ceph/src/rapidjson/include/rapidjson/filewritestream.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_FILEWRITESTREAM_H_
  16 #define RAPIDJSON_FILEWRITESTREAM_H_
  17
  18 #include "stream.h"
  19 #include <cstdio>
  20
  21 #ifdef __clang__
  22 RAPIDJSON_DIAG_PUSH
  23 RAPIDJSON_DIAG_OFF(unreachable-code)
  24 #endif
  25
  26 RAPIDJSON_NAMESPACE_BEGIN
  27
  28 //! Wrapper of C file stream for input using fread().
  29 /*!
  30     \note implements Stream concept
  31 */
  32 class FileWriteStream {
  33 public:
  34     typedef char Ch;    //!< Character type. Only support char.
  35
  36     FileWriteStream(std::FILE* fp, char* buffer, size_t bufferSize) : fp_(fp), buffer_(buffer), bufferEnd_(buffer + bufferSize), current_(buffer_) {
  37         RAPIDJSON_ASSERT(fp_ != 0);
  38     }
  39
  40     void Put(char c) {
  41         if (current_ >= bufferEnd_)
  42             Flush();
  43
  44         *current_++ = c;
  45     }
  46
  47     void PutN(char c, size_t n) {
  48         size_t avail = static_cast<size_t>(bufferEnd_ - current_);
  49         while (n > avail) {
  50             std::memset(current_, c, avail);
  51             current_ += avail;
  52             Flush();
  53             n -= avail;
  54             avail = static_cast<size_t>(bufferEnd_ - current_);
  55         }
  56
  57         if (n > 0) {
  58             std::memset(current_, c, n);
  59             current_ += n;
  60         }
  61     }
  62
  63     void Flush() {
  64         if (current_ != buffer_) {
  65             size_t result = fwrite(buffer_, 1, static_cast<size_t>(current_ - buffer_), fp_);
  66             if (result < static_cast<size_t>(current_ - buffer_)) {
  67                 // failure deliberately ignored at this time
  68                 // added to avoid warn_unused_result build errors
  69             }
  70             current_ = buffer_;
  71         }
  72     }
  73
  74     // Not implemented
  75     char Peek() const { RAPIDJSON_ASSERT(false); return 0; }
  76     char Take() { RAPIDJSON_ASSERT(false); return 0; }
  77     size_t Tell() const { RAPIDJSON_ASSERT(false); return 0; }
  78     char* PutBegin() { RAPIDJSON_ASSERT(false); return 0; }
  79     size_t PutEnd(char*) { RAPIDJSON_ASSERT(false); return 0; }
  80
  81 private:
  82     // Prohibit copy constructor & assignment operator.
  83     FileWriteStream(const FileWriteStream&);
  84     FileWriteStream& operator=(const FileWriteStream&);
  85
  86     std::FILE* fp_;
  87     char *buffer_;
  88     char *bufferEnd_;
  89     char *current_;
  90 };
  91
  92 //! Implement specialized version of PutN() with memset() for better performance.
  93 template<>
  94 inline void PutN(FileWriteStream& stream, char c, size_t n) {
  95     stream.PutN(c, n);
  96 }
  97
  98 RAPIDJSON_NAMESPACE_END
  99
 100 #ifdef __clang__
 101 RAPIDJSON_DIAG_POP
 102 #endif
 103
 104 #endif // RAPIDJSON_FILESTREAM_H_