org.simpleframework.xml.core.ElementLabel Maven / Gradle / Ivy
/*
* ElementLabel.java July 2006
*
* Copyright (C) 2006, Niall Gallagher
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General
* Public License along with this library; if not, write to the
* Free Software Foundation, Inc., 59 Temple Place, Suite 330,
* Boston, MA 02111-1307 USA
*/
package org.simpleframework.xml.core;
import org.simpleframework.xml.Element;
import org.simpleframework.xml.stream.Style;
/**
* The ElementLabel represents a label that is used to
* represent an XML element in a class schema. This element can be
* used to convert an XML node into either a primitive value such as
* a string or composite object value, which is itself a schema for
* a section of XML within the XML document.
*
* @author Niall Gallagher
*
* @see org.simpleframework.xml.Element
*/
class ElementLabel implements Label {
/**
* This is the decorator that is associated with the element.
*/
private Decorator decorator;
/**
* The contact that this element label represents.
*/
private Signature detail;
/**
* References the annotation that was used by the field.
*/
private Element label;
/**
* This is the type of the class that the field references.
*/
private Class type;
/**
* This is the name of the element for this label instance.
*/
private String name;
/**
* Constructor for the ElementLabel object. This is
* used to create a label that can convert a XML node into a
* composite object or a primitive type from an XML element.
*
* @param contact this is the field that this label represents
* @param label this is the annotation for the contact
*/
public ElementLabel(Contact contact, Element label) {
this.detail = new Signature(contact, this);
this.decorator = new Qualifier(contact);
this.type = contact.getType();
this.name = label.name();
this.label = label;
}
/**
* This is used to acquire the Decorator for this.
* A decorator is an object that adds various details to the
* node without changing the overall structure of the node. For
* example comments and namespaces can be added to the node with
* a decorator as they do not affect the deserialization.
*
* @return this returns the decorator associated with this
*/
public Decorator getDecorator() throws Exception {
return decorator;
}
/**
* Creates a converter that can be used to transform an XML node to
* an object and vice versa. The converter created will handles
* only XML elements and requires the context object to be provided.
*
* @param context this is the context object used for serialization
*
* @return this returns a converter for serializing XML elements
*/
public Converter getConverter(Context context) throws Exception {
if(context.isPrimitive(type)) {
return new Primitive(context, type);
}
return new Composite(context, type);
}
/**
* This is used to acquire the name of the element or attribute
* that is used by the class schema. The name is determined by
* checking for an override within the annotation. If it contains
* a name then that is used, if however the annotation does not
* specify a name the the field or method name is used instead.
*
* @param context this is used to provide a styled name
*
* @return returns the name that is used for the XML property
*/
public String getName(Context context) throws Exception{
Style style = context.getStyle();
String name = detail.getName();
return style.getElement(name);
}
/**
* This is used to provide a configured empty value used when the
* annotated value is null. This ensures that XML can be created
* with required details regardless of whether values are null or
* not. It also provides a means for sensible default values.
*
* @param context this is the context object for the serialization
*
* @return this returns the string to use for default values
*/
public Object getEmpty(Context context) {
return null;
}
/**
* This is used to acquire the name of the element or attribute
* that is used by the class schema. The name is determined by
* checking for an override within the annotation. If it contains
* a name then that is used, if however the annotation does not
* specify a name the the field or method name is used instead.
*
* @return returns the name that is used for the XML property
*/
public String getName() throws Exception{
return detail.getName();
}
/**
* This is used to acquire the contact object for this label. The
* contact retrieved can be used to set any object or primitive that
* has been deserialized, and can also be used to acquire values to
* be serialized in the case of object persistance. All contacts
* that are retrieved from this method will be accessible.
*
* @return returns the contact that this label is representing
*/
public Contact getContact() {
return detail.getContact();
}
/**
* This is used to acquire the name of the element or attribute
* as taken from the annotation. If the element or attribute
* explicitly specifies a name then that name is used for the
* XML element or attribute used. If however no overriding name
* is provided then the method or field is used for the name.
*
* @return returns the name of the annotation for the contact
*/
public String getOverride() {
return name;
}
/**
* This acts as a convenience method used to determine the type of
* contact this represents. This is used when an object is written
* to XML. It determines whether a class attribute
* is required within the serialized XML element, that is, if the
* class returned by this is different from the actual value of the
* object to be serialized then that type needs to be remembered.
*
* @return this returns the type of the contact class
*/
public Class getType() {
return type;
}
/**
* This is typically used to acquire the entry value as acquired
* from the annotation. However given that the annotation this
* represents does not have a entry attribute this will always
* provide a null value for the entry string.
*
* @return this will always return null for the entry value
*/
public String getEntry() {
return null;
}
/**
* This is used to acquire the dependent class for this label.
* This returns null as there are no dependents to the element
* annotation as it can only hold primitives with no dependents.
*
* @return this is used to return the dependent type of null
*/
public Class getDependent() {
return null;
}
/**
* This method is used to determine if the label represents an
* attribute. This is used to style the name so that elements
* are styled as elements and attributes are styled as required.
*
* @return this is used to determine if this is an attribute
*/
public boolean isAttribute() {
return false;
}
/**
* This is used to determine if the label is a collection. If the
* label represents a collection then any original assignment to
* the field or method can be written to without the need to
* create a new collection. This allows obscure collections to be
* used and also allows initial entries to be maintained.
*
* @return true if the label represents a collection value
*/
public boolean isCollection() {
return false;
}
/**
* This is used to determine whether the XML element is required.
* This ensures that if an XML element is missing from a document
* that deserialization can continue. Also, in the process of
* serialization, if a value is null it does not need to be
* written to the resulting XML document.
*
* @return true if the label represents a some required data
*/
public boolean isRequired() {
return label.required();
}
/**
* This is used to determine whether the annotation requires it
* and its children to be written as a CDATA block. This is done
* when a primitive or other such element requires a text value
* and that value needs to be encapsulated within a CDATA block.
*
* @return this returns true if the element requires CDATA
*/
public boolean isData() {
return label.data();
}
/**
* This method is used by the deserialization process to check
* to see if an annotation is inline or not. If an annotation
* represents an inline XML entity then the deserialization
* and serialization process ignores overrides and special
* attributes. By default all XML elements are not inline.
*
* @return this always returns false for element labels
*/
public boolean isInline() {
return false;
}
/**
* This is used to describe the annotation and method or field
* that this label represents. This is used to provide error
* messages that can be used to debug issues that occur when
* processing a method. This will provide enough information
* such that the problem can be isolated correctly.
*
* @return this returns a string representation of the label
*/
public String toString() {
return detail.toString();
}
}