content: /*
   * Copyright 1999-2012 Alibaba Group.
   *  
   * 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.alibaba.cobar.config.util;
  
  import java.lang.reflect.Field;
  import java.util.Collections;
  import java.util.HashMap;
  import java.util.Iterator;
  import java.util.Map;
  
  public class FieldDictionary {
  
      private final Map<String, Map<String, Field>> nameCache = Collections.synchronizedMap(new HashMap<String, Map<String, Field>>());
      private final Map<String, Map<FieldKey, Field>> keyCache = Collections.synchronizedMap(new HashMap<String, Map<FieldKey, Field>>());
  
      /**
       * Returns an iterator for all serializable fields for some class
       * 
       * @param cls the class you are interested on
       * @return an iterator for its serializable fields
       */
      public Iterator<Field> serializableFieldsFor(Class<?> cls) {
          return buildMap(cls, true).values().iterator();
      }
  
      /**
       * Returns an specific field of some class. If definedIn is null, it searchs
       * for the field named 'name' inside the class cls. If definedIn is
       * different than null, tries to find the specified field name in the
       * specified class cls which should be defined in class definedIn (either
       * equals cls or a one of it's superclasses)
       * 
       * @param cls the class where the field is to be searched
       * @param name the field name
       * @param definedIn the superclass (or the class itself) of cls where the
       *            field was defined
       * @return the field itself
       */
      public Field field(Class<?> cls, String name, Class<?> definedIn) {
          Map<?, Field> fields = buildMap(cls, definedIn != null);
          Field field = fields.get(definedIn != null ? new FieldKey(name, definedIn, 0) : name);
          if (field == null) {
              throw new ObjectAccessException("No such field " + cls.getName() + "." + name);
          } else {
              return field;
          }
      }
  
      private Map<?, Field> buildMap(Class<?> cls, boolean tupleKeyed) {
          final String clsName = cls.getName();
          if (!nameCache.containsKey(clsName)) {
              synchronized (keyCache) {
                  if (!nameCache.containsKey(clsName)) { // double check
                      final Map<String, Field> keyedByFieldName = new HashMap<String, Field>();
                      final Map<FieldKey, Field> keyedByFieldKey = new OrderRetainingMap<FieldKey, Field>();
                      while (!Object.class.equals(cls)) {
                          Field[] fields = cls.getDeclaredFields();
                          if (JVMInfo.reverseFieldDefinition()) {
                              for (int i = fields.length >> 1; i-- > 0;) {
                                  final int idx = fields.length - i - 1;
                                  final Field field = fields[i];
                                  fields[i] = fields[idx];
                                  fields[idx] = field;
                              }
                          }
                          for (int i = 0; i < fields.length; i++) {
                              Field field = fields[i];
                              field.setAccessible(true);
                              if (!keyedByFieldName.containsKey(field.getName())) {
                                  keyedByFieldName.put(field.getName(), field);
                              }
                              keyedByFieldKey.put(new FieldKey(field.getName(), field.getDeclaringClass(), i), field);
                          }
                          cls = cls.getSuperclass();
                      }
                      nameCache.put(clsName, keyedByFieldName);
                      keyCache.put(clsName, keyedByFieldKey);
                  }
              }
          }
          return tupleKeyed ? keyCache.get(clsName) : nameCache.get(clsName);
      }
  
      private static class FieldKey {
  
          private String fieldName;
          private Class<?> declaringClass;
          private Integer depth;
          private int order;
  
          public FieldKey(String fieldName, Class<?> declaringClass, int order) {
              this.fieldName = fieldName;
              this.declaringClass = declaringClass;
              this.order = order;
              Class<?> c = declaringClass;
              int i = 0;
              while (c.getSuperclass() != null) {
                  i++;
                  c = c.getSuperclass();
              }
              depth = new Integer(i);
          }
  
          @Override
          public boolean equals(Object o) {
              if (this == o) {
                  return true;
              }
              if (!(o instanceof FieldKey)) {
                  return false;
              }
  
              final FieldKey fieldKey = (FieldKey) o;
  
              if (declaringClass != null
                      ? !declaringClass.equals(fieldKey.declaringClass) : fieldKey.declaringClass != null) {
                  return false;
              }
  
              if (fieldName != null ? !fieldName.equals(fieldKey.fieldName) : fieldKey.fieldName != null) {
                  return false;
              }
  
              return true;
          }
  
          @Override
          public int hashCode() {
              int result;
              result = (fieldName != null ? fieldName.hashCode() : 0);
              result = 29 * result + (declaringClass != null ? declaringClass.hashCode() : 0);
              return result;
          }
  
          @Override
          public String toString() {
              return "FieldKey{" + "order=" + order + ", writer=" + depth + ", declaringClass=" + declaringClass
                      + ", fieldName='" + fieldName + "'" + "}";
          }
  
      }
  
  }
  