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/*
* VersionLabel.java July 2008
*
* Copyright (C) 2008, Niall Gallagher
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
* implied. See the License for the specific language governing
* permissions and limitations under the License.
*/
package org.simpleframework.xml.core;
import java.lang.annotation.Annotation;
import org.simpleframework.xml.Version;
import org.simpleframework.xml.strategy.Type;
import org.simpleframework.xml.stream.Format;
import org.simpleframework.xml.stream.Style;
/**
* The VersionLabel object is used convert any double
* retrieved from an XML attribute to a version revision. The version
* is used to determine how to perform serialization of a composite
* by determining version compatibility.
*
* @author Niall Gallagher
*/
class VersionLabel extends TemplateLabel {
/**
* This is the decorator that is associated with the attribute.
*/
private Decorator decorator;
/**
* This contains the details of the annotated contact object.
*/
private Introspector detail;
/**
* This is the path that is used to represent this version.
*/
private Expression path;
/**
* Represents the annotation used to label the field.
*/
private Version label;
/**
* This is used to format the paths associated with this.
*/
private Format format;
/**
* This is the type that the field object references.
*/
private Class type;
/**
* This is the name of the element for this label instance.
*/
private String name;
/**
* This is used to determine if the attribute is required.
*/
private boolean required;
/**
* Constructor for the VersionLabel object. This is
* used to create a label that can convert from a double to an
* XML attribute and vice versa. This requires the annotation and
* contact extracted from the XML schema class.
*
* @param contact this is the field from the XML schema class
* @param label represents the annotation for the field
* @param format this is the format used to style the paths
*/
public VersionLabel(Contact contact, Version label, Format format) {
this.detail = new Introspector(contact, this, format);
this.decorator = new Qualifier(contact);
this.required = label.required();
this.type = contact.getType();
this.name = label.name();
this.format = format;
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 convert an attribute
* to a double value. This requires the context object used for
* the current instance of XML serialization being performed.
*
* @param context this is context object used for serialization
*
* @return this returns the converted for this attribute object
*/
public Converter getConverter(Context context) throws Exception {
String ignore = getEmpty(context);
Type type = getContact();
if(!context.isFloat(type)) {
throw new AttributeException("Cannot use %s to represent %s", label, type);
}
return new Primitive(context, type, ignore);
}
/**
* 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 String 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 {
Style style = format.getStyle();
String name = detail.getName();
return style.getAttribute(name);
}
/**
* This is used to acquire the path of the element or attribute
* that is used by the class schema. The path is determined by
* acquiring the XPath expression and appending the name of the
* label to form a fully qualified path.
*
* @return returns the path that is used for the XML property
*/
public String getPath() throws Exception {
Expression path = getExpression();
String name = getName();
return path.getAttribute(name);
}
/**
* This method is used to return an XPath expression that is
* used to represent the position of this label. If there is no
* XPath expression associated with this then an empty path is
* returned. This will never return a null expression.
*
* @return the XPath expression identifying the location
*/
public Expression getExpression() throws Exception {
if(path == null) {
path = detail.getExpression();
}
return path;
}
/**
* This acquires the annotation associated with this label. This
* is typically the annotation acquired from the field or method.
* However, in the case of unions this will return the actual
* annotation within the union group that this represents.
*
* @return this returns the annotation that this represents
*/
public Annotation getAnnotation() {
return label;
}
/**
* 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 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 persistence. 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 acts as a convenience method used to determine the type of
* the contact this represents. This will be a primitive type of a
* primitive type from the java.lang primitives.
*
* @return this returns the type of the contact class
*/
public Class getType() {
return type;
}
/**
* 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 true;
}
/**
* This is used to determine whether the attribute is required.
* This ensures that if an attribute 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 required;
}
/**
* Because the attribute can contain only simple text values it
* is never required to specified as anything other than text.
* Therefore this will always return false as CDATA does not
* apply to the attribute values.
*
* @return this will always return false for XML attributes
*/
public boolean isData() {
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();
}
}