BufferedStreamReader Class Reference

A facade-like class, that implements buffered reading from the underlying data stream. More...

#include <BufferedStreamReader.h>

Inheritance diagram for BufferedStreamReader:

Public Member Functions
	BufferedStreamReader (size_t bufferSize=4096)
size_t	Read (void *buffer, size_t maxBytes)
	Read up to maxBytes into the buffer. Returns the number of bytes read. More...

Public Attributes
template<typename ValueType >
std::enable_if_t< sizeof(ValueType)<=RequiredAlignment, bool > ReadValue(ValueType &value) { constexpr size_t valueSize=sizeof(ValueType);const size_t availableBytes=mCurrentBytes - mCurrentIndex;if(availableBytes< valueSize) return valueSize==Read(&value, valueSize);if constexpr(valueSize==1) value=mBufferStart[mCurrentIndex];else value=UncheckedRead< ValueType >();mCurrentIndex+=valueSize;return true;} bool Eof() const ;int GetC();protected:virtual bool HasMoreData() const=0;virtual size_t ReadData(void *buffer, size_t maxBytes)=0;private:bool HandleUnderflow();template< typename T > T UncheckedRead() noexcept { T result;if((mCurrentIndex % sizeof(T))==0) { const void *ptr=mBufferStart+mCurrentIndex;result=*static_cast< const T * >(ptr);} else { const uint8_t *begin=mBufferStart+mCurrentIndex;const uint8_t *end=begin+sizeof(T);void *out=&result;std::copy(begin, end, static_cast< uint8_t * >(out));} return result;} std::vector< uint8_t >	mBufferData
	Read a single value of ValueType, where sizeof(ValueType) <= 8 and value is aligned to the size boundary. More...
uint8_t *	mBufferStart
size_t	mBufferSize
size_t	mCurrentIndex { 0 }
size_t	mCurrentBytes { 0 }

Static Public Attributes
static constexpr size_t	RequiredAlignment = 8

Detailed Description

A facade-like class, that implements buffered reading from the underlying data stream.

BufferedStreamReader provides optimal read performance for the built-in types of up to 8 bytes long.

Definition at line 23 of file BufferedStreamReader.h.

Constructor & Destructor Documentation

BufferedStreamReader()

BufferedStreamReader::BufferedStreamReader ( size_t  bufferSize = 4096 )

explicit

Definition at line 17 of file BufferedStreamReader.cpp.

    : mBufferSize(std::max(bufferSize, RequiredAlignment))
{
   mBufferData.resize(mBufferSize + RequiredAlignment);
 
   auto ptr = static_cast<void*>(mBufferData.data());
   auto space = mBufferData.size();
 
   std::align(RequiredAlignment, mBufferSize, ptr, space);
 
   mBufferStart = static_cast<uint8_t*>(ptr);
}

References mBufferData, mBufferSize, mBufferStart, and RequiredAlignment.

Member Function Documentation

Read()

size_t BufferedStreamReader::Read	(	void *	buffer,
		size_t	maxBytes
	)

Read up to maxBytes into the buffer. Returns the number of bytes read.

Definition at line 30 of file BufferedStreamReader.cpp.

{
   size_t bytesWritten = 0;
 
   while (maxBytes > 0)
   {
      if (mCurrentBytes == mCurrentIndex)
      {
         if (!HandleUnderflow())
            return bytesWritten;
      }
 
      const size_t availableBytes = mCurrentBytes - mCurrentIndex;
      const size_t bytesToRead = std::min(maxBytes, availableBytes);
 
      std::memcpy(static_cast<uint8_t*>(buffer) + bytesWritten, mBufferStart + mCurrentIndex, bytesToRead);
 
      maxBytes -= bytesToRead;
      bytesWritten += bytesToRead;
      mCurrentIndex += bytesToRead;
   }
 
   return bytesWritten;
}

References mBufferStart, mCurrentBytes, mCurrentIndex, and min().

Referenced by ProjectSerializer::Decode().

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Member Data Documentation

mBufferData

template<typename ValueType >

std::enable_if_t<sizeof(ValueType) <= RequiredAlignment, bool> ReadValue(ValueType& value) { constexpr size_t valueSize = sizeof(ValueType); const size_t availableBytes = mCurrentBytes - mCurrentIndex; if (availableBytes < valueSize) return valueSize == Read(&value, valueSize); if constexpr (valueSize == 1) value = mBufferStart[mCurrentIndex]; else value = UncheckedRead<ValueType>(); mCurrentIndex += valueSize; return true; } bool Eof() const; int GetC();protected: virtual bool HasMoreData() const = 0; virtual size_t ReadData(void* buffer, size_t maxBytes) = 0;private: bool HandleUnderflow(); template<typename T> T UncheckedRead() noexcept { T result; if ((mCurrentIndex % sizeof(T)) == 0) { const void* ptr = mBufferStart + mCurrentIndex; result = *static_cast<const T*>(ptr); } else { const uint8_t* begin = mBufferStart + mCurrentIndex; const uint8_t* end = begin + sizeof(T); void* out = &result; std::copy(begin, end, static_cast<uint8_t*>(out)); } return result; } std::vector<uint8_t> BufferedStreamReader::mBufferData

Read a single value of ValueType, where sizeof(ValueType) <= 8 and value is aligned to the size boundary.

Definition at line 103 of file BufferedStreamReader.h.

Referenced by BufferedStreamReader().

mBufferSize

size_t BufferedStreamReader::mBufferSize

Definition at line 108 of file BufferedStreamReader.h.

Referenced by BufferedStreamReader().

mBufferStart

uint8_t* BufferedStreamReader::mBufferStart

Definition at line 107 of file BufferedStreamReader.h.

Referenced by BufferedStreamReader(), and Read().

mCurrentBytes

size_t BufferedStreamReader::mCurrentBytes { 0 }

Definition at line 111 of file BufferedStreamReader.h.

Referenced by Read().

mCurrentIndex

size_t BufferedStreamReader::mCurrentIndex { 0 }

Definition at line 110 of file BufferedStreamReader.h.

Referenced by Read().

RequiredAlignment

constexpr size_t BufferedStreamReader::RequiredAlignment = 8

staticconstexpr

Definition at line 26 of file BufferedStreamReader.h.

Referenced by BufferedStreamReader().

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The documentation for this class was generated from the following files:

• BufferedStreamReader.h
• BufferedStreamReader.cpp