fn field_initializer()

in lain_derive/src/mutations.rs [533:584]

• 45 lines of code
• 5 McCabe index (conditional complexity)

fn field_initializer(
    field: &Field,
    name_prefix: &'static str,
) -> (TokenStream, String, TokenStream) {
    let default_constraints = struct_field_constraints(field, false);
    let ty = &field.ty;
    let field_ident_string = match field.member {
        syn::Member::Named(ref ident) => ident.to_string(),
        syn::Member::Unnamed(ref idx) => idx.index.to_string(),
    };

    let value_ident =
        TokenStream::from_str(&format!("{}{}", name_prefix, field_ident_string)).unwrap();

    let default_initializer = quote! {
        <#ty>::new_fuzzed(mutator, constraints.as_ref())
    };

    let initializer = if field.attrs.ignore() {
        quote! {
            let #value_ident = <#ty>::default();
        }
    } else if let Some(chance) = field.attrs.ignore_chance() {
        quote_spanned! { ty.span() =>
            let #value_ident = if mutator.gen_chance(#chance) {
                <#ty>::default()
            } else {
                #default_initializer
            };
        }
    } else if let Some(initializer) = field.attrs.initializer() {
        quote_spanned! { initializer.span() =>
            let #value_ident = #initializer;
        }
    } else {
        quote_spanned! { ty.span() =>
        //  println!("{:?}", constraints);
            let #value_ident = #default_initializer;
        }
    };

    let inc_max_size = decrement_max_size(&field, &value_ident);
    let initializer = quote! {
        #default_constraints

        #initializer

        #inc_max_size
    };

    (value_ident, field_ident_string, initializer)
}