FieldDeclaration - add attribute to a class

[Andrea Poli]

Hi, I'm writing a method which converts java static blocks inside a class
declaration into a new static method. The body of this method is composed of:
(1) an if statement which checks if the method has been already called
(2) pieces of code of static blocks

I have to add a bool static attribute in order to write (1).

To add a static attribute I perform the following steps:
1. creating a FieldDeclaration using createFieldDeclaration(TypeReference, Identifier) of factory class

ProgramFactory factory = clazz.getFactory();
String boolTypeName = clazz.getProgramModelInfo().getServiceConfiguration().ge
tNameInfo().getBooleanType().getName();
TypeReference boolType =
factory.createTypeReference(factory.createIdentifier(boolTypeName));

FieldDeclaration flag = factory.createFieldDeclaration(boolType, new
Identifier("static_initializer_flag"));

1. adding STATIC and PROTECTED to the FieldDeclarationSpecifier

ASTList<DeclarationSpecifier> decs = new
ASTArrayList<DeclarationSpecifier>();
decs.add(factory.createStatic());
decs.add(factory.createProtected());
flag.setDeclarationSpecifiers(decs);

1. adding FieldDeclaration to class members

clazz.addVariableToScope(flag.getVariables().get(0));
clazz.getMembers().add(flag);
clazz.makeParentRoleValid();

or

Transformation.doAttach(flag, clazz, 0);

1. updating the model

ChangeHistory changeHistory =
clazz.getProgramModelInfo().getServiceConfiguration().getChangeHistory();

changeHistory.attached(flag);
changeHistory.commit();
changeHistory.updateModel();

clazz is the ClassDeclaration related to the class where I want to add the
static attribute.

When the program executes I receive this execption when it tries to perform
step (4):

Unexpected error: java.lang.NullPointerException. End.
java.lang.NullPointerException
at recoder.service.DefaultSourceInfo.getVariable(DefaultSourceInfo.java:1656)
at recoder.service.DefaultSourceInfo.getField(DefaultSourceInfo.java:1756)
at recoder.service.DefaultSourceInfo.getVariable(DefaultSourceInfo.java:1796)
at recoder.service.DefaultCrossReferenceSourceInfo.analyzeReferences(DefaultCr
ossReferenceSourceInfo.java:599)
at recoder.service.DefaultCrossReferenceSourceInfo.reset(DefaultCrossReference
SourceInfo.java:705)
at recoder.service.DefaultCrossReferenceSourceInfo.modelChanged(DefaultCrossRe
ferenceSourceInfo.java:214)
at recoder.service.ChangeHistory.updateModel(ChangeHistory.java:500)
at ....IClassMethodFactory$StaticBlockAggregator.createMethod(IClassMethodFact
ory.java:147)

I'm doing something wrong but I don't understand what :-) Thanks.

[Tobias Gutzmann]

Hej,

it looks to me that parent links are not set. All program elements need to
have a link to their parent NonTerminalProgramElement set.
Four ways of doing it:
1. call "makeParentRoleValid" on everything where you add (I recommend that)
2. call set(Parent|StatementContainer) etc. for each element that has a new parent (not recommend, tedious and methods setting the parents have different names in different classes)
3. call CompilationUnit.makeAllParentRolesValid() - this will set the parent links for the entire AST. Good for testing if that's the case, but not necessarily the most performant way.
4. use Transformation.(doAttach|doReplace) - they should take care of setting proper parent links.

Regards,
Tobias

[Andrea Poli]

I created a subclass, XALTransformation, of recoder.kit.Transformation which
implements the following methods:

    public void attach(FieldDeclaration field, ClassDeclaration clazz){
        if (field == null || clazz == null)
            throw new IllegalArgumentException("field and clazz can't be null");
        this.attach(field, clazz, 0);
    }

    public void attach(MethodDeclaration method, ClassDeclaration clazz){
        if (method == null || clazz == null)
            throw new IllegalArgumentException("field and clazz can't be null");

        this.attach(method, clazz, 0);
    }

Then I wrote the following code to add a method to a class:

                /* other code ... */
                body.makeAllParentRolesValid();

        MethodDeclaration md = factory.createMethodDeclaration(modifiers, returnType, id, parameters, exceptions, body);

        md.setProgramModelInfo(clazz.getProgramModelInfo());
        md.setFactory((JavaProgramFactory) factory);
        md.makeAllParentRolesValid();

        XALTransformation t = new XALTransformation((CrossReferenceServiceConfiguration) clazz.getProgramModelInfo().getServiceConfiguration());

        t.attach(md, clazz);

        ChangeHistory changeHistory = clazz.getProgramModelInfo().getServiceConfiguration().getChangeHistory();

        try{
            changeHistory.begin(t);
            t.execute();
            changeHistory.updateModel();
            changeHistory.commit();
        }catch(Exception e){
            changeHistory.rollback(t);
            this.log(e, md.getName());
            return null;
        }

I added only an If and some CopyAssignment statement to method body. Every
time an If or a CopyAssignment is created the method makeAllParentRolesValid()
is called on it.

Using this code I can't still add methods to certain classes receiving an
error during updateModel call.

Thanks a lot :-)

[Andrea Poli]

I found that the error related to the model update depends on the following
TypingException:

inner type has type arguments, but the outer does not.

which is thrown after the following statement has been analyzed:

for (Map.Entry<String, Object> e : namedList.entrySet()) { ...

namedList is correctly declared previously:

protected Map<String, Object> namedList = new LinkedHashMap<String, Object>();

The TypingException is thrown inside the checkRawTypeOk method,
recoder.service.SemanticsChecker.

                    if (!trType.isStatic() && rpType instanceof ErasedType) {
                        errorHandler.reportError(
                                new TypingException(
                                        "inner type has type arguments, but the outer does not.",null));
                    }

[Tobias Gutzmann]

It's a bug. Fixed in SVN / next release.

[Andrea Poli]

Thanks. :-)