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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__
22RAPIDJSON_DIAG_PUSH
23RAPIDJSON_DIAG_OFF(padded)
24RAPIDJSON_DIAG_OFF(unreachable-code)
25RAPIDJSON_DIAG_OFF(missing-noreturn)
26#endif
27
28RAPIDJSON_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
93RAPIDJSON_NAMESPACE_END
94
95#ifdef __clang__
96RAPIDJSON_DIAG_POP
97#endif
98
99#endif // RAPIDJSON_FILESTREAM_H_
rapidjson::FileReadStream
File byte stream for input using fread().
Definition filereadstream.h:34
rapidjson::FileReadStream::FileReadStream
FileReadStream(std::FILE *fp, char *buffer, size_t bufferSize)
Constructor.
Definition filereadstream.h:44
rapidjson::FileReadStream::Ch
char Ch
Character type (byte).
Definition filereadstream.h:36
RAPIDJSON_ASSERT
#define RAPIDJSON_ASSERT(x)
Assertion.
Definition rapidjson.h:402