content: /*
   * Copyright 1999-2018 Alibaba Group Holding Ltd.
   *
   * 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.nacos.common.utils;
  
  import java.lang.reflect.ParameterizedType;
  import java.lang.reflect.Type;
  
  /**
   * type utils.
   *
   * @author zzq
   */
  public class TypeUtils {
  
      private TypeUtils() {
      }
      
      /**
       * Create a parameterized type instance.
       *
       * @param raw           raw class
       * @param typeArguments the types used for parameterization
       * @return {@link ParameterizedType}
       */
      public static ParameterizedType parameterize(final Class<?> raw, final Type... typeArguments) {
          checkParameterizeMethodParameter(raw, typeArguments);
          return new ParameterizedTypeImpl(raw, raw.getEnclosingClass(), typeArguments);
      }
      
      /**
       * Check parameterize method parameter.
       *
       * @param raw           raw class
       * @param typeArguments the types used for parameterization
       */
      private static void checkParameterizeMethodParameter(Class<?> raw, final Type... typeArguments) {
          if (raw == null) {
              throw new NullPointerException("raw cannot be null");
          }
          if (typeArguments == null) {
              throw new NullPointerException("typeArguments cannot be null");
          }
          if (typeArguments.length != raw.getTypeParameters().length) {
              throw new IllegalArgumentException(
                      String.format("invalid number of type parameters specified: expected %s, got %s",
                              raw.getTypeParameters().length, typeArguments.length));
          }
          
          for (int i = 0; i < typeArguments.length; i++) {
              if (typeArguments[i] == null) {
                  throw new IllegalArgumentException("There can be no null in typeArguments");
              }
          }
          
      }
      
      /**
       * ParameterizedType implementation class.
       */
      private static final class ParameterizedTypeImpl implements ParameterizedType {
          
          /**
           * type.
           */
          private final Class<?> raw;
          
          /**
           * owner type to use, if any.
           */
          private final Type useOwner;
          
          /**
           * formal type arguments.typeArguments
           */
          private final Type[] typeArguments;
          
          private ParameterizedTypeImpl(final Class<?> raw, final Type useOwner, final Type[] typeArguments) {
              this.raw = raw;
              this.useOwner = useOwner;
              this.typeArguments = typeArguments;
          }
          
          @Override
          public Type getRawType() {
              return raw;
          }
          
          @Override
          public Type getOwnerType() {
              return useOwner;
          }
          
          @Override
          public Type[] getActualTypeArguments() {
              return typeArguments.clone();
          }
          
          @Override
          public String toString() {
              final StringBuilder buf = new StringBuilder();
              
              buf.append(raw.getName());
              buf.append('<');
              buf.append(typeArguments[0].getTypeName());
              for (int i = 1; i < typeArguments.length; i++) {
                  buf.append(", ");
                  buf.append(typeArguments[i].getTypeName());
              }
              buf.append('>');
              
              return buf.toString();
          }
      }
      
  }
  