Proposal: Order independent parsing about participle HOT 3 CLOSED

Can you provide an example of what you're suggesting? Both a proposed grammar and some sample input, perhaps.

EBNF is very well established, so it would be surprising to me if you've encountered something that can't be expressed in it.

from participle.

The closest I can think of is something like this:

x = (a b c) | (a c b) | (b a c) | (b c a) | (c a b) | (c b a);
a = "foo" "{" { k "=" v "," } "}";
b = "bar" "{" { k "=" v "," } "}";
c = "baz" "{" { k "=" v "," } "}";
k = IDENTIFIER;
v = STRING;

basically the idea is to have multiple rules which can occur in any order but each rule may only occur once, so the following is valid:

foo {
a="b",
c="d",
}
bar {
a="b",
c="d",
}

but this is not:

foo {
a="b",
c="d",
}
foo {
e="f",
}

I'd like to specify something like this as semantically equivalent of the above:

x = <a b c>;
a = "foo" "{" { k "=" v "," } "}";
b = "bar" "{" { k "=" v "," } "}";
c = "baz" "{" { k "=" v "," } "}";
k = IDENTIFIER;
v = STRING;

from participle.

Ah, ok, interesting idea. I think that in the interest of keeping the grammar syntax simple (and sticking largely with EBNF), that it's fine to enforce this in semantic analysis, after parsing.

from participle.