Is a collection of utilities for making using the great nom parser combinator easier to use.
cosmic-nom is part of The Cosmic Initiative a WebAssembly orchestration framework--although you can use it for any project you want.
cosmic-nom synthesizes the utilities of two other derivatives of nom:
* nom-supreme A collection of excellent utilities for nom (which cosmic-nom uses for improved error handling)
* nom_locate A special input type for nom to locate tokens (which cosmic-nom uses to locate error spans in the parsed content)
To use cosmic-nom you must accept an input implementing trait cosmic_nom::Span and return a result of type cosmic_nom::Res:
rust
pub fn name<I:Span>( input:I ) -> Res<I,I> {
alpha(input)
}
Since It is hard to compose a combinator if your input type doesn't implement all of the traits used in every condition: InputLength, InputTakeAtPosition, AsBytes, etc...
So cosmic-nom provides a single trait that also supports location captures via nom_locate and seems to work with every combinator
in the complete package (not tested on streaming).
rust
pub trait Span:
Clone
+ ToString
+ AsBytes
+ Slice<Range<usize>>
+ Slice<RangeTo<usize>>
+ Slice<RangeFrom<usize>>
+ InputLength
+ Offset
+ InputTake
+ InputIter<Item = char>
+ InputTakeAtPosition<Item = char>
+ Compare<&'static str>
+ FindSubstring<&'static str>
+ core::fmt::Debug
To create a span call cosmic_nom::new_span("scott williams")
rust
name(new_span("scott williams"));
use result to transform your Res into a regular Result<O,E>
rust
let name: I = result(name(new_span("scott williams")))?;
and you can wrap your result in a log() which will output to stdout if an error occurs:
rust
let name: I = log(result(name(new_span("scott williams"))))?;
Be warned that in the service of making things easier and more reportable cosmic-nom
makes nom a little less awesome in some other ways... for instance nom has great efficiencies due to its "zero-copy"
input strategy and it seems to accomplish this by passing and slicing a single &str around...
cosmic-nom wraps input in an Arc and still takes great care to minimize overhead,
but it breaks with the pure spirit of nom in order to provide a little ease of use.