istreamwrapper.h
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3 // Copyright (C) 2015 THL A29 Limited, a Tencent company, and Milo Yip. All rights reserved.
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5 // Licensed under the MIT License (the "License"); you may not use this file except
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14 
15 #ifndef RAPIDJSON_ISTREAMWRAPPER_H_
16 #define RAPIDJSON_ISTREAMWRAPPER_H_
17 
18 #include "stream.h"
19 #include <iosfwd>
20 
21 #ifdef __clang__
22 RAPIDJSON_DIAG_PUSH
23 RAPIDJSON_DIAG_OFF(padded)
24 #elif defined(_MSC_VER)
25 RAPIDJSON_DIAG_PUSH
26 RAPIDJSON_DIAG_OFF(4351) // new behavior: elements of array 'array' will be default initialized
27 #endif
28 
29 RAPIDJSON_NAMESPACE_BEGIN
30 
31 //! Wrapper of \c std::basic_istream into RapidJSON's Stream concept.
32 /*!
33  The classes can be wrapped including but not limited to:
34 
35  - \c std::istringstream
36  - \c std::stringstream
37  - \c std::wistringstream
38  - \c std::wstringstream
39  - \c std::ifstream
40  - \c std::fstream
41  - \c std::wifstream
42  - \c std::wfstream
43 
44  \tparam StreamType Class derived from \c std::basic_istream.
45 */
46 
47 template <typename StreamType>
49 public:
50  typedef typename StreamType::char_type Ch;
51  BasicIStreamWrapper(StreamType& stream) : stream_(stream), count_(), peekBuffer_() {}
52 
53  Ch Peek() const {
54  typename StreamType::int_type c = stream_.peek();
55  return RAPIDJSON_LIKELY(c != StreamType::traits_type::eof()) ? static_cast<Ch>(c) : static_cast<Ch>('\0');
56  }
57 
58  Ch Take() {
59  typename StreamType::int_type c = stream_.get();
60  if (RAPIDJSON_LIKELY(c != StreamType::traits_type::eof())) {
61  count_++;
62  return static_cast<Ch>(c);
63  }
64  else
65  return '\0';
66  }
67 
68  // tellg() may return -1 when failed. So we count by ourself.
69  size_t Tell() const { return count_; }
70 
71  Ch* PutBegin() { RAPIDJSON_ASSERT(false); return 0; }
72  void Put(Ch) { RAPIDJSON_ASSERT(false); }
73  void Flush() { RAPIDJSON_ASSERT(false); }
74  size_t PutEnd(Ch*) { RAPIDJSON_ASSERT(false); return 0; }
75 
76  // For encoding detection only.
77  const Ch* Peek4() const {
78  RAPIDJSON_ASSERT(sizeof(Ch) == 1); // Only usable for byte stream.
79  int i;
80  bool hasError = false;
81  for (i = 0; i < 4; ++i) {
82  typename StreamType::int_type c = stream_.get();
83  if (c == StreamType::traits_type::eof()) {
84  hasError = true;
85  stream_.clear();
86  break;
87  }
88  peekBuffer_[i] = static_cast<Ch>(c);
89  }
90  for (--i; i >= 0; --i)
91  stream_.putback(peekBuffer_[i]);
92  return !hasError ? peekBuffer_ : 0;
93  }
94 
95 private:
97  BasicIStreamWrapper& operator=(const BasicIStreamWrapper&);
98 
99  StreamType& stream_;
100  size_t count_; //!< Number of characters read. Note:
101  mutable Ch peekBuffer_[4];
102 };
103 
106 
107 #if defined(__clang__) || defined(_MSC_VER)
108 RAPIDJSON_DIAG_POP
109 #endif
110 
111 RAPIDJSON_NAMESPACE_END
112 
113 #endif // RAPIDJSON_ISTREAMWRAPPER_H_
#define RAPIDJSON_LIKELY(x)
Compiler branching hint for expression with high probability to be true.
Definition: rapidjson.h:463
Wrapper of std::basic_istream into RapidJSON&#39;s Stream concept.
Definition: istreamwrapper.h:48
#define RAPIDJSON_ASSERT(x)
Assertion.
Definition: rapidjson.h:406