nom-derive 0.6.0-beta2

Custom derive nom parsers from struct
Documentation 
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pub mod attr;
pub mod attr_list;
pub mod error;

use error::MetaError;

pub fn parse_nom_top_level_attribute(
    attrs: &[syn::Attribute],
) -> Result<Vec<attr::MetaAttr>, MetaError> {
    // eprintln!("attrs: {:?}", attrs);
    let x: Vec<_> = attrs
        .iter()
        .filter(|x| x.path.is_ident("nom"))
        .map(meta_from_attribute)
        .collect::<Result<Vec<_>, _>>()?
        .into_iter()
        .map(|x| x.0.into_iter())
        .flatten()
        .collect();
    // eprintln!("XXX: {:?}", x);
    if let Some(attr) = x.iter().find(|m| !m.acceptable_tla()) {
        panic!("Attribute {} is not valid for top-level", attr);
    }
    Ok(x)
}

fn meta_from_attribute(
    attr: &syn::Attribute,
) -> Result<attr_list::AttrList<attr::MetaAttr>, syn::Error> {
    // eprintln!("tlas_from_attribute: {:?}", attr);
    Ok(syn::parse2(attr.tokens.clone())?)
}

pub fn parse_nom_attribute(attrs: &[syn::Attribute]) -> Result<Vec<attr::MetaAttr>, MetaError> {
    // eprintln!("attrs: {:?}", attrs);
    let x: Vec<_> = attrs
        .iter()
        .filter(|x| x.path.is_ident("nom"))
        .map(meta_from_attribute)
        .collect::<Result<Vec<_>, _>>()?
        .into_iter()
        .map(|x| x.0.into_iter())
        .flatten()
        .collect();
    // eprintln!("****\nXXX: {:?}\n", x);
    if let Some(attr) = x.iter().find(|m| !m.acceptable_fla()) {
        panic!("Attribute {} is not valid for field-level", attr);
    }
    Ok(x)
}