Qt/QML edition

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Floris Bos 2020-03-04 16:55:40 +01:00
commit d7b361ba44
2168 changed files with 721948 additions and 0 deletions

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These classes provide a C++ stream interface to the zlib library. It allows you
to do things like:
gzofstream outf("blah.gz");
outf << "These go into the gzip file " << 123 << endl;
It does this by deriving a specialized stream buffer for gzipped files, which is
the way Stroustrup would have done it. :->
The gzifstream and gzofstream classes were originally written by Kevin Ruland
and made available in the zlib contrib/iostream directory. The older version still
compiles under gcc 2.xx, but not under gcc 3.xx, which sparked the development of
this version.
The new classes are as standard-compliant as possible, closely following the
approach of the standard library's fstream classes. It compiles under gcc versions
3.2 and 3.3, but not under gcc 2.xx. This is mainly due to changes in the standard
library naming scheme. The new version of gzifstream/gzofstream/gzfilebuf differs
from the previous one in the following respects:
- added showmanyc
- added setbuf, with support for unbuffered output via setbuf(0,0)
- a few bug fixes of stream behavior
- gzipped output file opened with default compression level instead of maximum level
- setcompressionlevel()/strategy() members replaced by single setcompression()
The code is provided "as is", with the permission to use, copy, modify, distribute
and sell it for any purpose without fee.
Ludwig Schwardt
<schwardt@sun.ac.za>
DSP Lab
Electrical & Electronic Engineering Department
University of Stellenbosch
South Africa

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Possible upgrades to gzfilebuf:
- The ability to do putback (e.g. putbackfail)
- The ability to seek (zlib supports this, but could be slow/tricky)
- Simultaneous read/write access (does it make sense?)
- Support for ios_base::ate open mode
- Locale support?
- Check public interface to see which calls give problems
(due to dependence on library internals)
- Override operator<<(ostream&, gzfilebuf*) to allow direct copying
of stream buffer to stream ( i.e. os << is.rdbuf(); )

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/*
* Test program for gzifstream and gzofstream
*
* by Ludwig Schwardt <schwardt@sun.ac.za>
* original version by Kevin Ruland <kevin@rodin.wustl.edu>
*/
#include "zfstream.h"
#include <iostream> // for cout
int main() {
gzofstream outf;
gzifstream inf;
char buf[80];
outf.open("test1.txt.gz");
outf << "The quick brown fox sidestepped the lazy canine\n"
<< 1.3 << "\nPlan " << 9 << std::endl;
outf.close();
std::cout << "Wrote the following message to 'test1.txt.gz' (check with zcat or zless):\n"
<< "The quick brown fox sidestepped the lazy canine\n"
<< 1.3 << "\nPlan " << 9 << std::endl;
std::cout << "\nReading 'test1.txt.gz' (buffered) produces:\n";
inf.open("test1.txt.gz");
while (inf.getline(buf,80,'\n')) {
std::cout << buf << "\t(" << inf.rdbuf()->in_avail() << " chars left in buffer)\n";
}
inf.close();
outf.rdbuf()->pubsetbuf(0,0);
outf.open("test2.txt.gz");
outf << setcompression(Z_NO_COMPRESSION)
<< "The quick brown fox sidestepped the lazy canine\n"
<< 1.3 << "\nPlan " << 9 << std::endl;
outf.close();
std::cout << "\nWrote the same message to 'test2.txt.gz' in uncompressed form";
std::cout << "\nReading 'test2.txt.gz' (unbuffered) produces:\n";
inf.rdbuf()->pubsetbuf(0,0);
inf.open("test2.txt.gz");
while (inf.getline(buf,80,'\n')) {
std::cout << buf << "\t(" << inf.rdbuf()->in_avail() << " chars left in buffer)\n";
}
inf.close();
return 0;
}

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/*
* A C++ I/O streams interface to the zlib gz* functions
*
* by Ludwig Schwardt <schwardt@sun.ac.za>
* original version by Kevin Ruland <kevin@rodin.wustl.edu>
*
* This version is standard-compliant and compatible with gcc 3.x.
*/
#include "zfstream.h"
#include <cstring> // for strcpy, strcat, strlen (mode strings)
#include <cstdio> // for BUFSIZ
// Internal buffer sizes (default and "unbuffered" versions)
#define BIGBUFSIZE BUFSIZ
#define SMALLBUFSIZE 1
/*****************************************************************************/
// Default constructor
gzfilebuf::gzfilebuf()
: file(NULL), io_mode(std::ios_base::openmode(0)), own_fd(false),
buffer(NULL), buffer_size(BIGBUFSIZE), own_buffer(true)
{
// No buffers to start with
this->disable_buffer();
}
// Destructor
gzfilebuf::~gzfilebuf()
{
// Sync output buffer and close only if responsible for file
// (i.e. attached streams should be left open at this stage)
this->sync();
if (own_fd)
this->close();
// Make sure internal buffer is deallocated
this->disable_buffer();
}
// Set compression level and strategy
int
gzfilebuf::setcompression(int comp_level,
int comp_strategy)
{
return gzsetparams(file, comp_level, comp_strategy);
}
// Open gzipped file
gzfilebuf*
gzfilebuf::open(const char *name,
std::ios_base::openmode mode)
{
// Fail if file already open
if (this->is_open())
return NULL;
// Don't support simultaneous read/write access (yet)
if ((mode & std::ios_base::in) && (mode & std::ios_base::out))
return NULL;
// Build mode string for gzopen and check it [27.8.1.3.2]
char char_mode[6] = "\0\0\0\0\0";
if (!this->open_mode(mode, char_mode))
return NULL;
// Attempt to open file
if ((file = gzopen(name, char_mode)) == NULL)
return NULL;
// On success, allocate internal buffer and set flags
this->enable_buffer();
io_mode = mode;
own_fd = true;
return this;
}
// Attach to gzipped file
gzfilebuf*
gzfilebuf::attach(int fd,
std::ios_base::openmode mode)
{
// Fail if file already open
if (this->is_open())
return NULL;
// Don't support simultaneous read/write access (yet)
if ((mode & std::ios_base::in) && (mode & std::ios_base::out))
return NULL;
// Build mode string for gzdopen and check it [27.8.1.3.2]
char char_mode[6] = "\0\0\0\0\0";
if (!this->open_mode(mode, char_mode))
return NULL;
// Attempt to attach to file
if ((file = gzdopen(fd, char_mode)) == NULL)
return NULL;
// On success, allocate internal buffer and set flags
this->enable_buffer();
io_mode = mode;
own_fd = false;
return this;
}
// Close gzipped file
gzfilebuf*
gzfilebuf::close()
{
// Fail immediately if no file is open
if (!this->is_open())
return NULL;
// Assume success
gzfilebuf* retval = this;
// Attempt to sync and close gzipped file
if (this->sync() == -1)
retval = NULL;
if (gzclose(file) < 0)
retval = NULL;
// File is now gone anyway (postcondition [27.8.1.3.8])
file = NULL;
own_fd = false;
// Destroy internal buffer if it exists
this->disable_buffer();
return retval;
}
/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */
// Convert int open mode to mode string
bool
gzfilebuf::open_mode(std::ios_base::openmode mode,
char* c_mode) const
{
bool testb = mode & std::ios_base::binary;
bool testi = mode & std::ios_base::in;
bool testo = mode & std::ios_base::out;
bool testt = mode & std::ios_base::trunc;
bool testa = mode & std::ios_base::app;
// Check for valid flag combinations - see [27.8.1.3.2] (Table 92)
// Original zfstream hardcoded the compression level to maximum here...
// Double the time for less than 1% size improvement seems
// excessive though - keeping it at the default level
// To change back, just append "9" to the next three mode strings
if (!testi && testo && !testt && !testa)
strcpy(c_mode, "w");
if (!testi && testo && !testt && testa)
strcpy(c_mode, "a");
if (!testi && testo && testt && !testa)
strcpy(c_mode, "w");
if (testi && !testo && !testt && !testa)
strcpy(c_mode, "r");
// No read/write mode yet
// if (testi && testo && !testt && !testa)
// strcpy(c_mode, "r+");
// if (testi && testo && testt && !testa)
// strcpy(c_mode, "w+");
// Mode string should be empty for invalid combination of flags
if (strlen(c_mode) == 0)
return false;
if (testb)
strcat(c_mode, "b");
return true;
}
// Determine number of characters in internal get buffer
std::streamsize
gzfilebuf::showmanyc()
{
// Calls to underflow will fail if file not opened for reading
if (!this->is_open() || !(io_mode & std::ios_base::in))
return -1;
// Make sure get area is in use
if (this->gptr() && (this->gptr() < this->egptr()))
return std::streamsize(this->egptr() - this->gptr());
else
return 0;
}
// Fill get area from gzipped file
gzfilebuf::int_type
gzfilebuf::underflow()
{
// If something is left in the get area by chance, return it
// (this shouldn't normally happen, as underflow is only supposed
// to be called when gptr >= egptr, but it serves as error check)
if (this->gptr() && (this->gptr() < this->egptr()))
return traits_type::to_int_type(*(this->gptr()));
// If the file hasn't been opened for reading, produce error
if (!this->is_open() || !(io_mode & std::ios_base::in))
return traits_type::eof();
// Attempt to fill internal buffer from gzipped file
// (buffer must be guaranteed to exist...)
int bytes_read = gzread(file, buffer, buffer_size);
// Indicates error or EOF
if (bytes_read <= 0)
{
// Reset get area
this->setg(buffer, buffer, buffer);
return traits_type::eof();
}
// Make all bytes read from file available as get area
this->setg(buffer, buffer, buffer + bytes_read);
// Return next character in get area
return traits_type::to_int_type(*(this->gptr()));
}
// Write put area to gzipped file
gzfilebuf::int_type
gzfilebuf::overflow(int_type c)
{
// Determine whether put area is in use
if (this->pbase())
{
// Double-check pointer range
if (this->pptr() > this->epptr() || this->pptr() < this->pbase())
return traits_type::eof();
// Add extra character to buffer if not EOF
if (!traits_type::eq_int_type(c, traits_type::eof()))
{
*(this->pptr()) = traits_type::to_char_type(c);
this->pbump(1);
}
// Number of characters to write to file
int bytes_to_write = this->pptr() - this->pbase();
// Overflow doesn't fail if nothing is to be written
if (bytes_to_write > 0)
{
// If the file hasn't been opened for writing, produce error
if (!this->is_open() || !(io_mode & std::ios_base::out))
return traits_type::eof();
// If gzipped file won't accept all bytes written to it, fail
if (gzwrite(file, this->pbase(), bytes_to_write) != bytes_to_write)
return traits_type::eof();
// Reset next pointer to point to pbase on success
this->pbump(-bytes_to_write);
}
}
// Write extra character to file if not EOF
else if (!traits_type::eq_int_type(c, traits_type::eof()))
{
// If the file hasn't been opened for writing, produce error
if (!this->is_open() || !(io_mode & std::ios_base::out))
return traits_type::eof();
// Impromptu char buffer (allows "unbuffered" output)
char_type last_char = traits_type::to_char_type(c);
// If gzipped file won't accept this character, fail
if (gzwrite(file, &last_char, 1) != 1)
return traits_type::eof();
}
// If you got here, you have succeeded (even if c was EOF)
// The return value should therefore be non-EOF
if (traits_type::eq_int_type(c, traits_type::eof()))
return traits_type::not_eof(c);
else
return c;
}
// Assign new buffer
std::streambuf*
gzfilebuf::setbuf(char_type* p,
std::streamsize n)
{
// First make sure stuff is sync'ed, for safety
if (this->sync() == -1)
return NULL;
// If buffering is turned off on purpose via setbuf(0,0), still allocate one...
// "Unbuffered" only really refers to put [27.8.1.4.10], while get needs at
// least a buffer of size 1 (very inefficient though, therefore make it bigger?)
// This follows from [27.5.2.4.3]/12 (gptr needs to point at something, it seems)
if (!p || !n)
{
// Replace existing buffer (if any) with small internal buffer
this->disable_buffer();
buffer = NULL;
buffer_size = 0;
own_buffer = true;
this->enable_buffer();
}
else
{
// Replace existing buffer (if any) with external buffer
this->disable_buffer();
buffer = p;
buffer_size = n;
own_buffer = false;
this->enable_buffer();
}
return this;
}
// Write put area to gzipped file (i.e. ensures that put area is empty)
int
gzfilebuf::sync()
{
return traits_type::eq_int_type(this->overflow(), traits_type::eof()) ? -1 : 0;
}
/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */
// Allocate internal buffer
void
gzfilebuf::enable_buffer()
{
// If internal buffer required, allocate one
if (own_buffer && !buffer)
{
// Check for buffered vs. "unbuffered"
if (buffer_size > 0)
{
// Allocate internal buffer
buffer = new char_type[buffer_size];
// Get area starts empty and will be expanded by underflow as need arises
this->setg(buffer, buffer, buffer);
// Setup entire internal buffer as put area.
// The one-past-end pointer actually points to the last element of the buffer,
// so that overflow(c) can safely add the extra character c to the sequence.
// These pointers remain in place for the duration of the buffer
this->setp(buffer, buffer + buffer_size - 1);
}
else
{
// Even in "unbuffered" case, (small?) get buffer is still required
buffer_size = SMALLBUFSIZE;
buffer = new char_type[buffer_size];
this->setg(buffer, buffer, buffer);
// "Unbuffered" means no put buffer
this->setp(0, 0);
}
}
else
{
// If buffer already allocated, reset buffer pointers just to make sure no
// stale chars are lying around
this->setg(buffer, buffer, buffer);
this->setp(buffer, buffer + buffer_size - 1);
}
}
// Destroy internal buffer
void
gzfilebuf::disable_buffer()
{
// If internal buffer exists, deallocate it
if (own_buffer && buffer)
{
// Preserve unbuffered status by zeroing size
if (!this->pbase())
buffer_size = 0;
delete[] buffer;
buffer = NULL;
this->setg(0, 0, 0);
this->setp(0, 0);
}
else
{
// Reset buffer pointers to initial state if external buffer exists
this->setg(buffer, buffer, buffer);
if (buffer)
this->setp(buffer, buffer + buffer_size - 1);
else
this->setp(0, 0);
}
}
/*****************************************************************************/
// Default constructor initializes stream buffer
gzifstream::gzifstream()
: std::istream(NULL), sb()
{ this->init(&sb); }
// Initialize stream buffer and open file
gzifstream::gzifstream(const char* name,
std::ios_base::openmode mode)
: std::istream(NULL), sb()
{
this->init(&sb);
this->open(name, mode);
}
// Initialize stream buffer and attach to file
gzifstream::gzifstream(int fd,
std::ios_base::openmode mode)
: std::istream(NULL), sb()
{
this->init(&sb);
this->attach(fd, mode);
}
// Open file and go into fail() state if unsuccessful
void
gzifstream::open(const char* name,
std::ios_base::openmode mode)
{
if (!sb.open(name, mode | std::ios_base::in))
this->setstate(std::ios_base::failbit);
else
this->clear();
}
// Attach to file and go into fail() state if unsuccessful
void
gzifstream::attach(int fd,
std::ios_base::openmode mode)
{
if (!sb.attach(fd, mode | std::ios_base::in))
this->setstate(std::ios_base::failbit);
else
this->clear();
}
// Close file
void
gzifstream::close()
{
if (!sb.close())
this->setstate(std::ios_base::failbit);
}
/*****************************************************************************/
// Default constructor initializes stream buffer
gzofstream::gzofstream()
: std::ostream(NULL), sb()
{ this->init(&sb); }
// Initialize stream buffer and open file
gzofstream::gzofstream(const char* name,
std::ios_base::openmode mode)
: std::ostream(NULL), sb()
{
this->init(&sb);
this->open(name, mode);
}
// Initialize stream buffer and attach to file
gzofstream::gzofstream(int fd,
std::ios_base::openmode mode)
: std::ostream(NULL), sb()
{
this->init(&sb);
this->attach(fd, mode);
}
// Open file and go into fail() state if unsuccessful
void
gzofstream::open(const char* name,
std::ios_base::openmode mode)
{
if (!sb.open(name, mode | std::ios_base::out))
this->setstate(std::ios_base::failbit);
else
this->clear();
}
// Attach to file and go into fail() state if unsuccessful
void
gzofstream::attach(int fd,
std::ios_base::openmode mode)
{
if (!sb.attach(fd, mode | std::ios_base::out))
this->setstate(std::ios_base::failbit);
else
this->clear();
}
// Close file
void
gzofstream::close()
{
if (!sb.close())
this->setstate(std::ios_base::failbit);
}

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/*
* A C++ I/O streams interface to the zlib gz* functions
*
* by Ludwig Schwardt <schwardt@sun.ac.za>
* original version by Kevin Ruland <kevin@rodin.wustl.edu>
*
* This version is standard-compliant and compatible with gcc 3.x.
*/
#ifndef ZFSTREAM_H
#define ZFSTREAM_H
#include <istream> // not iostream, since we don't need cin/cout
#include <ostream>
#include "zlib.h"
/*****************************************************************************/
/**
* @brief Gzipped file stream buffer class.
*
* This class implements basic_filebuf for gzipped files. It doesn't yet support
* seeking (allowed by zlib but slow/limited), putback and read/write access
* (tricky). Otherwise, it attempts to be a drop-in replacement for the standard
* file streambuf.
*/
class gzfilebuf : public std::streambuf
{
public:
// Default constructor.
gzfilebuf();
// Destructor.
virtual
~gzfilebuf();
/**
* @brief Set compression level and strategy on the fly.
* @param comp_level Compression level (see zlib.h for allowed values)
* @param comp_strategy Compression strategy (see zlib.h for allowed values)
* @return Z_OK on success, Z_STREAM_ERROR otherwise.
*
* Unfortunately, these parameters cannot be modified separately, as the
* previous zfstream version assumed. Since the strategy is seldom changed,
* it can default and setcompression(level) then becomes like the old
* setcompressionlevel(level).
*/
int
setcompression(int comp_level,
int comp_strategy = Z_DEFAULT_STRATEGY);
/**
* @brief Check if file is open.
* @return True if file is open.
*/
bool
is_open() const { return (file != NULL); }
/**
* @brief Open gzipped file.
* @param name File name.
* @param mode Open mode flags.
* @return @c this on success, NULL on failure.
*/
gzfilebuf*
open(const char* name,
std::ios_base::openmode mode);
/**
* @brief Attach to already open gzipped file.
* @param fd File descriptor.
* @param mode Open mode flags.
* @return @c this on success, NULL on failure.
*/
gzfilebuf*
attach(int fd,
std::ios_base::openmode mode);
/**
* @brief Close gzipped file.
* @return @c this on success, NULL on failure.
*/
gzfilebuf*
close();
protected:
/**
* @brief Convert ios open mode int to mode string used by zlib.
* @return True if valid mode flag combination.
*/
bool
open_mode(std::ios_base::openmode mode,
char* c_mode) const;
/**
* @brief Number of characters available in stream buffer.
* @return Number of characters.
*
* This indicates number of characters in get area of stream buffer.
* These characters can be read without accessing the gzipped file.
*/
virtual std::streamsize
showmanyc();
/**
* @brief Fill get area from gzipped file.
* @return First character in get area on success, EOF on error.
*
* This actually reads characters from gzipped file to stream
* buffer. Always buffered.
*/
virtual int_type
underflow();
/**
* @brief Write put area to gzipped file.
* @param c Extra character to add to buffer contents.
* @return Non-EOF on success, EOF on error.
*
* This actually writes characters in stream buffer to
* gzipped file. With unbuffered output this is done one
* character at a time.
*/
virtual int_type
overflow(int_type c = traits_type::eof());
/**
* @brief Installs external stream buffer.
* @param p Pointer to char buffer.
* @param n Size of external buffer.
* @return @c this on success, NULL on failure.
*
* Call setbuf(0,0) to enable unbuffered output.
*/
virtual std::streambuf*
setbuf(char_type* p,
std::streamsize n);
/**
* @brief Flush stream buffer to file.
* @return 0 on success, -1 on error.
*
* This calls underflow(EOF) to do the job.
*/
virtual int
sync();
//
// Some future enhancements
//
// virtual int_type uflow();
// virtual int_type pbackfail(int_type c = traits_type::eof());
// virtual pos_type
// seekoff(off_type off,
// std::ios_base::seekdir way,
// std::ios_base::openmode mode = std::ios_base::in|std::ios_base::out);
// virtual pos_type
// seekpos(pos_type sp,
// std::ios_base::openmode mode = std::ios_base::in|std::ios_base::out);
private:
/**
* @brief Allocate internal buffer.
*
* This function is safe to call multiple times. It will ensure
* that a proper internal buffer exists if it is required. If the
* buffer already exists or is external, the buffer pointers will be
* reset to their original state.
*/
void
enable_buffer();
/**
* @brief Destroy internal buffer.
*
* This function is safe to call multiple times. It will ensure
* that the internal buffer is deallocated if it exists. In any
* case, it will also reset the buffer pointers.
*/
void
disable_buffer();
/**
* Underlying file pointer.
*/
gzFile file;
/**
* Mode in which file was opened.
*/
std::ios_base::openmode io_mode;
/**
* @brief True if this object owns file descriptor.
*
* This makes the class responsible for closing the file
* upon destruction.
*/
bool own_fd;
/**
* @brief Stream buffer.
*
* For simplicity this remains allocated on the free store for the
* entire life span of the gzfilebuf object, unless replaced by setbuf.
*/
char_type* buffer;
/**
* @brief Stream buffer size.
*
* Defaults to system default buffer size (typically 8192 bytes).
* Modified by setbuf.
*/
std::streamsize buffer_size;
/**
* @brief True if this object owns stream buffer.
*
* This makes the class responsible for deleting the buffer
* upon destruction.
*/
bool own_buffer;
};
/*****************************************************************************/
/**
* @brief Gzipped file input stream class.
*
* This class implements ifstream for gzipped files. Seeking and putback
* is not supported yet.
*/
class gzifstream : public std::istream
{
public:
// Default constructor
gzifstream();
/**
* @brief Construct stream on gzipped file to be opened.
* @param name File name.
* @param mode Open mode flags (forced to contain ios::in).
*/
explicit
gzifstream(const char* name,
std::ios_base::openmode mode = std::ios_base::in);
/**
* @brief Construct stream on already open gzipped file.
* @param fd File descriptor.
* @param mode Open mode flags (forced to contain ios::in).
*/
explicit
gzifstream(int fd,
std::ios_base::openmode mode = std::ios_base::in);
/**
* Obtain underlying stream buffer.
*/
gzfilebuf*
rdbuf() const
{ return const_cast<gzfilebuf*>(&sb); }
/**
* @brief Check if file is open.
* @return True if file is open.
*/
bool
is_open() { return sb.is_open(); }
/**
* @brief Open gzipped file.
* @param name File name.
* @param mode Open mode flags (forced to contain ios::in).
*
* Stream will be in state good() if file opens successfully;
* otherwise in state fail(). This differs from the behavior of
* ifstream, which never sets the state to good() and therefore
* won't allow you to reuse the stream for a second file unless
* you manually clear() the state. The choice is a matter of
* convenience.
*/
void
open(const char* name,
std::ios_base::openmode mode = std::ios_base::in);
/**
* @brief Attach to already open gzipped file.
* @param fd File descriptor.
* @param mode Open mode flags (forced to contain ios::in).
*
* Stream will be in state good() if attach succeeded; otherwise
* in state fail().
*/
void
attach(int fd,
std::ios_base::openmode mode = std::ios_base::in);
/**
* @brief Close gzipped file.
*
* Stream will be in state fail() if close failed.
*/
void
close();
private:
/**
* Underlying stream buffer.
*/
gzfilebuf sb;
};
/*****************************************************************************/
/**
* @brief Gzipped file output stream class.
*
* This class implements ofstream for gzipped files. Seeking and putback
* is not supported yet.
*/
class gzofstream : public std::ostream
{
public:
// Default constructor
gzofstream();
/**
* @brief Construct stream on gzipped file to be opened.
* @param name File name.
* @param mode Open mode flags (forced to contain ios::out).
*/
explicit
gzofstream(const char* name,
std::ios_base::openmode mode = std::ios_base::out);
/**
* @brief Construct stream on already open gzipped file.
* @param fd File descriptor.
* @param mode Open mode flags (forced to contain ios::out).
*/
explicit
gzofstream(int fd,
std::ios_base::openmode mode = std::ios_base::out);
/**
* Obtain underlying stream buffer.
*/
gzfilebuf*
rdbuf() const
{ return const_cast<gzfilebuf*>(&sb); }
/**
* @brief Check if file is open.
* @return True if file is open.
*/
bool
is_open() { return sb.is_open(); }
/**
* @brief Open gzipped file.
* @param name File name.
* @param mode Open mode flags (forced to contain ios::out).
*
* Stream will be in state good() if file opens successfully;
* otherwise in state fail(). This differs from the behavior of
* ofstream, which never sets the state to good() and therefore
* won't allow you to reuse the stream for a second file unless
* you manually clear() the state. The choice is a matter of
* convenience.
*/
void
open(const char* name,
std::ios_base::openmode mode = std::ios_base::out);
/**
* @brief Attach to already open gzipped file.
* @param fd File descriptor.
* @param mode Open mode flags (forced to contain ios::out).
*
* Stream will be in state good() if attach succeeded; otherwise
* in state fail().
*/
void
attach(int fd,
std::ios_base::openmode mode = std::ios_base::out);
/**
* @brief Close gzipped file.
*
* Stream will be in state fail() if close failed.
*/
void
close();
private:
/**
* Underlying stream buffer.
*/
gzfilebuf sb;
};
/*****************************************************************************/
/**
* @brief Gzipped file output stream manipulator class.
*
* This class defines a two-argument manipulator for gzofstream. It is used
* as base for the setcompression(int,int) manipulator.
*/
template<typename T1, typename T2>
class gzomanip2
{
public:
// Allows insertor to peek at internals
template <typename Ta, typename Tb>
friend gzofstream&
operator<<(gzofstream&,
const gzomanip2<Ta,Tb>&);
// Constructor
gzomanip2(gzofstream& (*f)(gzofstream&, T1, T2),
T1 v1,
T2 v2);
private:
// Underlying manipulator function
gzofstream&
(*func)(gzofstream&, T1, T2);
// Arguments for manipulator function
T1 val1;
T2 val2;
};
/*****************************************************************************/
// Manipulator function thunks through to stream buffer
inline gzofstream&
setcompression(gzofstream &gzs, int l, int s = Z_DEFAULT_STRATEGY)
{
(gzs.rdbuf())->setcompression(l, s);
return gzs;
}
// Manipulator constructor stores arguments
template<typename T1, typename T2>
inline
gzomanip2<T1,T2>::gzomanip2(gzofstream &(*f)(gzofstream &, T1, T2),
T1 v1,
T2 v2)
: func(f), val1(v1), val2(v2)
{ }
// Insertor applies underlying manipulator function to stream
template<typename T1, typename T2>
inline gzofstream&
operator<<(gzofstream& s, const gzomanip2<T1,T2>& m)
{ return (*m.func)(s, m.val1, m.val2); }
// Insert this onto stream to simplify setting of compression level
inline gzomanip2<int,int>
setcompression(int l, int s = Z_DEFAULT_STRATEGY)
{ return gzomanip2<int,int>(&setcompression, l, s); }
#endif // ZFSTREAM_H