This is a PHP 5.6 (and older) parser written in PHP. It's purpose is to simplify static code analysis and manipulation.
Documentation for version 0.9.x (stable; for running on PHP 5.2).
Documentation for version 1.0.x (beta; for running on PHP >= 5.3).
Note: This project is experimental, so the API is subject to change.
Basically, the parser does nothing more than turn some PHP code into an abstract syntax tree. ("nothing more" is kind of sarcastic here as PHP has a ... uhm, let's just say "not nice" ... grammar, which makes parsing PHP very hard.)
For example, if you stick this code in the parser:
<?php echo 'Hi', 'World'; hello\world('foo', 'bar' . 'baz');
You'll get a syntax tree looking roughly like this:
array( 0: Stmt_Echo( exprs: array( 0: Scalar_String( value: Hi ) 1: Scalar_String( value: World ) ) ) 1: Expr_FuncCall( name: Name( parts: array( 0: hello 1: world ) ) args: array( 0: Arg( value: Scalar_String( value: foo ) byRef: false ) 1: Arg( value: Expr_Concat( left: Scalar_String( value: bar ) right: Scalar_String( value: baz ) ) byRef: false ) ) ) )
You can then work with this syntax tree, for example to statically analyze the code (e.g. to find programming errors or security issues).
Additionally, you can convert a syntax tree back to PHP code. This allows you to do code preprocessing (like automatedly porting code to older PHP versions).
So, that's it, in a nutshell. You can find everything else in the docs.