1 files changed, 76 insertions, 0 deletions
diff --git a/starship_module_config_derive/src/lib.rs b/starship_module_config_derive/src/lib.rs
new file mode 100644
index 000000000..eeddf5a8b
--- /dev/null
+++ b/starship_module_config_derive/src/lib.rs
@@ -0,0 +1,76 @@
+extern crate proc_macro;
+extern crate proc_macro2;
+
+use proc_macro::TokenStream;
+use quote::quote;
+use syn::{parse_macro_input, DeriveInput};
+
+#[proc_macro_derive(ModuleConfig)]
+pub fn derive_module_config(input: TokenStream) -> TokenStream {
+    let dinput = parse_macro_input!(input as DeriveInput);
+    impl_module_config(dinput)
+}
+
+fn impl_module_config(dinput: DeriveInput) -> proc_macro::TokenStream {
+    let struct_ident = &dinput.ident;
+    let (_impl_generics, ty_generics, where_clause) = dinput.generics.split_for_impl();
+
+    let mut from_config = quote! {};
+    let mut load_config = quote! {};
+
+    if let syn::Data::Struct(data) = dinput.data {
+        if let syn::Fields::Named(fields_named) = data.fields {
+            let mut load_tokens = quote! {};
+            let mut from_tokens = quote! {};
+
+            for field in fields_named.named.iter() {
+                let ident = field.ident.as_ref().unwrap();
+                let ty = &field.ty;
+
+                let new_load_tokens = quote! {
+                    if let Some(config_str) = config.get(stringify!(#ident)) {
+                        new_module_config.#ident = new_module_config.#ident.load_config(config_str);
+                    }
+                };
+                let new_from_tokens = quote! {
+                    #ident: <#ty>::from_config(config.get(stringify!(#ident))?)?,
+                };
+
+                load_tokens = quote! {
+                    #load_tokens
+                    #new_load_tokens
+                };
+                from_tokens = quote! {
+                    #from_tokens
+                    #new_from_tokens
+                }
+            }
+
+            load_config = quote! {
+                fn load_config(&self, config: &'a toml::Value) -> Self {
+                    let mut new_module_config = self.clone();
+                    if let toml::Value::Table(config) = config {
+                        #load_tokens
+                    }
+                    new_module_config
+                }
+            };
+            from_config = quote! {
+                fn from_config(config: &'a toml::Value) -> Option<Self> {
+                    let config = config.as_table()?;
+
+                    Some(#struct_ident {
+                        #from_tokens
+                    })
+                }
+            };
+        }
+    }
+
+    TokenStream::from(quote! {
+        impl<'a> ModuleConfig<'a> for #struct_ident #ty_generics #where_clause {
+            #from_config
+            #load_config
+        }
+    })
+}