content: /*
   * ScannerFactory.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.util.Cache;
  import com.aliyun.odps.simpleframework.xml.util.ConcurrentCache;
  
  /**
   * The <code>ScannerFactory</code> is used to create scanner objects
   * that will scan a class for its XML class schema. Caching is done
   * by this factory so that repeat retrievals of a <code>Scanner</code>
   * will not require repeat scanning of the class for its XML schema.
   * 
   * @author Niall Gallagher
   * 
   * @see Context
   */
  class ScannerFactory {
     
     /**
      * This is used to cache all schemas built to represent a class.
      */
     private final Cache<Scanner> cache;
     
     /**
      * This is used to determine which objects are primitives.
      */
     private final Support support;
     
     /**
      * Constructor for the <code>ScannerFactory</code> object. This is
      * used to create a factory that will create and cache scanned 
      * data for a given class. Scanning the class is required to find
      * the fields and methods that have been annotated.
      * 
      * @param support this is used to determine if a type is primitive
      */
     public ScannerFactory(Support support) {
        this.cache = new ConcurrentCache<Scanner>();
        this.support = support;
     }
     
     /**
      * This creates a <code>Scanner</code> 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 
      */ 
     public Scanner getInstance(Class type) throws Exception {
        Scanner schema = cache.fetch(type);
        
        if(schema == null) {
           Detail detail = support.getDetail(type);
           
           if(support.isPrimitive(type)) {
              schema = new PrimitiveScanner(detail);
           } else {
              schema = new ObjectScanner(detail, support);
              
              if(schema.isPrimitive() && !support.isContainer(type)) {
                 schema = new DefaultScanner(detail, support);
              }
           }
           cache.cache(type, schema);
        }
        return schema;
     }
  }
  