94 lines
3.0 KiB
Rust
94 lines
3.0 KiB
Rust
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use proc_macro::TokenStream;
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use proc_macro2::TokenStream as TokenStream2;
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use quote::quote;
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use syn::DeriveInput;
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mod generate;
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/// This is the heart of the command api
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/// It mainly does two things:
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/// - Generate a command enum
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/// - Wrap the enum in all supported languages (only lua for now)
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/// - Generate wrapper lua function for each command
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/// - Generate a `add_lua_functions_to_globals` function, which adds
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/// the rust wrapper functions to the lua globals.
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///
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/// The input and output values of the wrapped functions are derived from the values specified in
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/// the `Commands` struct.
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/// The returned values will be returned directly to the lua context, this allows to nest functions.
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///
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/// For example this rust code:
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/// ```rust
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/// #[ci_command_enum]
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/// struct Commands {
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/// /// Greets the user
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/// greet: fn(String) -> String,
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/// }
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/// ```
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/// results in this expanded code:
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/// ```rust
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/// #[derive(Debug)]
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/// pub enum Command {
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/// Greet(String),
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/// }
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/// pub fn add_lua_functions_to_globals(
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/// lua: mlua::Lua,
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/// tx: tokio::sync::mpsc::Sender<Event>,
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/// ) -> mlua::Lua {
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/// lua.set_app_data(tx);
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/// let globals = lua.globals();
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/// {
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/// let wrapped_lua_function_greet = lua
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/// .create_async_function(greet)
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/// .expect(
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/// format!(
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/// "The function: `{}` should be defined",
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/// "greet",
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/// )
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/// );
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/// globals
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/// .set("greet", wrapped_lua_function_greet)
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/// .expect("Setting a static global value should work");
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/// }
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/// drop(globals);
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/// lua
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/// }
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/// async fn greet(lua: &mlua::Lua, input: String) -> Result<String, mlua::Error> {
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/// let (callback_tx, callback_rx) = tokio::sync::oneshot::channel::<String>();
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/// let tx: core::cell::Ref<tokio::sync::mpsc::Sender<Event>> = lua
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/// .app_data_ref()
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/// .expect("This should exist, it was set before");
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/// (*tx)
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/// .send(Event::CommandEvent(Command::Greet(input.clone()), Some(callback_tx)))
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/// .await
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/// .expect("This should work, as the receiver is not dropped");
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/// match callback_rx.await {
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/// Ok(output) => {
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/// return Ok(output);
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/// }
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/// Err(err) => {
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/// return Err(mlua::Error::ExternalError(std::sync::Arc::new(err)));
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/// }
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/// };
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/// }
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/// ```
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#[proc_macro_attribute]
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pub fn ci_command_enum(_attrs: TokenStream, input: TokenStream) -> TokenStream {
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// Construct a representation of Rust code as a syntax tree
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// that we can manipulate
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let input: DeriveInput = syn::parse(input)
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.expect("This should always be valid rust code, as it's extracted from direct code");
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// Build the language wrappers
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let lua_wrapper: TokenStream2 = generate::lua_wrapper(&input);
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// Build the final enum
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let command_enum = generate::command_enum(&input);
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quote! {
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#command_enum
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#lua_wrapper
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}
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.into()
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}
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