Macros (#8)

* Module proc-macro with name / path argument

Author: willothy

Cargo.toml

@@ -33,6 +33,7 @@ mlua = { version = "0.8.7", features = [
     "serialize",
 ] }
 serde = { version = "1.0.152", features = ["derive"] }
+nvim-utils-macros = { path = "macros" }
 
 [dev-dependencies]
 fs_extra = "1.3.0"

macros/.gitignore

@@ -0,0 +1,2 @@
+/target
+/Cargo.lock

macros/Cargo.lock

@@ -0,0 +1,13 @@
+[package]
+name = "nvim-utils-macros"
+version = "0.1.0"
+edition = "2021"
+
+[lib]
+proc-macro = true
+
+[dependencies]
+mlua = { version = "0.8.7", features = ["luajit", "vendored"] }
+proc-macro2 = "1.0.51"
+quote = "1.0.23"
+syn = { version = "1.0.109", features = ["full"] }

macros/Cargo.toml

@@ -0,0 +1,65 @@
+#[allow(unused_imports)]
+use mlua::lua_State;
+use proc_macro::TokenStream;
+use proc_macro2::Span;
+use quote::quote;
+use syn::{AttributeArgs, Error, Path, Result};
+
+struct Plugin {
+    path: Path,
+}
+
+impl Plugin {
+    fn parse(args: AttributeArgs) -> Result<Self> {
+        let mut path = None;
+
+        for arg in args {
+            use syn::Meta::Path;
+            use syn::NestedMeta::*;
+            match arg {
+                Meta(Path(p)) => path = Some(p),
+                _ => {
+                    return Err(Error::new_spanned(arg, "expected `name = \"...\"`"));
+                }
+            }
+        }
+
+        let path = path.ok_or_else(|| Error::new(Span::call_site(), "expected module path"))?;
+
+        Ok(Self { path })
+    }
+}
+
+#[proc_macro_attribute]
+pub fn module(attr: TokenStream, item: TokenStream) -> TokenStream {
+    let attr = syn::parse_macro_input!(attr as AttributeArgs);
+    let plugin = match Plugin::parse(attr) {
+        Ok(plugin) => plugin,
+        Err(err) => return err.to_compile_error().into(),
+    };
+
+    let path = plugin
+        .path
+        .segments
+        .iter()
+        .map(|s| s.ident.to_string())
+        .collect::<Vec<_>>()
+        .join("_");
+
+    let func = syn::parse_macro_input!(item as syn::ItemFn);
+    let name = func.sig.ident.to_string();
+
+    let entry = format!("luaopen_{}", path);
+    let wrapped = quote! {
+        #func
+
+        #[no_mangle]
+        unsafe extern "C" fn #entry(state: *mut lua_State) -> std::os::raw::c_int {
+            mlua::Lua::init_from_ptr(state)
+                .entrypoint1(#name)
+                .expect("failed to register module")
+        }
+    };
+
+    wrapped.into()
+}

macros/src/lib.rs

@@ -18,7 +18,6 @@
 //! - `unstable` includes unstable / untested API features (disabled by default)
 
 /// Includes [`mlua::prelude`], [`vim`], [`vim::ext::log`], and [`builder::ModuleBuilder`] if the corresponding features are enabled
-/// Also includes [`mlua::serde`] if the `serde` feature is enabled
 pub mod prelude {
     #[cfg(feature = "vim")]
     #[cfg_attr(docsrs, doc(cfg(feature = "vim")))]
@@ -32,14 +31,16 @@ pub mod prelude {
     #[cfg_attr(docsrs, doc(cfg(feature = "builder")))]
     pub use crate::builder::ModuleBuilder;
 
-    #[cfg(feature = "serde")]
-    #[cfg_attr(docsrs, doc(cfg(feature = "serde")))]
     pub use mlua::serde::{Deserializer, LuaSerdeExt, Serializer};
 
     pub use mlua::lua_module;
     pub use mlua::prelude::*;
 }
 
+#[allow(unused_imports)]
+#[macro_use]
+extern crate nvim_utils_macros;
+
 #[cfg(feature = "builder")]
 #[cfg_attr(docsrs, doc(cfg(feature = "builder")))]
 pub mod builder;