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/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at https://mozilla.org/MPL/2.0/. */
use proc_macro2::TokenStream;
use quote::quote;
use syn::{Data, Fields};
use synstructure::decl_derive;
decl_derive!([ServoPreferences] => servo_preferences_derive);
/// A derive macro that adds string-based getter and setter for each field of this struct
/// (enums and other types are not supported). Each field must be able to be convertable
/// (with `into()`) into a `PrefValue`.
fn servo_preferences_derive(input: synstructure::Structure) -> TokenStream {
let ast = input.ast();
let Data::Struct(ref data) = ast.data else {
unimplemented!();
};
let Fields::Named(ref named_fields) = data.fields else {
unimplemented!()
};
let mut get_match_cases = quote!();
for field in named_fields.named.iter() {
let name = field.ident.as_ref().unwrap();
get_match_cases.extend(quote!(stringify!(#name) => self.#name.clone().into(),))
}
let mut set_match_cases = quote!();
for field in named_fields.named.iter() {
let name = field.ident.as_ref().unwrap();
set_match_cases.extend(quote!(stringify!(#name) => self.#name = value.try_into().unwrap(),))
}
let structure_name = &ast.ident;
quote! {
impl #structure_name {
pub fn get_value(&self, name: &str) -> PrefValue {
match name {
#get_match_cases
_ => { panic!("Unknown preference: {:?}", name); }
}
}
pub fn set_value(&mut self, name: &str, value: PrefValue) {
match name {
#set_match_cases
_ => { panic!("Unknown preference: {:?}", name); }
}
}
}
}
}
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