Function enum_iter_inner

sea-orm-macros/src/strum/enum_iter.rs:7–174

(ast: &DeriveInput)

use super::helpers::{non_enum_error, HasStrumVariantProperties, HasTypeProperties};

pub fn enum_iter_inner(ast: &DeriveInput) -> syn::Result<TokenStream> {
    let name = &ast.ident;
    let gen = &ast.generics;
    let (impl_generics, ty_generics, where_clause) = gen.split_for_impl();
    let vis = &ast.vis;
    let type_properties = ast.get_type_properties()?;
    let strum_module_path = type_properties.crate_module_path();
    let doc_comment = format!("An iterator over the variants of [{name}]");

    if gen.lifetimes().count() > 0 {
        return Err(syn::Error::new(
            Span::call_site(),
            "This macro doesn't support enums with lifetimes. \
             The resulting enums would be unbounded.",
        ));
    }

    let phantom_data = if gen.type_params().count() > 0 {
        let g = gen.type_params().map(|param| &param.ident);
        quote! { < ( #(#g),* ) > }
    } else {
        quote! { < () > }
    };

    let variants = match &ast.data {
        Data::Enum(v) => &v.variants,
        _ => return Err(non_enum_error()),
    };

    let mut arms = Vec::new();
    let mut idx = 0usize;
    for variant in variants {
        if variant.get_variant_properties()?.disabled.is_some() {
            continue;
        }

        let ident = &variant.ident;
        let params = match &variant.fields {
            Fields::Unit => quote! {},
            Fields::Unnamed(fields) => {
                let defaults = ::core::iter::repeat(quote!(::core::default::Default::default()))
                    .take(fields.unnamed.len());
                quote! { (#(#defaults),*) }
            }
            Fields::Named(fields) => {
                let fields = fields
                    .named
                    .iter()
                    .map(|field| field.ident.as_ref().unwrap());
                quote! { {#(#fields: ::core::default::Default::default()),*} }
            }
        };

        arms.push(quote! {#idx => ::core::option::Option::Some(#name::#ident #params)});
        idx += 1;
    }

    let variant_count = arms.len();