Beatmup::ChunkStream Class Reference

Stream of chunks. More...

#include <chunkfile.h>

Inheritance diagram for Beatmup::ChunkStream:

Classes
struct	ChunkDesc

Public Member Functions
size_t	size () const
	Returns the number of chunks available in the collection after it is opened. More...
bool	chunkExists (const std::string &id) const
	Check if a specific chunk exists. More...
chunksize_t	chunkSize (const std::string &id) const
	Retrieves size of a specific chunk. More...
chunksize_t	fetch (const std::string &id, void *data, const chunksize_t limit)
	Reads a chunk. More...
void	save (const std::string &filename, bool append=false)
	Saves the collection to a file. More...
Public Member Functions inherited from Beatmup::ChunkCollection
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...
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 ()

Protected Member Functions
	ChunkStream (InputStream &stream)
bool	parse ()
	Goes through the input stream to build the list of existing chunks. More...

Private Attributes
std::map< std::string, ChunkDesc >	map
InputStream &	stream

Detailed Description

Stream of chunks.

Implements ChunkCollection from a streamed source.

Definition at line 132 of file chunkfile.h.

Constructor & Destructor Documentation

ChunkStream()

Beatmup::ChunkStream::ChunkStream ( InputStream &  stream )

inlineprotected

Definition at line 143 of file chunkfile.h.

: stream(stream) {}

Member Function Documentation

parse()

bool ChunkStream::parse ( )

protected

Goes through the input stream to build the list of existing chunks.

Does not read the chunks content, only headers.

Definition at line 39 of file chunkfile.cpp.

                        {
    map.clear();
    if (!stream.seek(0))
        return false;
 
    size_t pos = 0;
    id_size_t idLength;
    while (stream(&idLength, sizeof(id_size_t))) {
        // read id
        std::string id(idLength, 0);
        if (!stream(&id[0], idLength))
            return false;
        pos += idLength + sizeof(id_size_t);
 
        // read length
        ChunkDesc chunkDesc;
        if (!stream(&chunkDesc.size, sizeof(chunksize_t)))
            return false;
        pos += sizeof(chunksize_t);
 
        // read content
        chunkDesc.pos = pos;
        map[id] = chunkDesc;
        pos += chunkDesc.size;
        if (!stream.seek(pos))
            return false;
    }
    return true;
}

size()

size_t Beatmup::ChunkStream::size ( ) const

inlinevirtual

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

Implements Beatmup::ChunkCollection.

Definition at line 152 of file chunkfile.h.

{ return map.size(); }

chunkExists()

bool Beatmup::ChunkStream::chunkExists ( const std::string &  id ) const

inlinevirtual

Check if a specific chunk exists.

Parameters

[in]

id

The chunk id

Returns

true if the chunk exists in the collection.

Implements Beatmup::ChunkCollection.

Definition at line 154 of file chunkfile.h.

{ return map.find(id) != map.end(); }

chunkSize()

chunksize_t ChunkStream::chunkSize ( const std::string &  id ) const

virtual

Retrieves size of a specific chunk.

Parameters

[in]

id

The chunk id

Returns

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

Implements Beatmup::ChunkCollection.

Definition at line 70 of file chunkfile.cpp.

                                                            {
    const auto& chunk = map.find(id);
    return chunk == map.end() ? 0 : chunk->second.size;
}

fetch()

chunksize_t ChunkStream::fetch ( const std::string &  id, void *  data, const chunksize_t  limit  )

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.

Implements Beatmup::ChunkCollection.

Definition at line 76 of file chunkfile.cpp.

                                                                                       {
#ifdef BEATMUP_DEBUG
    ChunkIdTooLong::check(id);
#endif
 
    const auto& chunk = map.find(id);
    if (chunk == map.end())
        return 0;
 
    if (!stream.seek(chunk->second.pos))
        throw RuntimeError("Cannot seek for chunk " + id);
 
    const chunksize_t size = chunk->second.size < limit ? chunk->second.size : limit;
    if (!stream(data, size))
        throw RuntimeError("Cannot read chunk " + id);
 
    return size;
}

save()

void ChunkStream::save ( const std::string &  filename, bool  append = false  )

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.

Implements Beatmup::ChunkCollection.

Definition at line 96 of file chunkfile.cpp.

                                                             {
    ChunkFileWriter writer(filename, append);
    for (auto it : map) {
        Chunk chunk(*this, it.first);
        writer(it.first, chunk(), chunk.size());
    }
}

Member Data Documentation

map

std::map<std::string, ChunkDesc> Beatmup::ChunkStream::map

private

Definition at line 139 of file chunkfile.h.

stream

InputStream& Beatmup::ChunkStream::stream

private

Definition at line 140 of file chunkfile.h.

---

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

• core/utils/chunkfile.h
• core/utils/chunkfile.cpp