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istreamwrapper.h
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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 #endif
25 
26 #ifdef _MSC_VER
27 RAPIDJSON_DIAG_PUSH
28 RAPIDJSON_DIAG_OFF(4351) // new behavior: elements of array 'array' will be default initialized
29 #endif
30 
31 RAPIDJSON_NAMESPACE_BEGIN
32 
33 //! Wrapper of \c std::basic_istream into RapidJSON's Stream concept.
34 /*!
35  The classes can be wrapped including but not limited to:
36 
37  - \c std::istringstream
38  - \c std::stringstream
39  - \c std::wistringstream
40  - \c std::wstringstream
41  - \c std::ifstream
42  - \c std::fstream
43  - \c std::wifstream
44  - \c std::wfstream
45 
46  \tparam StreamType Class derived from \c std::basic_istream.
47 */
48 
49 template <typename StreamType>
51 public:
52  typedef typename StreamType::char_type Ch;
53  BasicIStreamWrapper(StreamType& stream) : stream_(stream), count_(), peekBuffer_() {}
54 
55  Ch Peek() const {
56  typename StreamType::int_type c = stream_.peek();
57  return RAPIDJSON_LIKELY(c != StreamType::traits_type::eof()) ? static_cast<Ch>(c) : static_cast<Ch>('\0');
58  }
59 
60  Ch Take() {
61  typename StreamType::int_type c = stream_.get();
62  if (RAPIDJSON_LIKELY(c != StreamType::traits_type::eof())) {
63  count_++;
64  return static_cast<Ch>(c);
65  }
66  else
67  return '\0';
68  }
69 
70  // tellg() may return -1 when failed. So we count by ourself.
71  size_t Tell() const { return count_; }
72 
73  Ch* PutBegin() { RAPIDJSON_ASSERT(false); return 0; }
74  void Put(Ch) { RAPIDJSON_ASSERT(false); }
75  void Flush() { RAPIDJSON_ASSERT(false); }
76  size_t PutEnd(Ch*) { RAPIDJSON_ASSERT(false); return 0; }
77 
78  // For encoding detection only.
79  const Ch* Peek4() const {
80  RAPIDJSON_ASSERT(sizeof(Ch) == 1); // Only usable for byte stream.
81  int i;
82  bool hasError = false;
83  for (i = 0; i < 4; ++i) {
84  typename StreamType::int_type c = stream_.get();
85  if (c == StreamType::traits_type::eof()) {
86  hasError = true;
87  stream_.clear();
88  break;
89  }
90  peekBuffer_[i] = static_cast<Ch>(c);
91  }
92  for (--i; i >= 0; --i)
93  stream_.putback(peekBuffer_[i]);
94  return !hasError ? peekBuffer_ : 0;
95  }
96 
97 private:
99  BasicIStreamWrapper& operator=(const BasicIStreamWrapper&);
100 
101  StreamType& stream_;
102  size_t count_; //!< Number of characters read. Note:
103  mutable Ch peekBuffer_[4];
104 };
105 
108 
109 #if defined(__clang__) || defined(_MSC_VER)
110 RAPIDJSON_DIAG_POP
111 #endif
112 
113 RAPIDJSON_NAMESPACE_END
114 
115 #endif // RAPIDJSON_ISTREAMWRAPPER_H_
#define RAPIDJSON_LIKELY(x)
Compiler branching hint for expression with high probability to be true.
Definition: rapidjson.h:468
Wrapper of std::basic_istream into RapidJSON's Stream concept.
Definition: istreamwrapper.h:50
#define RAPIDJSON_ASSERT(x)
Assertion.
Definition: rapidjson.h:411