excluding some characters from string

[MahaZaid]

Hi,
I want to match a keyword that does not include some specific words or characters, something like using regular expression for the matched keywords.
for example I want to match any sequence of characters that generates a word except AND keyword
any idea how I could do that using PEGTL?

[d-frey]

Start by having rules for your keywords:

struct kw_and : TAO_PEGTL_KEYWORD("AND") {};
struct kw_or : TAO_PEGTL_KEYWORD("OR") {};

Then have a rule for any keyword:

struct keywords : sor< kw_and, kw_or > {};

Finally, use the minus<> rule to match an identifier and make sure it is not a keyword.

struct label : minus< identifier, keywords > {};

This should do the trick. You can, of course, use more complicated grammars if you want to exclude everything that contains a keyword or more complicated patterns.

[MahaZaid]

okay cool, but is identifier by default includes space characters ? as when I try to match
test1 test2 it passes, while I want it to fail in my case.
I thought identifier supports only letters & numbers.
here is my grammar:

   struct kw_and : TAO_PEGTL_STRING("AND") {};
    struct kw_or : TAO_PEGTL_STRING("OR") {};
    struct keywords : sor<kw_and, kw_or> {};
    struct label : minus< identifier, keywords> {};
    struct grammar: must<label>{};

[d-frey]

That's just because the grammar matches the "test1" part of the input and ignores the rest. You need to explicitly enforce that the input ends after your label. Use:

struct grammar : must< label, eof > {};

[MahaZaid]

It worked!
thank you so much for your help :)

[d-frey]

You're welcome, thanks for choosing the PEGTL :)