Yichun Zhang (章亦春) > Filter-QuasiQuote > Filter::QuasiQuote

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Module Version: 0.07   Source  

NAME ^

Filter::QuasiQuote - Quasiquoting for Perl

VERSION ^

This document describes Filter::QuasiQuote 0.07 released on August 20, 2008.

SYNOPSIS ^

    package MyFilter;

    require Filter::QuasiQuote;
    our @ISA = qw( Filter::QuasiQuote );

    sub my_filter {
        my ($self, $s, $file, $line, $col) = @_;
        # parse the dsl source in $s and emit the perl source in ONE LINE
        return generate_perl_source( parse_dsl( $s ) );
    }

    # and in another file:
    use MyFilter;

    [:my_filter|This is my little DSL...|]

DESCRIPTION ^

GHC 6.10.x is going to have a nice quasiquoting feature for Haskell:

http://www.eecs.harvard.edu/~mainland/ghc-quasiquoting/

This module implements similar quasiquoting syntax for Perl by means of carefully designed source filters.

The user can subclass Filter::QuasiQuote and define her own DSL extensions. Besides, multiple concrete quasiquoting filters can be chained and composed within a single Perl file.

Special efforts have been made to ensure line numbers for the resulting Perl source won't be corrupted and support for precise file position information is also provided to user's DSL compilers as well.

This work is still in alpha phase and under active development. So please check back often ;)

EXAMPLES ^

SQL auto-quoter

The concrete filter class could be defined as follows:

    # QuoteSQL.pm
    package QuoteSQL;

    require Filter::QuasiQuote;
    our @ISA = qw( Filter::QuasiQuote );

    sub sql {
        my ($self, $s, $file, $line, $col) = @_;
        my $package = ref $self;
        #warn "SQL: $file: $line: $s\n";
        $s =~ s/\n+/ /g;
        $s =~ s/^\s+|\s+$//g;
        $s =~ s/\\/\\\\/g;
        $s =~ s/"/\\"/g;
        $s =~ s/\$\w+\b/".${package}::Q($&)."/g;
        $s = qq{"$s"};
        $s =~ s/\.""$//;
        $s;
    }

    sub Q {
        my $s = shift;
        $s =~ s/'/''/g;
        $s =~ s/\\/\\\\/g;
        $s =~ s/\n/ /g;
        "'$s'";
    }

    1;

And then use it this way:

    use QuoteSQL;

    my $sql = [:sql|
        select id, title
        from posts
        where id = $id and title = $title |];

which is actually equivalent to

    my ($id, $title) = (32, 'Hello');
    my $sql =
        "select id, title from posts where id = ".quote($id);

INTERNAL METHODS ^

The following methods are internal and are not intended to call directly.

debug

Used to print debug info to stderr when $Filter::QuasiQuote::Debug is set to 1.

filter

Main filter function which is usually inherited by concrete filter subclasses.

CAVEATS ^

Subclasses of Filter::QuasiQuote should NOT use it directly. For example, the following will break things:

    use Filter::QuasiQuote; # BAD!!!
    use base 'Filter::QuasiQuote'; # BAD TOO!!!

Because One should never call the import method of Filter::QuasiQuote directly. (Perl's use statement calls its import automatically while the require statement does not.)

TODO ^

BUGS ^

Please report bugs or send wish-list to the CPAN RT site:

http://rt.cpan.org/NoAuth/Bugs.html?Dist=Filter-QuasiQuote.

VERSION CONTROL ^

For the very latest version of this module, check out the source from the SVN repos below:

http://svn.openfoundry.org/filterquote

There is anonymous access to all. If you'd like a commit bit, please let me know. :)

AUTHOR ^

Agent Zhang <agentzh@yahoo.cn>

COPYRIGHT AND LICENSE ^

Copyright (c) 2008 by Agent Zhang (agentzh).

This software is released under the MIT license cited below. The "MIT" License

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

SEE ALSO ^

Quasiquoting support in Haskell (via GHC)

http://www.eecs.harvard.edu/~mainland/ghc-quasiquoting/,

Related CPAN modules

Filter::Util::Call, Filter::Simple, Module::Compile.

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