Document new flags for AST_TYPE (null/false)

[TysonAndre]

No description provided.

[nikic]

// php 8.0 union types for the sake of consistency?

[lisachenko]

Maybe add these flags and meta to the PHP core itself? In order to make this information useful for AST extension developers )

[TysonAndre]

Maybe add these flags and meta to the PHP core itself? In order to make this information useful for AST extension developers )

In README.md

ast\get_metadata() returns metadata about all AST node kinds. The return value is a map from AST

php > var_export(ast\get_metadata()[ast\AST_TYPE]);
ast\Metadata::__set_state(array(
   'kind' => 1,
   'name' => 'AST_TYPE',
   'flags' => 
  array (
    0 => 'ast\\flags\\TYPE_NULL',
    1 => 'ast\\flags\\TYPE_FALSE',
    2 => 'ast\\flags\\TYPE_BOOL',
    3 => 'ast\\flags\\TYPE_LONG',
    4 => 'ast\\flags\\TYPE_DOUBLE',
    5 => 'ast\\flags\\TYPE_STRING',
    6 => 'ast\\flags\\TYPE_ARRAY',
    7 => 'ast\\flags\\TYPE_OBJECT',
    8 => 'ast\\flags\\TYPE_CALLABLE',
    9 => 'ast\\flags\\TYPE_VOID',
    10 => 'ast\\flags\\TYPE_ITERABLE',
  ),
   'flagsCombinable' => false,
))

[lisachenko]

My question was not about php-ast extension ;) But about PHP core itself because this information is not available there.

[TysonAndre]

My question was not about php-ast extension ;) But about PHP core itself because this information is not available there.

There's various limitations. Right now, all of this information is implicit, and is figured out by reading Zend/zend_compile.c for the most part.

https://github.com/php/php-src/blob/0a2f6c55279c506dad65a6711567107d6aceec2d/Zend/zend_ast.c#L2074-L2111

1. AST child nodes don't have names, they have indexes. php-ast is what chooses names to assign to them.
2. flagsCombinable and flags of ast\Metadata are also found by reading the source right now.

zend_ast_export is the closest thing (that I can find) to ast introspection in the php-src core itself, and it's limited - it just converts an AST back to similar source code, so that C developers can debug code.

• My guess is that there wouldn't be support for introspection APIs (e.g. fetching possible flags for a node kind) unless there was something depending on them in php-src - When someone implemented new RFCs for new syntax, they might not even know such introspection APIs needed to be updated.
• Also, php-ast differs from the real node kind in subtle ways to maintain compatibility with ASTs generated with older php versions

If #5 was done (merge php-ast into core), there might be better APIs for php-ast and other extensions to use.

• I don't know what the status of that is. php-ast's API seems to have stabilized (certain types of new features will require bumps to current_version in the future), so it might be a good time for that.