Kent Fredric

NAME

Gentoo::ChangeLog::Parser::Eventual - Rudimentary Event-Based ChangeLog format parser, inspired by Pod::Eventual.

VERSION

version 0.1.2

SYNOPSIS

    use Gentoo::ChangeLog::Parser::Eventual
    my $parser = Gentoo::ChangeLog::Parser::Eventual->new(
        callback => sub {
            my ( $parser, $event, $opts ) = @_ ;
        },
    );

    $parser->handle_line( "This is a line", { key => 'value', line => 1 });

DESCRIPTION

In the proceeds of making a ChangeLog parser, I kept getting stuck on various parts with writing it cleanly.

This design, inspired by RJBS' Great Pod::Eventual, greatly simplifies the process by using very rudimentary and loose data validation.

Lines are fed in manually, because we didn't want to implement all the File IO our self and didn't want to limit the interface by forcing passing a file handle.

You can do the IO quite simply anyway.

    while( my $line = <$fh> ){
        chomp $line;
        $parser->handle_line( $line , { line => $. } );
    }

A parser instance has a bit of state persistence, so you should use only 1 parser per input file.

Currently, it can only detect a few basic things.

1. Header blocks.

We go naive and classify that entire "# ChangeLog for " section at the top of a ChangeLog as a "Header".

The header itself is not validated or parsed in any way beyond the notion that its a series of comments.

2. Release statements.

Raises an event when it sees

    *perl-5.12.2 (10 Jun 2010)
3. Change Headers.

This is the part on the top of each ChangeLog entry as follows:

    10 Jun 2010; Bob Smith <asd>:

There are multiple ways this can be done however, so there are 3 events for this.

4. Change bodies.

This is the part after the header.

5. Blank Lines.

METHODS

handle_line

handle_line is the only public method on this object. It takes one line, processes its own state a bit, works out what event(s) need to be thrown, and call the passed callback.

Specification: $object->handle_line( Str $line, HashRef $opts )

Parameter: $line : Mandatory, Str

This must be a string, and this is the string that represents a singular line from the ChangeLog to be parsed. This code is written under the assumption that you have also pre-chomped all your lines, but doesn't enforce it. However, its not guaranteed to work, and is not tested for, and may in a future revision be enforced.

Parameter: $opts : Mandatory, HashRef

This is a HashRef of data to be sent through to the event handler.

This is a good place to specify the source line number of the line you are currently parsing if you want that.

     $object->handle_line("this line", { line => 4 } );

and then in the callback:

     my( $parser, $event, $opts ) = @_ ;
     print $opts->{line} = 4;

ATTRIBUTES

_callback

Outside construction and providing this (required) attribute, no public methods exist for working with it.

Specification: CodeRef, rw, required, init_arg => callback

Construction.

    my $object = ::Elemental->new( callback => sub {
        my( $parser, $event, $opts ) = @_ ;
         .... event handler code here ....
    });

Parameter: $event : Str

This is the name of the event that has been triggered. See "EVENTS".

Parameter: $opts : HashRef

This is a Hash Reference of data about the event. Mostly, it contains whatever data was passed from "handle_line", but it injects its own 'content' key containing a copy of the string that was parsed.

Executing.

You can manually execute the CodeRef as if it were called internally, but there is little point to this.

    $object->handle_event( 'an-event-name' => { } );

Note, that the event-names list is baked into this class, and manually calling this method and passing an unsupported event name will result in casualties.

EVENTS

start

Fires when the first line is parsed.

blank

Fires on blank ( i.e.: all white space ) lines.

Fires on the first header line.

header_comment

Fires on all comments that are deemed "part of the header"

header_end

Fires on the first line that is obviously not part of the header, terminating the header.

release_line

Fires on *perl-5.12.2 lines.

change_header

Fires on Single-line change headers.

change_body

Fires on each line that looks like it was a child of the previous change header.

end_change_body

Fires when the first line is seen that indicates the change body is complete.

begin_change_header

Fires on the first line of a multi-line change header.

continue_change_header

Fires on all non-blank lines in a multi-line change header other than the first and last.

end_change_header

Fires on the last line of a multi-line change header

UNKNOWN

Fires in the event no processing rules indicated a success state.

AUTHOR

Kent Fredric <kentnl@cpan.org>

COPYRIGHT AND LICENSE

This software is copyright (c) 2013 by Kent Fredric <kentnl@cpan.org>.

This is free software; you can redistribute it and/or modify it under the same terms as the Perl 5 programming language system itself.