istreamwrapper.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_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>
50 class BasicIStreamWrapper {
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) : '\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:
98 BasicIStreamWrapper(const BasicIStreamWrapper&);
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
106 typedef BasicIStreamWrapper<std::istream> IStreamWrapper;
107 typedef BasicIStreamWrapper<std::wistream> WIStreamWrapper;
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_
RAPIDJSON_LIKELY
#define RAPIDJSON_LIKELY(x)
Compiler branching hint for expression with high probability to be true.
Definition: rapidjson.h:455
rapidjson::BasicIStreamWrapper
Wrapper of std::basic_istream into RapidJSON&#39;s Stream concept.
Definition: istreamwrapper.h:50
RAPIDJSON_ASSERT
#define RAPIDJSON_ASSERT(x)
Assertion.
Definition: rapidjson.h:402