NAME

Devel::Declare::Lexer

SYNOPSIS

# Add :debug tag to enable debugging
# Add :lexer_test to enable variable assignment
# Anything not starting with : becomes a keyword
use Devel::Declare::Lexer qw/ keyword /;

BEGIN {
    # Create a callback for the keyword (inside a BEGIN block!)
    Devel::Declare::Lexer::lexed(keyword => sub {
        # Get the stream out (given as an arrayref)
        my ($stream_r) = @_;
        my @stream = @$stream_r;

        my $str = $stream[2]; # in the example below, the string is the 3rd token

        # Create a new stream (we could manipulate the existing one though)
        my @ns = ();
        tie @ns, "Devel::Declare::Lexer::Stream";

        # Add a few tokens to print the string 
        push @ns, (
            # You need this (for now)
            new Devel::Declare::Lexer::Token::Declarator( value => 'keyword' ),
            new Devel::Declare::Lexer::Token::Whitespace( value => ' ' ),

            # Everything else is your own custom code
            new Devel::Declare::Lexer::Token( value => 'print' ),
            new Devel::Declare::Lexer::Token::Whitespace( value => ' ' ),
            $string,
            new Devel::Declare::Lexer::Token::EndOfStatement,
            new Devel::Declare::Lexer::Token::Newline,
        );

        # Stream now contains:
        # keyword and print "This is a string";
        # keyword evaluates to 1, everything after the and gets executed

        # Return an arrayref
        return \@ns;
    });
}

# Use the keyword anywhere in this package
keyword "This is a string";

DESCRIPTION

Devel::Declare::Lexer makes it easier to parse code using Devel::Declare by generating a token stream from the statement and providing a callback for you to manipulate it before its parsed by Perl.

The example in the synopsis creates a keyword named 'keyword', which accepts a string and prints it.

Although this simple example could be done using print, say or any other simple subroutine, Devel::Declare::Lexer supports much more flexible syntax.

For example, it could be used to auto-expand subroutine declarations, e.g. method MethodName ( $a, @b ) { ... } into sub MethodName ($@) { my ($self, $a, @b) = @_; ... }

Unlike Devel::Declare, there's no need to worry about parsing text and taking care of multiline strings or code blocks - it's all done for you.

SEE ALSO

Some examples can be found in the source download.

For more information about how Devel::Declare::Lexer works, read the documentation for Devel::Declare.

AUTHORS

Ian Kent - E<iankent@cpan.org> - original author

http://www.iankent.co.uk/

COPYRIGHT AND LICENSE

This library is free software under the same terms as perl itself

Copyright (c) 2013 Ian Kent

Devel::Declare::Lexer is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the license for more details.