What do all those files mean?
=============================
* `php5.y`: PHP 5 grammar written in a pseudo language
* `php7.y`: PHP 7 grammar written in a pseudo language
* `tokens.y`: Tokens definition shared between PHP 5 and PHP 7 grammars
* `parser.template`: A `kmyacc` parser prototype file for PHP
* `tokens.template`: A `kmyacc` prototype file for the `Tokens` class
* `rebuildParsers.php`: Preprocesses the grammar and builds the parser using `kmyacc`
.phpy pseudo language
=====================
The `.y` file is a normal grammar in `kmyacc` (`yacc`) style, with some transformations
applied to it:
* Nodes are created using the syntax `Name[..., ...]`. This is transformed into
`new Name(..., ..., attributes())`
* Some function-like constructs are resolved (see `rebuildParsers.php` for a list)
Building the parser
===================
Run `php grammar/rebuildParsers.php` to rebuild the parsers. Additional options:
* The `KMYACC` environment variable can be used to specify an alternative `kmyacc` binary.
By default the `phpyacc` dev dependency will be used. To use the original `kmyacc`, you
need to compile [moriyoshi's fork](https://github.com/moriyoshi/kmyacc-forked).
* The `--debug` option enables emission of debug symbols and creates the `y.output` file.
* The `--keep-tmp-grammar` option preserves the preprocessed grammar file.