Provided by: libbobcat-dev_4.08.02-2build1_amd64 
NAME
FBB::OFoldStreambuf - Folds long lines written to ostream
SYNOPSIS
#include <bobcat/ofoldstreambuf>
Linking option: -lbobcat
DESCRIPTION
FBB::OFoldStreambuf is a specialization of FBB::OFilterStreambuf folding long lines written to an
std::ostream object. The OFoldStreambuf writes the (folded) lines to a second ostream (the destination
stream which is either used by or opened by the OFoldStreambuf object).
Internally the OFoldStreambuf defines its actions using a little finite state automation distinguishing
three states (INDENT, WS and NON_WS) and three character categories (\n, other white space characters
(space), and non-space characters). The nine combinations resulting from these two sets are discussed
below.
OFoldStreambuf objects will never fold lines in the middle of series of non-blank characters (called a
`word’ below) but will always break a line at a white space character. The resulting lines will always
appear to the right of a configurable left margin and to the left of a configurable right margin. There
is a somewhat pathological exception to this: if a word is too long to fit in between the margins then
the word will exceed the right hand margin.
The indentation used for the left margins is configurable to either blanks (the default) or tabs. When
tabs are used the width of a tab character is configurable, using a default of 8 positions in the
destination stream.
What follows is a description of the Finite State Automaton (FSA) defining what happens when various
character types appear at its three states. The phrase `... is written’ means that the described
information is written to the ostream used or opened by the OFoldStreambuf object. OFoldStreambuf’s
initial state is INDENT:
State char. description
───────────────────────────────────────────────────────────────────────
INDENT \n a new line character is written
space the indentation is set;
the space character is added to the indentation;
next state: WS
non-ws the character is added to the currently stored word;
next state: NON_WS
───────────────────────────────────────────────────────────────────────
WS \n a new line character is written;
stored white-space is erased;
next state: INDENT
space white space character is added to the currently
stored space characters;
non-ws the character is added to the currently stored word;
next state: NON_WS
───────────────────────────────────────────────────────────────────────
NON_WS \n stored white space and word are written;
a new line is written;
next state: INDENT
space stored white space and word are written;
white space character is added to the currently
stored space characters;
next state: WS
non-ws the character is added to the currently stored word;
───────────────────────────────────────────────────────────────────────
NAMESPACE
FBB
All constructors, members, operators and manipulators, mentioned in this man-page, are defined in the
namespace FBB.
INHERITS FROM
FBB::OFilterStreambuf
ENUMERATION
The enumeration TabsOrBlanks is used to select tabs or blanks when writing the indentation. The default
is blanks. When tabs are selected the display width of tabs characters can be configured as well (using
the default of 8 positions for each tab-character). The enumeration has two values:
o BLANKS:
The default, indicating that the left margin is specified and written as a number of blanks;
o TABS:
Indicating that the left margin is specified and written as a number of tab-characters.
The enumeration TrailingBlanks is used to configure the OFoldStreambuf object with respect to any
trailing blanks that may appear on the final line. These trailing blanks can appear on the final line it
it is not properly terminated with a newline character but instead ends in white space. By default these
white space characters are ignored, but they may be kept as well. The enumeration has two values:
o IGNORE_TRAILING_BLANKS:
This indicates that trailing blanks appearing at the final line if it is not terminated by a
newline should not be written to the destination std::ostream. This is the default used by
OFoldStreambuf objects.
o KEEP_TRAILING_BLANKS:
This indicates that trailing blanks at the final line if it is not terminated by a newline should
be written to the destination std::ostream
CONSTRUCTORS
o OFoldStreambuf(size_t leftIndent = 0, size_t rightMargin = 80, TabsOrBlanks tob = BLANKS,
TrailingBlanks tb = IGNORE_TRAILING_BLANKS):
This constructor initializes an OFoldStreambuf object but does not associate it with a destination
stream. It can also be used as the default constructor.
o OFoldStreambuf(char const *fname, size_t leftIndent = 0, size_t rightMargin = 80, TabsOrBlanks tob
= BLANKS, TrailingBlanks tb = IGNORE_TRAILING_BLANKS):
This constructor initializes an OFoldStreambuf object and opens (using std::ios::out) the
destination stream using the name specified as its fname argument.
o OFoldStreambuf(std::ostream &stream, size_t leftIndent = 0, size_t rightMargin = 80, TabsOrBlanks
tob = BLANKS, TrailingBlanks tb = IGNORE_TRAILING_BLANKS):
This constructor initializes an OFoldStreambuf object and uses as its destination stream the
std::ostream stream.
The destructor writes any buffered information to the destination stream and will then flush the
destination stream.
MEMBER FUNCTIONS
All members of FBB::OFilterStreambuf, in particular its out() and open() members are available, as
FBB::OFoldStreambuf inherits from this class.
o void setMargins(size_t leftMargin, size_t rightMargin):
This member can be used to modify the left- and right folding margins. Note that the left margin
may also be modified using the FBB::lm and FBB::mlm manipulators.
o void setTrailingBlanks(TrailingBlanks tb):
This member can be used to modify the currently used TrailingBlanks parameter.
o void useBlanks():
This member can be used to select blanks to be used when inserting left margins.
o void useTabs(size_t tabWidth = 8):
This member can be used to select tab-characters to be used when inserting left margins. The
second parameter is used to specify the display width of a tab-character.
STATIC MEMBER FUNCTIONS
o size_t leftMargin(std::ostreambuf const *buffer):
This member returns the current left margin setting of the OFoldStreambuf object passed to it as
its argument. The member defines a std::streambuf parameter which is down cast to an
OFoldStreambuf and an FBB::Exception exception is thrown if that cast fails.
o size_t rightMargin(std::ostreambuf const *buffer):
This member returns the current right margin setting of the OFoldStreambuf object passed to it as
its argument. The member’s parameter is down cast in the same way as leftMargin()’s argument: an
FBB::Exception exception is thrown if that cast fails.
PROTECTED MEMBER FUNCTION
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
OFoldStreambuf can, in accordance with Liskov’s Substitution Principle, be used as a std:streambuf; but
it also offers a facility for classes deriving from OFoldStreambuf. This facility is listed here.
o int pSync():
The contents of the OFoldStreambuf’s internal buffer is flushed.
EXAMPLE
#include <iostream>
#include <ostream>
#include <string>
#include <bobcat/ofoldstreambuf>
using namespace std;
using namespace FBB;
int main()
{
OFoldStreambuf fb(cout, 4, 40);
ostream out(&fb);
out << lm(4);
string line;
while (getline(cin, line))
out << line << ’\n’;
return 0;
}
FILES
bobcat/ofoldstreambuf - defines the class interface
SEE ALSO
bobcat(7), lm(3bobcat), mlm(3bobcat), ofilterstreambuf(3bobcat), ofoldstream(3bobcat)
BUGS
None Reported.
DISTRIBUTION FILES
o bobcat_4.08.02-x.dsc: detached signature;
o bobcat_4.08.02-x.tar.gz: source archive;
o bobcat_4.08.02-x_i386.changes: change log;
o libbobcat1_4.08.02-x_*.deb: debian package holding the libraries;
o libbobcat1-dev_4.08.02-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).