Now that destructuring is always represented using List nodes,
make sure that Array nodes can no longer contain null elements,
so well-typed code doesn't have to deal with them unnecessarily.
If an array does contain empty elements, these are now result in
an error and are represented as a ArrayItem with Error value if
error recovery is used.
The implementation is a bit tricky because at the time the Array
node is created, we cannot tell whether it will be used in a
creation or destructuring context. For this reason the error
reporting is delayed parsing has finished.
Closes#876.
The formatting in this project has become something of a mess,
because it changed over time. Add a CS fixer config and reformat
to the desired style, which is PSR-12, but with sane brace placement.
Empty productions are supposed to be assigned the start attributes
of the lookahead token. Currently, this happens by assigning above
the current stack position when the token it read.
This fails in a situation where we first reduce an empty production
higher up in the stack, and then again reduce an empty production
lower in the stack, without consuming the lookahead token in the
meantime.
Fix this by moving the assignment into the reduction phase. We
also need to do this for error productions, which are effectively
empty.
Previously zero-length nop nodes used the lookahead start attributes
and current end attributes. This choice ends up being somewhat weird,
because the end attributes will be the at the last non-whitespace,
non-comment token, which might be quite far back. More problematically,
we may not have encountered any non-discarded token if we're at the
start of the file, in which case we will have no end attributes to
assign.
Change things to use a canonical "zero-length" node representation,
where the end position (token & file) will be exactly one before the
start position.
Fixes#589.
If indentation is invalid, we strip on a best-effort basis.
The error position information is not great, but I don't want to
introduce sub-token error positioning at this point in time.
Move doc string parsing logic from rebuildParsers.php and
String_::parseDocString() into ParserAbstract. This stuff is
going to get complicated now.
For now only implement the validation of the indentation on the
end label.
