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#-*- perl -*-
#
# Copyright (C) 2001 Ken'ichi Fukamachi
# All rights reserved. This program is free software; you can
# redistribute it and/or modify it under the same terms as Perl itself.
#
# $FML: Standalone.pm,v 1.6 2001/05/29 16:21:17 fukachan Exp $
#
package Standalone;
use strict;
use Carp;
=head1 NAME
Standalone - minimal parser for libexec/* programs
=head1 SYNOPSIS
use Standalone;
my $main_cf = Standalone::load_cf($main_cf_file, $params);
where $param is optional. The format of it is
$params = "key1=value1 key2=value2";
=head1 DESCRIPTION
C<load_cf()> reads the C<key = value> style configuration file and
return the hash. The file format is like this:
key1 = value1
key2 = value2
value3
key2 is equivalent to
key2 = value2 value3
A set of space separeted elements constructs an array of values.
=head1 METHODS
=head2 C<load_cf()>
load "key = value" style configuration file and build a hash.
return HASH REFERENCE.
=cut
# Descriptions: load "key = value" style configuration.
# It is available to use the following style.
# key = value1 value2
# value3
# XXX This file is non-Object Oriented style but
# XXX this is minimum module used in standalone program.
# Arguments: $file $params
# $params is 'key1=value1 key2=value2' syntax.
# Side Effects: $config (hash reference) is allocated on memory here.
# Return Value: hash reference to configuration parameters
sub load_cf
{
my ($file, $params) = @_;
my $config = $params ? _parse_params($params) : {};
use FileHandle;
my $fh = new FileHandle $file;
if (defined $fh) {
my $curkey;
while (<$fh>) {
next if /^\#/;
chop;
if (/^([A-Za-z]\w+)\s+=\s*(.*)/) {
my ($key, $value) = ($1, $2);
$curkey = $key;
$config->{$key} = $value;
}
if (/^\s+(.*)/) {
$config->{ $curkey } .= " ". $1;
}
}
$fh->close;
}
else {
croak("Error: cannot open $file");
}
_expand_variables( $config );
return $config;
}
# Descriptions: expand $var to the value of $var.
# Arguments: $ref_to_config
# Side Effects: rewrite the given $config
# Return Value: none
sub _expand_variables
{
my ($config) = @_;
my @order = keys %$config;
# check whether the variable definition is recursive.
# For example, definition "var_a = $var_a/b/c" causes a loop.
for my $x ( @order ) {
if ((defined $x) && defined ($config->{ $x })) {
if ($config->{ $x } =~ /\$$x/) {
croak("loop1: definition of $x is recursive\n");
}
}
}
# main expansion loop
my $org = '';
my $max = 0;
KEY:
for my $x ( @order ) {
next KEY unless defined($config->{ $x });
next KEY if $config->{ $x } !~ /\$/o;
# we need a loop to expand nested variables, for example,
# a = $x/y and b = $a/c/0
#
$max = 0;
EXPANSION_LOOP:
while ($max++ < 16) {
$org = $config->{ $x };
$config->{ $x } =~ s/\$([a-z_]+)/$config->{$1}/g;
last EXPANSION_LOOP if $config->{ $x } !~ /\$/o;
last EXPANSION_LOOP if $org eq $config->{ $x };
if ($config->{ $x } =~ /\$$x/) {
croak("loop2: definition of $x is recursive\n");
}
}
if ($max >= 16) {
croak("variable expansion of $x causes infinite loop\n");
}
}
}
sub _parse_params
{
my ($params) = @_;
my %config = ();
for my $x (split(/\s+/, $params)) {
my ($key, $value) = split(/=/, $x);
$config{ $key } = $value;
}
\%config;
}
=head1 AUTHOR
Ken'ichi Fukamachi
=head1 COPYRIGHT
Copyright (C) 2001 Ken'ichi Fukamachi
All rights reserved. This program is free software; you can
redistribute it and/or modify it under the same terms as Perl itself.
=head1 HISTORY
Standalone appeared in fml5 mailing list driver package.
See C<http://www.fml.org/> for more details.
=cut
1;
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