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stream.h
// 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.
#include "rapidjson.h"
#ifndef RAPIDJSON_STREAM_H_
#define RAPIDJSON_STREAM_H_
#include "encodings.h"
RAPIDJSON_NAMESPACE_BEGIN
///////////////////////////////////////////////////////////////////////////////
// Stream
/*! \class rapidjson::Stream
\brief Concept for reading and writing characters.
For read-only stream, no need to implement PutBegin(), Put(), Flush() and PutEnd().
For write-only stream, only need to implement Put() and Flush().
\code
concept Stream {
typename Ch; //!< Character type of the stream.
//! Read the current character from stream without moving the read cursor.
Ch Peek() const;
//! Read the current character from stream and moving the read cursor to next character.
Ch Take();
//! Get the current read cursor.
//! \return Number of characters read from start.
size_t Tell();
//! Begin writing operation at the current read pointer.
//! \return The begin writer pointer.
Ch* PutBegin();
//! Write a character.
void Put(Ch c);
//! Flush the buffer.
void Flush();
//! End the writing operation.
//! \param begin The begin write pointer returned by PutBegin().
//! \return Number of characters written.
size_t PutEnd(Ch* begin);
}
\endcode
*/
//! Provides additional information for stream.
/*!
By using traits pattern, this type provides a default configuration for stream.
For custom stream, this type can be specialized for other configuration.
See TEST(Reader, CustomStringStream) in readertest.cpp for example.
*/
template<typename Stream>
struct StreamTraits {
//! Whether to make local copy of stream for optimization during parsing.
/*!
By default, for safety, streams do not use local copy optimization.
Stream that can be copied fast should specialize this, like StreamTraits<StringStream>.
*/
enum { copyOptimization = 0 };
};
//! Reserve n characters for writing to a stream.
template<typename Stream>
inline void PutReserve(Stream& stream, size_t count) {
(void)stream;
(void)count;
}
//! Write character to a stream, presuming buffer is reserved.
template<typename Stream>
inline void PutUnsafe(Stream& stream, typename Stream::Ch c) {
stream.Put(c);
}
//! Put N copies of a character to a stream.
template<typename Stream, typename Ch>
inline void PutN(Stream& stream, Ch c, size_t n) {
PutReserve(stream, n);
for (size_t i = 0; i < n; i++)
PutUnsafe(stream, c);
}
///////////////////////////////////////////////////////////////////////////////
// StringStream
//! Read-only string stream.
/*! \note implements Stream concept
*/
template <typename Encoding>
struct GenericStringStream {
typedef typename Encoding::Ch Ch;
GenericStringStream(const Ch *src) : src_(src), head_(src) {}
Ch Peek() const { return *src_; }
Ch Take() { return *src_++; }
size_t Tell() const { return static_cast<size_t>(src_ - head_); }
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; }
const Ch* src_; //!< Current read position.
const Ch* head_; //!< Original head of the string.
};
template <typename Encoding>
struct StreamTraits<GenericStringStream<Encoding> > {
enum { copyOptimization = 1 };
};
//! String stream with UTF8 encoding.
typedef GenericStringStream<UTF8<> > StringStream;
///////////////////////////////////////////////////////////////////////////////
// InsituStringStream
//! A read-write string stream.
/*! This string stream is particularly designed for in-situ parsing.
\note implements Stream concept
*/
template <typename Encoding>
struct GenericInsituStringStream {
typedef typename Encoding::Ch Ch;
GenericInsituStringStream(Ch *src) : src_(src), dst_(0), head_(src) {}
// Read
Ch Peek() { return *src_; }
Ch Take() { return *src_++; }
size_t Tell() { return static_cast<size_t>(src_ - head_); }
// Write
void Put(Ch c) { RAPIDJSON_ASSERT(dst_ != 0); *dst_++ = c; }
Ch* PutBegin() { return dst_ = src_; }
size_t PutEnd(Ch* begin) { return static_cast<size_t>(dst_ - begin); }
void Flush() {}
Ch* Push(size_t count) { Ch* begin = dst_; dst_ += count; return begin; }
void Pop(size_t count) { dst_ -= count; }
Ch* src_;
Ch* dst_;
Ch* head_;
};
template <typename Encoding>
struct StreamTraits<GenericInsituStringStream<Encoding> > {
enum { copyOptimization = 1 };
};
//! Insitu string stream with UTF8 encoding.
typedef GenericInsituStringStream<UTF8<> > InsituStringStream;
RAPIDJSON_NAMESPACE_END
#endif // RAPIDJSON_STREAM_H_
Encoding
Concept for encoding of Unicode characters.
Stream
Concept for reading and writing characters.
RAPIDJSON_ASSERT
#define RAPIDJSON_ASSERT(x)
Assertion.
Definition rapidjson.h:402
rapidjson::PutUnsafe
void PutUnsafe(Stream &stream, typename Stream::Ch c)
Write character to a stream, presuming buffer is reserved.
Definition stream.h:91
rapidjson::PutN
void PutN(FileWriteStream &stream, char c, size_t n)
Implement specialized version of PutN() with memset() for better performance.
Definition filewritestream.h:94
rapidjson::PutReserve
void PutReserve(Stream &stream, size_t count)
Reserve n characters for writing to a stream.
Definition stream.h:84
rapidjson.h
common definitions and configuration
rapidjson::GenericInsituStringStream
A read-write string stream.
Definition stream.h:144
rapidjson::GenericStringStream
Read-only string stream.
Definition stream.h:110
rapidjson::GenericStringStream::head_
const Ch * head_
Original head of the string.
Definition stream.h:125
rapidjson::GenericStringStream::src_
const Ch * src_
Current read position.
Definition stream.h:124
rapidjson::StreamTraits
Provides additional information for stream.
Definition stream.h:73