I wished there was a way to do this in smaller steps, but with
every line fixed an error somewhere else became visible. Here
is a (probably incomplete) list of the issues:
* Only one set of parentheses was supported. This is a hard
to solve problem without a real parser (one solution is to
use an recursive RE, see below).
* The precedence order was wrong. Might have been adapted just
to give a positive result for the arbitrary state of the tree.
* Numbered match variables (e.g. $1, $2, etc.) are not local.
Calling handle_expressions() recursively once with $1, then
with $2, resulted in using the final $2 after the first
recursive call (garbage, practically).
Also, symbol and expression parsing was mixed, making things
harder to follow.
To remedy the issues:
* Split handle_symbol() out. It is called with whitespace
stripped, to keep the uglier REs in handle_expressions().
* Match balanced parentheses and quotes when splitting
expressions. In this recursive RE
/(\((?:[^\(\)]++|(?-1))*\))/
the `(?-1)` references the outer-most group, thus the whole
expression itself. So it matches a pair of parentheses with
a mix of non-parentheses and the recursive rule itself inside.
This allows us to:
* Order the expression matches according to their precedence
rules. Now we can match `<expr> '||' <expr>` first as we should
and everything else falls into its place.
* Remove the bail-out that silenced the undefined behavior.
Change-Id: Ibc1be79adc07792f0721f0dc08b50422b6da88a9
Signed-off-by: Nico Huber <nico.h@gmx.de>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/52067
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Angel Pons <th3fanbus@gmail.com>
f6b2baa3e8