[−][src]Macro nom::permutation
permutation!(I -> IResult<I,A>, I -> IResult<I,B>, ... I -> IResult<I,X> ) => I -> IResult<I, (A,B,...X)>
applies its sub parsers in a sequence, but independent from their order
this parser will only succeed if all of its sub parsers succeed
the tuple of results is in the same order as the parsers are declared
named!(perm<(&[u8], &[u8], &[u8])>, permutation!(tag!("abcd"), tag!("efg"), tag!("hi")) ); // whatever the order, if the parser succeeds, each // tag should have matched correctly let expected = (&b"abcd"[..], &b"efg"[..], &b"hi"[..]); let a = &b"abcdefghijk"[..]; assert_eq!(perm(a), Ok((&b"jk"[..], expected))); let b = &b"efgabcdhijkl"[..]; assert_eq!(perm(b), Ok((&b"jkl"[..], expected))); let c = &b"hiefgabcdjklm"[..]; assert_eq!(perm(c), Ok((&b"jklm"[..], expected))); let d = &b"efgxyzabcdefghi"[..]; assert_eq!(perm(d), Err(Err::Error(error_node_position!(&b"efgxyzabcdefghi"[..], ErrorKind::Permutation, error_position!(&b"xyzabcdefghi"[..], ErrorKind::Permutation))))); let e = &b"efgabc"[..]; assert_eq!(perm(e), Err(Err::Incomplete(Needed::Size(4))));
If one of the child parsers is followed by a ?
, that parser is now
optional:
named!(perm<&str, (Option<&str>, &str, &str)>, permutation!(tag!("abcd")?, tag!("efg"), tag!("hi")) ); // whatever the order, if the parser succeeds, each // tag should have matched correctly let expected = (Some("abcd"), "efg", "hi"); let a = "abcdefghijk"; assert_eq!(perm(a), Ok(("jk", expected))); let b = "efgabcdhijkl"; assert_eq!(perm(b), Ok(("jkl", expected))); let c = "hiefgabcdjklm"; assert_eq!(perm(c), Ok(("jklm", expected))); // if `abcd` is missing: let expected = (None, "efg", "hi"); let a = "efghijk"; assert_eq!(perm(a), Ok(("jk", expected))); let b = "efghijkl"; assert_eq!(perm(b), Ok(("jkl", expected))); let c = "hiefgjklm"; assert_eq!(perm(c), Ok(("jklm", expected))); let e = "efgabc"; assert_eq!(perm(e), Err(Err::Incomplete(Needed::Size(4))));