FBB::OFilterStreambuf(3bobcat)					 ostream filtering				    FBB::OFilterStreambuf(3bobcat)

NAME

       FBB::OFilterStreambuf - Base class for std::ostream filtering

SYNOPSIS

       #include <bobcat/ofilterstreambuf>
       Linking option: -lbobcat

DESCRIPTION

       The  FBB::OFilterStreambuf  class  is a specialization of the std::streambuf class and can be used as a base class for classes implementing
       ostream-filtering.

       Ostream filtering is defined here as the process by which inserted characters are subject to  processing  before  they  are  passed  on	to
       another	(filtered)  ostream  object  (or they may be rejected). The filtering may also result in inserting additional information into the
       filtered ostream.

       Chaining of filters is also possible: the filtered ostream may itself use an OFilterStreambuf to filter	its  received  information  before
       passing it on to yet another ostream.

       As OFilterStreambuf inherits from std::streambuf an OFilterStreambuf object can be used to provide an ostream object with a std::streambuf.
       Information inserted into such a stream travels the following route:

       o      The information is converted to characters using the standard conversion facilities implemented by std::ostream objects. E.g.,  when
	      inserting the value 123 this value is converted to the characters '1', '2' and '3', respectively.

       o      Each  of	the  characters is then offered (in turn) to the std::streambuf that is associated with the ostream object. In particular,
	      the std::streambuf's overflow() member is called.

       o      OFstreamBuf's default overflow() function ignores characters, but specializations can override overflow() to  process  the  received
	      characters ad lib.

       o      A  overriding overflow() function has access to the member OFstreambuf::out() which is a reference to the std::ostream receiving the
	      filtered information.  To implement a simple copy-filter (i.e., all characters are accepted as-is) a  class  must  be  derived  from
	      OFilterStreambuf providing an overriding implementation of overflow(), e.g., as follows:

		  int DerivedClass::overflow(int ch)
		  {
		      out().put(ch);
		  }

	      Next  this  std::streambuf  specialization  can  be  associated  with an ostream into which information to be `copy filtered' can be
	      inserted (cf. the EXAMPLE section below).

NAMESPACE

       FBB
       All constructors, members, operators and manipulators, mentioned in this man-page, are defined in the namespace FBB.

INHERITS FROM

       std::streambuf

CONSTRUCTORS

       o      OFilterStreambuf():
	      This constructor creates a OFilterStreambuf object without associating it with a destination (filtered) ostream.

       o      OFilterStreambuf(char const *fname, openmode mode = std::ios::out):
	      This constructor creates a OFilterStreambuf object and opens a private std::ofstream object whose  filename  is  provided  and  that
	      should receive the filtered information.

       o      OFilterStreambuf(std::ostream &out):
	      This  constructor creates a OFilterStreambuf object and will insert any filtered information into the provided  ostream object.  The
	      class's destructor closes the destination (filtered) stream (cf. the description of close() below).

MEMBER FUNCTIONS

       All members of std::ostreambuf are available, as FBB::OFilterStreambuf inherits from that class. In particular, derived classes should pro-
       vide their own implementation of int underflow(int ch) to implement any non-trivial filtering.

       o      void close():
	      This member calls the streambuf::sync() member to flush any pending information to the destination (filtered) stream and then closes
	      the destination stream. Note that the default sync() member performs no special actions but it can be overridden by derived  classes
	      to flush the destination stream just prior to its closing.

       o      void open(char const *fname, openmode mode = std::ios::out):
	      This  member closes the current destination (filtered) std::ostream object and associates the OFilterStreambuf object with a private
	      std::ofstream object whose filename is provided and that should receive subsequently filtered information.

       o      void open(std::ostream &out):
	      This member closes the current destination (filtered) std::ostream object and associates the OFilterStreambuf object with  the  pro-
	      vided ostream object.

PROTECTED MEMBER FUNCTION

       o      std::ostream &out() const:
	      This member is available to derived classes to insert information into the destination (filtered) stream.

EXAMPLE

	   #include <iostream>
	   #include <cctype>
	   #include <bobcat/ofilterstreambuf>

	   class NoDigits: public FBB::OFilterStreambuf
	   {
	       public:
		   int overflow(int ch)
		   {
		       if (not isdigit(ch))
			   out().put(ch);
		       return ch;
		   }
		   int sync()
		   {
		       out() << flush;
		       return 0;
		   }
	   };

	   using namespace FBB;
	   using namespace std;

	   int main()
	   {
	       NoDigits nod(cout);     // no digits to cout
	       ostream out(&nod);

	       out << in.rdbuf();      // rm digits from cin
	       return 0;
	   }

FILES

       bobcat/ofilterstreambuf - defines the class interface

SEE ALSO

       bobcat(7)

BUGS

       None Reported.

DISTRIBUTION FILES

       o      bobcat_3.01.00-x.dsc: detached signature;

       o      bobcat_3.01.00-x.tar.gz: source archive;

       o      bobcat_3.01.00-x_i386.changes: change log;

       o      libbobcat1_3.01.00-x_*.deb: debian package holding the libraries;

       o      libbobcat1-dev_3.01.00-x_*.deb: debian package holding the libraries, headers and manual pages;

       o      http://sourceforge.net/projects/bobcat: public archive location;

BOBCAT

       Bobcat is an acronym of `Brokken's Own Base Classes And Templates'.

COPYRIGHT

       This is free software, distributed under the terms of the GNU General Public License (GPL).

AUTHOR

       Frank B. Brokken (f.b.brokken@rug.nl).

libbobcat1-dev_3.01.00-x.tar.gz 				     2005-2012					    FBB::OFilterStreambuf(3bobcat)