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/*
* Source.java July 2006
*
* Copyright (C) 2006, 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 org.simpleframework.xml.Version;
import org.simpleframework.xml.filter.Filter;
import org.simpleframework.xml.strategy.Type;
import org.simpleframework.xml.strategy.Strategy;
import org.simpleframework.xml.strategy.Value;
import org.simpleframework.xml.stream.InputNode;
import org.simpleframework.xml.stream.NodeMap;
import org.simpleframework.xml.stream.OutputNode;
import org.simpleframework.xml.stream.Style;
/**
* The Source object acts as a contextual object that is
* used to store all information regarding an instance of serialization
* or deserialization. This maintains the Strategy as
* well as the Filter used to replace template variables.
* When serialization and deserialization are performed the source is
* required as it acts as a factory for objects used in the process.
*
* For serialization the source object is required as a factory for
* Schema objects, which are used to visit each field
* in the class that can be serialized. Also this can be used to get
* any data entered into the session Map object.
*
* When deserializing the source object provides the contextual data
* used to replace template variables extracted from the XML source.
* This is performed using the Filter object. Also, as
* in serialization it acts as a factory for the Schema
* objects used to examine the serializable fields of an object.
*
* @author Niall Gallagher
*/
class Source implements Context {
/**
* This is used to replace variables within the XML source.
*/
private TemplateEngine engine;
/**
* This is the strategy used to resolve the element classes.
*/
private Strategy strategy;
/**
* This support is used to convert the strings encountered.
*/
private Support support;
/**
* This is used to store the source context attribute values.
*/
private Session session;
/**
* This is the filter used by this object for templating.
*/
private Filter filter;
/**
* Constructor for the Source object. This is used to
* maintain a context during the serialization process. It holds
* the Strategy and Context used in the
* serialization process. The same source instance is used for
* each XML element evaluated in a the serialization process.
*
* @param strategy this is used to resolve the classes used
* @param support this is the context used to process strings
* @param session this is the session to use for this context
*/
public Source(Strategy strategy, Support support, Session session) {
this.filter = new TemplateFilter(this, support);
this.engine = new TemplateEngine(filter);
this.strategy = strategy;
this.support = support;
this.session = session;
}
/**
* This is used to determine if the deserialization mode is strict
* or not. If this is not strict then deserialization will be done
* in such a way that additional elements and attributes can be
* ignored. This allows external XML formats to be used without
* having to match the object structure to the XML fully.
*
* @return this returns true if the deserialization is strict
*/
public boolean isStrict() {
return session.isStrict();
}
/**
* This is used to acquire the Session object that
* is used to store the values used within the serialization
* process. This provides the internal map that is passed to all
* of the call back methods so that is can be populated.
*
* @return this returns the session that is used by this source
*/
public Session getSession() {
return session;
}
/**
* This is used to acquire the Support object.
* The support object is used to translate strings to and from
* their object representations and is also used to convert the
* strings to their template values. This is the single source
* of translation for all of the strings encountered.
*
* @return this returns the support used by the context
*/
public Support getSupport() {
return support;
}
/**
* This is used to acquire the Style for the format.
* If no style has been set a default style is used, which does
* not modify the attributes and elements that are used to build
* the resulting XML document.
*
* @return this returns the style used for this format object
*/
public Style getStyle() {
return support.getStyle();
}
/**
* This is used to determine if the type specified is a floating
* point type. Types that are floating point are the double and
* float primitives as well as the java types for this primitives.
*
* @param type this is the type to determine if it is a float
*
* @return this returns true if the type is a floating point
*/
public boolean isFloat(Class type) throws Exception {
return support.isFloat(type);
}
/**
* This is used to determine if the type specified is a floating
* point type. Types that are floating point are the double and
* float primitives as well as the java types for this primitives.
*
* @param type this is the type to determine if it is a float
*
* @return this returns true if the type is a floating point
*/
public boolean isFloat(Type type) throws Exception {
return isFloat(type.getType());
}
/**
* This is used to determine whether the scanned class represents
* a primitive type. A primitive type is a type that contains no
* XML annotations and so cannot be serialized with an XML form.
* Instead primitives a serialized using transformations.
*
* @param type this is the type to determine if it is primitive
*
* @return this returns true if no XML annotations were found
*/
public boolean isPrimitive(Class type) throws Exception {
return support.isPrimitive(type);
}
/**
* This is used to determine whether the scanned type represents
* a primitive type. A primitive type is a type that contains no
* XML annotations and so cannot be serialized with an XML form.
* Instead primitives a serialized using transformations.
*
* @param type this is the type to determine if it is primitive
*
* @return this returns true if no XML annotations were found
*/
public boolean isPrimitive(Type type) throws Exception {
return isPrimitive(type.getType());
}
/**
* This will create an Instance that can be used
* to instantiate objects of the specified class. This leverages
* an internal constructor cache to ensure creation is quicker.
*
* @param type this is the type that is to be instantiated
*
* @return this will return an object for instantiating objects
*/
public Instance getInstance(Class type) {
return support.getInstance(type);
}
/**
* This will create an Instance that can be used
* to instantiate objects of the specified class. This leverages
* an internal constructor cache to ensure creation is quicker.
*
* @param value this contains information on the object instance
*
* @return this will return an object for instantiating objects
*/
public Instance getInstance(Value value) {
return support.getInstance(value);
}
/**
* This is used to acquire the name of the specified type using
* the Root annotation for the class. This will
* use either the name explicitly provided by the annotation or
* it will use the name of the class that the annotation was
* placed on if there is no explicit name for the root.
*
* @param type this is the type to acquire the root name for
*
* @return this returns the name of the type from the root
*/
public String getName(Class type) throws Exception {
return support.getName(type);
}
/**
* This returns the version for the type specified. The version is
* used to determine how the deserialization process is performed.
* If the version of the type is different from the version for
* the XML document, then deserialization is done in a best effort.
*
* @param type this is the type to acquire the version for
*
* @return the version that has been set for this XML schema class
*/
public Version getVersion(Class type) throws Exception {
return getScanner(type).getRevision();
}
/**
* This creates a Scanner object that can be used to
* examine the fields within the XML class schema. The scanner
* maintains information when a field from within the scanner is
* visited, this allows the serialization and deserialization
* process to determine if all required XML annotations are used.
*
* @param type the schema class the scanner is created for
*
* @return a scanner that can maintains information on the type
*
* @throws Exception if the class contains an illegal schema
*/
private Scanner getScanner(Class type) throws Exception {
return support.getScanner(type);
}
/**
* This will acquire the Decorator for the type.
* 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.
*
* @param type this is the type to acquire the decorator for
*
* @return this returns the decorator associated with this
*/
public Decorator getDecorator(Class type) throws Exception {
return getScanner(type).getDecorator();
}
/**
* This is used to acquire the Caller object. This
* is used to call the callback methods within the object. If the
* object contains no callback methods then this will return an
* object that does not invoke any methods that are invoked.
*
* @param type this is the type to acquire the caller for
*
* @return this returns the caller for the specified type
*/
public Caller getCaller(Class type) throws Exception {
return getScanner(type).getCaller(this);
}
/**
* This creates a Schema object that can be used to
* examine the fields within the XML class schema. The schema
* maintains information when a field from within the schema is
* visited, this allows the serialization and deserialization
* process to determine if all required XML annotations are used.
*
* @param type the schema class the schema is created for
*
* @return a new schema that can track visits within the schema
*
* @throws Exception if the class contains an illegal schema
*/
public Schema getSchema(Class type) throws Exception {
Scanner schema = getScanner(type);
if(schema == null) {
throw new PersistenceException("Invalid schema class %s", type);
}
return new ClassSchema(schema, this);
}
/**
* This is used to acquire the attribute mapped to the specified
* key. In order for this to return a value it must have been
* previously placed into the context as it is empty by default.
*
* @param key this is the name of the attribute to retrieve
*
* @return this returns the value mapped to the specified key
*/
public Object getAttribute(Object key) {
return session.get(key);
}
/**
* This is used to resolve and load a class for the given element.
* The class should be of the same type or a subclass of the class
* specified. It can be resolved using the details within the
* provided XML element, if the details used do not represent any
* serializable values they should be removed so as not to disrupt
* the deserialization process. For example the default strategy
* removes all "class" attributes from the given elements.
*
* @param type this is the type of the root element expected
* @param node this is the element used to resolve an override
*
* @return returns the type that should be used for the object
*
* @throws Exception thrown if the class cannot be resolved
*/
public Value getOverride(Type type, InputNode node) throws Exception {
NodeMap map = node.getAttributes();
if(map == null) {
throw new PersistenceException("No attributes for %s", node);
}
return strategy.read(type, map, session);
}
/**
* This is used to attach elements or attributes to the given
* element during the serialization process. This method allows
* the strategy to augment the XML document so that it can be
* deserialized using a similar strategy. For example the
* default strategy adds a "class" attribute to the element.
*
* @param type this is the field type for the associated value
* @param value this is the instance variable being serialized
* @param node this is the element used to represent the value
*
* @return this returns true if serialization has complete
*
* @throws Exception thrown if the details cannot be set
*/
public boolean setOverride(Type type, Object value, OutputNode node) throws Exception {
NodeMap map = node.getAttributes();
if(map == null) {
throw new PersistenceException("No attributes for %s", node);
}
return strategy.write(type, value, map, session);
}
/**
* This is used to determine the type of an object given the
* source instance. To provide a best match approach this will
* first attempt to get the value for the actual instance, if
* however the instance is null the type is delegated to.
*
* @param type this is the type used in the serialization
* @param value this is the source instance being used
*
* @return the best match given the criteria
*/
public Class getType(Type type, Object value) {
if(value != null) {
return value.getClass();
}
return type.getType();
}
/**
* Replaces any template variables within the provided string.
* This is used in the deserialization process to replace
* variables with system properties, environment variables, or
* used specified mappings. If a template variable does not have
* a mapping from the Filter is is left unchanged.
*
* @param text this is processed by the template engine object
*
* @return this returns the text will all variables replaced
*/
public String getProperty(String text) {
return engine.process(text);
}
}