/ 
Inline-Filters-0.12
River stage zero No dependents
/ Inline::Filters

NAME

Inline::Filters - Common source code filters for Inline Modules.

DESCRIPTION

Inline::Filters provides common source code filters to Inline Language Modules. Unless you're an Inline module developer, you can just read the next section.

Supported Filters

This section describes each filter in Inline::Filters.

Strip_POD

Strips embedded POD from a block of code in any language. This is implemented as a regular expression:

$code =~ s/^=\w+[^\n]*\n\n(.*?)(^=cut\n\n|\Z)//gsm;

That means if you have a language which contains POD-like syntax, it will be stripped by this filter (i.e. don't use this filter with such a language). This filter is useful for making code like this compile:

use Inline C => <<'END', FILTERS => 'Strip_POD';
=head1 add

Returns the sum of two integers.

=cut

int add(int x, int y) { return x + y; }
END

Strip_Comments

Strips comments from a block of code in whatever language you are using. The comment stripper is string-safe -- i.e. it will not strip comments embedded in strings.

The feature is useful because both the C and C++ grammars cannot deal with comments at arbitrary points in the source code; to do so would bloat the grammar. Instead, code like this should have its comments stripped before parsing:

   use Inline C => <<'END', FILTERS => 'Strip_Comments';

   int md5_block(char *block,   /* the block to operate on */
		 long length,   /* the number of bytes */
		 char **result) /* the resulting 128-bit sum */
   {
	/* some code here */
   }

   END

Strip_Comments is available for the following languages:

  1. C

  2. C++

  3. Python

  4. Java

The Python and Java filters are available for convenience only. There is little need for them, since Inline::Python and Inline::Java use the official language compilers to parse the code, and these compilers know about comments.

Preprocess

Now available for all languages. Uses the C pre-processor ($Config{cpprun}) to pre-process a block of code. This is useful if you want to expand macros and conditional code before parsing. For example:

use Inline CPP => <<'END', FILTERS => 'Preprocess';
class Foo
#ifdef FOO_INHERITS_BAR
   : public Bar
#endif
{

};
END

The code shown above will not parse correctly without the Preprocess filter, since the Inline::CPP grammar can't understand preprocessor directives.

DETAILS

Built-in Filters

Built-in source code filters are implemented as a blessed reference to a hash containing two elements: 'filter' is the name of the filter, and 'coderef' is a code reference to the appropriate filter. The object has a filter() method, which should be called with the ILSM object as the first parameter, and source code as the second parameter. The filters always return the filtered code.

User-supplied Filters

As of Inline 0.42, you can supply your own filters to Inline by passing a code reference to the FILTERS option, like this:

sub my_filter { };
use Inline C => DATA => FILTERS => [\&my_filter];

The filter sub is passed one argument: the unfiltered code. It must return the filtered code as its only return value. If something goes wrong and you need to pass inform the user, just croak.

Note: in some circumstances, you must put your filter subroutine above the use Inline statement. When possible, Inline compiles your code at compile time, meaning the subroutine must be defined. If you're reading code from the 'DATA' filehandle, you can put the filter anywhere in your script, since Inline delays compilation until runtime.

Applying Filters

Inline provides a filter() method which applies the requested filters one after the other on the source code. All ILSMs should save the result of $o->filter() and consider it the source code. If no filters have been requested, this just returns the unfiltered source code.

SEE ALSO

For more information about specifying Inline source code filters, see Inline::C or Inline::CPP.

For more information about using other languages inside Perl, see Inline. For more information about using C from Perl, see Inline::C.

BUGS OR OMISSIONS

You can pass in arbitrary subroutine references as filters. However, if you find yourself using a filter on a regular basis and you'd like to see it included in Inline::Filters, please contact me.

If you wish to report a bug, please refer to Inline for instructions on how to submit a bug report.

AUTHOR

Neil Watkiss (NEILW@cpan.org)

COPYRIGHT

Copyright (C) 2001, Neil Watkiss.

This module is free software. It may be used, redistributed and/or modified under the same terms as Perl itself.

(see http://www.perl.com/perl/misc/Artistic.html)