Provided by: libbobcat-dev_3.19.01-1ubuntu1_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_3.19.01-x.dsc: detached signature;
o bobcat_3.19.01-x.tar.gz: source archive;
o bobcat_3.19.01-x_i386.changes: change log;
o libbobcat1_3.19.01-x_*.deb: debian package holding the libraries;
o libbobcat1-dev_3.19.01-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).