Implement custom interpreter directives - and a wtf?

See the comment about &mut self vs &self

schala-codegen/src/lib.rs

@@ -69,7 +69,7 @@ fn get_attribute_identifier(attr_name: &str, attrs: &Vec<Attribute>) -> Option<p
 }
 
 #[proc_macro_derive(ProgrammingLanguageInterface,
-  attributes(LanguageName, SourceFileExtension, PipelineSteps, DocMethod))]
+  attributes(LanguageName, SourceFileExtension, PipelineSteps, DocMethod, HandleCustomInterpreterDirectives))]
 pub fn derive_programming_language_interface(input: TokenStream) -> TokenStream {
   let ast: DeriveInput = syn::parse(input).unwrap();
   let name = &ast.ident;
@@ -89,6 +89,16 @@ pub fn derive_programming_language_interface(input: TokenStream) -> TokenStream
     }
   };
 
+  let handle_custom_interpreter_directives_impl = match get_attribute_identifier("HandleCustomInterpreterDirectives", attrs) {
+    None => quote! { },
+    Some(method_name) => quote! {
+      fn handle_custom_interpreter_directives(&mut self, commands: &Vec<&str>) -> Option<String> {
+        //println!("If #method_name is &self not &mut self, this runs forever");
+        self.#method_name(commands)
+      }
+    }
+  };
+
   let pass_descriptors = passes.iter().map(|pass| {
     let name = pass.0.to_string();
     let opts: Vec<String> = match &pass.1 {
@@ -121,6 +131,7 @@ pub fn derive_programming_language_interface(input: TokenStream) -> TokenStream
         vec![ #(#pass_descriptors),* ]
       }
       #get_doc_impl
+      #handle_custom_interpreter_directives_impl
     }
   };
 

schala-lang/src/lib.rs

@@ -37,6 +37,7 @@ mod eval;
 #[SourceFileExtension = "schala"]
 #[PipelineSteps(tokenizing, parsing(compact,expanded,trace), symbol_table, typechecking, ast_reducing, eval)]
 #[DocMethod = get_doc]
+#[HandleCustomInterpreterDirectives = handle_custom_interpreter_directives]
 pub struct Schala {
   state: eval::State<'static>,
   symbol_table: Rc<RefCell<symbol_table::SymbolTable>>,
@@ -47,6 +48,10 @@ impl Schala {
   fn get_doc(&self, commands: &Vec<&str>) -> Option<String> {
     Some(format!("Documentation on commands: {:?}", commands))
   }
+
+  fn handle_custom_interpreter_directives(&mut self, commands: &Vec<&str>) -> Option<String> {
+    Some(format!("You typed a command but I can't handle it"))
+  }
 }
 
 impl Schala {

schala-repl/src/repl.rs

@@ -232,9 +232,11 @@ impl Repl {
       "doc" => self.languages[self.current_language_index]
         .get_doc(&commands)
         .or(Some(format!("No docs implemented"))),
-      e => self.languages[self.current_language_index]
+      e => {
+        self.languages[self.current_language_index]
         .handle_custom_interpreter_directives(&commands)
         .or(Some(format!("Unknown command: {}", e)))
+      }
     }
   }
   fn handle_debug(&mut self, commands: Vec<&str>) -> Option<String> {