Adds support for PHP 8 attributes, represented using `AttrGroup` nodes
containing `Attribute` nodes. The `attrGroup` subnode is added to all
nodes that can have attributes.
This is still missing FPPP support.
Co-authored-by: Nikita Popov <nikita.ppv@gmail.com>
Nearly all special errors are now handled gracefully, i.e. the
parser will be able to continue after encountering them. In some
cases the associated error range has been improved using the new
end attribute stack.
To achieve this the error handling code has been moved out of the
node constructors and into special methods in the parser.
Instead of storing subnodes in a subNodes dictionary, they are
now stored as simple properties. This requires declarating the
properties, assigning them in the constructor, overriding
the getSubNodeNames() method and passing NULL to the first argument
of the NodeAbstract constructor.
[Deprecated: It's still possible to use the old mode of operation
for custom nodes by passing an array of subnodes to the constructor.]
The only behavior difference this should cause is that getSubNodeNames()
will always return the original subnode names and skip any additional
properties that were dynamically added. E.g. this means that the
"namespacedName" node added by the NameResolver visitor is not treated
as a subnode, but as a dynamic property instead.
This change improves performance and memory usage.
