xdebug/blog/vendor/nikic/php-parser/grammar/README.md

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 grammer 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

In order to rebuild the parser, you need moriyoshi's fork of kmyacc. After you compiled/installed it, run the rebuildParsers.php script.

By default only the Parser.php is built. If you want to additionally emit debug symbols and create y.output, run the script with --debug. If you want to retain the preprocessed grammar pass --keep-tmp-grammar.