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FBB::ConfigFile - A class processing standard unix-like configuration files
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 ConfigFile(CommentcType=KeepComment,SearchCasingsType=SearchCaseSensitive,IndicesiType=IgnoreIndices):
This constructor is used to create an empty ConfigFile object. It is not associated with an input
stream: the open member can be used for that. The parameters can be used to specify specific
handling of comment, letter-casing and storage of line numbers in the original configuration file.
o ConfigFile(std::stringconst&fname,CommentcType=KeepComment,SearchCasingsType=SearchCaseSensitive,IndicesiType=IgnoreIndices):
This constructor is used to create a ConfigFile object, which is filled with the information from
a file whose name is provided as the constructor’s first argument. The other parameters are used
as described with the first constructor. It throws an FBB::Exception exception if the file could
not be opened.
Copyright
This is free software, distributed under the terms of the GNU General Public License (GPL).
Description
This class is deprecated: the class FBB::Config (cf. config(3bobcat)) should be used instead.
ConfigFile objects read standard unix-style configuration files. Lines are stored with initial
white-space (blanks and tabs) removed. If a line ends in \, then the next line (initial white-space
removed) is appended to the current line.
If the rmComment flag is set to true blanks lines and information on lines from the first # are removed.
If the comment character (#) is prefixed by a backslash (i.e., \#) it is not considered comment, but
replaced by a single # character. Likewise, if the rmComment flag was set two consecutive backslash
characters are replaced by a single backslash character, In the retrieved configuration information it
appears as a single # character. If the configuration file should contain \# write \\#, this results in
replacing \# by #, leaving \#.
All non-empty lines of the configuration file (when comment is ignored comment is not considered to be
line-content) are stored in the ConfigFile object. When line indices should be stored the (0-based) line
indices of lines are available as well.
At construction time comment handling (keep comment / remove comment), case-sensitive searching
(sensitive / insensitive) and index storage (store / don’t store) can be specified.
It can’t be modified using the open member, but overloaded assignment is supported and comment and letter
case handling can be modified by set-members.
Enumerations
The following enumerations are defined by the class ConfigFile:
o Comment:
This enumeration has two values:
ConfigFile::KeepComment is used to indicate that comment on lines must be kept;
ConfigFile::RemoveComment is used to indicate that comment on lines must be removed;
o SearchCasing:
This enumeration also has two values:
ConfigFile::SearchCaseSensitive is used to do case sensitive searches for targets;
ConfigFile::SearchCaseInsensitive is used to do case insensitive searches for targets.
o Indices:
This enumeration also has two values:
ConfigFile::IgnoreIndices when used, the line numbers of the original configuration file are not
available;
ConfigFile::StoreIndices when used, the line numbers of the original configuration file are also
available;
Example
Assume the configuration file is called config.rc and contains the following lines:
# this is ignored
noline: this one too
line: this is found
this is not a line containing line: at the beginning of the line
line: this one is
line: what about this one? it’s extending over multiple lines
and there may, of course, be more lines in this file
The following program may be compiled and run as a.outconfig.rc:
#include <iostream>
#include <iterator>
#include <algorithm>
#include <string>
#include <bobcat/configfile>
using namespace std;
using namespace FBB;
int main(int argc, char **argv)
{
ConfigFile cf(argv[1]);
cout << *cf.find("this one") << ’\n’; // find text within a line
// find all lines matching
auto [begin, end] = cv.beginEndRE("^line:"); // `^line:’
copy(begin, end, ostream_iterator<string>(cout, "\n"));
}
Producing the output:
noline: this one too
line: this is found
line: this one is
line: what about this one? it’s extending over multiple lines
Files
bobcat/configfile - defines the class interface
Inherits From
-
Member Functions
o ConfigFile::const_iteratorbegin()const:
This member returns a const_iterator to the first line of the configuration file.
o ConfigFile::const_iteratorend()const:
This member returns a const_iterator pointing beyond the last line of the configuration file.
o std::pair<ConfigFile::const_RE_iterator,ConfigFile::const_RE_iterator>beginEndRE(std::stringconst&target)const:
A pair of const_RE_iterators is returned. The first field of the pair is a const iterator to the
first element (i.e., line) of the ConfigFile object in which the regular expression target is
found.
The second field is a const iterator marking the end of the series of lines started at the the
first line matching the regular expression specified by target.
If the RemoveComment flag was specified, then comment-text is not searched. The iterator returned
in the pair’s first field can be incremented until the iteratr returned in the pair’s second field
is reached; all iterators (unequal the iterator in second) point to lines matching the specified
regular expression.
The iterator’s increment operator searches the next line matching the specified regular
expression.
Although the difference between two const_RE_iterators can be computed it is a relatively
expensive operation. The difference is obtained by performing repeated regular expression
matchings rather than the mere algebraic subtraction of pointer values. If the difference cannot
be computed std::numeric_limits<size_t>::max() is returned.
This member also interprets the SearchCasing flag.
o std::pair<ConfigFile::const_RE_iterator,ConfigFile::const_RE_iterator>beginEndRE()const:
A pair of const_RE_iterators is returned, both marking the end of a regular expression search.
o ConfigFile::const_iteratorfind(std::stringconst&target)const:
This member returns an iterator to the first element (i.e., line) of the FBB::ConfigFile object in
which target is found. Note that target may appear anywhere within a line. If the RemoveComment
flag was specified, then comment-text is not searched. Use the end member to determine the
end-iterator. It is not guaranteed that all lines between the returned iterator and end contain
target. This member also interprets the SearchCasing flag.
o std::stringfindKey(std::stringconst&keyPattern,size_tcount=1)const:
This member can be used to retrieve information from lines having the general pattern `keyPatternvalue’. Initial and trailing white space on lines are ignored. keyPattern itself should not
contain initial or trailing white space. At least one white space character must appear between
keyPattern and value. If at least count lines were found matching keyPatternvalue then this
member returns the first sequence of non white space characters following keyPattern after
matching count lines matching keyPatternvalue (i.e., `value’ is returned). If value is empty or
if fewer than count lines match keyPattern an empty string is returned. An FBB::Exception
exception is thrown if count equals 0.
o std::stringfindKeyTail(std::stringconst&keyPattern,size_tcount=1)const:
This member can be used to retrieve information from lines having the general pattern `keyPatternvalue’, merely followed by white space. Initial and trailing white space on lines are ignored.
keyPattern itself should not contain initial or trailing white space. At least one white space
character must appear between keyPattern and value. If at least count lines were found matching
keyPatternvalue then this member returns the information beyond keyPattern after matching count
lines matching keyPattern (i.e., `value’ is returned). This function differs from findKey in that
all information trailing keyPattern is returned in value. If value is empty or if fewer than
count lines match keyPattern an empty string is returned. An FBB::Exception exception is thrown if
count equals 0.
o ConfigFile::const_iteratorfindRE(std::stringconst&target)const:
This member returns an iterator to the first line of the ConfigFile object matching the regular
expression target. After calling this function beginEndRE returns an iterator pair whose first
field is an iterator to the same line and whose second field is the end-iterator for lines
matching target. If the RemoveComment flag was specified, then comment-text is not searched. The
inherited end member can be used to determine the end-iterator. It is not guaranteed that all
lines between the returned iterator and end also contain target.
o size_tindex(size_tidx):
This function should only be used when the parameter StoreIndices was specified at construction
time. In that case it returns the original 0-based line index in the configuration file associated
with the idx (0-based) index in the current Configuration object.
o size_tindex(const_iteratorconst&iter):
This function should only be used when the parameter StoreIndices was specified at construction
time. In that case it returns the original 0-based line index in the configuration file associated
with the configuration line in the current Configuration object pointed to by iter. This may also
be an (incremented version of the) iterator returned by the member findRE.
o voidopen(std::stringconst&fname):
This member reads the configuration file having name fname. It redefines the current content of
the ConfigFile object, destroying any information previously stored in it. The configuration file
is read according to the latest setting of the comment-flag. It throws an FBB::Exception exception
if the file cannot be opened.
This member clears previously available information and reinitializes the object with information
read from the new file.
o voidsetCommentHandling(Commenttype):
This member can be used to change the comment-handling type originally set by the constructor, or
set by earlier calls of this function. When called it won’t affect the current content of the
ConfigFile object, but new calls of its open member reads the configuration file according to the
last setting of the comment flag.
o voidsetSearchCasing(SearchCasingtype):
This member can be used to change the handling of the letter-casing originally set by the
constructor, or set by earlier calls of this function. When called it won’t affect the current
content of the ConfigFile object, but new calls of its open member reads the configuration file
according to the last setting of the letter-casing flag.
o size_tsize()const:
This member returns the number of lines in the configuration file.
Name
FBB::ConfigFile - A class processing standard unix-like configuration files
Namespace
FBB
All constructors, members, operators and manipulators, mentioned in this man-page, are defined in the
namespace FBB.
Overloaded Operators
o std::stringconst&operator[](size_tidx)const:
This member returns the (0-based) idx-th line of the configuration file.
Copy and move constructors (and assignment operators) are available.
See Also
argconfig(3bobcat), bobcat(7), config(3bobcat) exception(3bobcat), pattern(3bobcat)
Synopsis
#include<bobcat/configfile>
Linking option: -lbobcatTypes
The following types are defined by the class ConfigFile:
o const_iterator:
a const_iterator is an iterator pointing to a line (std::string) of the configuration file;
o const_RE_iterator:
a const_RE_iterator is an iterator pointing to lines matching a regular expression. It supports
the following operations:
o const_RE_iterator&operator++(): the prefix increment operator increments the iterator to point to
the next line in the configuration file matching the iterator’s regular expression;
o std::stringconst&operator*(): the dereferencing operator returns the line of the configuration
file the iterator refers to;
o std::stringconst*operator->(): the pointer operator returns the address of the line of the
configuration file the iterator refers to; const_RE_iterators can be compared for (in)equality and
they can be copy-constructed; const_RE_iterator objects are returned by the ConfigFile::beginEndRE
member and cannot otherwise be constructed.
When two const_RE_iterator objects are subtracted the number of lines matching their regular
expression is returned. E.g., (see below for a description of the functions used in the next
example):
ConfigFile cf(...)
auto iters = cf.beginEndRE("^hello");
cout << "There are " << (iters.second - iters.first) <<
" lines starting with hello\n";
The two const_RE_iterator objects should refer to the same regular expression. The provided
example illustrates how this is realized using beginEndRE.
FBB::Pattern is used to perform the regular expression pattern matching.
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