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 "rapidjson.h"
19 #include <cstdio>
20 
21 RAPIDJSON_NAMESPACE_BEGIN
22 
23 //! File byte stream for input using fread().
24 /*!
25     \note implements Stream concept
26 */
27 class FileReadStream {
28 public:
29     typedef char Ch;    //!< Character type (byte).
30 
31     //! Constructor.
32     /*!
33         \param fp File pointer opened for read.
34         \param buffer user-supplied buffer.
35         \param bufferSize size of buffer in bytes. Must >=4 bytes.
36     */
FileReadStream(std::FILE * fp,char * buffer,size_t bufferSize)37     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) {
38         RAPIDJSON_ASSERT(fp_ != 0);
39         RAPIDJSON_ASSERT(bufferSize >= 4);
40         Read();
41     }
42 
Peek()43     Ch Peek() const { return *current_; }
Take()44     Ch Take() { Ch c = *current_; Read(); return c; }
Tell()45     size_t Tell() const { return count_ + static_cast<size_t>(current_ - buffer_); }
46 
47     // Not implemented
Put(Ch)48     void Put(Ch) { RAPIDJSON_ASSERT(false); }
Flush()49     void Flush() { RAPIDJSON_ASSERT(false); }
PutBegin()50     Ch* PutBegin() { RAPIDJSON_ASSERT(false); return 0; }
PutEnd(Ch *)51     size_t PutEnd(Ch*) { RAPIDJSON_ASSERT(false); return 0; }
52 
53     // For encoding detection only.
Peek4()54     const Ch* Peek4() const {
55         return (current_ + 4 <= bufferLast_) ? current_ : 0;
56     }
57 
58 private:
Read()59     void Read() {
60         if (current_ < bufferLast_)
61             ++current_;
62         else if (!eof_) {
63             count_ += readCount_;
64             readCount_ = fread(buffer_, 1, bufferSize_, fp_);
65             bufferLast_ = buffer_ + readCount_ - 1;
66             current_ = buffer_;
67 
68             if (readCount_ < bufferSize_) {
69                 buffer_[readCount_] = '\0';
70                 ++bufferLast_;
71                 eof_ = true;
72             }
73         }
74     }
75 
76     std::FILE* fp_;
77     Ch *buffer_;
78     size_t bufferSize_;
79     Ch *bufferLast_;
80     Ch *current_;
81     size_t readCount_;
82     size_t count_;  //!< Number of characters read
83     bool eof_;
84 };
85 
86 RAPIDJSON_NAMESPACE_END
87 
88 #endif // RAPIDJSON_FILESTREAM_H_
89