oracular (3) App::Info::Util.3pm.gz
NAME
App::Info::Util - Utility class for App::Info subclasses
SYNOPSIS
use App::Info::Util;
my $util = App::Info::Util->new;
# Subclasses File::Spec.
my @paths = $util->paths;
# First directory that exists in a list.
my $dir = $util->first_dir(@paths);
# First directory that exists in a path.
$dir = $util->first_path($ENV{PATH});
# First file that exists in a list.
my $file = $util->first_file('this.txt', '/that.txt', 'C:\\foo.txt');
# First file found among file base names and directories.
my $files = ['this.txt', 'that.txt'];
$file = $util->first_cat_file($files, @paths);
DESCRIPTION
This class subclasses File::Spec and adds its own methods in order to offer utility methods to App::Info
classes. Although intended to be used by App::Info subclasses, in truth App::Info::Util's utility may be
considered more general, so feel free to use it elsewhere.
The methods added in addition to the usual File::Spec suspects are designed to facilitate locating files
and directories on the file system, as well as searching those files. The assumption is that, in order to
provide useful meta data about a given software package, an App::Info subclass must find relevant files
and directories and parse them with regular expressions. This class offers methods that simplify those
tasks.
CONSTRUCTOR
new
my $util = App::Info::Util->new;
This is a very simple constructor that merely returns an App::Info::Util object. Since, like its
File::Spec super class, App::Info::Util manages no internal data itself, all methods may be used as class
methods, if one prefers to. The constructor here is provided merely as a convenience.
OBJECT METHODS
In addition to all of the methods offered by its super class, File::Spec, App::Info::Util offers the
following methods.
first_dir
my @paths = $util->paths;
my $dir = $util->first_dir(@dirs);
Returns the first file system directory in @paths that exists on the local file system. Only the first
item in @paths that exists as a directory will be returned; any other paths leading to non-directories
will be ignored.
first_path
my $path = $ENV{PATH};
$dir = $util->first_path($path);
Takes the $path string and splits it into a list of directory paths, based on the path delimiter on the
local file system. Then calls "first_dir()" to return the first directory in the path list that exists on
the local file system. The path delimiter is specified for the following file systems:
• MacOS: ","
• MSWin32: ";"
• os2: ";"
• VMS: undef
This method always returns undef on VMS. Patches welcome.
• epoc: undef
This method always returns undef on epoch. Patches welcome.
• Unix: ":"
All other operating systems are assumed to be Unix-based.
first_file
my $file = $util->first_file(@filelist);
Examines each of the files in @filelist and returns the first one that exists on the file system. The
file must be a regular file -- directories will be ignored.
first_exe
my $exe = $util->first_exe(@exelist);
Examines each of the files in @exelist and returns the first one that exists on the file system as an
executable file. Directories will be ignored.
first_cat_path
my $file = $util->first_cat_path('ick.txt', @paths);
$file = $util->first_cat_path(['this.txt', 'that.txt'], @paths);
The first argument to this method may be either a file or directory base name (that is, a file or
directory name without a full path specification), or a reference to an array of file or directory base
names. The remaining arguments constitute a list of directory paths. "first_cat_path()" processes each of
these directory paths, concatenates (by the method native to the local operating system) each of the file
or directory base names, and returns the first one that exists on the file system.
For example, let us say that we were looking for a file called either httpd or apache, and it could be in
any of the following paths: /usr/local/bin, /usr/bin/, /bin. The method call looks like this:
my $httpd = $util->first_cat_path(['httpd', 'apache'], '/usr/local/bin',
'/usr/bin/', '/bin');
If the OS is a Unix variant, "first_cat_path()" will then look for the first file that exists in this
order:
/usr/local/bin/httpd
/usr/local/bin/apache
/usr/bin/httpd
/usr/bin/apache
/bin/httpd
/bin/apache
The first of these complete paths to be found will be returned. If none are found, then undef will be
returned.
first_cat_dir
my $dir = $util->first_cat_dir('ick.txt', @paths);
$dir = $util->first_cat_dir(['this.txt', 'that.txt'], @paths);
Functionally identical to "first_cat_path()", except that it returns the directory path in which the
first file was found, rather than the full concatenated path. Thus, in the above example, if the file
found was /usr/bin/httpd, while "first_cat_path()" would return that value, "first_cat_dir()" would
return /usr/bin instead.
first_cat_exe
my $exe = $util->first_cat_exe('ick.exe', @paths);
$exe = $util->first_cat_exe(['this.exe', 'that.exe'], @paths);
Functionally identical to "first_cat_path()", except that it returns the full path to the first
executable file found, rather than simply the first file found.
search_file
my $file = 'foo.txt';
my $regex = qr/(text\s+to\s+find)/;
my $value = $util->search_file($file, $regex);
Opens $file and executes the $regex regular expression against each line in the file. Once the line
matches and one or more values is returned by the match, the file is closed and the value or values
returned.
For example, say foo.txt contains the line "Version 6.5, patch level 8", and you need to grab each of the
three version parts. All three parts can be grabbed like this:
my $regex = qr/Version\s+(\d+)\.(\d+),[^\d]*(\d+)/;
my @nums = $util->search_file($file, $regex);
Now @nums will contain the values "(6, 5, 8)". Note that in a scalar context, the above search would
yield an array reference:
my $regex = qr/Version\s+(\d+)\.(\d+),[^\d]*(\d+)/;
my $nums = $util->search_file($file, $regex);
So now $nums contains "[6, 5, 8]". The same does not hold true if the match returns only one value,
however. Say foo.txt contains the line "king of the who?", and you wish to know who the king is king of.
Either of the following two calls would get you the data you need:
my $minions = $util->search_file($file, qr/King\s+of\s+(.*)/);
my @minions = $util->search_file($file, qr/King\s+of\s+(.*)/);
In the first case, because the regular expression contains only one set of parentheses, "search_file()"
will simply return that value: $minions contains the string "the who?". In the latter case, @minions of
course contains a single element: "("the who?")".
Note that a regular expression without parentheses -- that is, one that doesn't grab values and put them
into $1, $2, etc., will never successfully match a line in this method. You must include something to
parenthetically match. If you just want to know the value of what was matched, parenthesize the whole
thing and if the value returns, you have a match. Also, if you need to match patterns across lines, try
using multiple regular expressions with "multi_search_file()", instead.
files_in_dir
my @files = $util->files_in_dir($dir);
@files = $util->files_in_dir($dir, $filter);
my $files = $util->files_in_dir($dir);
$files = $util->files_in_dir($dir, $filter);
Returns an list or array reference of all of the files and directories in the file system directory $dir.
An optional second argument is a code reference that filters the files. The code reference should examine
the $_ for a file name and return true if it's a file that you're interested and false if it's not.
multi_search_file
my @regexen = (qr/(one)/, qr/(two)\s+(three)/);
my @matches = $util->multi_search_file($file, @regexen);
Like "search_file()", this method opens $file and parses it for regular expression matches. This method,
however, can take a list of regular expressions to look for, and will return the values found for all of
them. Regular expressions that match and return multiple values will be returned as array references,
while those that match and return a single value will return just that single value.
For example, say you are parsing a file with lines like the following:
#define XML_MAJOR_VERSION 1
#define XML_MINOR_VERSION 95
#define XML_MICRO_VERSION 2
You need to get each of these numbers, but calling "search_file()" for each of them would be wasteful, as
each call to "search_file()" opens the file and parses it. With "multi_search_file()", on the other hand,
the file will be opened only once, and, once all of the regular expressions have returned matches, the
file will be closed and the matches returned.
Thus the above values can be collected like this:
my @regexen = ( qr/XML_MAJOR_VERSION\s+(\d+)$/,
qr/XML_MINOR_VERSION\s+(\d+)$/,
qr/XML_MICRO_VERSION\s+(\d+)$/ );
my @nums = $file->multi_search_file($file, @regexen);
The result will be that @nums contains "(1, 95, 2)". Note that "multi_file_search()" tries to do the
right thing by only parsing the file until all of the regular expressions have been matched. Thus, a
large file with the values you need near the top can be parsed very quickly.
As with "search_file()", "multi_search_file()" can take regular expressions that match multiple values.
These will be returned as array references. For example, say the file you're parsing has files like this:
FooApp Version 4
Subversion 2, Microversion 6
To get all of the version numbers, you can either use three regular expressions, as in the previous
example:
my @regexen = ( qr/FooApp\s+Version\s+(\d+)$/,
qr/Subversion\s+(\d+),/,
qr/Microversion\s+(\d$)$/ );
my @nums = $file->multi_search_file($file, @regexen);
In which case @nums will contain "(4, 2, 6)". Or, you can use just two regular expressions:
my @regexen = ( qr/FooApp\s+Version\s+(\d+)$/,
qr/Subversion\s+(\d+),\s+Microversion\s+(\d$)$/ );
my @nums = $file->multi_search_file($file, @regexen);
In which case @nums will contain "(4, [2, 6])". Note that the two parentheses that return values in the
second regular expression cause the matches to be returned as an array reference.
lib_dirs
my @dirs = $util->lib_dirs;
Returns a list of possible library directories to be searched. These are gathered from the "libsdirs" and
"loclibpth" Config settings. These are useful for passing to "first_cat_dir()" to search typical
directories for library files.
SUPPORT
This module is stored in an open GitHub repository <http://github.com/theory/app-info/>. Feel free to fork and contribute! Please file bug reports via GitHub Issues <http://github.com/theory/app-info/issues/> or by sending mail to bug-App-Info@rt.cpan.org <mailto:bug-App-Info@rt.cpan.org>.
AUTHOR
David E. Wheeler <david@justatheory.com>
SEE ALSO
App::Info, File::Spec, App::Info::HTTPD::Apache App::Info::RDBMS::PostgreSQL
COPYRIGHT AND LICENSE
Copyright (c) 2002-2011, David E. Wheeler. Some Rights Reserved.
This module is free software; you can redistribute it and/or modify it under the same terms as Perl
itself.