Line data    Source code

       1              : /*
       2              :  *
       3              :  *    Copyright (c) 2022 Project CHIP Authors
       4              :  *
       5              :  *    Licensed under the Apache License, Version 2.0 (the "License");
       6              :  *    you may not use this file except in compliance with the License.
       7              :  *    You may obtain a copy of the License at
       8              :  *
       9              :  *        http://www.apache.org/licenses/LICENSE-2.0
      10              :  *
      11              :  *    Unless required by applicable law or agreed to in writing, software
      12              :  *    distributed under the License is distributed on an "AS IS" BASIS,
      13              :  *    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
      14              :  *    See the License for the specific language governing permissions and
      15              :  *    limitations under the License.
      16              :  */
      17              : 
      18              : /**
      19              :  *    @file
      20              :  *          Contains a standard iterator class.
      21              :  */
      22              : 
      23              : #pragma once
      24              : 
      25              : #include <stddef.h>
      26              : 
      27              : namespace chip {
      28              : 
      29              : /**
      30              :  * Template used to generate a custom iterator
      31              :  */
      32              : template <typename T>
      33              : class CommonIterator
      34              : {
      35              : public:
      36         3127 :     virtual ~CommonIterator() = default;
      37              : 
      38              :     /**
      39              :      *  @retval The number of entries in total that will be iterated.
      40              :      */
      41              :     virtual size_t Count() = 0;
      42              : 
      43              :     /**
      44              :      *   @param[out] item  Value associated with the next element in the iteration.
      45              :      *  @retval true if the next entry is successfully retrieved.
      46              :      *  @retval false if no more entries can be found.
      47              :      */
      48              :     virtual bool Next(T & item) = 0;
      49              : 
      50              :     /**
      51              :      * Release the memory allocated by this iterator.
      52              :      * Must be called before the iterator goes out of scope if the iterator was dynamically allocated.
      53              :      */
      54              :     virtual void Release() = 0;
      55              : 
      56              :     /**
      57              :      * Wraps an iterator pointer and auto-releases it when going out of scope.
      58              :      */
      59              :     class AutoReleasing
      60              :     {
      61              :     public:
      62          123 :         AutoReleasing(CommonIterator * iterator) : mIterator(iterator) {}
      63          123 :         ~AutoReleasing()
      64              :         {
      65          123 :             if (mIterator != nullptr)
      66              :             {
      67          123 :                 mIterator->Release();
      68              :             }
      69          123 :         }
      70              : 
      71              :         AutoReleasing(const AutoReleasing &)             = delete;
      72              :         AutoReleasing & operator=(const AutoReleasing &) = delete;
      73              : 
      74          122 :         bool IsValid() const { return mIterator != nullptr; }
      75           63 :         size_t Count() const { return mIterator != nullptr ? mIterator->Count() : 0; }
      76          183 :         bool Next(T & value) { return (mIterator == nullptr) ? false : mIterator->Next(value); }
      77              : 
      78              :     private:
      79              :         CommonIterator * mIterator;
      80              :     };
      81              : 
      82              : protected:
      83         3127 :     CommonIterator() = default;
      84              : };
      85              : 
      86              : } // namespace chip