Initial implementation of node graph based on structs

node-graph/proc-macro/src/lib.rs

@@ -0,0 +1,76 @@
+use proc_macro::TokenStream;
+use quote::{quote, ToTokens};
+use syn::punctuated::Punctuated;
+use syn::{parse_macro_input,  FnArg, ItemFn, Pat,  Type};
+
+fn extract_type(a: FnArg) -> Box<Type> {
+    match a {
+        FnArg::Typed(p) => p.ty, // notice `ty` instead of `pat`
+        _ => panic!("Not supported on types with `self`!"),
+    }
+}
+
+fn extract_arg_types(fn_args: Punctuated<FnArg, syn::token::Comma>) -> Vec<Box<Type>> {
+    return fn_args.into_iter().map(extract_type).collect::<Vec<_>>();
+}
+
+fn extract_arg_idents(fn_args: Punctuated<FnArg, syn::token::Comma>) -> Vec<Box<Pat>> {
+    return fn_args.into_iter().map(extract_arg_pat).collect::<Vec<_>>();
+}
+
+fn extract_arg_pat(a: FnArg) -> Box<Pat> {
+    match a {
+        FnArg::Typed(p) => p.pat,
+        _ => panic!("Not supported on types with `self`!"),
+    }
+}
+
+#[proc_macro_attribute] // 2
+pub fn to_node(_attr: TokenStream, item: TokenStream) -> TokenStream {
+    let string = item.to_string();
+    let item2 = item.clone();
+    let parsed = parse_macro_input!(item2 as ItemFn); // 3
+                                                      //item.extend(generate_to_string(parsed, string)); // 4
+                                                      //item
+    generate_to_string(parsed, string)
+}
+
+fn generate_to_string(parsed: ItemFn, string: String) -> TokenStream {
+    let whole_function = parsed.clone();
+    //let fn_body = parsed.block; // function body
+    let sig = parsed.sig; // function signature
+    //let vis = parsed.vis; // visibility, pub or not
+    let generics = sig.generics;
+    let fn_args = sig.inputs; // comma separated args
+    let fn_return_type = sig.output; // return type
+    let fn_name = sig.ident; // function name/identifier
+    let idents = extract_arg_idents(fn_args.clone());
+    let types = extract_arg_types(fn_args);
+    let types = types.iter().map(|t| t.to_token_stream()).collect::<Vec<_>>();
+    let idents = idents.iter().map(|t| t.to_token_stream()).collect::<Vec<_>>();
+
+    let node_fn_name = syn::Ident::new(&(fn_name.to_string() + "_node"), proc_macro2::Span::call_site()); // function name/identifier
+    let return_type_string = fn_return_type.to_token_stream().to_string().replace("->","");
+    let arg_type_string = types.iter().map(|t|t.to_string()).collect::<Vec<_>>().join(", ");
+    let error = format!("called {} with the wrong type", fn_name.to_string());
+
+    let x = quote! {
+        //#whole_function
+        fn #node_fn_name #generics() -> Node {
+            Node { func: Box::new(move |x| {
+               let  args = x.downcast::<(#(#types,)*)>().expect(#error);
+               let  (#(#idents,)*) = *args;
+               #whole_function
+
+               Box::new(#fn_name(#(#idents,)*))
+            }),
+            code:  #string.to_string(),
+             return_type: #return_type_string.trim().to_string(),
+             args: format!("({})",#arg_type_string.trim()),
+            }
+        }
+
+    };
+    //panic!("{}\n{:?}", x.to_string(), x);
+    x.into()
+}