FBB::OFoldBuf(3bobcat) | Fold long lines | FBB::OFoldBuf(3bobcat) |
FBB::OFoldBuf - Folds long lines written to ostream
#include <bobcat/ofoldbuf>
Linking option: -lbobcat
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 destination stream 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 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 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; | |
FBB
All constructors, members, operators and manipulators, mentioned in this
man-page, are defined in the namespace FBB.
FBB::OFilterBuf
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:
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:
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.
All members of FBB::OFilterBuf, in particular its out() and reset members are available, as FBB::OFoldBuf inherits from this class.
#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’;
}
bobcat/ofoldbuf - defines the class interface
bobcat(7), lm(3bobcat), mlm(3bobcat), ofilterbuf(3bobcat), ofoldstream(3bobcat)
None Reported.
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).
2005-2020 | libbobcat-dev_5.07.00 |