I ran into this bug many years ago - but back then I either assumed or got told that the first rule must not be != but has to be plain =. However I think it simply did not work instead of throwing a stack overflow. On 7 August 2017 at 22:43, Steve Ratcliffe <steve@parabola.me.uk> wrote:
Hi
Every now and again, there is a bug report on a style rule that gives an error when it shouldn't. The most recent from Mike Baggaley, included a case where the rule was accepted but the result was incorrect.
I wrote a little program to generate random rules and test them using the style tester.
This showed that there were many rules that should be accepted that are not and worse there are cases where the wrong result is given.
Worst of all this simple rule:
a>=1 & (a=1 | b~2) [0x2]
(and many others) crash mkgmap with a StackOverflowError. I'm surprised that no-one has found that. Perhaps they have and it just hasn't been reported.
An example of a rule that is accepted but doesn't work is:
(a!=1 | b~2) & a<2 & a>=2 [0x2]
This matches (with trunk) with a way with tags a=2 and b=2 but it should not.
So not very complex rules fail. There are also vast number of rules that involve using not (!) such as !(highway=service & ...) that are not accepted or do not work. Probably not many styles have many such rules though.
So I re-wrote and simplified the code and the result is on the expr branch.
There is also a new feature that was needed to help make it work. There is now a not regex match operator !~. It is probably not all that useful but it is now availabl.
name !~ 'Main.*'
is exactly the same as
!(name ~ 'Main.*')
The latest branch build can be downloaded from:
http://www.mkgmap.org.uk/download/mkgmap-expr-latest.zip
It is important to test it, as although I believe that the branch is now correct, some styles may have been relying on previous bugs.
..Steve _______________________________________________ mkgmap-dev mailing list mkgmap-dev@lists.mkgmap.org.uk http://www.mkgmap.org.uk/mailman/listinfo/mkgmap-dev
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