Implement node output destructuring #3806
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,115 @@ | ||
| use convert_case::{Case, Casing}; | ||
|
Keavon marked this conversation as resolved.
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| use proc_macro_crate::FoundCrate; | ||
| use proc_macro2::{Span, TokenStream as TokenStream2}; | ||
| use quote::{format_ident, quote}; | ||
| use syn::{Data, DeriveInput, Error, LitStr, Meta, Type, spanned::Spanned}; | ||
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| pub fn derive(input: DeriveInput) -> syn::Result<TokenStream2> { | ||
| let struct_name = input.ident; | ||
| let generics = input.generics; | ||
| let (impl_generics, ty_generics, where_clause) = generics.split_for_impl(); | ||
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| let Data::Struct(data_struct) = input.data else { | ||
| return Err(Error::new(Span::call_site(), "Deriving `Destruct` is currently only supported for structs")); | ||
| }; | ||
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||
| let core_types = match proc_macro_crate::crate_name("core-types") | ||
| .map_err(|e| Error::new(Span::call_site(), format!("Failed to find location of core_types. Make sure it is imported as a dependency: {e}")))? | ||
| { | ||
| FoundCrate::Itself => quote!(crate), | ||
| FoundCrate::Name(name) => { | ||
| let ident = syn::Ident::new(&name, Span::call_site()); | ||
| quote!(#ident) | ||
| } | ||
| }; | ||
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| let mut node_implementations = Vec::with_capacity(data_struct.fields.len()); | ||
| let mut output_fields = Vec::with_capacity(data_struct.fields.len()); | ||
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| for field in data_struct.fields { | ||
| let Some(field_name) = field.ident else { | ||
| return Err(Error::new(field.span(), "Destruct cannot be used on tuple structs")); | ||
| }; | ||
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| let ty = field.ty; | ||
| let output_name = parse_output_name(&field.attrs)?.unwrap_or_else(|| field_name.to_string().to_case(Case::Title)); | ||
| let output_name_lit = LitStr::new(&output_name, field_name.span()); | ||
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| let fn_name = format_ident!("extract_{}_{}", struct_name.to_string().to_case(Case::Snake), field_name); | ||
| let node_struct_name = format_ident!("{}Node", fn_name.to_string().to_case(Case::Pascal)); | ||
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||
| node_implementations.push(generate_extractor_node(&core_types, &fn_name, &struct_name, &field_name, &ty, &output_name_lit)); | ||
| output_fields.push(quote! { | ||
| #core_types::registry::StructField { | ||
| name: #output_name_lit, | ||
| node_path: concat!(std::module_path!(), "::", stringify!(#node_struct_name)), | ||
| ty: #core_types::concrete!(#ty), | ||
| } | ||
| }); | ||
| } | ||
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||
| Ok(quote! { | ||
| #(#node_implementations)* | ||
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| impl #impl_generics #core_types::registry::Destruct for #struct_name #ty_generics #where_clause { | ||
| fn fields() -> &'static [#core_types::registry::StructField] { | ||
| static FIELDS: std::sync::OnceLock<Vec<#core_types::registry::StructField>> = std::sync::OnceLock::new(); | ||
| FIELDS.get_or_init(|| vec![ | ||
| #(#output_fields,)* | ||
| ]).as_slice() | ||
|
Comment on lines
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Member
There was a problem hiding this comment. Why do you use heap memory + syncronization here instead of constructing a slice in place? |
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| } | ||
| } | ||
| }) | ||
| } | ||
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| fn generate_extractor_node(core_types: &TokenStream2, fn_name: &syn::Ident, struct_name: &syn::Ident, field_name: &syn::Ident, ty: &Type, output_name: &LitStr) -> TokenStream2 { | ||
| quote! { | ||
| #[node_macro::node(category(""), name(#output_name))] | ||
|
Member
There was a problem hiding this comment. Why do we add the |
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| fn #fn_name(_: impl #core_types::Ctx, data: #struct_name) -> #ty { | ||
| data.#field_name | ||
| } | ||
| } | ||
| } | ||
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| fn parse_output_name(attrs: &[syn::Attribute]) -> syn::Result<Option<String>> { | ||
| let mut output_name = None; | ||
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| for attr in attrs { | ||
| if !attr.path().is_ident("output") { | ||
| continue; | ||
| } | ||
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| let mut this_output_name = None; | ||
| match &attr.meta { | ||
| Meta::Path(_) => { | ||
| return Err(Error::new_spanned(attr, "Expected output metadata like #[output(name = \"Result\")]")); | ||
| } | ||
| Meta::NameValue(_) => { | ||
| return Err(Error::new_spanned(attr, "Expected output metadata like #[output(name = \"Result\")]")); | ||
| } | ||
| Meta::List(_) => { | ||
| attr.parse_nested_meta(|meta| { | ||
| if meta.path.is_ident("name") { | ||
| if this_output_name.is_some() { | ||
| return Err(meta.error("Multiple output names provided for one field")); | ||
| } | ||
| let value = meta.value()?; | ||
| let lit: LitStr = value.parse()?; | ||
| this_output_name = Some(lit.value()); | ||
| Ok(()) | ||
| } else { | ||
| Err(meta.error("Unsupported output metadata. Supported syntax is #[output(name = \"...\")]")) | ||
| } | ||
| })?; | ||
| } | ||
| } | ||
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| let this_output_name = this_output_name.ok_or_else(|| Error::new_spanned(attr, "Missing output name. Use #[output(name = \"...\")]"))?; | ||
| if output_name.is_some() { | ||
| return Err(Error::new_spanned(attr, "Multiple #[output(...)] attributes are not allowed on one field")); | ||
| } | ||
| output_name = Some(this_output_name); | ||
| } | ||
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| Ok(output_name) | ||
| } | ||
|
Comment on lines
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Member
There was a problem hiding this comment. Is this function only used for overriding the field name? I don't think this code is currently used anywhere right? If it is indeed not used, it should be removed to reduce the code complexity |
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