append("   public int foo(int s, String s) { }\n");
	buf.append("   public int bar(String s) { this.foo(2,  ) }\n");
	buf.append("}\n");
	ICompilationUnit cu = pack1.createCompilationUnit("E.java", buf.toString(), false, null);

	SignatureHelp help = getSignatureHelp(cu, 5, 42);
	assertNotNull(help);
	assertEquals(3, help.getSignatures().size());
	assertEquals((Integer) 1, help.getActiveParameter());
	assertEquals(help.getSignatures().get(help.getActiveSignature()).getLabel(), "foo(int s, String s) : int");
}
 

@Test
public void testSignatureHelp_binary() throws JavaModelException {
	IPackageFragment pack1 = sourceFolder.createPackageFragment("test1", false, null);
	StringBuilder buf = new StringBuilder();
	buf.append("package test1;\n");
	buf.append("public class E {\n");
	buf.append("   public int bar(String s) { System.out.println(  }\n");
	buf.append("}\n");
	ICompilationUnit cu = pack1.createCompilationUnit("E.java", buf.toString(), false, null);

	SignatureHelp help = getSignatureHelp(cu, 2, 50);
	assertNotNull(help);
	assertTrue(help.getSignatures().size() >= 10);
	assertTrue(help.getSignatures().get(help.getActiveSignature()).getLabel().equals("println() : void"));
	SignatureHelp help2 = getSignatureHelp(cu, 2, 49);
	assertEquals(help.getSignatures().size(), help2.getSignatures().size());
	assertEquals(help.getActiveSignature(), help2.getActiveSignature());
}
 

@Test
public void testSignatureHelp_varargs2() throws JavaModelException {
	IJavaProject javaProject = JavaCore.create(project);
	IType type = javaProject.findType("test1.Varargs");
	ICompilationUnit cu = type.getCompilationUnit();
	SignatureHelp help = getSignatureHelp(cu, 4, 16);
	assertNotNull(help);
	assertEquals(2, help.getSignatures().size());
	assertTrue(help.getSignatures().get(help.getActiveSignature()).getLabel().equals("run(Class<?> clazz, String... args) : void"));
}
 

@Test
void testSignatureHelpOnMethod() throws Exception {
	Path filePath = srcRoot.resolve("Completion.groovy");
	String uri = filePath.toUri().toString();
	StringBuilder contents = new StringBuilder();
	contents.append("class SignatureHelp {\n");
	contents.append("  public SignatureHelp() {\n");
	contents.append("    method(\n");
	contents.append("  }\n");
	contents.append("  public void method(int param0) {}\n");
	contents.append("}");
	TextDocumentItem textDocumentItem = new TextDocumentItem(uri, LANGUAGE_GROOVY, 1, contents.toString());
	services.didOpen(new DidOpenTextDocumentParams(textDocumentItem));
	TextDocumentIdentifier textDocument = new TextDocumentIdentifier(uri);
	Position position = new Position(2, 11);
	SignatureHelp signatureHelp = services.signatureHelp(new TextDocumentPositionParams(textDocument, position))
			.get();
	List<SignatureInformation> signatures = signatureHelp.getSignatures();
	Assertions.assertEquals(1, signatures.size());
	SignatureInformation signature = signatures.get(0);
	Assertions.assertEquals("public void method(int param0)", signature.getLabel());
	List<ParameterInformation> params = signature.getParameters();
	Assertions.assertEquals(1, params.size());
	ParameterInformation param0 = params.get(0);
	Assertions.assertEquals("int param0", param0.getLabel().get());
	Assertions.assertEquals((int) 0, (int) signatureHelp.getActiveSignature());
	Assertions.assertEquals((int) 0, (int) signatureHelp.getActiveParameter());
}
 

@Test
public void testSignatureHelp_lambda() throws JavaModelException {
	IJavaProject javaProject = JavaCore.create(project);
	IType type = javaProject.findType("test1.SignatureHelp");
	ICompilationUnit cu = type.getCompilationUnit();
	SignatureHelp help = getSignatureHelp(cu, 8, 14);
	assertNotNull(help);
	assertEquals(1, help.getSignatures().size());
	assertTrue(help.getSignatures().get(help.getActiveSignature()).getLabel().equals("test(Function<String,String> f) : void"));
}
 

private void testStringLiteral(ICompilationUnit cu, int line, int character) {
	SignatureHelp help = getSignatureHelp(cu, line, character);
	assertNotNull(help);
	assertEquals(1, help.getSignatures().size());
	assertNotNull(help.getActiveParameter());
	assertTrue(help.getSignatures().get(help.getActiveSignature()).getLabel().equals("foo(String p, int x) : void"));
}
 

private void testAssertEquals(ICompilationUnit cu, int line, int character) {
	SignatureHelp help = getSignatureHelp(cu, line, character);
	assertNotNull(help);
	assertEquals(12, help.getSignatures().size());
	assertNotNull(help.getActiveParameter());
	assertTrue(help.getSignatures().get(help.getActiveSignature()).getLabel().equals("assertEquals(long expected, long actual) : void"));
}
 

/**
 * Displays a function's parameters, including which one is currently
 * active. Called automatically by VSCode any time that the user types "(",
 * so be sure to check that a function call is actually happening at the
 * current position.
 */
@Override
public CompletableFuture<SignatureHelp> signatureHelp(SignatureHelpParams params)
{
    return CompletableFutures.computeAsync(compilerWorkspace.getExecutorService(), cancelToken ->
    {
        cancelToken.checkCanceled();

        //make sure that the latest changes have been passed to
        //workspace.fileChanged() before proceeding
        if(realTimeProblemsChecker != null)
        {
            realTimeProblemsChecker.updateNow();
        }

        compilerWorkspace.startBuilding();
        try
        {
            SignatureHelpProvider provider = new SignatureHelpProvider(workspaceFolderManager, fileTracker);
            return provider.signatureHelp(params, cancelToken);
        }
        finally
        {
            compilerWorkspace.doneBuilding();
        }
    });
}
 

protected String _toExpectation(final SignatureHelp it) {
  String _xblockexpression = null;
  {
    int _size = it.getSignatures().size();
    boolean _tripleEquals = (_size == 0);
    if (_tripleEquals) {
      StringConcatenation _builder = new StringConcatenation();
      _builder.append("Signature index is expected to be null when no signatures are available. Was: ");
      Integer _activeSignature = it.getActiveSignature();
      _builder.append(_activeSignature);
      _builder.append(".");
      Assert.assertNull(_builder.toString(), 
        it.getActiveSignature());
      return "<empty>";
    }
    Assert.assertNotNull("Active signature index must not be null when signatures are available.", it.getActiveSignature());
    String _xifexpression = null;
    Integer _activeParameter = it.getActiveParameter();
    boolean _tripleEquals_1 = (_activeParameter == null);
    if (_tripleEquals_1) {
      _xifexpression = "<empty>";
    } else {
      _xifexpression = it.getSignatures().get((it.getActiveSignature()).intValue()).getParameters().get(
        (it.getActiveParameter()).intValue()).getLabel().getLeft();
    }
    final String param = _xifexpression;
    StringConcatenation _builder_1 = new StringConcatenation();
    final Function1<SignatureInformation, String> _function = (SignatureInformation it_1) -> {
      return it_1.getLabel();
    };
    String _join = IterableExtensions.join(ListExtensions.<SignatureInformation, String>map(it.getSignatures(), _function), " | ");
    _builder_1.append(_join);
    _builder_1.append(" | ");
    _builder_1.append(param);
    _xblockexpression = _builder_1.toString();
  }
  return _xblockexpression;
}
 

/**
 * Compute the signature help. Executed in a read request.
 * @since 2.20
 */
protected SignatureHelp signatureHelp(SignatureHelpParams params, CancelIndicator cancelIndicator) {
	URI uri = getURI(params);
	ISignatureHelpService helper = getService(uri, ISignatureHelpService.class);
	if (helper == null) {
		return ISignatureHelpService.EMPTY;
	}
	return workspaceManager.doRead(uri,
			(doc, resource) -> helper.getSignatureHelp(doc, resource, params, cancelIndicator));
}
 

private boolean isSameParameters(IMethod m, SignatureHelp help, SignatureHelpRequestor collector, IJavaProject javaProject) throws JavaModelException {
	if (m == null || help == null || javaProject == null) {
		return false;
	}
	List<SignatureInformation> infos = help.getSignatures();
	for (int i = 0; i < infos.size(); i++) {
		CompletionProposal proposal = collector.getInfoProposals().get(infos.get(i));
		IMethod method = JDTUtils.resolveMethod(proposal, javaProject);
		if (isSameParameters(method, m)) {
			return true;
		}
	}
	return false;
}
 

@Test
void testSignatureHelpOnMethodWithMultipleParameters() throws Exception {
	Path filePath = srcRoot.resolve("Completion.groovy");
	String uri = filePath.toUri().toString();
	StringBuilder contents = new StringBuilder();
	contents.append("class SignatureHelp {\n");
	contents.append("  public SignatureHelp() {\n");
	contents.append("    method(\n");
	contents.append("  }\n");
	contents.append("  public void method(int param0, String param1) {}\n");
	contents.append("}");
	TextDocumentItem textDocumentItem = new TextDocumentItem(uri, LANGUAGE_GROOVY, 1, contents.toString());
	services.didOpen(new DidOpenTextDocumentParams(textDocumentItem));
	TextDocumentIdentifier textDocument = new TextDocumentIdentifier(uri);
	Position position = new Position(2, 11);
	SignatureHelp signatureHelp = services.signatureHelp(new TextDocumentPositionParams(textDocument, position))
			.get();
	List<SignatureInformation> signatures = signatureHelp.getSignatures();
	Assertions.assertEquals(1, signatures.size());
	SignatureInformation signature = signatures.get(0);
	Assertions.assertEquals("public void method(int param0, String param1)", signature.getLabel());
	List<ParameterInformation> params = signature.getParameters();
	Assertions.assertEquals(2, params.size());
	ParameterInformation param0 = params.get(0);
	Assertions.assertEquals("int param0", param0.getLabel().get());
	ParameterInformation param1 = params.get(1);
	Assertions.assertEquals("String param1", param1.getLabel().get());
	Assertions.assertEquals((int) 0, (int) signatureHelp.getActiveSignature());
	Assertions.assertEquals((int) 0, (int) signatureHelp.getActiveParameter());
}
 

@Test
void testSignatureHelpOnMethodWithActiveParameter() throws Exception {
	Path filePath = srcRoot.resolve("Completion.groovy");
	String uri = filePath.toUri().toString();
	StringBuilder contents = new StringBuilder();
	contents.append("class SignatureHelp {\n");
	contents.append("  public SignatureHelp() {\n");
	contents.append("    method(123,\n");
	contents.append("  }\n");
	contents.append("  public void method(int param0, String param1) {}\n");
	contents.append("}");
	TextDocumentItem textDocumentItem = new TextDocumentItem(uri, LANGUAGE_GROOVY, 1, contents.toString());
	services.didOpen(new DidOpenTextDocumentParams(textDocumentItem));
	TextDocumentIdentifier textDocument = new TextDocumentIdentifier(uri);
	Position position = new Position(2, 15);
	SignatureHelp signatureHelp = services.signatureHelp(new TextDocumentPositionParams(textDocument, position))
			.get();
	List<SignatureInformation> signatures = signatureHelp.getSignatures();
	Assertions.assertEquals(1, signatures.size());
	SignatureInformation signature = signatures.get(0);
	Assertions.assertEquals("public void method(int param0, String param1)", signature.getLabel());
	List<ParameterInformation> params = signature.getParameters();
	Assertions.assertEquals(2, params.size());
	ParameterInformation param0 = params.get(0);
	Assertions.assertEquals("int param0", param0.getLabel().get());
	ParameterInformation param1 = params.get(1);
	Assertions.assertEquals("String param1", param1.getLabel().get());
	Assertions.assertEquals((int) 0, (int) signatureHelp.getActiveSignature());
	Assertions.assertEquals((int) 1, (int) signatureHelp.getActiveParameter());
}
 

/** @return string for given element */
public String toString(SignatureHelp signatureHelp) {
	if (signatureHelp == null) {
		return "";
	}

	String str = Strings.join(", ",
			signatureHelp.getActiveSignature(),
			signatureHelp.getActiveParameter(),
			Strings.toString(this::toString, signatureHelp.getSignatures()));

	return "(" + str + ")";
}
 

@Override
public CompletableFuture<SignatureHelp> signatureHelp(TextDocumentPositionParams params) {
	URI uri = getURI(params);
	return openFilesManager.runInOpenFileContext(uri, "signatureHelp", (ofc, ci) -> {
		return signatureHelp(ofc, params, ci);
	});
}
 

/**
 * Compute the signature help. Executed in a read request.
 */
protected SignatureHelp signatureHelp(OpenFileContext ofc, TextDocumentPositionParams params,
		CancelIndicator cancelIndicator) {
	URI uri = ofc.getURI();
	ISignatureHelpService helper = getService(uri, ISignatureHelpService.class);
	if (helper == null) {
		return ISignatureHelpService.EMPTY;
	}
	XtextResource res = ofc.getResource();
	XDocument doc = ofc.getDocument();
	return helper.getSignatureHelp(doc, res, params, cancelIndicator);
}
 

@Test
public void testSignatureHelp_invalid() throws JavaModelException {
	IPackageFragment pack1 = sourceFolder.createPackageFragment("test1", false, null);
	StringBuilder buf = new StringBuilder();
	buf.append("package test1;\n");
	buf.append("public class E {\n");
	buf.append("   public int bar(String s) { if (  }\n");
	buf.append("}\n");
	ICompilationUnit cu = pack1.createCompilationUnit("E.java", buf.toString(), false, null);
	SignatureHelp help = getSignatureHelp(cu, 2, 34);
	assertNotNull(help);
	assertEquals(0, help.getSignatures().size());
}