Macro eagre_asn1::der_sequence

macro_rules! der_sequence {
    ($struct_name:ident : $($field_name:ident : $tagtype:ident $(TAG $tagclass:ident $tagval:expr ;)* TYPE $field_type:ty),+) => { ... };
    ($struct_name:ident : $($field_name:ident : $tagtype:ident $(TAG $tagclass:ident $tagval:expr ;)* TYPE $field_type:ty),+,) => { ... };
}

Macro to create sequence implementation for a struct

The macro is basically repeating the structure of the struct, but it includes additional information about what tag should be used.

• EXPLICIT TAG <CLASS> <TAG>; is used for explicit tagging
• IMPLICIT TAG <CLASS> <TAG>; is used for implicit tagging
• NOTAG is used if no tagging is required

<CLASS> is replaced by one of

• UNIVERSAL for 00
• APPLICATION for 01
• CONTEXT for 10
• PRIVATE for 11

Example

struct SomeStruct {
    pub foo: String,
    pub bar: i32,
}

der_sequence! {
    SomeStruct:
        foo: EXPLICIT TAG APPLICATION 42; TYPE String,
        bar: NOTAG TYPE i32,
}

let data = SomeStruct {
    foo: "I am a random String".to_string(),
    bar: 42,
};

let encoded = data.der_bytes().unwrap();
// Send to far away planet
let decoded = SomeStruct::der_from_bytes(encoded).unwrap();
assert_eq!(data, decoded);

Implementation Details

Because I am not the best with macro_rules! the only way I got this macro working is using idents which are converted to strings and matched against other strings. Improvements are welcome :)