Read ini files without section names - perl

Question

I want to make a configuration file which hold some objects, like this (where of course none of the paramaters can be considered as a primary key)
param1=abc
param2=ghj
param1=bcd
param2=hjk
; always the sames parameters
This file could be read, lets say with Config::IniFiles, because it has a direct transcription into ini file, like this
[0]
param1=abc
param2=ghj
[1]
param1=bcd
param2=hjk
with, for example, something like
perl -pe 'if (m/^\s*$/ || !$section ) print "[", ($section++ || 0) , "]"'
And finish with
open my $fh, '<', "/path/to/config_file.ini" or die $!;
$cfg = Config::IniFiles->new( -file => $fh );
(...parse here the sections starting with 0.)
But, I here ask me some question about the thing becoming quite complex....
(A) Is There a way to transform the $fh, so that it is not required to execute the perl one-liner BEFORE reading the file sequentially? So, to transform the file during perl is actually reading it.
or
(B) Is there a module to read my wonderfull flat database? Or something approching? I let myslef said, that Gnu coreutils does this kind of flat file reading, but I cannot remember how.

Answer 1

You can create a simple subclass of Config::INI::Reader:
package MyReader;
use strict;
use warnings;
use base 'Config::INI::Reader';
sub new {
my $class = shift;
my $self = $class->SUPER::new( #_ );
$self->{section} = 0;
return $self;
}
sub starting_section { 0 };
sub can_ignore { 0 };
sub parse_section_header {
my ( $self, $line ) = #_;
return $line =~ /^\s*$/ ? ++$self->{section} : undef ;
}
1;
With your input this gives:
% perl -MMyReader -MData::Dumper -e 'print Dumper( MyReader->read_file("cfg") )'
$VAR1 = {
'1' => {
'param2' => 'hjk',
'param1' => 'bcd'
},
'0' => {
'param2' => 'ghj',
'param1' => 'abc'
}
};

Answer 2

You can use a variable reference instead of a file name to create a filehandle that reads from it:
use strict;
use warnings;
use autodie;
my $config = "/path/to/config_file.ini";
my $content = do {
local $/;
open my $fh, "<", $config;
"\n". <$fh>;
};
# one liner replacement
my $section = 0;
$content =~ s/^\s*$/ "\n[". $section++ ."]" /mge;
open my $fh, '<', \$content;
my $cfg = Config::IniFiles->new( -file => $fh );
# ...

Answer 3

You can store the modified data in a real file or a string variable, but I suggest that you use paragraph mode by setting the input record separator $/ to the empty string. Like this
use strict;
use warnings;
{
local $/ = ''; # Read file in "paragraphs"
my $section = 0;
while (<DATA>) {
printf "[%d]\n", $section++;
print;
}
}
__DATA__
param1=abc
param2=ghj
param1=bcd
param2=hjk
output
[0]
param1=abc
param2=ghj
[1]
param1=bcd
param2=hjk
Update
If you read the file into a string, adding section identifiers as above, then you can read the result directly into a Config::IniFiles object using a string reference, for instance
my $config = Config::IniFiles->new(-file => \$modified_contents)
This example shows the tie interface, which results in a Perl hash that contains the configuration information. I have used Data::Dump only to show the structure of the resultant hash.
use strict;
use warnings;
use Config::IniFiles;
my $config;
{
open my $fh, '<', 'config_file.ini' or die "Couldn't open config file: $!";
my $section = 0;
local $/ = '';
while (<$fh>) {
$config .= sprintf "[%d]\n", $section++;
$config .= $_;
}
};
tie my %config, 'Config::IniFiles', -file => \$config;
use Data::Dump;
dd \%config;
output
{
# tied Config::IniFiles
"0" => {
# tied Config::IniFiles::_section
param1 => "abc",
param2 => "ghj",
},
"1" => {
# tied Config::IniFiles::_section
param1 => "bcd",
param2 => "hjk",
},
}

Answer 4

You may want to perform operations on a flux of objects (as Powershell) instead of a flux of text, so
use strict;
use warnings;
use English;
sub operation {
# do something with objects
...
}
{
local $INPUT_RECORD_SEPARATOR = '';
# object are separated with empty lines
while (<STDIN>) {
# key value
my %object = ( m/^ ([^=]+) = ([[:print:]]*) $ /xmsg );
# key cannot have = included, which is the delimiter
# value are printable characters (one line only)
operation ( \%object )
}
A like also other answers.