How to parse this minimalist program?

[ethindp]

I'm learning PEGs by trying out a basic pascal-ish language. I've got the following grammar:

struct Word: pad<sor<plus<identifier>>, space> { };
struct BasicReal: rep_min_max<1, 1, star<digit>, string<'.'>,plus<digit>> { };
struct Exponent: sor<string<'e'>, string<'E'>> { };
struct OptNegPos: opt<sor<string<'+'>, string<'-'>>> {};
struct RealDigits: rep_min_max<3, 3, digit> { };
struct ScientificForm: rep_min_max<1, 1, sor<rep_min_max<1, 1, Exponent, OptNegPos, RealDigits>>> { };
struct Real: pad<sor<BasicReal, rep_min_max<1, 1, BasicReal, ScientificForm>>, space> { };
struct Special: pad<sor<string<','>, string<'('>, string<')'>, string<'['>, string<']'>, string<';'>, string<'<'>, string<'>'>, string<'*'>, string<'/'>, string<'+'>, string<'-'>, string<'='>>, space> { };
struct Integer: pad<plus<digit>, space>{ };
struct HexInteger: pad<rep_min_max<1, 1, string<'0', 'x'>, plus<xdigit>>, space> { };
struct Grammar: must<opt<sor<bof, bol>>, until<plus<sor<Word, Real, Special, Integer, HexInteger>>>> { };

All my code does right now is tokenize the input, but I keep getting a parse error when I try to evaluate the following code:

program abc
integer a,b,c
real x
begin
    b=6;
    a=b+-4;
    x=-5.63e002;
end
end

It always breaks on the final line, either the "end" or, if I add an extra newline, on that newline. Is there something I'm missing?

[d-frey]

Your grammar contains a lot of weird things, e.g. sor<plus<identifier>> (part of the first rule) matches identifier. Both the sor and the plus are useless. Since it seems you are starting with writing grammars, I suggest you take a look at our tracer, which can help you to verify whether and how your grammar matches to your input.

[ColinH]

How are things going, have you managed to make some progress? Any further questions or issues that you might want to discuss?

[ethindp]

Yes, I have. I don't have any further questions at this time. I probably will sometime later though. :)

…

On 11/19/20, Dr. Colin Hirsch ***@***.***> wrote: How are things going, have you managed to make some progress? Any further questions or issues that you might want to discuss? -- You are receiving this because you authored the thread. Reply to this email directly or view it on GitHub: https://github.com/taocpp/PEGTL/issues/227#issuecomment-730576767

-- Signed, Ethin D. Probst