I'm trying to create a grammar, using implicit declarations. After reading the a forum entry (http://www.eclipse.org/forums/index.php?t=msg&S=2e4a29d7fff0322e71b35e3a3aa63e3f&th=198813&goto=634090#msg_634090) I wrote my own LinkingService:
public class OntMLLinkingService extends DefaultLinkingService {
private final Map<Rule, Resource> implicitVariables = new HashMap<>();
public List<EObject> getLinkedObjects(EObject context, EReference ref, INode node) throws IllegalNodeException {
List<EObject> linking = super.getLinkedObjects(context, ref, node);
if (!linking.isEmpty())
return linking;
if (context instanceof VariableReference && ref.equals(OntMLPackage.eINSTANCE.getVariableReference_Variable())) {
// Find the rule, the references is used in
EObject container = context.eContainer();
while (!(container instanceof Rule))
container = container.eContainer();
Rule rule = (Rule) container;
// Check, if a resource was already created for the rule
Resource res = implicitVariables.get(rule);
if (res == null) {
// Create and register new resource
res =
rule.eResource().getResourceSet()
.createResource(URI.createURI("http://wwwcs.vs.hs-rm.de/OntML/Variable/" + UUID.randomUUID()));
implicitVariables.put(rule, res);
}
// Get the cross ref string
final String crossRefString = getCrossRefNodeAsString(node);
if (crossRefString != null && !crossRefString.equals("")) {
// Search for the variable in the resource
Optional<Variable> existingVar =
res.getContents().stream().map(eobj -> (Variable) eobj).filter(var -> var.getName().equals(crossRefString))
.findAny();
if (!existingVar.isPresent()) {
// Create and register new variable, if the variable does not exist yet
Variable newvar = OntMLFactory.eINSTANCE.createVariable();
newvar.setName(crossRefString);
res.getContents().add(newvar);
}
}
// Add all contents of the resource to the linked objects
linking.addAll(res.getContents());
}
return linking;
}
}
I've debugged the "getLinkedObjects" method and everything seems to work fine, but my editor won't show errors anymore, even though I write invalid code and my compiler gets a null pointer, when invoking the "getName" method of any "Variable". I think it's a problem with the LazyLinker and EMF proxies.
Related
I am trying to make a source generator that would mimic C# anonymous objects, because they are great for when you are manipulating with collections (Select, GroupBy, etc.).
Imagine this code:
class Person {
final String firstName;
final String lastName;
final int age;
Person(this.firstName, this.age, this.lastName);
}
class TestClass {
final _data = [
Person('John', 'Doe', 51),
Person('Jane', 'Doe', 50),
Person('John', 'Smith', 40),
];
void testMethod() {
final map1 = _data.map((p) => _$$1(name: p.firstName, age: p.age));
final map2 = _data.map((p) => _$$2(fullName: '${p.firstName} ${p.lastName}', age: p.age));
}
}
Those _$$x objects are what I want to generate now. I need to somehow find them and find what is being passed into them, so my code generator would generate this:
class _$$1 {
final String name;
final int age;
const _$$1({required this.name, required this.age});
}
class _$$2 {
final String fullName;
final int age;
const _$$1({required this.fullName, required this.age});
}
but I cannot seem to even find method content:
FutureOr<String?> generate(LibraryReader library, BuildStep buildStep) {
for (final clazz in library.classes) {
final method = clazz.methods.first;
method.visitChildren(RecursiveElementVisitor<dynamic>());
}
}
it looks like the MethodElement doesn't have any children? so this doesn't look like the right way.
Is there any other way to find what I need?
A visitor can be used at the lower-level Abstract Syntax Tree to find the _$$x constructor invocations.
The visitor should also visit the whole library rather than just classes as is done in your example, in order to locate top-level usages as well.
The AST does not distinguish between constructor and method invocations, but we can use a series of checks to make sure that the invocation in question is an appropriate target for code generation nonetheless. In a similar fashion, checks can also be put in place to ensure that the invocation is done in a closure.
The following example implements this approach, and leaves you with a map of '_$$x' to MethodInvocations to work with:
FutureOr<String?> generate(LibraryReader library, BuildStep buildStep) {
final libraryElement = libraryReader.element;
final parsedLibraryResult = libraryElement.session
.getParsedLibraryByElement(libraryElement) as ParsedLibraryResult;
final libraryCompilationUnit = parsedLibraryResult.units[0].unit;
final selectorInstantiationLocator = SelectorInstantiationLocator();
libraryCompilationUnit.visitChildren(selectorInstantiationLocator);
final selectorInstantiations =
selectorInstantiationLocator.selectorInstantiations;
// ...
}
class SelectorInstantiationLocator extends RecursiveAstVisitor<void> {
final selectorInstantiations = <String, MethodInvocation>{};
#override
void visitMethodInvocation(MethodInvocation node) {
// Ensure that the invocation is an appropriate target for code generation.
// &= is not used in favour of the short-circuit && operator (https://github.com/dart-lang/language/issues/23).
// Stop if the invocation doesn't match the required prefix.
final className = node.methodName.name;
var isSelectorInstantiation = className.startsWith(r'_$$');
final classIndex = int.tryParse(className.substring(3));
isSelectorInstantiation =
isSelectorInstantiation && (classIndex != null && classIndex >= 0);
// No target will exist for a constructor invocation.
isSelectorInstantiation =
isSelectorInstantiation && node.realTarget == null;
// The selector instantiation should be done in an expression function body (=>).
isSelectorInstantiation =
isSelectorInstantiation && node.parent is ExpressionFunctionBody;
// The function body should be part of a function expression (rather than a method declaration)
isSelectorInstantiation =
isSelectorInstantiation && node.parent!.parent is FunctionExpression;
// The function expression should be inside an argument list.
isSelectorInstantiation =
isSelectorInstantiation && node.parent!.parent!.parent is ArgumentList;
if (isSelectorInstantiation) selectorInstantiations[className] = node;
return super.visitMethodInvocation(node);
}
}
This question already has answers here:
"The operator can’t be unconditionally invoked because the receiver can be null" error after migrating to Dart null-safety
(3 answers)
Closed 12 months ago.
I have migrated my Dart code to NNBD / Null Safety. Some of it looks like this:
class Foo {
String? _a;
void foo() {
if (_a != null) {
_a += 'a';
}
}
}
class Bar {
Bar() {
_a = 'a';
}
String _a;
}
This causes two analysis errors. For _a += 'a';:
An expression whose value can be 'null' must be null-checked before it can be dereferenced.
Try checking that the value isn't 'null' before dereferencing it.
For Bar() {:
Non-nullable instance field '_a' must be initialized.
Try adding an initializer expression, or add a field initializer in this constructor, or mark it 'late'.
In both cases I have already done exactly what the error suggests! What's up with that?
I'm using Dart 2.12.0-133.2.beta (Tue Dec 15).
Edit: I found this page which says:
The analyzer can’t model the flow of your whole application, so it can’t predict the values of global variables or class fields.
But that doesn't make sense to me - there's only one possible flow control path from if (_a != null) to _a += 'a'; in this case - there's no async code and Dart is single-threaded - so it doesn't matter that _a isn't local.
And the error message for Bar() explicitly states the possibility of initialising the field in the constructor.
The problem is that class fields can be overridden even if it is marked as final. The following example illustrates the problem:
class A {
final String? text = 'hello';
String? getText() {
if (text != null) {
return text;
} else {
return 'WAS NULL!';
}
}
}
class B extends A {
bool first = true;
#override
String? get text {
if (first) {
first = false;
return 'world';
} else {
return null;
}
}
}
void main() {
print(A().getText()); // hello
print(B().getText()); // null
}
The B class overrides the text final field so it returns a value the first time it is asked but returns null after this. You cannot write your A class in such a way that you can prevent this form of overrides from being allowed.
So we cannot change the return value of getText from String? to String even if it looks like we checks the text field for null before returning it.
An expression whose value can be 'null' must be null-checked before it can be dereferenced. Try checking that the value isn't 'null' before dereferencing it.
It seems like this really does only work for local variables. This code has no errors:
class Foo {
String? _a;
void foo() {
final a = _a;
if (a != null) {
a += 'a';
_a = a;
}
}
}
It kind of sucks though. My code is now filled with code that just copies class members to local variables and back again. :-/
Non-nullable instance field '_a' must be initialized. Try adding an initializer expression, or add a field initializer in this constructor, or mark it 'late'.
Ah so it turns out a "field initializer" is actually like this:
class Bar {
Bar() : _a = 'a';
String _a;
}
There are few ways to deal with this situation. I've given a detailed answer here so I'm only writing the solutions from it:
Use local variable (Recommended)
void foo() {
var a = this.a; // <-- Local variable
if (a != null) {
a += 'a';
this.a = a;
}
}
Use ??
void foo() {
var a = (this.a ?? '') + 'a';
this.a = a;
}
Use Bang operator (!)
You should only use this solution when you're 100% sure that the variable (a) is not null at the time you're using it.
void foo() {
a = a! + 'a'; // <-- Bang operator
}
To answer your second question:
Non-nullable fields should always be initialized. There are generally three ways of initializing them:
In the declaration:
class Bar {
String a = 'a';
}
In the initializing formal
class Bar {
String a;
Bar({required this.a});
}
In the initializer list:
class Bar {
String a;
Bar(String b) : a = b;
}
You can create your classes in null-safety like this
class JobDoc {
File? docCam1;
File? docCam2;
File? docBarcode;
File? docSignature;
JobDoc({this.docCam1, this.docCam2, this.docBarcode, this.docSignature});
JobDoc.fromJson(Map<String, dynamic> json) {
docCam1 = json['docCam1'] ?? null;
docCam2 = json['docCam2'] ?? null;
docBarcode = json['docBarcode'] ?? null;
docSignature = json['docSignature'] ?? null;
}
}
Given a build definition, I extract the following pieces from it:
m_template = (DynamicActivity)WorkflowHelpers.DeserializeWorkflow(buildDefinition.Process.Parameters);
Properties = m_template.Properties.ToDictionary(p => p.Name, StringComparer.OrdinalIgnoreCase);
Metadata = WorkflowHelpers.GetCombinedMetadata(m_template).ToDictionary(m => m.ParameterName);
m_parameters = WorkflowHelpers.DeserializeProcessParameters(buildDefinition.ProcessParameters)
Now I wish to know the value of an arbitrary process parameter.
My current code is:
public ParameterValue GetParameterValue(string name)
{
object propValue;
var valueType = GetParameterType(name, out propValue);
object value;
if (!m_parameters.TryGetValue(name, out value))
{
value = propValue;
}
return new ParameterValue(valueType, value);
}
private Type GetParameterType(string name, out object value)
{
value = null;
if (Properties != null)
{
DynamicActivityProperty property;
if (Properties.TryGetValue(name, out property))
{
var inArgument = property.Value as InArgument;
if (inArgument != null)
{
if (inArgument.Expression != null)
{
var exprString = inArgument.Expression.ToString();
if (!exprString.StartsWith(": VisualBasicValue<"))
{
value = exprString;
}
}
return inArgument.ArgumentType;
}
if (property.Value != null)
{
value = property.Value;
return property.Value.GetType();
}
var typeName = property.Type.ToString();
if (typeName.StartsWith(IN_ARGUMENT_TYPE_NAME_PREFIX))
{
typeName = typeName.Substring(IN_ARGUMENT_TYPE_NAME_PREFIX.Length, typeName.Length - IN_ARGUMENT_TYPE_NAME_PREFIX.Length - 1);
return Type.GetType(typeName, true);
}
return property.Type;
}
}
return typeof(string);
}
Unfortunately, this code stumbles for parameters satisfying all of the following conditions:
The parameter value is wrapped as InArgument<T>.
T is a non primitive type, for example string[]
The build definition does not override the value inherited from the process template.
What happens is that:
Because the value is non primitive exprString.StartsWith(": VisualBasicValue<") and I do not know how to handle it. Hence propValue is null.
Because the value is not overridden by the build definition !m_parameters.TryGetValue(name, out value) and hence I just return propValue.
As a result my logic returns null. But it is wrong! For example, I have a string[] parameter which has a list of string in the process template, but my logic returns null for the reasons explained.
So, what is the proper way to compute it?
You can use the following code (included in another link) to get value and type of one process parameter:
TfsTeamProjectCollection tfctc = new TfsTeamProjectCollection(new Uri("http://tfsservername:8080/tfs/DefaultCollection"));
IBuildServer bs = tfctc.GetService<IBuildServer>();
IBuildDetail[] builds = bs.QueryBuilds("teamprojectname", "builddefinitionname");
foreach (var build in builds)
{
var buildefinition = build.BuildDefinition;
IDictionary<String, Object> paramValues = WorkflowHelpers.DeserializeProcessParameters(buildefinition.ProcessParameters);
string processParametersValue = paramValues["argument1"].ToString();
Console.WriteLine(processParametersValue);
}
Also have a check on this case: TFS 2010: Why is it not possible to deserialize a Dictionary<string, object> with XamlWriter.Save when I can use XamlReader for deserializing
I am new to the dependency injection pattern and I am having issues getting a new instance of a class from container.Resolve in tinyioc it just keeps returning the same instance rather than a new instance. Now for the code
public abstract class HObjectBase : Object
{
private string _name = String.Empty;
public string Name
{
get
{
return this._name;
}
set
{
if (this._name == string.Empty && value.Length > 0 && value != String.Empty)
this._name = value;
else if (value.Length < 1 && value == String.Empty)
throw new FieldAccessException("Objects names cannot be blank");
else
throw new FieldAccessException("Once the internal name of an object has been set it cannot be changed");
}
}
private Guid _id = new Guid();
public Guid Id
{
get
{
return this._id;
}
set
{
if (this._id == new Guid())
this._id = value;
else
throw new FieldAccessException("Once the internal id of an object has been set it cannot be changed");
}
}
private HObjectBase _parent = null;
public HObjectBase Parent
{
get
{
return this._parent;
}
set
{
if (this._parent == null)
this._parent = value;
else
throw new FieldAccessException("Once the parent of an object has been set it cannot be changed");
}
}
}
public abstract class HZoneBase : HObjectBase
{
public new HObjectBase Parent
{
get
{
return base.Parent;
}
set
{
if (value == null || value.GetType() == typeof(HZoneBase))
{
base.Parent = value;
}
else
{
throw new FieldAccessException("Zones may only have other zones as parents");
}
}
}
private IHMetaDataStore _store;
public HZoneBase(IHMetaDataStore store)
{
this._store = store;
}
public void Save()
{
this._store.SaveZone(this);
}
}
And the derived class is a dummy at the moment but here it is
public class HZone : HZoneBase
{
public HZone(IHMetaDataStore store)
: base(store)
{
}
}
Now since this is meant to be an external library I have a faced class for accessing
everything
public class Hadrian
{
private TinyIoCContainer _container;
public Hadrian(IHMetaDataStore store)
{
this._container = new TinyIoCContainer();
this._container.Register(store);
this._container.AutoRegister();
}
public HZoneBase NewZone()
{
return _container.Resolve<HZoneBase>();
}
public HZoneBase GetZone(Guid id)
{
var metadataStore = this._container.Resolve<IHMetaDataStore>();
return metadataStore.GetZone(id);
}
public List<HZoneBase> ListRootZones()
{
var metadataStore = this._container.Resolve<IHMetaDataStore>();
return metadataStore.ListRootZones();
}
}
However the test is failing because the GetNewZone() method on the Hadrian class keeps returning the same instance.
Test Code
[Fact]
public void ListZones()
{
Hadrian instance = new Hadrian(new MemoryMetaDataStore());
Guid[] guids = { Guid.NewGuid(), Guid.NewGuid(), Guid.NewGuid() };
int cnt = 0;
foreach (Guid guid in guids)
{
HZone zone = (HZone)instance.NewZone();
zone.Id = guids[cnt];
zone.Name = "Testing" + cnt.ToString();
zone.Parent = null;
zone.Save();
cnt++;
}
cnt = 0;
foreach (HZone zone in instance.ListRootZones())
{
Assert.Equal(zone.Id, guids[cnt]);
Assert.Equal(zone.Name, "Testing" + cnt.ToString());
Assert.Equal(zone.Parent, null);
}
}
I know its probably something simple I'm missing with the pattern but I'm not sure, any help would be appreciated.
First, please always simplify the code to what is absolutely necessary to demonstrate the problem, but provide enough that it will actually run; I had to guess what MemoryMetaDataStore does and implement it myself to run the code.
Also, please say where and how stuff fails, to point others straight to the issue. I spent a few minues figuring out that the exception I was getting was your problem and you weren't even getting to the assertions.
That said, container.Resolve<HZoneBase>() will always return the same instance because that's how autoregistration in TinyIoC works - once an abstraction has been resolved, the same instance is always returned for subsequent calls.
To change this, add the following line to the Hadrian constructor:
this._container.Register<HZoneBase, HZone>().AsMultiInstance();
This will tell the container to create a new instance for each resolution request for HZoneBase.
Also, Bassetassen's answer about the Assert part is correct.
In general, if you want to learn DI, you should read Mark Seemann's excellent book "Dependency Injection in .NET" - not quite an easy read as the whole topic is inherently complex, but it's more than worth it and will let you get into it a few years faster than by learning it on your own.
In your assert stage you are not incrementing cnt. You are also using the actual value as the expected one in the assert. This will be confusing, becuase it says something is excpected when it actually is the actual value that is returned.
The assert part should be:
cnt = 0;
foreach (HZone zone in instance.ListRootZones())
{
Assert.Equal(guids[cnt], zone.Id);
Assert.Equal("Testing" + cnt.ToString(), zone.Name);
Assert.Equal(null, zone.Parent);
cnt++;
}
I need to allow my content pipeline extension to use a pattern similar to a factory. I start with a dictionary type:
public delegate T Mapper<T>(MapFactory<T> mf, XElement d);
public class MapFactory<T>
{
Dictionary<string, Mapper<T>> map = new Dictionary<string, Mapper<T>>();
public void Add(string s, Mapper<T> m)
{
map.Add(s, m);
}
public T Get(XElement xe)
{
if (xe == null) throw new ArgumentNullException(
"Invalid document");
var key = xe.Name.ToString();
if (!map.ContainsKey(key)) throw new ArgumentException(
key + " is not a valid key.");
return map[key](this, xe);
}
public IEnumerable<T> GetAll(XElement xe)
{
if (xe == null) throw new ArgumentNullException(
"Invalid document");
foreach (var e in xe.Elements())
{
var val = e.Name.ToString();
if (map.ContainsKey(val))
yield return map[val](this, e);
}
}
}
Here is one type of object I want to store:
public partial class TestContent
{
// Test type
public string title;
// Once test if true
public bool once;
// Parameters
public Dictionary<string, object> args;
public TestContent()
{
title = string.Empty;
args = new Dictionary<string, object>();
}
public TestContent(XElement xe)
{
title = xe.Name.ToString();
args = new Dictionary<string, object>();
xe.ParseAttribute("once", once);
}
}
XElement.ParseAttribute is an extension method that works as one might expect. It returns a boolean that is true if successful.
The issue is that I have many different types of tests, each of which populates the object in a way unique to the specific test. The element name is the key to MapFactory's dictionary. This type of test, while atypical, illustrates my problem.
public class LogicTest : TestBase
{
string opkey;
List<TestBase> items;
public override bool Test(BehaviorArgs args)
{
if (items == null) return false;
if (items.Count == 0) return false;
bool result = items[0].Test(args);
for (int i = 1; i < items.Count; i++)
{
bool other = items[i].Test(args);
switch (opkey)
{
case "And":
result &= other;
if (!result) return false;
break;
case "Or":
result |= other;
if (result) return true;
break;
case "Xor":
result ^= other;
break;
case "Nand":
result = !(result & other);
break;
case "Nor":
result = !(result | other);
break;
default:
result = false;
break;
}
}
return result;
}
public static TestContent Build(MapFactory<TestContent> mf, XElement xe)
{
var result = new TestContent(xe);
string key = "Or";
xe.GetAttribute("op", key);
result.args.Add("key", key);
var names = mf.GetAll(xe).ToList();
if (names.Count() < 2) throw new ArgumentException(
"LogicTest requires at least two entries.");
result.args.Add("items", names);
return result;
}
}
My actual code is more involved as the factory has two dictionaries, one that turns an XElement into a content type to write and another used by the reader to create the actual game objects.
I need to build these factories in code because they map strings to delegates. I have a service that contains several of these factories. The mission is to make these factory classes available to a content processor. Neither the processor itself nor the context it uses as a parameter have any known hooks to attach an IServiceProvider or equivalent.
Any ideas?
I needed to create a data structure essentially on demand without access to the underlying classes as they came from a third party, in this case XNA Game Studio. There is only one way to do this I know of... statically.
public class TestMap : Dictionary<string, string>
{
private static readonly TestMap map = new TestMap();
private TestMap()
{
Add("Logic", "LogicProcessor");
Add("Sequence", "SequenceProcessor");
Add("Key", "KeyProcessor");
Add("KeyVector", "KeyVectorProcessor");
Add("Mouse", "MouseProcessor");
Add("Pad", "PadProcessor");
Add("PadVector", "PadVectorProcessor");
}
public static TestMap Map
{
get { return map; }
}
public IEnumerable<TestContent> Collect(XElement xe, ContentProcessorContext cpc)
{
foreach(var e in xe.Elements().Where(e => ContainsKey(e.Name.ToString())))
{
yield return cpc.Convert<XElement, TestContent>(
e, this[e.Name.ToString()]);
}
}
}
I took this a step further and created content processors for each type of TestBase:
/// <summary>
/// Turns an imported XElement into a TestContent used for a LogicTest
/// </summary>
[ContentProcessor(DisplayName = "LogicProcessor")]
public class LogicProcessor : ContentProcessor<XElement, TestContent>
{
public override TestContent Process(XElement input, ContentProcessorContext context)
{
var result = new TestContent(input);
string key = "Or";
input.GetAttribute("op", key);
result.args.Add("key", key);
var items = TestMap.Map.Collect(input, context);
if (items.Count() < 2) throw new ArgumentNullException(
"LogicProcessor requires at least two items.");
result.args.Add("items", items);
return result;
}
}
Any attempt to reference or access the class such as calling TestMap.Collect will generate the underlying static class if needed. I basically moved the code from LogicTest.Build to the processor. I also carry out any needed validation in the processor.
When I get to reading these classes I will have the ContentService to help.