protected String toStringExpression(JType type, String expr) {
    if (type.isPrimitive() != null) {
      return "\"\"+" + expr;
    }
    if (STRING_TYPE == type) {
      return expr;
    }
    if (type.isClass() != null && isOverlayArrayType(type.isClass())) {
      return "(new " + JSON_ARRAY_CLASS + "(" + expr + ")).toString()";
    }
    if (type.isClass() != null && OVERLAY_VALUE_TYPE.isAssignableFrom(type.isClass())) {
      return "(new " + JSON_OBJECT_CLASS + "(" + expr + ")).toString()";
    }

    return String.format("(%s != null ? %s.toString() : null)", expr, expr);
  }
  protected String toFormStringExpression(JParameter argument, Style classStyle)
      throws UnableToCompleteException {
    JType type = argument.getType();
    String expr = argument.getName();

    if (type.isPrimitive() != null) {
      return "\"\"+" + expr;
    }
    if (STRING_TYPE == type) {
      return expr;
    }
    if (type.isClass() != null && isOverlayArrayType(type.isClass())) {
      return "(new " + JSON_ARRAY_CLASS + "(" + expr + ")).toString()";
    }
    if (type.isClass() != null && OVERLAY_VALUE_TYPE.isAssignableFrom(type.isClass())) {
      return "(new " + JSON_OBJECT_CLASS + "(" + expr + ")).toString()";
    }
    if (type.getQualifiedBinaryName().startsWith("java.lang.")) {
      return String.format("(%s != null ? %s.toString() : null)", expr, expr);
    }

    Json jsonAnnotation = argument.getAnnotation(Json.class);
    final Style style = jsonAnnotation != null ? jsonAnnotation.style() : classStyle;

    return locator.encodeExpression(type, expr, style) + ".toString()";
  }
  private void buildMethodInterceptor(
      JDefinedClass definedClass,
      ConstructorInjectionPoint proxyConstructorInjectionPoint,
      JMethod constructor,
      JBlock constructorBody,
      Map<ASTMethod, Map<InjectionNode, JFieldVar>> interceptorFields,
      Map.Entry<ASTMethod, Set<InjectionNode>> methodInterceptorEntry)
      throws ClassNotFoundException {
    ASTMethod method = methodInterceptorEntry.getKey();

    if (method.getAccessModifier().equals(ASTAccessModifier.PRIVATE)) {
      throw new TransfuseAnalysisException("Unable to provide AOP on private methods");
    }

    if (!interceptorFields.containsKey(methodInterceptorEntry.getKey())) {
      interceptorFields.put(
          methodInterceptorEntry.getKey(), new HashMap<InjectionNode, JFieldVar>());
    }
    Map<InjectionNode, JFieldVar> injectionNodeInstanceNameMap =
        interceptorFields.get(methodInterceptorEntry.getKey());

    // setup interceptor fields
    for (InjectionNode interceptorInjectionNode : methodInterceptorEntry.getValue()) {
      String interceptorInstanceName = namer.generateName(interceptorInjectionNode);

      JFieldVar interceptorField =
          definedClass.field(
              JMod.PRIVATE,
              codeModel.ref(interceptorInjectionNode.getClassName()),
              interceptorInstanceName);

      injectionNodeInstanceNameMap.put(interceptorInjectionNode, interceptorField);

      JVar interceptorParam =
          constructor.param(
              codeModel.ref(interceptorInjectionNode.getClassName()),
              namer.generateName(interceptorInjectionNode));

      constructorBody.assign(interceptorField, interceptorParam);

      proxyConstructorInjectionPoint.addInjectionNode(interceptorInjectionNode);
    }

    JType returnType = codeModel.parseType(method.getReturnType().getName());

    JMethod methodDeclaration =
        definedClass.method(
            method.getAccessModifier().getCodeModelJMod(), returnType, method.getName());
    JBlock body = methodDeclaration.body();

    // define method parameter
    Map<ASTParameter, JVar> parameterMap = new HashMap<ASTParameter, JVar>();
    for (ASTParameter parameter : method.getParameters()) {
      parameterMap.put(
          parameter,
          methodDeclaration.param(
              JMod.FINAL,
              codeModel.ref(parameter.getASTType().getName()),
              namer.generateName(parameter.getASTType())));
    }

    // aop interceptor
    Map<InjectionNode, JFieldVar> interceptorNameMap =
        interceptorFields.get(methodInterceptorEntry.getKey());

    JArray paramArray = JExpr.newArray(codeModel.ref(Object.class));

    for (ASTParameter astParameter : method.getParameters()) {
      paramArray.add(parameterMap.get(astParameter));
    }

    JInvocation interceptorInvocation =
        buildInterceptorChain(
                definedClass,
                method,
                parameterMap,
                methodInterceptorEntry.getValue(),
                interceptorNameMap)
            .invoke("invoke");
    interceptorInvocation.arg(paramArray);

    if (method.getReturnType().equals(ASTVoidType.VOID)) {
      body.add(interceptorInvocation);
    } else {
      body._return(JExpr.cast(returnType.boxify(), interceptorInvocation));
    }
  }