content: /*
   * ClassInstantiator.java December 2009
   *
   * Copyright (C) 2009, 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 java.util.ArrayList;
  import java.util.List;
  
  /**
   * The <code>ClassInstantiator</code> is used for instantiating 
   * objects using either the default no argument constructor or one
   * that takes deserialized values as parameters. This also exposes 
   * the parameters and constructors used to instantiate the object.
   * 
   * @author Niall Gallagher
   */
  class ClassInstantiator implements Instantiator {
     
     /**
      * This contains a list of all the creators for the class.
      */
     private final List<Creator> creators;  
     
     /**
      * This is used to acquire a parameter by the parameter name.
      */
     private final ParameterMap registry;
     
     /**
      * This represents the default no argument constructor used.
      */
     private final Creator primary;
  
     /**
      * This contains the details for the class to instantiate.
      */
     private final Detail detail;
     
     /**
      * Constructor for the <code>ClassCreator</code> object. This is
      * used to create an object that contains all information that
      * relates to the construction of an instance. 
      * 
      * @param creators contains the list of all constructors available
      * @param primary this is the default no argument constructor
      * @param registry contains all parameters for the constructors
      * @param detail contains the details for the instantiated class
      */
     public ClassInstantiator(List<Creator> creators, Creator primary, ParameterMap registry, Detail detail) {
        this.creators = creators;
        this.registry = registry;
        this.primary = primary;
        this.detail = detail;
     }
  
     /**
      * This is used to determine if this <code>Creator</code> has a
      * default constructor. If the class does contain a no argument
      * constructor then this will return true.
      * 
      * @return true if the class has a default constructor
      */
     public boolean isDefault() {
        int count = creators.size();
        
        if(count <= 1) {
           return primary != null;
        }
        return false;
     }
     
     /**
      * This is used to instantiate the object using the default no
      * argument constructor. If for some reason the object can not be
      * instantiated then this will throw an exception with the reason.
      * 
      * @return this returns the object that has been instantiated
      */
     public Object getInstance() throws Exception {
        return primary.getInstance();
     }
     
     /**
      * This is used to instantiate the object using a constructor that
      * takes deserialized objects as arguments. The object that have
      * been deserialized can be taken from the <code>Criteria</code>
      * object which contains the deserialized values.
      * 
      * @param criteria this contains the criteria to be used
      * 
      * @return this returns the object that has been instantiated
      */
     public Object getInstance(Criteria criteria) throws Exception {
        Creator creator = getCreator(criteria);
        
        if(creator == null) {
           throw new PersistenceException("Constructor not matched for %s", detail);
        }
        return creator.getInstance(criteria);
     }
     
     /**
      * This is used to acquire an <code>Instantiator</code> which is used
      * to instantiate the object. If there is no match for the instantiator
      * then the default constructor is provided.
      * 
      * @param criteria this contains the criteria to be used for this
      * 
      * @return this returns the instantiator that has been matched
      */
     private Creator getCreator(Criteria criteria) throws Exception {
        Creator result = primary;
        double max = 0.0;
        
        for(Creator instantiator : creators) {
           double score = instantiator.getScore(criteria);
           
           if(score > max) {
              result = instantiator;
              max = score;
           }
        }
        return result;
     }
  
     /**
      * This is used to acquire the named <code>Parameter</code> from
      * the creator. A parameter is taken from the constructor which
      * contains annotations for each object that is required. These
      * parameters must have a matching field or method.
      * 
      * @param name this is the name of the parameter to be acquired
      * 
      * @return this returns the named parameter for the creator
      */
     public Parameter getParameter(String name) {
        return registry.get(name);
     }
     
     /**
      * This is used to acquire all parameters annotated for the class
      * schema. Providing all parameters ensures that they can be
      * validated against the annotated methods and fields to ensure
      * that each parameter is valid and has a corresponding match.
      * 
      * @return this returns the parameters declared in the schema     
      */
     public List<Parameter> getParameters() {
        return registry.getAll();
     }
     
     /**
      * This is used to acquire all of the <code>Instantiator</code> 
      * objects used to create an instance of the object. Each represents 
      * a constructor and contains the parameters to the constructor. 
      * This is primarily used to validate each constructor against the
      * fields and methods annotated to ensure they are compatible.
      * 
      * @return this returns a list of instantiators for the creator
      */
     public List<Creator> getCreators() {
        return new ArrayList<Creator>(creators);
     }
     
     /**
      * This is used to acquire a description of the creator. This is
      * useful when debugging an issue as it allows a representation
      * of the instance to be viewed with the class it represents.
      * 
      * @return this returns a visible description of the creator
      */
     public String toString() {
        return String.format("creator for %s", detail);
     }
  }