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RHEOSTREAM(2RHEOLEF) - Linux man page online | System calls

Large data streams.

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NAME

irheostream, orheostream - large data streams

ABSTRACT

This class provides a stream interface for large data management. File decompresion is assumed using gzip and a recursive seach in a directory list is provided for input. orheostream foo("NAME", "suffix"); is like ofstream foo("NAME.suffix"). However, if NAME does not end with `.suffix', then `.suffix' is automatically added. By default, compression is performed on the fly with gzip, adding an additional `.gz' suffix. The flush action is nicely handled in compression mode: foo.flush(); This feature allows intermediate results to be available during long computations. The compression can be deactivated while opening a file by an optional argument: orheostream foo("NAME", "suffix", io::nogz); An existing compressed file can be reopen in append mode: new results will be appended at the end of an existing file: orheostream foo("NAME", "suffix", io::app); Conversely, irheostream foo("NAME","suffix"); is like ifstream foo("NAME.suffix"). However, we look at a search path environment variable RHEOPATH in order to find NAME while suffix is assumed. Moreover, gzip compressed files, ending with the `.gz' suffix is assumed, and decompression is done. Finally, a set of useful functions are provided.

DESCRIPTION

The following code: irheostream is("results", "data"); will recursively look for a `results[.data[.gz]]' file in the directory mentionned by the RHEOPATH environment variable. For instance, if you insert in our ".cshrc" something like: setenv RHEOPATH ".:/home/dupont:/usr/local/math/demo" the process will study the current directory `.', then, if neither `square.data.gz' nor `square.data' exits, it scan all subdirectory of the current directory. Then, if file is not founded, it start recusively in `/home/dupond' and then in `/usr/local/math/demo'. File decompression is performed by using the gzip command, and data are pipe-lined directly in memory. If the file start with `.' as `./square' or with a `/' as `/home/oscar/square', no search occurs and RHEOPATH environment variable is not used. Also, if the environment variable RHEOPATH is not set, the default value is the current directory `.'. For output stream: orheostream os("newresults", "data"); file compression is assumed, and "newresults.data.gz" will be created. File loading and storing are mentionned by a message, either: ! load "./results.data.gz" or: ! file "./newresults.data.gz" created. on the clog stream. By adding the following: clog << noverbose; you turn off these messages (see iorheo(4)).

IMPLEMENTATION

class irheostream : public boost::iostreams::filtering_stream<boost::iostreams::input> { public: irheostream() : boost::iostreams::filtering_stream<boost::iostreams::input>() {} irheostream(const std::string& name, const std::string& suffix = std::string()); virtual ~irheostream(); void open (const std::string& name, const std::string& suffix = std::string()); void close(); protected: std::ifstream _ifs; }; static const bool dont_gzip = false; class orheostream : public boost::iostreams::filtering_stream<boost::iostreams::output> { public: orheostream() : boost::iostreams::filtering_stream<boost::iostreams::output>() {} orheostream(const std::string& name, const std::string& suffix = std::string(), io::mode_type mode = io::out); virtual ~orheostream(); void open (const std::string& name, const std::string& suffix = std::string(), io::mode_type mode = io::out); void flush(); void close(); const std::string& filename() const { return _full_name; } protected: void _open_internal (io::mode_type mode); void _close_internal (); // data: io::mode_type _mode; std::string _full_name; }; std::string itos (std::string::size_type i); std::string ftos (const Float& x); // catch first occurence of string in file bool scatch (std::istream& in, const std::string& ch, bool full_match = true); // has_suffix("toto.suffix", "suffix") -> true bool has_suffix (const std::string& name, const std::string& suffix); // "toto.suffix" --> "toto" std::string delete_suffix (const std::string& name, const std::string& suffix); // "/usr/local/dir/toto.suffix" --> "toto.suffix" std::string get_basename (const std::string& name); // "/usr/local/dir/toto.suffix" --> "/usr/local/dir" std::string get_dirname (const std::string& name); // "toto" --> "/usr/local/math/data/toto.suffix" std::string get_full_name_from_rheo_path (const std::string& rootname, const std::string& suf ↲ fix); // "." + "../geodir" --> ".:../geodir" void append_dir_to_rheo_path (const std::string& dir); // "../geodir" + "." --> "../geodir:." void prepend_dir_to_rheo_path (const std::string& dir); bool file_exists (const std::string& filename); // string to float bool is_float (const std::string&); Float to_float (const std::string&); // in TMPDIR environment variable or "/tmp" by default std::string get_tmpdir();

SEE ALSO

iorheo(4)
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