pflib::packing::Reader Class Reference

Reading a raw data stream with some underlying backend. More...

#include <Reader.h>

Inheritance diagram for pflib::packing::Reader:

Public Member Functions
	Reader ()=default
	default constructor
virtual	~Reader ()=default
	virtual destructor for inheritance
virtual void	seek (int off)=0
	Go ("seek") a specific position in the stream.
template<typename WordType , std::enable_if_t< std::is_integral< WordType >::value, bool > = true>
void	seek (int off)
	Seek by number of words.
virtual int	tell ()=0
	Tell us where the reader is.
template<typename WordType >
int	tell ()
	Tell by number of words.
virtual Reader &	read (char *w, std::size_t count)=0
	Read the next 'count' bytes into the input handle w.
template<typename WordType , std::enable_if_t< std::is_integral< WordType >::value, bool > = true>
Reader &	read (WordType *w, std::size_t count)
	Read the next 'count' words into the input handle.
template<typename WordType , std::enable_if_t< std::is_integral< WordType >::value, bool > = true>
Reader &	operator>> (WordType &w)
	Stream the next word into the input handle.
template<typename ObjectType , std::enable_if_t< std::is_class< ObjectType >::value, bool > = true>
Reader &	operator>> (ObjectType &o)
	Stream into a class object.
template<typename ContentType >
Reader &	read (std::vector< ContentType > &vec, std::size_t count, std::size_t offset=0)
	Read the next 'count' objects into the input vector.
virtual bool	good () const =0
	Check if reader is in a good state.
virtual bool	operator! () const
	Check if reader is in a fail state.
virtual	operator bool () const
	Check if reader is in good/bad state.
virtual bool	eof ()=0
	check if file is done

Detailed Description

Reading a raw data stream with some underlying backend.

This abstract base class assumes a derived class defines how to extract the next byte of data from some input data stream (e.g. either a in-memory buffer or a binary file). Then this interface has several templated methods that deduce how many bytes to extract and calls read methods on objects that are not integral types.

Constructor & Destructor Documentation

Reader()

pflib::packing::Reader::Reader ( )

default

default constructor

We make sure that our input file stream will not skip white space.

Member Function Documentation

eof()

virtual bool pflib::packing::Reader::eof ( )

pure virtual

check if file is done

Returns

true if we have reached the end of file.

Implemented in pflib::packing::FileReader.

good()

virtual bool pflib::packing::Reader::good ( ) const

pure virtual

Check if reader is in a good state.

Returns

bool true if reader is good and can keep reading

Implemented in pflib::packing::BufferReader, and pflib::packing::FileReader.

operator bool()

virtual pflib::packing::Reader::operator bool ( ) const

inlinevirtual

Check if reader is in good/bad state.

Defining this operator allows us to do the following.

// r is some concreate instance of a Reader
if (r) {
  std::cout << "r can read more data" << std::endl;
}

Returns

bool true if reader is in good state

operator!()

virtual bool pflib::packing::Reader::operator! ( ) const

inlinevirtual

Check if reader is in a fail state.

Returns

bool true if reader is in fail state

operator>>() [1/2]

template<typename ObjectType , std::enable_if_t< std::is_class< ObjectType >::value, bool > = true>

Reader & pflib::packing::Reader::operator>> ( ObjectType & o )

inline

Stream into a class object.

We assume that the class we are streaming to has a specific method defined.

Reader& read(Reader&)

This can be satisfied by the classes that we own and operate.

Template Parameters

in] ObjectType class type to read

Parameters

[in]

o

instance of object to read into

Returns

*this

operator>>() [2/2]

template<typename WordType , std::enable_if_t< std::is_integral< WordType >::value, bool > = true>

Reader & pflib::packing::Reader::operator>> ( WordType & w )

inline

Stream the next word into the input handle.

This implementation of the stream operator is only available to handles of integral types. Helps for shorthand of only grabbing a single word from the reader.

See also

read

Template Parameters

in] WordType integral-type word to read out

Parameters

[in]

w

reference to word to read into

Returns

handle to modified reader

read() [1/3]

virtual Reader & pflib::packing::Reader::read ( char * w, std::size_t count )

pure virtual

Read the next 'count' bytes into the input handle w.

Parameters

[in]	w	pointer to array to write data into
[in]	count	number of bytes to read

Returns

(*this)

Implemented in pflib::packing::BufferReader, and pflib::packing::FileReader.

read() [2/3]

template<typename ContentType >

Reader & pflib::packing::Reader::read ( std::vector< ContentType > & vec, std::size_t count, std::size_t offset = 0 )

inline

Read the next 'count' objects into the input vector.

This is common enough, I wanted to specialize the read function.

The std::vector::resize is helpful for avoiding additional copies while the vector is being expanded. After allocating the space for each entry in the vector, we call the stream operator from *this into each entry in order, leaving early if a failure occurs.

Template Parameters

in] ContentType type of object inside the vector

Parameters

[in]	vec	object vector to read into
[in]	count	number of objects to read

Returns

*this

read() [3/3]

template<typename WordType , std::enable_if_t< std::is_integral< WordType >::value, bool > = true>

Reader & pflib::packing::Reader::read ( WordType * w, std::size_t count )

inline

Read the next 'count' words into the input handle.

This implementation of read is only available to pointers to integral types. We assume that whatever space pointed to by w already has the space reserved necessary for the input words.

Template Parameters

in] WordType integral-type word to read out

Parameters

[in]	w	pointer to WordType array to write data to
[in]	count	number of words to read

Returns

(*this)

seek() [1/2]

template<typename WordType , std::enable_if_t< std::is_integral< WordType >::value, bool > = true>

void pflib::packing::Reader::seek ( int off )

inline

Seek by number of words.

This template version of seek uses the input word type to move around by the count of the input words rather than the count of bytes.

Template Parameters

in] WordType Integral-type to count by

Parameters

[in]	off	number of words to move relative to dir
[in]	dir	location flag for the file, default is beginning

seek() [2/2]

virtual void pflib::packing::Reader::seek ( int off )

pure virtual

Go ("seek") a specific position in the stream.

This non-template version of seek uses the default meaning of the "off" parameter in which it counts bytes.

Parameters

[in]	off	number of bytes to move relative to dir
[in]	dir	location flag for the file, default is beginning

Implemented in pflib::packing::BufferReader, and pflib::packing::FileReader.

tell() [1/2]

template<typename WordType >

int pflib::packing::Reader::tell ( )

inline

Tell by number of words.

Returns

int number of words relative to beginning of file

tell() [2/2]

virtual int pflib::packing::Reader::tell ( )

pure virtual

Tell us where the reader is.

Returns

int number of bytes relative to beginning of file

Implemented in pflib::packing::BufferReader, and pflib::packing::FileReader.

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

• include/pflib/packing/Reader.h