implement auto-documenting routes

Author: ThouCheese

core/codegen/src/attribute/route/mod.rs

@@ -296,6 +296,38 @@ fn sentinels_expr(route: &Route) -> TokenStream {
     quote!(::std::vec![#(#sentinel),*])
 }
 
+fn schemas_expr(route: &Route) -> TokenStream {
+    let ret_ty = match route.handler.sig.output {
+        syn::ReturnType::Default => None,
+        syn::ReturnType::Type(_, ref ty) => Some(ty.with_stripped_lifetimes())
+    };
+
+    let generic_idents: Vec<_> = route.handler.sig.generics
+        .type_params()
+        .map(|p| &p.ident)
+        .collect();
+
+    let eligible_types = route.guards()
+        .map(|guard| &guard.ty)
+        .chain(ret_ty.as_ref().into_iter())
+        .flat_map(|ty| ty.unfold())
+        .filter(|ty| ty.is_concrete(&generic_idents))
+        .map(|child| (child.parent, child.ty));
+
+    let sentinel = eligible_types.map(|(parent, ty)| {
+        define_spanned_export!(ty.span() => _doc);
+
+        match parent {
+            Some(p) if p.is_concrete(&generic_idents) => {
+                quote_spanned!(ty.span() => #_doc::resolve_doc!(#ty))
+            }
+            Some(_) | None => quote_spanned!(ty.span() => #_doc::resolve_doc!(#ty)),
+        }
+    });
+
+    quote!(::std::vec![#(#sentinel),*])
+}
+
 fn codegen_route(route: Route) -> Result<TokenStream> {
     use crate::exports::*;
 
@@ -305,8 +337,9 @@ fn codegen_route(route: Route) -> Result<TokenStream> {
     let query_guards = query_decls(&route);
     let data_guard = route.data_guard.as_ref().map(data_guard_decl);
 
-    // Extract the sentinels from the route.
+    // Extract the sentinels and schemas from the route.
     let sentinels = sentinels_expr(&route);
+    let schemas = schemas_expr(&route);
 
     // Gather info about the function.
     let (vis, handler_fn) = (&route.handler.vis, &route.handler);
@@ -319,6 +352,9 @@ fn codegen_route(route: Route) -> Result<TokenStream> {
     let rank = Optional(route.attr.rank);
     let format = Optional(route.attr.format.as_ref());
 
+    // Get the doc comment
+    let docstring = &route.docstring;
+
     Ok(quote! {
         #handler_fn
 
@@ -353,6 +389,8 @@ fn codegen_route(route: Route) -> Result<TokenStream> {
                     format: #format,
                     rank: #rank,
                     sentinels: #sentinels,
+                    schemas: #schemas,
+                    docstring: #docstring,
                 }
             }
 

core/codegen/src/attribute/route/parse.rs

@@ -29,6 +29,8 @@ pub struct Route {
     pub handler: syn::ItemFn,
     /// The parsed arguments to the user's function.
     pub arguments: Arguments,
+    /// The doc comment describing this route
+    pub docstring: String,
 }
 
 type ArgumentMap = IndexMap<Name, (syn::Ident, syn::Type)>;
@@ -209,9 +211,11 @@ impl Route {
             })
             .collect();
 
+        let docstring = String::from_attrs("doc", &handler.attrs)?.join("\n");
+
         diags.head_err_or(Route {
             attr, path_params, query_params, data_guard, request_guards,
-            handler, arguments,
+            handler, arguments, docstring
         })
     }
 }

core/codegen/src/exports.rs

@@ -72,6 +72,7 @@ define_exported_paths! {
     _route => ::rocket::route,
     _catcher => ::rocket::catcher,
     _sentinel => ::rocket::sentinel,
+    _doc => ::rocket::doc,
     _log => ::rocket::log,
     _form => ::rocket::form::prelude,
     _http => ::rocket::http,