dars-macros 0.1.0

Declarative Agents in Rust
Documentation 
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use syn::{Attribute, Expr, Lit, MetaNameValue, spanned::Spanned};

pub(crate) fn parse_desc(attr: &Attribute) -> syn::Result<Option<String>> {
    match attr.parse_args::<MetaNameValue>() {
        Ok(args) => match args.path.get_ident() {
            Some(ident) => {
                if ident == "desc" {
                    match args.value {
                        Expr::Lit(lit) => match lit.lit {
                            Lit::Str(str) => Ok(Some(str.value())),
                            _ => {
                                return Err(syn::Error::new(lit.span(), "Expected string literal"));
                            }
                        },
                        _ => {
                            return Err(syn::Error::new(
                                args.value.span(),
                                "Expected string literal",
                            ));
                        }
                    }
                } else {
                    return Err(syn::Error::new(
                        attr.span(),
                        format!("Invalid parameter: {ident}"),
                    ));
                }
            }
            None => {
                return Err(syn::Error::new(attr.span(), "Missing attribute name"));
            }
        },
        Err(_) => Ok(None),
    }
}