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FBB::OFoldBuf - Folds long lines written to ostream
Contents
Bobcat
Bobcat is an acronym of `Brokken’s Own Base Classes And Templates’.
Bobcat Project Files
o https://fbb-git.gitlab.io/bobcat/: gitlab project page;
Debian Bobcat project files:
o libbobcat6: debian package containing the shared library, changelog and copyright note;
o libbobcat-dev: debian package containing the static library, headers, manual pages, and developer
info;
Bugs
None Reported.
Constructors
o OFoldBuf(size_tleftIndent=0,size_trightMargin=80,TabsOrBlankstob=BLANKS,TrailingBlankstb=IGNORE_TRAILING_BLANKS):
This constructor initializes an OFoldBuf object but does not associate it with a destination
stream. It can also be used as the default constructor.
o OFoldBuf(charconst*fname,size_tleftIndent=0,size_trightMargin=80,TabsOrBlankstob=BLANKS,TrailingBlankstb=IGNORE_TRAILING_BLANKS):
This constructor initializes an OFoldBuf object and opens (using std::ios::out) the destination
stream using the name specified as its fname argument.
o OFoldBuf(std::ostream&stream,size_tleftIndent=0,size_trightMargin=80,TabsOrBlankstob=BLANKS,TrailingBlankstb=IGNORE_TRAILING_BLANKS):
This constructor initializes an OFoldBuf object and uses as its destination stream the
std::ostreamstream.
The destructor writes any buffered information to the destination stream and will then flush the
destination stream.
Copy and move constructors (and assignment operators) are not available.
Copyright
This is free software, distributed under the terms of the GNU General Public License (GPL).
Description
FBB::OFoldBuf is a specialization of FBB::OFilterBuf folding long lines written to an std::ostream
object. The OFoldBuf writes the (folded) lines to a second ostream (the destinationstream which is
either used by or opened by the OFoldBuf object).
Internally the OFoldBuf 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.
OFoldBuf 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 FiniteStateAutomaton (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 OFoldBuf object. OFoldBuf’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;
───────────────────────────────────────────────────────────────────────
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 OFoldBuf 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
OFoldBuf 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::ostreamExample
#include <iostream>
#include <ostream>
#include <string>
#include <bobcat/ofoldbuf>
using namespace std;
using namespace FBB;
int main()
{
OFoldBuf fb(cout, 4, 40);
ostream out(&fb);
out << lm(4);
string line;
while (getline(cin, line))
out << line << ’\n’;
}
Files
bobcat/ofoldbuf - defines the class interface
Inherits From
FBB::OFilterBuf
Member Functions
All members of FBB::OFilterBuf, in particular its out() and reset members are available, as FBB::OFoldBuf
inherits from this class.
o voidsetMargins(size_tleftMargin,size_trightMargin):
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 voidsetTrailingBlanks(TrailingBlankstb):
This member can be used to modify the currently used TrailingBlanks parameter.
o voiduseBlanks():
This member can be used to select blanks to be used when inserting left margins.
o voiduseTabs(size_ttabWidth=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.
Name
FBB::OFoldBuf - Folds long lines written to ostream
Namespace
FBB
All constructors, members, operators and manipulators, mentioned in this man-page, are defined in the
namespace FBB.
See Also
bobcat(7), lm(3bobcat), mlm(3bobcat), ofilterbuf(3bobcat), ofoldstream(3bobcat)
Static Member Functions
o size_tleftMargin(std::ostreambufconst*buffer):
This member returns the current left margin setting of the OFoldBuf object passed to it as its
argument. The member defines a std::streambuf parameter which is down cast to an OFoldBuf and an
FBB::Exception exception is thrown if that cast fails.
o size_trightMargin(std::ostreambufconst*buffer):
This member returns the current right margin setting of the OFoldBuf 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.
Synopsis
#include<bobcat/ofoldbuf>
Linking option: -lbobcat
PNG Icons
Emojis
