1use proc_macro::TokenStream;
2use quote::quote;
3use syn::{Data, DeriveInput, Fields, 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/// Registers the setting type with the SettingsStore. Note that you need to
81/// have `gpui` in your dependencies for this to work.
82#[proc_macro_derive(RegisterSetting)]
83pub fn derive_register_setting(input: TokenStream) -> TokenStream {
84 let input = syn::parse_macro_input!(input as DeriveInput);
85 let type_name = &input.ident;
86
87 quote! {
88 settings::private::inventory::submit! {
89 settings::private::RegisteredSetting {
90 settings_value: || {
91 Box::new(settings::private::SettingValue::<#type_name> {
92 global_value: None,
93 local_values: Vec::new(),
94 })
95 },
96 from_settings: |content| Box::new(<#type_name as settings::Settings>::from_settings(content)),
97 id: || std::any::TypeId::of::<#type_name>(),
98 }
99 }
100 }
101 .into()
102}