view release on metacpan or  search on metacpan

lib/Apache/Config/Preproc.pm  view on Meta::CPAN

    };

    *{_preproc_section_internal} = \&_preproc_section_optimized;
}

sub install_preproc_default {
    *{_preproc_section_internal} = \&_preproc_section_default;
}

1;
__END__

=head1 NAME

Apache::Config::Preproc - Preprocess Apache configuration files

=head1 SYNOPSIS

    use Apache::Config::Preproc;
    
    $x = new Apache::Config::Preproc '/path/to/httpd.conf',
             -expand => [ qw(include compact macro ifmodule ifdefine) ] 
             or die $Apache::Admin::Config::ERROR;

=head1 DESCRIPTION

B<Apache::Config::Preproc> reads and parses Apache configuration
file, expanding the syntactic constructs selected by the B<-expand> option.
In the simplest case, the argument to that option is a reference to the
list of names. Each name in the list identifies a module responsible for
processing specific Apache configuration keywords. For convenience, most
modules are named after the keyword they process, so that, e.g. B<include> is
responsible for inclusion of the files listed with B<Include> and
B<IncludeOptional> statements. The list of built-in module names follows:    

=over 4

=item B<compact>

Removes empty lines and comments.

=item B<include>

Expands B<Include> and B<IncludeOptional> statements by replacing them
with the content of the corresponding files.

=item B<ifmodule>

Expands the B<E<lt>IfModuleE<gt>> statements.

=item B<ifdefine>
    
Expands the B<E<lt>IfDefineE<gt>> statements.

=item B<locus>

Attaches file location information to each node in the parse tree.    
    
=item B<macro>

Expands the B<E<lt>MacroE<gt>> statements.    

=back

See the section B<MODULES> for a detailed description of these modules.

More expansions can be easily implemented by supplying a corresponding
expansion module (see the section B<MODULE INTERNALS> below).

If the B<-expand> argument is not supplied, the following default is
used:

    [ 'include' ]
    
The rest of methods is inherited from B<Apache::Admin::Config>.

=head1 IMPORT

The package provides two implementations of the main preprocessing
method.  The default implementation uses only the documented methods
of the base B<Apache::Admin::Config> class and due to its deficiences
shows the O(N**2) time complexity.  The optimized implementations does
some introspection into the internals of the base class, which allow it
to reduce the time complexity to O(N).  Whenever possible, the optimized
implementation is selected.  You can, however, force using the particular
implementation by supplying keywords to the C<use> statement.  To
select the default implementation:

    use Apache::Config::Preproc qw(:default);

To select the optimized implementation:

    use Apache::Config::Preproc qw(:optimized);

See the source code for details.

=head1 CONSTRUCTOR

=head2 new

    $obj = new Apache::Config::Preproc $file,
          [-expand => $modlist],
          [-indent => $integer], ['-create'], ['-no-comment-grouping'],
          ['-no-blank-grouping']

Reads the Apache configuration file from I<$file> and preprocesses it.
The I<$file> argument can be either the file name or file handle.

The keyword arguments are:

=over 4

=item B<-expand> =E<gt> I<$arrayref>

Define what expansions are to be performed. B<$arrayref> is a reference to
array of module names with optional arguments. To supply arguments,
use either a list reference where the first element is the module
name and rest of elements are arguments, or a hash reference with the name
of the module as key and a reference to the list of arguments as its value.
Consider, for example:

lib/Apache/Config/Preproc.pm  view on Meta::CPAN

Processes B<IfModule> statements. If the statement's argument evaluates to
true, it is replaced by the statements inside it. Otherwise, it is removed.
Nested statements are allowed. The B<LoadModule> statements are examined in
order to evaluate the argument.

The constructor understands the following arguments:

=over 4

=item B<preloaded =E<gt>> I<LISTREF>

Supplies a list of preloaded module names. You can use this argument to
pass a list of modules linked statically in your version of B<httpd>.

=item B<probe =E<gt>> I<LISTREF> | B<1>

Provides an alternative way of handling statically linked Apache modules.
If I<LISTREF> is given, each its element is treated as the pathname of
the Apache B<httpd> binary. The first of them that is found is run with
the B<-l> option to list the statically linked modules, and its output
is parsed.

The option

    probe => 1

is a shorthand for

    probe => [qw(/usr/sbin/httpd /usr/sbin/apache2)]

=back

=head2 ifdefine

Eliminates the B<Define> and B<UnDefine> statements and expands the
B<E<lt>IfDefineE<gt>> statements in the Apache configuration parse
tree. Optional arguments to the constructor are treated as the names
of symbols to define (similar to the B<httpd> B<-D> options). Example:   

    -expand => [ { ifdefine => [ qw(SSL FOREGROUND) ] } ]

=head2 locus

Attaches to each node in the parse tree a L<Text::Locus> object
which describes the location of the corresponding statement in the source
file.  The location for each node can be accessed via the B<locus> method.
E.g. the following prints location and type of each statement:

    $x = new Apache::Config::Preproc '/etc/httpd.conf',
                                     -expand => [ qw(locus) ];

    foreach ($x->select) {
        print $_->locus
    }
    
See L<Text::Locus> for a detailed discussion of the locus object and its
methods.

=head2 macro

Processes B<Macro> and B<Use> statements (see B<mod_macro>).  B<Macro>
statements are removed. Each B<Use> statement is replaced by the expansion
of the macro named in its argument.

The constructor accepts the following arguments:
    
=over 4

=item B<keep =E<gt>> I<$listref>

List of macro names to exclude from expanding. Each B<E<lt>MacroE<gt>> and
B<Use> statement with a name from I<$listref> as its first argument will be
retained in the parse tree.

As a syntactic sugar, I<$listref> can also be a scalar value. This is
convenient when a single macro name is to be retained.    

=back
    
=head1 MODULE INTERNALS 

Each keyword I<phase> listed in the B<-expand> array causes loading of the
package B<Apache::Config::Preproc::I<phase>>.  This package must inherit
from B<Apache::Config::Preproc::Expand> and overload at least the
B<expand> method.  See the description of B<Apache::Config::Preproc::Expand>
for a detailed description.

=head1 EXAMPLE

    my $obj = new Apache::Config::Preproc('/etc/httpd/httpd.conf',
                   -expand => [qw(compact include ifmodule macro)],
                   -indent => 4) or die $Apache::Admin::Config::ERROR;
    print $obj->dump_raw

This snippet loads the Apache configuration from file
F</etc/httpd/httpd.conf>, performs all the built-in expansions, and prints
the result on standard output, using 4 character indent for each additional
level of nesting.    

=head1 SEE ALSO

L<Apache::Admin::Config>

L<Apache::Config::Preproc::compact>

L<Apache::Config::Preproc::ifdefine>

L<Apache::Config::Preproc::ifmodule>

L<Apache::Config::Preproc::include>

L<Apache::Config::Preproc::locus>

L<Apache::Config::Preproc::macro>

=cut