Attribute Macro ebml_iterable_specification_derive::ebml_specification

#[ebml_specification]

Attribute that derives implementations of EbmlSpecification and EbmlTag for an enum.

This macro is intended to make implementing the traits in ebml-iterable-specification easier to manage. Rather than requiring handwritten implementations for EbmlSpecification and EbmlTag methods, this macro understands attributes assigned to enum members and generates an implementation accordingly.

When deriving EbmlSpecification for an enum, the following attributes are required for each variant:

• #[id(u64)] - This attribute specifies the “id” of the tag. e.g. 0x1a45dfa3
• #[data_type(TagDataType)] - This attribute specifies the type of data contained in the tag. e.g. TagDataType::UnsignedInt

The following attribute is optional for each variant:

• #[doc_path(Path/To/Element)] - This attribute specifies the document path of the current element. If this attribute is not present, the variant is treated as a Root element. Global elements can be defined with wildcard paths, e.g. #[doc_path(Segment/(1-)/)].

Note

This attribute modifies the variants in the enumeration by adding fields to them. It also will add the following variants to the enum:

• Crc32(Vec<u8>) - global tag defined in the EBML spec
• Void(Vec<u8>) - global tag defined in the EBML spec
• RawTag(u64, Vec<u8>) - used to support reading “unknown” tags that aren’t in the spec