content: /*
   * Context.java July 2006
   *
   * Copyright (C) 2006, Niall Gallagher <niallg@users.sf.net>
   *
   * 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 com.aliyun.odps.simpleframework.xml.core;
  
  import com.aliyun.odps.simpleframework.xml.Version;
  import com.aliyun.odps.simpleframework.xml.strategy.Strategy;
  import com.aliyun.odps.simpleframework.xml.strategy.Type;
  import com.aliyun.odps.simpleframework.xml.strategy.Value;
  import com.aliyun.odps.simpleframework.xml.stream.InputNode;
  import com.aliyun.odps.simpleframework.xml.stream.OutputNode;
  import com.aliyun.odps.simpleframework.xml.stream.Style;
  
  /**
   * The <code>Context</code> object acts as a contextual object that is
   * used to store all information regarding an instance of serialization
   * or deserialization. This maintains the <code>Strategy</code> as
   * well as the <code>Filter</code> 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.
   * <p>
   * For serialization the source object is required as a factory for
   * <code>Schema</code> 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 <code>Map</code> object.
   * <p>
   * When deserializing the source object provides the contextual data
   * used to replace template variables extracted from the XML source.
   * This is performed using the <code>Filter</code> object. Also, as 
   * in serialization it acts as a factory for the <code>Schema</code> 
   * objects used to examine the serializable fields of an object.
   * 
   * @author Niall Gallagher
   * 
   * @see Strategy
   */ 
  interface Context {
     
     /**
      * 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
      */
     boolean isStrict();
     
     /**
      * This is used to acquire the <code>Style</code> 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
      */
     Style getStyle();
     
     /**
      * This is used to acquire the <code>Session</code> 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
      */
     Session getSession();
     
     /**
      * This is used to acquire the <code>Support</code> 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
      */
     Support getSupport();
     
     /**
      * 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
      */
     boolean isFloat(Class type) throws Exception;
     
     /**
      * 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
      */
     boolean isFloat(Type type) throws Exception;
     
     /**
      * 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
      */
     boolean isPrimitive(Class type) throws Exception;  
     
     /**
      * 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
      */
     boolean isPrimitive(Type type) throws Exception;   
     
     /**
      * This will create an <code>Instance</code> 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
      */
     Instance getInstance(Value value);
  
     /**
      * This will create an <code>Instance</code> 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
      */
     Instance getInstance(Class type);
     
     /**
      * This is used to acquire the name of the specified type using
      * the <code>Root</code> 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
      * 
      * @throws Exception if the class contains an illegal schema
      */
     String getName(Class type) throws Exception;
     
     /**
      * This is used to acquire the <code>Caller</code> 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
      */
     Caller getCaller(Class type) throws Exception;
     
     /**
      * 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
      */
     Version getVersion(Class type) throws Exception;
     
     /**
      * This will acquire the <code>Decorator</code> 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
      */
     Decorator getDecorator(Class type) throws Exception;
  
     /**
      * This creates a <code>Schema</code> 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 
      */   
     Schema getSchema(Class type) throws Exception;
     
     /**
      * 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  
      */
     Value getOverride(Type type, InputNode node) throws Exception;
  
     /**    
      * 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
      */
     boolean setOverride(Type type, Object value, OutputNode node) throws Exception;
     
     /**
      * 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
      */
     Class getType(Type type, Object value);
  
     /**
      * 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
      */     
     Object getAttribute(Object key);
     
     /**
      * 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 <code>Filter</code> is is left unchanged.  
      * 
      * @param text this is processed by the template engine object
      * 
      * @return this returns the text will all variables replaced
      */
     String getProperty(String text);
  }
  