ceph/src/rapidjson/include/rapidjson/filereadstream.h

   1 // Tencent is pleased to support the open source community by making RapidJSON available.
   2 //
   3 // Copyright (C) 2015 THL A29 Limited, a Tencent company, and Milo Yip. All rights reserved.
   4 //
   5 // Licensed under the MIT License (the "License"); you may not use this file except
   6 // in compliance with the License. You may obtain a copy of the License at
   7 //
   8 // http://opensource.org/licenses/MIT
   9 //
  10 // Unless required by applicable law or agreed to in writing, software distributed
  11 // under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR
  12 // CONDITIONS OF ANY KIND, either express or implied. See the License for the
  13 // specific language governing permissions and limitations under the License.
  14
  15 #ifndef RAPIDJSON_FILEREADSTREAM_H_
  16 #define RAPIDJSON_FILEREADSTREAM_H_
  17
  18 #include "stream.h"
  19 #include <cstdio>
  20
  21 #ifdef __clang__
  22 RAPIDJSON_DIAG_PUSH
  23 RAPIDJSON_DIAG_OFF(padded)
  24 RAPIDJSON_DIAG_OFF(unreachable-code)
  25 RAPIDJSON_DIAG_OFF(missing-noreturn)
  26 #endif
  27
  28 RAPIDJSON_NAMESPACE_BEGIN
  29
  30 //! File byte stream for input using fread().
  31 /*!
  32     \note implements Stream concept
  33 */
  34 class FileReadStream {
  35 public:
  36     typedef char Ch;    //!< Character type (byte).
  37
  38     //! Constructor.
  39     /*!
  40         \param fp File pointer opened for read.
  41         \param buffer user-supplied buffer.
  42         \param bufferSize size of buffer in bytes. Must >=4 bytes.
  43     */
  44     FileReadStream(std::FILE* fp, char* buffer, size_t bufferSize) : fp_(fp), buffer_(buffer), bufferSize_(bufferSize), bufferLast_(0), current_(buffer_), readCount_(0), count_(0), eof_(false) {
  45         RAPIDJSON_ASSERT(fp_ != 0);
  46         RAPIDJSON_ASSERT(bufferSize >= 4);
  47         Read();
  48     }
  49
  50     Ch Peek() const { return *current_; }
  51     Ch Take() { Ch c = *current_; Read(); return c; }
  52     size_t Tell() const { return count_ + static_cast<size_t>(current_ - buffer_); }
  53
  54     // Not implemented
  55     void Put(Ch) { RAPIDJSON_ASSERT(false); }
  56     void Flush() { RAPIDJSON_ASSERT(false); }
  57     Ch* PutBegin() { RAPIDJSON_ASSERT(false); return 0; }
  58     size_t PutEnd(Ch*) { RAPIDJSON_ASSERT(false); return 0; }
  59
  60     // For encoding detection only.
  61     const Ch* Peek4() const {
  62         return (current_ + 4 <= bufferLast_) ? current_ : 0;
  63     }
  64
  65 private:
  66     void Read() {
  67         if (current_ < bufferLast_)
  68             ++current_;
  69         else if (!eof_) {
  70             count_ += readCount_;
  71             readCount_ = fread(buffer_, 1, bufferSize_, fp_);
  72             bufferLast_ = buffer_ + readCount_ - 1;
  73             current_ = buffer_;
  74
  75             if (readCount_ < bufferSize_) {
  76                 buffer_[readCount_] = '\0';
  77                 ++bufferLast_;
  78                 eof_ = true;
  79             }
  80         }
  81     }
  82
  83     std::FILE* fp_;
  84     Ch *buffer_;
  85     size_t bufferSize_;
  86     Ch *bufferLast_;
  87     Ch *current_;
  88     size_t readCount_;
  89     size_t count_;  //!< Number of characters read
  90     bool eof_;
  91 };
  92
  93 RAPIDJSON_NAMESPACE_END
  94
  95 #ifdef __clang__
  96 RAPIDJSON_DIAG_POP
  97 #endif
  98
  99 #endif // RAPIDJSON_FILESTREAM_H_