We previously had another parser type, 'type ErroringJournalParser =
ExceptT String ...' for throwing parse errors without the possibility of
backtracking. This parser type was removed under the assumption that it
would be possible to write our parser without this capability. However,
after a hairy backtracking bug, we would now prefer to have the option
to prevent backtracking.
- Define a 'FinalParseError' type specifically for the 'ExceptT' layer
- Any parse error can be raised as a "final" parse error
- Tracks the stack of include files for parser errors, anticipating the
removal of the tracking of stacks of include files in megaparsec 7
- Although a stack of include files is also tracked in the 'StateT
Journal' layer of the parser, it seems easier to guarantee correct
error messages in the 'ExceptT FinalParserError' layer
- This does not make the 'StateT Journal' stack redundant because the
'ExceptT FinalParseError' stack cannot be used to detect cycles of
include files
This makes skipping/unskipping tests easier, and improves readability
a bit.
Note it's also possible to just write the test name with no preceding
function, when the type is constrained (see Journal.hs).
... for displaying the source line on which parse errors occured
Over the following set of commits, I will to refactor the parsers to
obviate the `ExceptT String` layer of the `ErroringJournalParser` type
so that all parse errors go through Megaparsec's parse error machinery.
- Simplify doctests for periodexpr.
- Besides consuming leading space consume ending space for periodexpr also.
- Drop implicit option (def, def) behaviour of periodexpr. I.e. disallow
hledger reg -p '' and auto-transaction with heading just '~'.
- Slightly re-factor periodexpr.
- Ensure that reportinginterval doesn't consume trailing space.
Useful if we'll start disallowing periods like "every1stjan2009-".
