feat(rossweisse): initial implementation of struct router framework

1 files changed, 86 insertions, 0 deletions

diff --git a/rossweisse/src/implementations/router/fields.rs b/rossweisse/src/implementations/router/fields.rs
new file mode 100644
index 0000000..e1a92b9
--- /dev/null
+++ b/rossweisse/src/implementations/router/fields.rs
@@ -0,0 +1,86 @@
+// This file is part of Windmark <https://github.com/gemrest/windmark>.
+//
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, version 3.
+//
+// This program is distributed in the hope that it will be useful, but
+// WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+// General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with this program. If not, see <http://www.gnu.org/licenses/>.
+//
+// Copyright (C) 2022-2023 Fuwn <[email protected]>
+// SPDX-License-Identifier: GPL-3.0-only
+
+use proc_macro::TokenStream;
+use quote::quote;
+use syn::parse_macro_input;
+
+pub fn fields(arguments: TokenStream, item: syn::ItemStruct) -> TokenStream {
+  let field_initializers =
+    parse_macro_input!(arguments as super::parser::FieldInitializers);
+  let router_identifier = item.ident;
+  let named_fields = match item.fields {
+    syn::Fields::Named(fields) => fields,
+    _ =>
+      panic!(
+        "`#[rossweisse::router]` can only be used on `struct`s with named \
+         fields"
+      ),
+  };
+  let mut default_expressions = vec![];
+  let new_method_fields = named_fields.named.iter().map(|field| {
+    let name = &field.ident;
+    let initialiser = field_initializers
+      .0
+      .iter()
+      .find(|initialiser| initialiser.ident == name.clone().unwrap())
+      .map(|initialiser| &initialiser.expr)
+      .unwrap_or_else(|| {
+        default_expressions.push({
+          let default_expression: syn::Expr =
+            syn::parse_quote! { ::std::default::Default::default() };
+
+          default_expression
+        });
+
+        default_expressions.last().unwrap()
+      });
+
+    quote! {
+        #name: #initialiser,
+    }
+  });
+  let new_methods = quote! {
+    fn _new() -> Self {
+      Self {
+        #(#new_method_fields)*
+        router: ::windmark::Router::new(),
+      }
+    }
+
+    pub async fn run(&mut self) -> Result<(), Box<dyn std::error::Error>> {
+      self.router.run().await
+    }
+
+    pub fn router(&mut self) -> &mut ::windmark::Router {
+      &mut self.router
+    }
+  };
+  let output_fields = named_fields.named;
+  let output = quote! {
+    struct #router_identifier {
+      #output_fields
+      router: ::windmark::Router,
+    }
+
+    impl #router_identifier {
+      #new_methods
+    }
+  };
+
+  output.into()
+}