yog_interop/
lib.rs

1//! Yog inter-mod communication — proc-macros for cross-mod function calls.
2//!
3//! # Export (manual registration, auto-generated binding symbol)
4//!
5//! ```ignore
6//! use yog_api::{yog_export, Registry};
7//!
8//! #[yog_export]
9//! pub fn register_pipe(api: *const yog_api::YogApi, json: *const std::ffi::c_char) {
10//!     // ...
11//! }
12//!
13//! fn register(registry: &mut Registry) {
14//!     // Manual export registration (loader scanning coming later)
15//!     registry.interop().export("register_pipe", register_pipe as *const std::ffi::c_void);
16//! }
17//! ```
18//!
19//! # Import (auto-wired by loader)
20//!
21//! ```ignore
22//! yog_api::import! {
23//!     from "yog-pipes" {
24//!         fn register_pipe(api: *const yog_api::YogApi, json: *const std::ffi::c_char);
25//!     }
26//! }
27//!
28//! // Use like a normal function — loader wires it at init time
29//! register_pipe(api, json_ptr);
30//! ```
31
32use proc_macro::TokenStream;
33use quote::{format_ident, quote};
34
35// ── #[yog_export] ─────────────────────────────────────────────────────────
36
37/// Marks a function for inter-mod export.
38///
39/// Generates a `__yog_export_get_NAME` symbol that a future loader scanner
40/// can use to auto-discover exports. For now, the mod must also call
41/// `registry.interop().export("name", fn_ptr)` during `register()`.
42#[proc_macro_attribute]
43pub fn yog_export(_attr: TokenStream, item: TokenStream) -> TokenStream {
44    let func = syn::parse_macro_input!(item as syn::ItemFn);
45    let name = &func.sig.ident;
46    let vis = &func.vis;
47    let sig = &func.sig;
48    let block = &func.block;
49    let name_str = name.to_string();
50    let getter_name = format_ident!("__yog_export_get_{}", name);
51
52    let expanded = quote! {
53        #vis #sig #block
54
55        #[doc(hidden)]
56        #[no_mangle]
57        pub unsafe extern "C" fn #getter_name(
58            out_name: *mut *const ::std::os::raw::c_char,
59            out_ptr: *mut *const ::std::os::raw::c_void,
60        ) {
61            if !out_name.is_null() {
62                *out_name = concat!(#name_str, "\0").as_ptr() as *const ::std::os::raw::c_char;
63            }
64            if !out_ptr.is_null() {
65                *out_ptr = #name as *const ::std::os::raw::c_void;
66            }
67        }
68    };
69
70    TokenStream::from(expanded)
71}
72
73// ── import! macro ────────────────────────────────────────────────────────
74
75/// Declare imported functions from another mod. Generates public wrapper
76/// functions and `__yog_bind_NAME` entry points for the loader.
77///
78/// ```ignore
79/// yog_api::import! {
80///     from "yog-pipes" {
81///         fn register_pipe(api: *const YogApi, json: *const c_char) -> bool;
82///     }
83/// }
84/// register_pipe(api, json_ptr); // auto-wired
85/// ```
86#[proc_macro]
87pub fn import(input: TokenStream) -> TokenStream {
88    let import_block = syn::parse_macro_input!(input as ImportBlock);
89    let mod_name = &import_block.mod_name;
90    let mut out = proc_macro2::TokenStream::new();
91
92    for func in &import_block.funcs {
93        let name = &func.sig.ident;
94        let name_str = name.to_string();
95        let slot_name = format_ident!("__yog_slot_{}", name);
96        let bind_name = format_ident!("__yog_bind_{}", name);
97        let fn_sig = &func.sig;
98        let vis = &func.vis;
99        let inputs = &fn_sig.inputs;
100        let output = &fn_sig.output;
101
102        let arg_names: Vec<_> = inputs.iter().map(|arg| {
103            match arg {
104                syn::FnArg::Typed(pat_type) => &pat_type.pat,
105                syn::FnArg::Receiver(_) => unreachable!("self not allowed in imports"),
106            }
107        }).collect();
108
109        let wrapper = quote! {
110            #[allow(non_snake_case)]
111            #vis fn #name(#inputs) #output {
112                let f = #slot_name.get()
113                    .expect(concat!("yog: import '", #mod_name, ":", #name_str, "' not bound — is mod '", #mod_name, "' loaded?"));
114                unsafe { f(#(#arg_names),*) }
115            }
116
117            static #slot_name: ::std::sync::OnceLock<unsafe extern "C" fn(#inputs) #output>
118                = ::std::sync::OnceLock::new();
119
120            #[doc(hidden)]
121            #[no_mangle]
122            pub unsafe extern "C" fn #bind_name(ptr: *const ::std::os::raw::c_void) {
123                let f: unsafe extern "C" fn(#inputs) #output = ::std::mem::transmute(ptr);
124                #slot_name.set(f).ok();
125            }
126        };
127
128        out.extend(wrapper);
129    }
130
131    TokenStream::from(out)
132}
133
134// ── Parse helpers ────────────────────────────────────────────────────────
135
136struct ImportBlock {
137    mod_name: String,
138    funcs: Vec<syn::ItemFn>,
139}
140
141impl syn::parse::Parse for ImportBlock {
142    fn parse(input: syn::parse::ParseStream) -> syn::Result<Self> {
143        let from_kw: syn::Ident = input.parse()?;
144        if from_kw != "from" {
145            return Err(syn::Error::new(from_kw.span(), "expected `from`"));
146        }
147        let lit: syn::LitStr = input.parse()?;
148        let mod_name = lit.value();
149
150        let content;
151        syn::braced!(content in input);
152        let mut funcs = Vec::new();
153        while !content.is_empty() {
154            funcs.push(content.parse::<syn::ItemFn>()?);
155            let _ = content.parse::<syn::Token![;]>();
156        }
157
158        Ok(ImportBlock { mod_name, funcs })
159    }
160}
yog_interop/lib.rs

yog_interop/
lib.rs
