Beatmup::ChunkCollection Class Reference

A key-value pair set storing pieces of arbitrary data (chunks) under string keys. More...

#include <chunkfile.h>

Inheritance diagram for Beatmup::ChunkCollection:

Public Member Functions
virtual void	open ()=0
	Opens the collection to read chunks from it. More...
virtual void	close ()=0
	Closes the collection after a reading session. More...
virtual size_t	size () const =0
	Returns the number of chunks available in the collection after it is opened. More...
virtual bool	chunkExists (const std::string &id) const =0
	Check if a specific chunk exists. More...
virtual chunksize_t	chunkSize (const std::string &id) const =0
	Retrieves size of a specific chunk. More...
virtual chunksize_t	fetch (const std::string &id, void *data, const chunksize_t limit)=0
	Reads a chunk. More...
virtual void	save (const std::string &filename, bool append=false)=0
	Saves the collection to a file. More...
template<typename datatype >
datatype	read (const std::string &id)
	Reads a chunk and casts it into a given type. More...
template<typename datatype >
std::vector< datatype >	readVector (const std::string &id)
	Reads a chunk into a vector of a specific type. More...
template<>
std::string	read (const std::string &id)
Public Member Functions inherited from Beatmup::Object
virtual	~Object ()

Detailed Description

A key-value pair set storing pieces of arbitrary data (chunks) under string keys.

A chunk is a header and a piece of data packed in memory like this: (idLength[4], id[idLength], size[sizeof(chunksize_t)], data[size]) ChunkCollection defines an interface to retrieve chunks by their ids.

Definition at line 36 of file chunkfile.h.

Member Function Documentation

open()

virtual void Beatmup::ChunkCollection::open ( )

pure virtual

Opens the collection to read chunks from it.

Implemented in Beatmup::Python::WritableChunkCollection, Beatmup::ChunkFile, and Beatmup::Android::ChunkAsset.

close()

virtual void Beatmup::ChunkCollection::close ( )

pure virtual

Closes the collection after a reading session.

Implemented in Beatmup::Python::WritableChunkCollection, Beatmup::ChunkFile, and Beatmup::Android::ChunkAsset.

size()

virtual size_t Beatmup::ChunkCollection::size ( ) const

pure virtual

Returns the number of chunks available in the collection after it is opened.

Implemented in Beatmup::Python::WritableChunkCollection, and Beatmup::ChunkStream.

chunkExists()

virtual bool Beatmup::ChunkCollection::chunkExists ( const std::string &  id ) const

pure virtual

Check if a specific chunk exists.

Parameters

[in]

id

The chunk id

Returns

true if the chunk exists in the collection.

Implemented in Beatmup::Python::WritableChunkCollection, and Beatmup::ChunkStream.

chunkSize()

virtual chunksize_t Beatmup::ChunkCollection::chunkSize ( const std::string &  id ) const

pure virtual

Retrieves size of a specific chunk.

Parameters

[in]

id

The chunk id

Returns

size of the chunk in bytes, 0 if not found.

Implemented in Beatmup::Python::WritableChunkCollection, and Beatmup::ChunkStream.

fetch()

virtual chunksize_t Beatmup::ChunkCollection::fetch ( const std::string &  id, void *  data, const chunksize_t  limit  )

pure virtual

Reads a chunk.

The collection is expected to be opened.

Parameters

[in]	id	Wanted chunk id.
[out]	data	A buffer to write out the wanted chunk content.
[in]	limit	The buffer capacity in bytes.

Returns

number of bytes written out to the buffer: if the chunk is found fits the buffer, the chunk size is returned; if the chunk is found and too big, limit is returned (number of bytes actually written); if no chunk found, 0 is returned.

Implemented in Beatmup::Python::WritableChunkCollection, and Beatmup::ChunkStream.

save()

virtual void Beatmup::ChunkCollection::save ( const std::string &  filename, bool  append = false  )

pure virtual

Saves the collection to a file.

Parameters

[in]	filename	The name of the file to write chunks to
[in]	append	If true, writing to the end of the file (keeping the existing content). Rewriting the file otherwise.

Implemented in Beatmup::Python::WritableChunkCollection, and Beatmup::ChunkStream.

read() [1/2]

template<typename datatype >

datatype Beatmup::ChunkCollection::read ( const std::string &  id )

inline

Reads a chunk and casts it into a given type.

Parameters

[in]

id

The searched chunk id.

Definition at line 91 of file chunkfile.h.

                                                                              {
            datatype result;
#ifdef BEATMUP_DEBUG
            DebugAssertion::check(sizeof(result) == chunkSize(id),
                "Cannot fit chunk " + id + " of " + std::to_string(chunkSize(id)) + " bytes into " + std::to_string(sizeof(result)) + " bytes");
#endif
            fetch(id, &result, sizeof(result));
            return result;
        }

readVector()

template<typename datatype >

std::vector<datatype> Beatmup::ChunkCollection::readVector ( const std::string &  id )

inline

Reads a chunk into a vector of a specific type.

Parameters

[in]

id

The searched chunk id.

Definition at line 106 of file chunkfile.h.

                                                                   {
#ifdef BEATMUP_DEBUG
            DebugAssertion::check(chunkSize(id) % sizeof(datatype) == 0,
                "Cannot read chunk " + id + " of " + std::to_string(chunkSize(id)) + " bytes in a vector of elements"
                " of " + std::to_string(sizeof(datatype)) + " bytes each");
#endif
            std::vector<datatype> result;
            result.resize(chunkSize(id) / sizeof(datatype));
            fetch(id, static_cast<void*>(result.data()), result.size() * sizeof(datatype));
            return result;
        }

read() [2/2]

template<>

std::string Beatmup::ChunkCollection::read ( const std::string &  id )

inline

Definition at line 121 of file chunkfile.h.

                                                              {
        std::string result;
        result.resize(chunkSize(id));
        fetch(id, const_cast<char*>(result.data()), result.size());
        return result;
    }

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

• core/utils/chunkfile.h