This module introduces support for the variable repetition
meta-syntactic construct as defined in RFC 5234. It also offers
several other metasyntactic constructs that are specializations of
variable repetition, including specific repetition (`#'), Kleene
star (`*'), Kleene sum (`+'), and optional sequence (`?').
There are variants that allow a separator Sep_0 to be processed in
between productions of Dcg_n. This covers several very common cases,
like comma-separated lists or tokens separated by whitespace.
This module also defines the DCGs correlates to the ISO call/[1-8]
predicates. Since DCGs take two extra predicate, we can only define
dcg_call//[1,6].
- See also
- - https://tools.ietf.org/html/rfc5234
- Compatibility
- - RFC 5234 ― Augmented BNF for Syntax Specifications: ABNF
- ?N # :Dcg_0// is semidet
- #(?N, :Dcg_1, ?Args:list)// is semidet
- *(:Dcg_0)// is nondet
- :Dcg_1 * ?Args:list// is nondet
- + :Dcg_0// is nondet
- :Dcg_1 + ?Args:list// is nondet
- ? :Dcg_0// is nondet
- :Dcg_1 ? ?Arg// is nondet
- m*(?M:nonneg, :Dcg_0)// is nondet
- m*(?M:nonneg, :Dcg_1, ?Args:list)// is nondet
- *n(?N:nonneg, :Dcg_0)// is nondet
- *n(?N:nonneg, :Dcg_1, ?Args:list)// is nondet
- m*n(?M:nonneg, ?N:nonneg, :Dcg_0)// is nondet
- m*n(?M:nonneg, ?N:nonneg, :Dcg_1, ?Args:list)// is nondet
- #!(?N, :Dcg_0)// is semidet
- #!(?N, :Dcg_1, ?Args:list)// is semidet
- *!(:Dcg_0)// is nondet
- *!(:Dcg_1, ?Args:list)// is nondet
- +!(:Dcg_0)// is nondet
- +!(:Dcg_1, ?Args:list)// is nondet
- ?!(:Dcg_0)// is nondet
- ?!(:Dcg_1, ?Arg)// is nondet
- m*!(?M:nonneg, :Dcg_0)// is nondet
- m*!(?M:nonneg, :Dcg_1, ?Args:list)// is nondet
- *n!(?N:nonneg, :Dcg_0)// is nondet
- *n!(?N:nonneg, :Dcg_1, ?Args:list)// is nondet
- m*n!(?M:nonneg, ?N:nonneg, :Dcg_0)// is nondet
- m*n!(?M:nonneg, ?N:nonneg, :Dcg_1, ?Args:list)// is nondet
- #&(?N, :Dcg_0, :Sep_0)// is semidet
- #&(?N, :Dcg_1, :Sep_0, ?Args:list)// is semidet
- *&(:Dcg_0, :Sep_0)// is nondet
- *&(:Dcg_1, :Sep_0, ?Args:list)// is nondet
- +&(:Dcg_0, :Sep_0)// is nondet
- +&(:Dcg_1, :Sep_0, ?Args:list)// is nondet
- m*&(?M:nonneg, :Dcg_0, :Sep_0)// is nondet
- m*&(?M:nonneg, :Dcg_1, :Sep_0, ?Args:list)// is nondet
- *&n(?N:nonneg, :Dcg_0, :Sep_0)// is nondet
- *&n(?N:nonneg, :Dcg_1, :Sep_0, ?Args:list)// is nondet
- m*&n(?M:nonneg, ?N:nonneg, :Dcg_0, :Sep_0)// is nondet
- m*&n(?M:nonneg, ?N:nonneg, :Dcg_1, :Sep_0, ?Args:list)// is nondet
- Notice that it is possible for a production of ~Sep_0~ to appear
after the last production of ~Dcg_n~. This meand that eager parsing
must cut after ~(Sep_0, Dcg_n)~, and not after ~Sep_0~ alone.
- #&!(?N, :Dcg_0, :Sep_0)// is semidet
- #&!(?N, :Dcg_1, :Sep_0, ?Args:list)// is semidet
- *&!(:Dcg_0, :Sep_0)// is det
- *&!(:Dcg_1, :Sep_0, ?Args:list)// is det
- +&!(:Dcg_0, :Sep_0)// is det
- +&!(:Dcg_1, :Sep_0, ?Args:list)// is det
- m*&!(?M:nonneg, :Dcg_0, :Sep_0)// is det
- m*&!(?M:nonneg, :Dcg_1, :Sep_0, ?Args:list)// is det
- *&n!(?N:nonneg, :Dcg_0, :Sep_0)// is det
- *&n!(?N:nonneg, :Dcg_1, :Sep_0, ?Args:list)// is det
- m*&n!(?M:nonneg, ?N:nonneg, :Dcg_0, :Sep_0)// is det
- m*&n!(?M:nonneg, ?N:nonneg, :Dcg_1, :Sep_0, ?Args:list)// is det
- Notice that it is possible for a production of ~Sep_0~ to appear
after the last production of ~Dcg_n~. This meand that eager parsing
must cut after ~(Sep_0, Dcg_n)~, and not after ~Sep_0~ alone.
Undocumented predicates
The following predicates are exported, but not or incorrectly documented.
- #(Arg1, Arg2, Arg3, Arg4, Arg5)
- *(Arg1, Arg2, Arg3, Arg4)
- +(Arg1, Arg2, Arg3, Arg4)
- ?(Arg1, Arg2, Arg3, Arg4)
- m*(Arg1, Arg2, Arg3, Arg4, Arg5)
- *n(Arg1, Arg2, Arg3, Arg4, Arg5)
- m*n(Arg1, Arg2, Arg3, Arg4, Arg5, Arg6)
- #!(Arg1, Arg2, Arg3, Arg4, Arg5)
- *!(Arg1, Arg2, Arg3, Arg4)
- +!(Arg1, Arg2, Arg3, Arg4)
- ?!(Arg1, Arg2, Arg3, Arg4)
- m*!(Arg1, Arg2, Arg3, Arg4, Arg5)
- *n!(Arg1, Arg2, Arg3, Arg4, Arg5)
- m*n!(Arg1, Arg2, Arg3, Arg4, Arg5, Arg6)
- #&(Arg1, Arg2, Arg3, Arg4, Arg5, Arg6)
- *&(Arg1, Arg2, Arg3, Arg4, Arg5)
- +&(Arg1, Arg2, Arg3, Arg4, Arg5)
- m*&(Arg1, Arg2, Arg3, Arg4, Arg5, Arg6)
- *&n(Arg1, Arg2, Arg3, Arg4, Arg5, Arg6)
- m*&n(Arg1, Arg2, Arg3, Arg4, Arg5, Arg6, Arg7)
- #&!(Arg1, Arg2, Arg3, Arg4, Arg5, Arg6)
- *&!(Arg1, Arg2, Arg3, Arg4, Arg5)
- +&!(Arg1, Arg2, Arg3, Arg4, Arg5)
- m*&!(Arg1, Arg2, Arg3, Arg4, Arg5, Arg6)
- *&n!(Arg1, Arg2, Arg3, Arg4, Arg5, Arg6)
- m*&n!(Arg1, Arg2, Arg3, Arg4, Arg5, Arg6, Arg7)