in midst of refactor

orchid-api-derive/src/common.rs

@@ -0,0 +1,30 @@
+use proc_macro2 as pm2;
+use quote::ToTokens;
+use syn::spanned::Spanned;
+
+pub fn add_trait_bounds(mut generics: syn::Generics, bound: syn::TypeParamBound) -> syn::Generics {
+  for param in &mut generics.params {
+    if let syn::GenericParam::Type(ref mut type_param) = *param {
+      type_param.bounds.push(bound.clone())
+    }
+  }
+  generics
+}
+
+pub fn destructure(fields: &syn::Fields) -> Option<pm2::TokenStream> {
+  match fields {
+    syn::Fields::Unit => None,
+    syn::Fields::Named(_) => {
+      let field_list = fields.iter().map(|f| f.ident.as_ref().unwrap());
+      Some(quote! { { #(#field_list),* } })
+    },
+    syn::Fields::Unnamed(un) => {
+      let field_list = (0..fields.len()).map(|i| pos_field_name(i, un.span()));
+      Some(quote! { ( #(#field_list),* ) })
+    },
+  }
+}
+
+pub fn pos_field_name(i: usize, span: pm2::Span) -> pm2::TokenStream {
+  syn::Ident::new(&format!("field_{i}"), span).to_token_stream()
+}