FBB::MultiBuf - Selectively writes multiple streams
#include <bobcat/multibuf>
Linking option: -lbobcat
The FBB::MultiBuf class is a specialization of
std::streambuf. It can be used to write selectively to multiple
std::ostreams. Each std::ostream that is associated with a
MultiBuf is given a mode-tag indicating whether the stream should
always be used when information is inserted into the MultiBuf, just
once, or not at all. Each of the stream’s mode-tags may be set to any
of the defined tag-values.
When the address of a MultiBuf is used to initialize a
std::ostream the constructed std::ostream becomes an
output-multiplexer: by inserting information into the std::ostream
object, all std::ostream objects added to its MultiBuf buffer
which have an active mode receive that information.
An MultiBuf object should be outlived by all active streams
that are associated with it.
MultiBuf objects refer to std::ostreams which are
passed to it, and not to their std::streambufs. So it is possible to
change these std::ostream’s std::streambufs without
reinstalling the std::ostreams themselves.
No assumptions should be made about the order in which the
std::ostream objects that are associated with the MultiBuf
objects are visited when information is inserted.
FBB
All constructors, members, operators and manipulators, mentioned in this
man-page, are defined in the namespace FBB.
In the Mode enumeration the following values are
defined:
- o
- OFF:
A std::ostream having this mode will not be used when information is
inserted into a MultiBuf
- o
- ON:
A std::ostream having this mode will be used when information is
inserted into a MultiBuf
- o
- ONCE:
A std::ostream having this mode will be used once, until the next
flushing operation, when information is inserted into an
MultiBuf
- o
- RESET:
A std::ostream having this mode will not be used when information is
inserted into a MultiBuf. At a flush operation all ONCE
modes will be set to RESET
- o
- ALL:
This mode is used in combination with the member remove to remove all
std::ostream elements matching a specified std::ostream
argument.
The following subtypes are defined in the class
FBB:MultiBuf:
- o
- iterator:
This is a synonym of std::vector<stream>::iterator
- o
- const_iterator:
This is a synonym of std::vector<stream>::const_iterator
The class MultiBuf::stream is defined as a nested class of
MultiBuf. It offers the following constructor and public members:
- o
- stream(std::ostream &os, Mode mode = ON):
The constructor stores a std::ostream object, and associates a
Mode value with it.
- o
- void setMode(Mode mode):
This member is used to redefine the stream’s Mode
value.
- o
- void mode() const:
This member returns the stream’s Mode value.
- o
- operator std::ostream &():
This member returns the stream’s std::ostream.
- o
- MultiBuf():
The default constructor creates a MultiBuf object which contains no
associated std::ostream objects.
- o
- MultiBuf(std::ostream &os, Mode mode = ON):
This constructor creates a MultiBuf object which is immediately
associated with the std::ostream specified as its first
argument.
- o
- MultiBuf(std::vector<MultiBuf::stream> const &osvector):
This constructor creates a MultiBuf object which is immediately
associated with all std::ostream objects that are stored in the
MultiBuf::stream elements of the specified vector.
Copy and move constructors (and assignment operators) are not
available.
All members of std::ostringstream and std::exception
are available, as MultiBuf inherits from these classes.
- o
- iterator begin():
This member returns an iterator to the first stream element that is
stored in a MultiBuf object.
- o
- const_iterator begin():
This member returns an iterator to the first (unmodifiable) stream
element that is stored in a MultiBuf object.
- o
- iterator end():
This member returns an iterator pointing beyond the last stream
element that is stored in a MultiBuf object.
- o
- const_iterator end():
This member returns an iterator pointing beyond the last (unmodifiable)
stream element that is stored in a MultiBuf object.
- o
- void insert(std::ostream &os, Mode mode = ON):
This member adds the specified std::ostream using the specified
Mode to the current set of stream objects. Note that if
called multiple times for identical std::ostreams these objects are
inserted multiple times as well.
- o
- void insert(std::vector<stream> const &os):
This member adds all stream objects stored in the os vector to
the current set of stream objects.
- o
- bool remove(std::ostream &os, Mode mode = ONCE):
If os is stored in the MultiBuf it is removed, and true
is returned. If mode ALL is specified all os objects that
were stored in the MultiBuf object are removed (and true is
returned). If the os object was not stored false is
returned. To determine whether os has been stored in the
MultiBuf object its address is compared to the addresses of the
std::ostream objects that are stored inside the MultiBuf
object: the object(s) having addresses &os is (are)
removed.
- o
- void void setOnce():
This member will reset all the RESET Mode values of the stored
stream objects to ONCE.
- o
- size_t size() const:
The number of streams currently serviced by the MultiBuf object is
returned.
#include <iostream>
#include <fstream>
#include <bobcat/multibuf>
using namespace std;
using namespace FBB;
int main()
{
MultiBuf msb(cout);
ostream os(&msb);
ofstream out("out");
msb.insert(out, MultiBuf::ONCE);
os << "This is on cout and out\n"
"This is on cout only\n";
msb.setOnce();
os << "This is on cout and out\n"
"This is on cout only\n";
}
bobcat/multibuf - defines the class interface
- o
- https://fbb-git.gitlab.io/bobcat/: gitlab project page;
- o
- bobcat_6.02.02-x.dsc: detached signature;
- o
- bobcat_6.02.02-x.tar.gz: source archive;
- o
- bobcat_6.02.02-x_i386.changes: change log;
- o
- libbobcat1_6.02.02-x_*.deb: debian package containing the
libraries;
- o
- libbobcat1-dev_6.02.02-x_*.deb: debian package containing the
libraries, headers and manual pages;
Bobcat is an acronym of `Brokken’s Own Base Classes And
Templates’.
This is free software, distributed under the terms of the GNU
General Public License (GPL).
Frank B. Brokken (f.b.brokken@rug.nl).