derived 0.4.2

Derive macros for automating the boring stuff
Documentation 
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//! This module is responsible for the actual generation of the stor
//!

use crate::util;
use crate::util::ATTR_PHANTOM;
use ::proc_macro::TokenStream;
use ::quote::quote;
use ::syn::{parse_macro_input, DeriveInput, Ident};

const ATTR_STOR_SKIP: &str = "stor_skip";

pub(crate) fn derive_stor(input: TokenStream) -> TokenStream {
    let ast: DeriveInput = parse_macro_input!(input);
    let struct_name = ast.ident.clone();
    err_if_subattr_on_primary_attr!(
        "entire struct",
        // a struct cannot be entirely phantom
        ATTR_PHANTOM in ast.attrs,
        // marking an entire struct to be skipped is useless
        ATTR_STOR_SKIP in ast.attrs,
    );

    let (impl_gen, ty_gen, where_clause) = &ast.generics.split_for_impl();
    let fields = ok_else_ret!(util::get_struct_field_names(&ast));
    if !fields.is_empty() {
        let mut q = quote!();
        for (field, ty, attrs) in fields {
            let is_skipped = ok_else_ret!(util::single_instance_of_attr(&attrs, ATTR_STOR_SKIP));
            let is_phantom = ok_else_ret!(util::single_instance_of_attr(attrs, util::ATTR_PHANTOM));
            if !(is_skipped && is_phantom) {
                // not skipped or phantom, so go ahead
                let field_name_str = field.to_string();
                let mut fname = "set_".to_owned();
                fname.push_str(&field_name_str);
                let doc_comment = format!(
                    "Sets the value for the `{field}` field in struct [`{struct_name}`]",
                    struct_name = struct_name,
                    field = field_name_str
                );
                let fname = Ident::new(&fname, field.span());
                q = quote! {
                    #q
                    #[doc = #doc_comment]
                    pub fn #fname(&mut self, #field: #ty) {
                        self.#field = #field;
                    }
                };
            }
        }
        q = quote! {
            impl #impl_gen #struct_name #ty_gen #where_clause {
                #q
            }
        };
        q.into()
    } else {
        return "".parse().unwrap();
    }
}