Subclasses are responsible for setting this value to false if we'd need to investigate this condition (usually because a child element has been added that is a subclass of DataType).

 protected  void checkAttributesAllowed() 
{
        if (isReference()) {
            throw tooManyAttributes();
        }
}

check that it is ok to set attributes, i.e that no reference is defined

 protected  void checkChildrenAllowed() 
{
        if (isReference()) {
            throw noChildrenAllowed();
        }
}

check that it is ok to add children, i.e that no reference is defined

 protected BuildException circularReference() 
{
        return new BuildException("This data type contains a circular "
            + "reference.");
}

Creates an exception that indicates the user has generated a loop of data types referencing each other.

 public Object clone() throws CloneNotSupportedException 
{
        DataType dt = (DataType) super.clone();
        dt.setDescription(getDescription());
        if (getRefid() != null) {
            dt.setRefid(getRefid());
        }
        dt.setChecked(isChecked());
        return dt;
}

 protected  void dieOnCircularReference() 
{
        dieOnCircularReference(getProject());
}

Convenience method.

 protected  void dieOnCircularReference(Project p) 
{
        if (checked || !isReference()) {
            return;
        }
        dieOnCircularReference(new IdentityStack(this), p);
}

Convenience method.

 protected  void dieOnCircularReference(Stack stack,
    Project project) throws BuildException 
{
        if (checked || !isReference()) {
            return;
        }
        Object o = ref.getReferencedObject(project);
        if (o instanceof DataType) {
            IdentityStack id = IdentityStack.getInstance(stack);
            if (id.contains(o)) {
                throw circularReference();
            } else {
                id.push(o);
                ((DataType) o).dieOnCircularReference(id, project);
                id.pop();
            }
        }
        checked = true;
}

Check to see whether any DataType we hold references to is included in the Stack (which holds all DataType instances that directly or indirectly reference this instance, including this instance itself).

If one is included, throw a BuildException created by circularReference .

This implementation is appropriate only for a DataType that cannot hold other DataTypes as children.

The general contract of this method is that it shouldn't do anything if checked is true and set it to true on exit.

 protected Object getCheckedRef() 
{
        return getCheckedRef(getProject());
}

Performs the check for circular references and returns the referenced object.

 protected Object getCheckedRef(Project p) 
{
        return getCheckedRef(getClass(), getDataTypeName(), p);
}

Performs the check for circular references and returns the referenced object.

 protected Object getCheckedRef(Class requiredClass,
    String dataTypeName) 
{
        return getCheckedRef(requiredClass, dataTypeName, getProject());
}

Performs the check for circular references and returns the referenced object.

 protected Object getCheckedRef(Class requiredClass,
    String dataTypeName,
    Project project) 
{
        if (project == null) {
            throw new BuildException("No Project specified");
        }
        dieOnCircularReference(project);
        Object o = ref.getReferencedObject(project);
        if (!(requiredClass.isAssignableFrom(o.getClass()))) {
            log("Class " + o.getClass() + " is not a subclass of " + requiredClass,
                    Project.MSG_VERBOSE);
            String msg = ref.getRefId() + " doesn\'t denote a " + dataTypeName;
            throw new BuildException(msg);
        }
        return o;
}

Performs the check for circular references and returns the referenced object. This version allows the fallback Project instance to be specified.

 protected String getDataTypeName() 
{
        return ComponentHelper.getElementName(getProject(), this, true);
}

Gets as descriptive as possible a name used for this datatype instance.

 public Reference getRefid() 
{
        return ref;
}

get the reference set on this object

 public static  void invokeCircularReferenceCheck(DataType dt,
    Stack stk,
    Project p) 
{
        dt.dieOnCircularReference(stk, p);
}

Allow DataTypes outside org.apache.tools.ant.types to indirectly call dieOnCircularReference on nested DataTypes.

 protected boolean isChecked() 
{
        return checked;
}

The flag that is used to indicate that circular references have been checked.

 public boolean isReference() 
{
    // CheckStyle:VisibilityModifier ON
        return ref != null;
}

Has the refid attribute of this element been set?

 protected BuildException noChildrenAllowed() 
{
        return new BuildException("You must not specify nested elements "
            + "when using refid");
}

Creates an exception that indicates that this XML element must not have child elements if the refid attribute is set.

 protected  void setChecked(boolean checked) 
{
        this.checked = checked;
}

Set the flag that is used to indicate that circular references have been checked.

 public  void setRefid(Reference ref) 
{
        this.ref = ref;
        checked = false;
}

Set the value of the refid attribute.

Subclasses may need to check whether any other attributes have been set as well or child elements have been created and thus override this method. if they do the must call super.setRefid.

 public String toString() 
{
        String d = getDescription();
        return d == null ? getDataTypeName() : getDataTypeName() + " " + d;
}

Basic DataType toString().

 protected BuildException tooManyAttributes() 
{
        return new BuildException("You must not specify more than one "
            + "attribute when using refid");
}

Creates an exception that indicates that refid has to be the only attribute if it is set.