Add concept of how asn proc_macro_attributes should look like #11

asn1rs-macros/Cargo.toml

@@ -16,7 +16,10 @@ proc-macro = true
 
 
 [dependencies]
-syn = "1.0.17"
+syn = {version = "1.0.17", features = ["full"] }
+quote = "1.0.3"
+proc-macro2 = "1.0.10"
+
 
 [dependencies.asn1rs-model]
 path = "../asn1rs-model"

asn1rs-macros/src/lib.rs

@@ -1,12 +1,14 @@
 extern crate proc_macro;
+extern crate proc_macro2;
 
 use asn1rs_model::gen::rust::RustCodeGenerator as RustGenerator;
 use asn1rs_model::gen::Generator;
 use asn1rs_model::model::Model;
 use asn1rs_model::parser::Tokenizer;
 use proc_macro::TokenStream;
-use syn::parse_macro_input;
-use syn::LitStr;
+use quote::quote;
+use syn::{parse_macro_input, AttributeArgs};
+use syn::{Item, LitStr};
 
 #[proc_macro]
 pub fn asn_to_rust(item: TokenStream) -> TokenStream {
@@ -27,3 +29,23 @@ pub fn asn_to_rust(item: TokenStream) -> TokenStream {
         .parse()
         .unwrap()
 }
+
+#[proc_macro_attribute]
+pub fn asn(attr: TokenStream, item: TokenStream) -> TokenStream {
+    let attributes = parse_macro_input!(attr as AttributeArgs);
+    let item = parse_macro_input!(item as Item);
+
+    let item = match item {
+        Item::Struct(mut strct) => {
+            for field in strct.fields.iter_mut() {
+                field
+                    .attrs
+                    .retain(|a| !a.path.segments.first().unwrap().ident.to_string().eq("asn"));
+            }
+            Item::Struct(strct)
+        }
+        item => item,
+    };
+
+    TokenStream::from(quote! {#item})
+}

tests/basic_proc_macro_attribute.rs

@@ -0,0 +1,18 @@
+use asn1rs_macros::asn;
+
+#[asn(sequence)]
+#[derive(Default)]
+pub struct Potato {
+    #[asn(Integer)]
+    size: u64,
+    #[asn(Utf8String)]
+    string: String,
+}
+
+#[test]
+fn test_compiles() {
+    let _ = Potato {
+        size: 123,
+        string: String::from("where is the content"),
+    };
+}