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__
 22RAPIDJSON_DIAG_PUSH
 23RAPIDJSON_DIAG_OFF(padded)
 24#endif
 25
 26#ifdef _MSC_VER
 27RAPIDJSON_DIAG_PUSH
 28RAPIDJSON_DIAG_OFF(4351) // new behavior: elements of array 'array' will be default initialized
 29#endif
 30
 31RAPIDJSON_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   
 49template <typename StreamType>
 50class BasicIStreamWrapper {
 51public:
 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
 97private:
 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
106typedef BasicIStreamWrapper<std::istream> IStreamWrapper;
107typedef BasicIStreamWrapper<std::wistream> WIStreamWrapper;
108
109#if defined(__clang__) || defined(_MSC_VER)
110RAPIDJSON_DIAG_POP
111#endif
112
113RAPIDJSON_NAMESPACE_END
114
115#endif // RAPIDJSON_ISTREAMWRAPPER_H_