@NotNull
 public static Object[] getReferenceVariantsByFilter(
     @NotNull PsiJavaCodeReferenceElement reference, @NotNull ElementFilter filter) {
   FilterScopeProcessor processor = new FilterScopeProcessor(filter);
   PsiScopesUtil.resolveAndWalk(processor, reference, null, true);
   return processor.getResults().toArray();
 }
  private static void addAvailableMethodsOfType(
      final PsiClassType type,
      final PsiLiteralExpression context,
      final Collection<String> result) {
    PsiScopesUtil.treeWalkUp(
        new PsiScopeProcessor() {
          @Override
          public boolean execute(@NotNull PsiElement element, @NotNull ResolveState state) {
            if (element instanceof PsiMethod) {
              PsiMethod method = (PsiMethod) element;
              PsiType returnType = method.getReturnType();
              if (returnType != null
                  && TypeConversionUtil.isAssignable(type, returnType)
                  && method.getParameterList().getParametersCount() == 0) {
                result.add(method.getName() + "()");
              }
            }
            return true;
          }

          @Override
          public <T> T getHint(@NotNull Key<T> hintKey) {
            return null;
          }

          @Override
          public void handleEvent(@NotNull Event event, Object associated) {}
        },
        context,
        null);
  }
  @Nullable
  public static PsiType getQualifiedMemberReferenceType(
      @Nullable PsiType qualifierType, @NotNull final PsiMember member) {
    final Ref<PsiSubstitutor> subst = Ref.create(PsiSubstitutor.EMPTY);
    class MyProcessor extends BaseScopeProcessor implements NameHint, ElementClassHint {
      @Override
      public boolean execute(@NotNull PsiElement element, @NotNull ResolveState state) {
        if (element == member) {
          subst.set(state.get(PsiSubstitutor.KEY));
        }
        return true;
      }

      @Override
      public String getName(@NotNull ResolveState state) {
        return member.getName();
      }

      @Override
      public boolean shouldProcess(DeclarationKind kind) {
        return member instanceof PsiEnumConstant
            ? kind == DeclarationKind.ENUM_CONST
            : member instanceof PsiField
                ? kind == DeclarationKind.FIELD
                : kind == DeclarationKind.METHOD;
      }

      @Override
      public <T> T getHint(@NotNull Key<T> hintKey) {
        return hintKey == NameHint.KEY || hintKey == ElementClassHint.KEY ? (T) this : null;
      }
    }

    PsiScopesUtil.processTypeDeclarations(qualifierType, member, new MyProcessor());

    PsiType rawType =
        member instanceof PsiField
            ? ((PsiField) member).getType()
            : member instanceof PsiMethod
                ? ((PsiMethod) member).getReturnType()
                : JavaPsiFacade.getElementFactory(member.getProject())
                    .createType((PsiClass) member);
    return subst.get().substitute(rawType);
  }
  @Nullable
  private static PsiExpression createDefaultValue(
      JavaChangeInfo changeInfo,
      final PsiElementFactory factory,
      final JavaParameterInfo info,
      final PsiExpressionList list)
      throws IncorrectOperationException {
    if (info.isUseAnySingleVariable()) {
      final PsiResolveHelper resolveHelper =
          JavaPsiFacade.getInstance(list.getProject()).getResolveHelper();
      final PsiType type = info.getTypeWrapper().getType(changeInfo.getMethod(), list.getManager());
      final VariablesProcessor processor =
          new VariablesProcessor(false) {
            protected boolean check(PsiVariable var, ResolveState state) {
              if (var instanceof PsiField
                  && !resolveHelper.isAccessible((PsiField) var, list, null)) return false;
              if (var instanceof PsiLocalVariable
                  && list.getTextRange().getStartOffset() <= var.getTextRange().getStartOffset())
                return false;
              if (PsiTreeUtil.isAncestor(var, list, false)) return false;
              final PsiType varType = state.get(PsiSubstitutor.KEY).substitute(var.getType());
              return type.isAssignableFrom(varType);
            }

            public boolean execute(PsiElement pe, ResolveState state) {
              super.execute(pe, state);
              return size() < 2;
            }
          };
      PsiScopesUtil.treeWalkUp(processor, list, null);
      if (processor.size() == 1) {
        final PsiVariable result = processor.getResult(0);
        return factory.createExpressionFromText(result.getName(), list);
      }
      if (processor.size() == 0) {
        final PsiClass parentClass = PsiTreeUtil.getParentOfType(list, PsiClass.class);
        if (parentClass != null) {
          PsiClass containingClass = parentClass;
          final Set<PsiClass> containingClasses = new HashSet<PsiClass>();
          while (containingClass != null) {
            if (type.isAssignableFrom(factory.createType(containingClass, PsiSubstitutor.EMPTY))) {
              containingClasses.add(containingClass);
            }
            containingClass = PsiTreeUtil.getParentOfType(containingClass, PsiClass.class);
          }
          if (containingClasses.size() == 1) {
            return RefactoringUtil.createThisExpression(
                parentClass.getManager(),
                containingClasses.contains(parentClass)
                    ? null
                    : containingClasses.iterator().next());
          }
        }
      }
    }
    final PsiCallExpression callExpression =
        PsiTreeUtil.getParentOfType(list, PsiCallExpression.class);
    final String defaultValue = info.getDefaultValue();
    return callExpression != null
        ? info.getValue(callExpression)
        : defaultValue.length() > 0 ? factory.createExpressionFromText(defaultValue, list) : null;
  }
 protected boolean processUnqualifiedVariants(final PsiScopeProcessor processor) {
   return PsiScopesUtil.treeWalkUp(processor, this, null);
 }