1use proc_macro::TokenStream;
  2use quote::{format_ident, quote};
  3use syn::{Data, DeriveInput, Fields, Ident, parse_macro_input};
  4
  5/// Derives the `MergeFrom` trait for a struct.
  6///
  7/// This macro automatically implements `MergeFrom` by calling `merge_from`
  8/// on all fields in the struct.
  9///
 10/// # Example
 11///
 12/// ```ignore
 13/// #[derive(Clone, MergeFrom)]
 14/// struct MySettings {
 15///     field1: Option<String>,
 16///     field2: SomeOtherSettings,
 17/// }
 18/// ```
 19#[proc_macro_derive(MergeFrom)]
 20pub fn derive_merge_from(input: TokenStream) -> TokenStream {
 21    let input = parse_macro_input!(input as DeriveInput);
 22
 23    let name = &input.ident;
 24    let (impl_generics, ty_generics, where_clause) = input.generics.split_for_impl();
 25
 26    let merge_body = match &input.data {
 27        Data::Struct(data_struct) => match &data_struct.fields {
 28            Fields::Named(fields) => {
 29                let field_merges = fields.named.iter().map(|field| {
 30                    let field_name = &field.ident;
 31                    quote! {
 32                        self.#field_name.merge_from(&other.#field_name);
 33                    }
 34                });
 35
 36                quote! {
 37                    #(#field_merges)*
 38                }
 39            }
 40            Fields::Unnamed(fields) => {
 41                let field_merges = fields.unnamed.iter().enumerate().map(|(i, _)| {
 42                    let field_index = syn::Index::from(i);
 43                    quote! {
 44                        self.#field_index.merge_from(&other.#field_index);
 45                    }
 46                });
 47
 48                quote! {
 49                    #(#field_merges)*
 50                }
 51            }
 52            Fields::Unit => {
 53                quote! {
 54                    // No fields to merge for unit structs
 55                }
 56            }
 57        },
 58        Data::Enum(_) => {
 59            quote! {
 60                *self = other.clone();
 61            }
 62        }
 63        Data::Union(_) => {
 64            panic!("MergeFrom cannot be derived for unions");
 65        }
 66    };
 67
 68    let expanded = quote! {
 69        impl #impl_generics crate::merge_from::MergeFrom for #name #ty_generics #where_clause {
 70            fn merge_from(&mut self, other: &Self) {
 71                use crate::merge_from::MergeFrom as _;
 72                #merge_body
 73            }
 74        }
 75    };
 76
 77    TokenStream::from(expanded)
 78}
 79
 80/// This can be used to register an action with the GPUI runtime when you want to manually implement
 81/// the `Action` trait. Typically you should use the `Action` derive macro or `actions!` macro
 82/// instead.
 83#[proc_macro_derive(RegisterSetting)]
 84pub fn register_settings(ident: TokenStream) -> TokenStream {
 85    let type_name = parse_macro_input!(ident as Ident);
 86
 87    let settings_registration_fn_name = format_ident!(
 88        "__settings_registration_{}",
 89        type_name.to_string().to_lowercase()
 90    );
 91
 92    quote! {
 93        impl #type_name {
 94            /// This is an auto generated function, do not use.
 95            #[automatically_derived]
 96            #[doc(hidden)]
 97            fn __autogenerated() {
 98                /// This is an auto generated function, do not use.
 99                #[doc(hidden)]
100                fn #settings_registration_fn_name(cx: &mut gpui::AppContext) {
101                    #type_name::register(cx);
102                }
103
104                settings::settings_registration::inventory::submit! {
105                    settings::settings_registration::RegisterSettingFn(#settings_registration_fn_name)
106                }
107            }
108        }
109    }
110    .into()
111}