For representing Identifiers that have an implicit leading $.
With this done, maybe go one step further?
* Rename VarLikeIdentifier -> VarIdentifier / VarName
* Use VarIdentifier / VarName also as an inner node in Variable.
Not sure if this adds any real value.
The parameter case is a bit weird, because the subnode is called
"name" here, rather than "var". Nothing we can do about that in
this version though.
The two parser options might be merged. I've kept it separate,
because I think this variable representation should become the
default (or even only representation) in the future, while I'm
less sure about the Identifier thing.
In this mode non-namespaced names that are currently represented
using strings will be represented using Identifier nodes instead.
Identifier nodes have a string $name subnode and coerce to string.
This allows preserving attributes and in particular location
information on identifiers.
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.
Lexer::startLexing() no longer throws, instead errors can be fetched
using Lexer::getErrors().
Lexer errors now also contain full line and position information.
It's likely that an error after -> will trigger another one due to
missing semicolon without shifting a single token. We prevent an
immediate failure in this case by manually setting errorState to 2,
which will suppress the duplicate error message, but allow error
recovery.
Expr\List will now contain ArrayItems instead of plain variables.
I'm reusing ArrayItem, because code handling list() must also handle
arrays, and this allows both to go through the same code path.
This also renames Expr\List->vars to ->items.
TODO: Should Expr\List be dropped in favor of Expr\Array with an
extra flag?
