istreamwrapper.h

Go to the documentation of this file.

// Tencent is pleased to support the open source community by making RapidJSON available.
// 
// Copyright (C) 2015 THL A29 Limited, a Tencent company, and Milo Yip. All rights reserved.
//
// Licensed under the MIT License (the "License"); you may not use this file except
// in compliance with the License. You may obtain a copy of the License at
//
// http://opensource.org/licenses/MIT
//
// Unless required by applicable law or agreed to in writing, software distributed 
// under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR 
// CONDITIONS OF ANY KIND, either express or implied. See the License for the 
// specific language governing permissions and limitations under the License.

#ifndef RAPIDJSON_ISTREAMWRAPPER_H_
#define RAPIDJSON_ISTREAMWRAPPER_H_

#include "stream.h"
#include <iosfwd>

#ifdef __clang__
RAPIDJSON_DIAG_PUSH
RAPIDJSON_DIAG_OFF(padded)
#endif

#ifdef _MSC_VER
RAPIDJSON_DIAG_PUSH
RAPIDJSON_DIAG_OFF(4351) // new behavior: elements of array 'array' will be default initialized
#endif

RAPIDJSON_NAMESPACE_BEGIN


template <typename StreamType>
class BasicIStreamWrapper {
public:
 typedef typename StreamType::char_type Ch;
 BasicIStreamWrapper(StreamType& stream) : stream_(stream), count_(), peekBuffer_() {}

 Ch Peek() const { 
 typename StreamType::int_type c = stream_.peek();
 return RAPIDJSON_LIKELY(c != StreamType::traits_type::eof()) ? static_cast<Ch>(c) : '\0';
 }

 Ch Take() { 
 typename StreamType::int_type c = stream_.get();
 if (RAPIDJSON_LIKELY(c != StreamType::traits_type::eof())) {
 count_++;
 return static_cast<Ch>(c);
 }
 else
 return '\0';
 }

 // tellg() may return -1 when failed. So we count by ourself.
 size_t Tell() const { return count_; }

 Ch* PutBegin() { RAPIDJSON_ASSERT(false); return 0; }
 void Put(Ch) { RAPIDJSON_ASSERT(false); }
 void Flush() { RAPIDJSON_ASSERT(false); }
 size_t PutEnd(Ch*) { RAPIDJSON_ASSERT(false); return 0; }

 // For encoding detection only.
 const Ch* Peek4() const {
 RAPIDJSON_ASSERT(sizeof(Ch) == 1); // Only usable for byte stream.
 int i;
 bool hasError = false;
 for (i = 0; i < 4; ++i) {
 typename StreamType::int_type c = stream_.get();
 if (c == StreamType::traits_type::eof()) {
 hasError = true;
 stream_.clear();
 break;
 }
 peekBuffer_[i] = static_cast<Ch>(c);
 }
 for (--i; i >= 0; --i)
 stream_.putback(peekBuffer_[i]);
 return !hasError ? peekBuffer_ : 0;
 }

private:
 BasicIStreamWrapper(const BasicIStreamWrapper&);
 BasicIStreamWrapper& operator=(const BasicIStreamWrapper&);

 StreamType& stream_;
 size_t count_; 
 mutable Ch peekBuffer_[4];
};

typedef BasicIStreamWrapper<std::istream> IStreamWrapper;
typedef BasicIStreamWrapper<std::wistream> WIStreamWrapper;

#if defined(__clang__) || defined(_MSC_VER)
RAPIDJSON_DIAG_POP
#endif

RAPIDJSON_NAMESPACE_END

#endif // RAPIDJSON_ISTREAMWRAPPER_H_