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Juxtaposing quotation mark #436
Description
This grammar Exp. Exp ::= Ident "'" ; generates a parser that correctly parses x ', but not x' for some reason. I've played with other characters, including other quotation symbols, such as ’ and then both x’ and x ’ are recognized, which is imho the correct behaviour. Any particular reasons, why ' is treated specially (and how to avoid it?)? Thanks!
Activity
andreasabel commentedon Feb 8, 2023
Since
Idents can contain quotation marks,x'will parse as an identifier.You can define your own identifier tokens, e.g.:
This works as expected in the "imperative" backends (C, C++, Java) but not in the "functional" ones (Haskell, OCaml).
The problem is in how the functional backends implement the lexer: they always include lexing of
Ident, so that keywords can be lexed asIdentand then classified as keywords later. This is to prevent explosion of the lexer automata.Unfortunately, it leads to this bug.
Related:
sergey-goncharov commentedon Feb 8, 2023
Thanks, Andreas, for a quick reply!
That is roughly how I started. I've just minimized that example, since the problem persisted. I am following the basics steps from the tutorial, which suggests to use
Test, generated withbnfc -d -mfor basic testing.andreasabel commentedon Feb 8, 2023
Yes, unfortunately
"'"isn't a proper operator character atm in the standard backend (Haskell).You can use this invocation instead, to use the C backend instead of the Haskell one.
jasper-e commentedon Sep 3, 2023
My problem is that I combine bnfc Haskell backend with Haskell-based uuagc...
I would highly appreciate a command line flag for the Haskell backend to omit including Ident, which I could put in my Makefile...