FBB::MultiStreambuf - Selectively writes multiple streams
#include <bobcat/multistreambuf>
Linking option: -lbobcat
The FBB::MultiStreambuf 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
MultiStreambuf is given a mode-tag indicating whether the stream
should always be used when information is inserted into the
MultiStreambuf, 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 MultiStreambuf 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 MultiStreambuf
buffer which have an active mode receive that information.
An MultiStreambuf object should be outlived by all active
streams that are associated with it.
MultiStreambuf 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
MultiStreambuf 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 MultiStreambuf
- o
- ON:
A std::ostream having this mode will be used when information is
inserted into a MultiStreambuf
- o
- ONCE:
A std::ostream having this mode will be used once, until the next
flushing operation, when information is inserted into an
MultiStreambuf
- o
- RESET:
A std::ostream having this mode will not be used when information is
inserted into a MultiStreambuf. 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:MultiStreambuf:
- 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 MultiStreambuf::stream is defined as a nested
class of MultiStreambuf. 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
- MultiStreambuf():
The default constructor creates a MultiStreambuf object which
contains no associated std::ostream objects.
- o
- MultiStreambuf(std::ostream &os, Mode mode = ON):
This constructor creates a MultiStreambuf object which is immediately
associated with the std::ostream specified as its first
argument.
- o
- MultiStreambuf(std::vector<MultiStreambuf::stream> const
&osvector):
This constructor creates a MultiStreambuf object which is immediately
associated with all std::ostream objects that are stored in the
MultiStreambuf::stream elements of the specified vector. The copy
constructor is available.
All members of std::ostringstream and std::exception
are available, as MultiStreambuf inherits from these classes.
- o
- iterator begin():
This member returns an iterator to the first stream element that is
stored in a MultiStreambuf object.
- o
- const_iterator begin():
This member returns an iterator to the first (unmodifiable) stream
element that is stored in a MultiStreambuf object.
- o
- iterator end():
This member returns an iterator pointing beyond the last stream
element that is stored in a MultiStreambuf object.
- o
- const_iterator end():
This member returns an iterator pointing beyond the last (unmodifiable)
stream element that is stored in a MultiStreambuf
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 MultiStreambuf it is removed, and
true is returned. If mode ALL is specified all os
objects that were stored in the MultiStreambuf 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 MultiStreambuf object its address is compared to the
addresses of the std::ostream objects that are stored inside the
MultiStreambuf 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 MultiStreambuf object
is returned.
The member listed in this section implements the tasks of the
comparably named virtual function in the class’s private interface.
This separates the redefinable interface from the user-interface. The class
MultiStreamBuf can, in accordance with Liskov’s Substitution
Principle, be used as a std:streambuf; but it also offers a facility
for classes deriving from MultiStreamBuf. This facility is listed
here.
- o
- int pSync():
The contents of the MultiStreamBuf’s internal buffer is
written to each of the std::ostream objects to which the
MultiStreamBuf object has access.
#include <iostream>
#include <fstream>
#include <bobcat/multistreambuf>
using namespace std;
using namespace FBB;
int main()
{
MultiStreambuf msb(cout);
ostream os(&msb);
ofstream out("out");
msb.insert(out, MultiStreambuf::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/multistreambuf - defines the class interface
- o
- bobcat_4.08.06-x.dsc: detached signature;
- o
- bobcat_4.08.06-x.tar.gz: source archive;
- o
- bobcat_4.08.06-x_i386.changes: change log;
- o
- libbobcat1_4.08.06-x_*.deb: debian package holding the
libraries;
- o
- libbobcat1-dev_4.08.06-x_*.deb: debian package holding the
libraries, headers and manual pages;
- o
- http://sourceforge.net/projects/bobcat: public archive location;
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).