refactor!: Rewrote device implementation macro once again

This time with a bit more though put into the design of the code, as a
result the macro should be a lot more robust.

This did result in the macro getting renamed from LuaDevice to Device as
this should be _the_ Device macro.
The attribute also got renamed from traits() to device(traits()) and the
syntax got overhauled to allow for a bit more expression.
This commit is contained in:
2025-09-09 02:48:44 +02:00
parent aad089aa10
commit 2dbd491b81
18 changed files with 268 additions and 139 deletions

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@@ -0,0 +1,198 @@
use std::collections::HashMap;
use proc_macro2::TokenStream as TokenStream2;
use quote::{ToTokens, quote};
use syn::parse::{Parse, ParseStream};
use syn::punctuated::Punctuated;
use syn::{Attribute, DeriveInput, Token, parenthesized};
enum Attr {
Trait(TraitAttr),
}
impl Parse for Attr {
fn parse(input: ParseStream) -> syn::Result<Self> {
let ident: syn::Ident = input.parse()?;
let attr;
_ = parenthesized!(attr in input);
let attr = match ident.to_string().as_str() {
"traits" => Attr::Trait(attr.parse()?),
_ => return Err(syn::Error::new(ident.span(), "Expected 'traits'")),
};
Ok(attr)
}
}
struct TraitAttr {
traits: Traits,
generics: Generics,
}
impl Parse for TraitAttr {
fn parse(input: ParseStream) -> syn::Result<Self> {
Ok(Self {
traits: input.parse()?,
generics: input.parse()?,
})
}
}
#[derive(Default)]
struct Traits(Vec<syn::Ident>);
impl Traits {
fn extend(&mut self, other: &Traits) {
self.0.extend_from_slice(&other.0);
}
}
impl Parse for Traits {
fn parse(input: ParseStream) -> syn::Result<Self> {
input
.call(Punctuated::<_, Token![,]>::parse_separated_nonempty)
.map(|traits| traits.into_iter().collect())
.map(Self)
}
}
impl ToTokens for Traits {
fn to_tokens(&self, tokens: &mut TokenStream2) {
let Self(traits) = &self;
tokens.extend(quote! {
#(
::automation_lib::lua::traits::#traits::add_methods(methods);
)*
});
}
}
#[derive(Default)]
struct Generics(Vec<syn::AngleBracketedGenericArguments>);
impl Generics {
fn has_generics(&self) -> bool {
!self.0.is_empty()
}
}
impl Parse for Generics {
fn parse(input: ParseStream) -> syn::Result<Self> {
if !input.peek(Token![for]) {
if input.is_empty() {
return Ok(Default::default());
} else {
return Err(input.error("Expected ')' or 'for'"));
}
}
_ = input.parse::<syn::Token![for]>()?;
input
.call(Punctuated::<_, Token![,]>::parse_separated_nonempty)
.map(|generics| generics.into_iter().collect())
.map(Self)
}
}
struct Implementation {
generics: Option<syn::AngleBracketedGenericArguments>,
traits: Traits,
}
impl From<(Option<syn::AngleBracketedGenericArguments>, Traits)> for Implementation {
fn from(value: (Option<syn::AngleBracketedGenericArguments>, Traits)) -> Self {
Self {
generics: value.0,
traits: value.1,
}
}
}
impl quote::ToTokens for Implementation {
fn to_tokens(&self, tokens: &mut TokenStream2) {
let Self { generics, traits } = &self;
tokens.extend(quote! {
#generics {
fn add_methods<M: mlua::UserDataMethods<Self>>(methods: &mut M) {
methods.add_async_function("new", async |_lua, config| {
let device: Self = LuaDeviceCreate::create(config)
.await
.map_err(mlua::ExternalError::into_lua_err)?;
Ok(device)
});
methods.add_method("__box", |_lua, this, _: ()| {
let b: Box<dyn Device> = Box::new(this.clone());
Ok(b)
});
methods.add_async_method("get_id", async |_lua, this, _: ()| { Ok(this.get_id()) });
#traits
}
}
});
}
}
struct Implementations(Vec<Implementation>);
impl From<Vec<Attr>> for Implementations {
fn from(attributes: Vec<Attr>) -> Self {
let mut all = Traits::default();
let mut implementations: HashMap<_, Traits> = HashMap::new();
for attribute in attributes {
match attribute {
Attr::Trait(attribute) => {
if attribute.generics.has_generics() {
for generic in &attribute.generics.0 {
implementations
.entry(Some(generic.clone()))
.or_default()
.extend(&attribute.traits);
}
} else {
all.extend(&attribute.traits);
}
}
}
}
if implementations.is_empty() {
implementations.entry(None).or_default().extend(&all);
} else {
for traits in implementations.values_mut() {
traits.extend(&all);
}
}
Self(implementations.into_iter().map(Into::into).collect())
}
}
pub fn device(input: &DeriveInput) -> TokenStream2 {
let name = &input.ident;
let Implementations(imp) = match input
.attrs
.iter()
.filter(|attr| attr.path().is_ident("device"))
.map(Attribute::parse_args)
.try_collect::<Vec<_>>()
{
Ok(result) => result.into(),
Err(err) => return err.into_compile_error(),
};
quote! {
#(
impl mlua::UserData for #name #imp
)*
}
}

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@@ -1,88 +0,0 @@
use proc_macro2::TokenStream;
use quote::{ToTokens, quote};
use syn::parse::Parse;
use syn::punctuated::Punctuated;
use syn::{AngleBracketedGenericArguments, Attribute, DeriveInput, Ident, Path, Token};
#[derive(Debug, Default)]
struct Impl {
generics: Option<AngleBracketedGenericArguments>,
traits: Vec<Path>,
}
impl Parse for Impl {
fn parse(input: syn::parse::ParseStream) -> syn::Result<Self> {
let generics = if input.peek(Token![<]) {
let generics = input.parse()?;
input.parse::<Token![:]>()?;
Some(generics)
} else {
None
};
let traits: Punctuated<_, _> = input.parse_terminated(Path::parse, Token![,])?;
let traits = traits.into_iter().collect();
Ok(Impl { generics, traits })
}
}
impl Impl {
fn generate(&self, name: &Ident) -> TokenStream {
let generics = &self.generics;
// If an identifier is specified, assume it is placed in ::automation_lib::lua::traits,
// otherwise use the provided path
let traits = self.traits.iter().map(|t| {
if let Some(ident) = t.get_ident() {
quote! {::automation_lib::lua::traits::#ident }
} else {
t.to_token_stream()
}
});
quote! {
impl mlua::UserData for #name #generics {
fn add_methods<M: mlua::UserDataMethods<Self>>(methods: &mut M) {
methods.add_async_function("new", async |_lua, config| {
let device: Self = LuaDeviceCreate::create(config)
.await
.map_err(mlua::ExternalError::into_lua_err)?;
Ok(device)
});
methods.add_method("__box", |_lua, this, _: ()| {
let b: Box<dyn Device> = Box::new(this.clone());
Ok(b)
});
methods.add_async_method("get_id", async |_lua, this, _: ()| { Ok(this.get_id()) });
#(
#traits::add_methods(methods);
)*
}
}
}
}
}
pub fn impl_device_macro(ast: &DeriveInput) -> TokenStream {
let name = &ast.ident;
let impls: TokenStream = ast
.attrs
.iter()
.filter(|attr| attr.path().is_ident("traits"))
.flat_map(Attribute::parse_args::<Impl>)
.map(|im| im.generate(name))
.collect();
if impls.is_empty() {
Impl::default().generate(name)
} else {
impls
}
}

View File

@@ -1,13 +1,12 @@
#![feature(iter_intersperse)]
mod impl_device;
#![feature(iterator_try_collect)]
mod device;
mod lua_device_config;
use lua_device_config::impl_lua_device_config_macro;
use quote::quote;
use syn::{DeriveInput, parse_macro_input};
use crate::impl_device::impl_device_macro;
#[proc_macro_derive(LuaDeviceConfig, attributes(device_config))]
pub fn lua_device_config_derive(input: proc_macro::TokenStream) -> proc_macro::TokenStream {
let ast = parse_macro_input!(input as DeriveInput);
@@ -15,13 +14,6 @@ pub fn lua_device_config_derive(input: proc_macro::TokenStream) -> proc_macro::T
impl_lua_device_config_macro(&ast).into()
}
#[proc_macro_derive(LuaDevice, attributes(traits))]
pub fn impl_device(input: proc_macro::TokenStream) -> proc_macro::TokenStream {
let ast = parse_macro_input!(input as DeriveInput);
impl_device_macro(&ast).into()
}
#[proc_macro_derive(LuaSerialize, attributes(traits))]
pub fn lua_serialize(input: proc_macro::TokenStream) -> proc_macro::TokenStream {
let ast = parse_macro_input!(input as DeriveInput);
@@ -37,3 +29,31 @@ pub fn lua_serialize(input: proc_macro::TokenStream) -> proc_macro::TokenStream
}
.into()
}
/// Derive macro generating an impl for the trait `::mlua::UserData`
///
/// The `device(traits)` attribute can be used to tell the macro what traits are implemented so that
/// the appropriate methods can automatically be registered.
/// If the struct does not have any type parameters the syntax is very simple:
/// ```
/// #[device(traits(TraitA, TraitB))]
/// ```
///
/// If the type does have type parameters you will have to manually specify all variations that
/// have the trait available:
/// ```
/// #[device(traits(TraitA, TraitB for <StateA>, <StateB>))]
/// ```
/// If multiple of these attributes are specified they will all combined appropriately.
///
///
/// # NOTE
/// If your type _has_ type parameters any instance of the traits attribute that does not specify
/// any type parameters will have the traits applied to _all_ other type parameter variations
/// listed in the other trait attributes. This behavior only applies if there is at least one
/// instance with type parameters specified.
#[proc_macro_derive(Device, attributes(device))]
pub fn device(input: proc_macro::TokenStream) -> proc_macro::TokenStream {
let ast = parse_macro_input!(input as DeriveInput);
device::device(&ast).into()
}