Tudor Girba <tu...@tudorgirba.com> writes:
> But, does it solve your problem?
Not yet. Not sure it will.
>> More generally, there seems to be a bug in how PetitParser handles
>> PPFailure return values. The actually reported error is always different
>> from what is passed to PPFailure. I love software ;-)
>
> What do you mean?
If I return
PPFailure message: 'whatever' at: 0
from my parser, then it does fail but it reports a different error.
After some more experiments, it looks like this is perhaps not a bug,
but a feature that makes returning failures not so useful after all. I
suspect that PetitParser simply backtracks after my failure and tries a
different rule that then fails as well.
A simple example:
| p |
p := #digit asParser plus flatten
==> [ :value | value asSet size = 1 ifTrue: [ value ] ifFalse:
[ PPFailure message: 'not equal' at: 0 ]].
p parse: '22233'
The reported failure is "digit expected at 5".
On the other hand, if there is no path for backtracking, the reported
failure is the expected one:
| p |
p := (#digit asParser, #digit asParser) flatten
==> [ :value | value first = value second ifTrue: [ value ]
ifFalse: [ PPFailure message: 'not equal' at: 0 ]].
p parse: '23'
Konrad.
