README

Parser generator (currently generates recursive descent parser and canonical LR(1) parser) for PHP.

Big refactoring from Jakub Kulhan's original pacc.

Get ready

add the axmachado/pacc as a development requirement:

php composer.phar require axmachado/pacc

There is executable bin/pacc, that is installed by Composer as vendor/bin/pacc.

Then, you can run the "pacc" command from your project directory:

./vendor/bin/pacc -h

Write parsers

Files consumed by pacc are structured like this:

    grammar <<parser_name>>;

    option <<option_name>> = <<option_value>>;

    @<<code>> {
        <<php code>>
    }

    <<rules>>

Rules are compiled into PHP parser code, header and footer are left as they are.

pacc uses YACC/Bison syntax for rules. Each rule constist of its name, :, body, and ;. Name has to match regular expression [a-z][a-z_]*. Body consists of expressions separated by vertical bar – |. Each expression can have some attached PHP code. For example:

    numerical_operation
        : number '+' number { $$ = $1 + $3; /* $1 is first number, $2 is plus sign, and $3 is second number */ }
        | number '-' number { $$ = $1 - $3; }
        ;

In PHP code, you can use special variables like $$, $1, $2, $3, etc. In $$ is saved result of expression. Through numerical variables you get result of subexpressions.

Look for inspiration in examples/ directory.

License

The MIT license

Copyright (c) 2009-2010 Jakub Kulhan <jakub.kulhan@gmail.com>
Copyright (c) 2017      Alexandre Machado <axmachado@gmail.com>

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.