[−][src]Crate nom_derive
nom-derive
Overview
nom-derive is a custom derive attribute, to derive nom parsers automatically from the structure definition.
It is not meant to replace nom, but to provide a quick and easy way to generate parsers for structures, especially for simple structures. This crate aims at simplifying common cases. In some cases, writing the parser manually will remain more efficient.
- API documentation
- Documentation of
Nom
attribute. This is the main documentation for this crate, with all possible options and many examples.
Feedback welcome !
#[derive(Nom)]
This crate exposes a single custom-derive macro Nom
which
implements parse
for the struct it is applied to.
The goal of this project is that:
derive(Nom)
should be enough for you to derive nom parsers for simple structures easily, without having to write it manually- it allows overriding any parsing method by your own
- it allows using generated parsing functions along with handwritten parsers and combining them without efforts
nom-derive
adds declarative parsing to nom
. It also allows mixing with
procedural parsing easily, making writing parsers for byte-encoded formats
very easy.
For example:
use nom_derive::Nom; #[derive(Nom)] struct S { a: u32, b: u16, c: u16 }
This adds a static method parse
to S
, with the following signature:
impl S { pub fn parse(i: &[u8]) -> nom::IResult(&[u8], S); }
To parse input, just call let res = S::parse(input);
.
For extensive documentation of all attributes and examples, see the Nom derive attribute documentation.
Many examples are provided, and more can be found in the project tests.
Debug tips
- If the generated parser does not compile, add
#[nom(DebugDerive)]
to the structure. It will dump the generated parser tostderr
. - If the generated parser fails at runtime, try adding
#[nom(Debug)]
to the structure or to fields. It wraps subparsers indbg_dmp
and will print the field name and input tostderr
if the parser fails.
Derive Macros
Nom | The |
NomDeriveDebug | Deprecated This derive macro behaves exactly like Nom derive, except it prints the generated parser on stderr. This is helpful for debugging generated parsers. |