Initial commit

.github/workflows/ci.yml

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+name: CI
+
+on: [push, pull_request]
+
+jobs:
+  ci:
+    runs-on: ubuntu-latest
+    strategy:
+      fail-fast: false
+      matrix:
+        rust-toolchain: [nightly]
+        targets: [x86_64-unknown-linux-gnu, x86_64-unknown-none, riscv64gc-unknown-none-elf, aarch64-unknown-none-softfloat]
+    steps:
+    - uses: actions/checkout@v4
+    - uses: dtolnay/rust-toolchain@nightly
+      with:
+        toolchain: ${{ matrix.rust-toolchain }}
+        components: rust-src, clippy, rustfmt
+        targets: ${{ matrix.targets }}
+    - name: Check rust version
+      run: rustc --version --verbose
+    - name: Check code format
+      run: cargo fmt --all -- --check
+    - name: Clippy
+      run: cargo clippy --target ${{ matrix.targets }} --all-features -- -A clippy::new_without_default
+    - name: Build
+      run: cargo build --target ${{ matrix.targets }} --all-features
+    - name: Unit test
+      if: ${{ matrix.targets == 'x86_64-unknown-linux-gnu' }}
+      run: cargo test --target ${{ matrix.targets }} -- --nocapture
+
+  doc:
+    runs-on: ubuntu-latest
+    strategy:
+      fail-fast: false
+    permissions:
+      contents: write
+    env:
+      default-branch: ${{ format('refs/heads/{0}', github.event.repository.default_branch) }}
+      RUSTDOCFLAGS: -D rustdoc::broken_intra_doc_links -D missing-docs
+    steps:
+    - uses: actions/checkout@v4
+    - uses: dtolnay/rust-toolchain@nightly
+    - name: Build docs
+      continue-on-error: ${{ github.ref != env.default-branch && github.event_name != 'pull_request' }}
+      run: |
+        cargo doc --no-deps --all-features
+        printf '<meta http-equiv="refresh" content="0;url=%s/index.html">' $(cargo tree | head -1 | cut -d' ' -f1) > target/doc/index.html
+    - name: Deploy to Github Pages
+      if: ${{ github.ref == env.default-branch }}
+      uses: JamesIves/github-pages-deploy-action@v4
+      with:
+        single-commit: true
+        branch: gh-pages
+        folder: target/doc

.gitignore

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+/target
+/.vscode
+.DS_Store
+Cargo.lock

Cargo.toml

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+[package]
+name = "crate_interface"
+version = "0.1.1"
+edition = "2021"
+authors = ["Yuekai Jia <[email protected]>"]
+description = "Provides a way to define an interface (trait) in a crate, but can implement or use it in any crate."
+license = "GPL-3.0-or-later OR Apache-2.0 OR MulanPSL-2.0"
+homepage = "https://github.com/arceos-org/arceos"
+repository = "https://github.com/arceos-org/crate_interface"
+keywords = ["arceos", "api", "macro"]
+categories = ["development-tools::procedural-macro-helpers", "no-std"]
+
+[dependencies]
+proc-macro2 = "1.0"
+quote = "1.0"
+syn = { version = "2.0", features = ["full"] }
+
+[lib]
+proc-macro = true

README.md

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+# crate_interface
+
+[![Crates.io](https://img.shields.io/crates/v/crate_interface)](https://crates.io/crates/crate_interface)
+
+Provides a way to **define** an interface (trait) in a crate, but can
+**implement** or **use** it in any crate. It 's usually used to solve
+the problem of *circular dependencies* between crates.
+
+## Example
+
+```rust
+// Define the interface
+#[crate_interface::def_interface]
+pub trait HelloIf {
+    fn hello(&self, name: &str, id: usize) -> String;
+}
+
+// Implement the interface in any crate
+struct HelloIfImpl;
+
+#[crate_interface::impl_interface]
+impl HelloIf for HelloIfImpl {
+    fn hello(&self, name: &str, id: usize) -> String {
+        format!("Hello, {} {}!", name, id)
+    }
+}
+
+// Call `HelloIfImpl::hello` in any crate
+use crate_interface::call_interface;
+assert_eq!(
+    call_interface!(HelloIf::hello("world", 123)),
+    "Hello, world 123!"
+);
+assert_eq!(
+    call_interface!(HelloIf::hello, "rust", 456), // another calling style
+    "Hello, rust 456!"
+);
+```

src/lib.rs

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+#![doc = include_str!("../README.md")]
+#![feature(iter_next_chunk)]
+
+use proc_macro::TokenStream;
+use proc_macro2::Span;
+use quote::{format_ident, quote};
+use syn::{Error, FnArg, ImplItem, ImplItemFn, ItemImpl, ItemTrait, TraitItem, Type};
+
+fn compiler_error(err: Error) -> TokenStream {
+    err.to_compile_error().into()
+}
+
+/// Define an interface.
+///
+/// This attribute should be added above the definition of a trait. All traits
+/// that use the attribute cannot have the same name.
+///
+/// It is not necessary to define it in the same crate as the implementation,
+/// but it is required that these crates are linked together.
+///
+/// See the [crate-level documentation](crate) for more details.
+#[proc_macro_attribute]
+pub fn def_interface(attr: TokenStream, item: TokenStream) -> TokenStream {
+    if !attr.is_empty() {
+        return compiler_error(Error::new(
+            Span::call_site(),
+            "expect an empty attribute: `#[crate_interface_def]`",
+        ));
+    }
+
+    let ast = syn::parse_macro_input!(item as ItemTrait);
+    let trait_name = &ast.ident;
+
+    let mut extern_fn_list = vec![];
+    for item in &ast.items {
+        if let TraitItem::Fn(method) = item {
+            let mut sig = method.sig.clone();
+            let fn_name = &sig.ident;
+            sig.ident = format_ident!("__{}_{}", trait_name, fn_name);
+            sig.inputs = syn::punctuated::Punctuated::new();
+
+            for arg in &method.sig.inputs {
+                if let FnArg::Typed(_) = arg {
+                    sig.inputs.push(arg.clone());
+                }
+            }
+
+            let extern_fn = quote! {
+                #sig;
+            };
+            extern_fn_list.push(extern_fn);
+        }
+    }
+
+    quote! {
+        #ast
+        extern "Rust" {
+            #(#extern_fn_list)*
+        }
+    }
+    .into()
+}
+
+/// Implement the interface for a struct.
+///
+/// This attribute should be added above the implementation of a trait for a
+/// struct, and the trait must be defined with
+/// [`#[def_interface]`](macro@crate::def_interface).
+///
+/// It is not necessary to implement it in the same crate as the definition, but
+/// it is required that these crates are linked together.
+///
+/// See the [crate-level documentation](crate) for more details.
+#[proc_macro_attribute]
+pub fn impl_interface(attr: TokenStream, item: TokenStream) -> TokenStream {
+    if !attr.is_empty() {
+        return compiler_error(Error::new(
+            Span::call_site(),
+            "expect an empty attribute: `#[crate_interface_impl]`",
+        ));
+    }
+
+    let mut ast = syn::parse_macro_input!(item as ItemImpl);
+    let trait_name = if let Some((_, path, _)) = &ast.trait_ {
+        &path.segments.last().unwrap().ident
+    } else {
+        return compiler_error(Error::new_spanned(ast, "expect a trait implementation"));
+    };
+    let impl_name = if let Type::Path(path) = &ast.self_ty.as_ref() {
+        path.path.get_ident().unwrap()
+    } else {
+        return compiler_error(Error::new_spanned(ast, "expect a trait implementation"));
+    };
+
+    for item in &mut ast.items {
+        if let ImplItem::Fn(method) = item {
+            let (attrs, vis, sig, stmts) =
+                (&method.attrs, &method.vis, &method.sig, &method.block.stmts);
+            let fn_name = &sig.ident;
+            let extern_fn_name = format_ident!("__{}_{}", trait_name, fn_name).to_string();
+
+            let mut new_sig = sig.clone();
+            new_sig.ident = format_ident!("{}", extern_fn_name);
+            new_sig.inputs = syn::punctuated::Punctuated::new();
+
+            let mut args = vec![];
+            let mut has_self = false;
+            for arg in &sig.inputs {
+                match arg {
+                    FnArg::Receiver(_) => has_self = true,
+                    FnArg::Typed(ty) => {
+                        args.push(ty.pat.clone());
+                        new_sig.inputs.push(arg.clone());
+                    }
+                }
+            }
+
+            let call_impl = if has_self {
+                quote! {
+                    let IMPL: #impl_name = #impl_name;
+                    IMPL.#fn_name( #(#args),* )
+                }
+            } else {
+                quote! { #impl_name::#fn_name( #(#args),* ) }
+            };
+
+            let item = quote! {
+                #(#attrs)*
+                #vis
+                #sig
+                {
+                    {
+                        #[export_name = #extern_fn_name]
+                        extern "Rust" #new_sig {
+                            #call_impl
+                        }
+                    }
+                    #(#stmts)*
+                }
+            }
+            .into();
+            *method = syn::parse_macro_input!(item as ImplItemFn);
+        }
+    }
+
+    quote! { #ast }.into()
+}
+
+/// Call a function in the interface.
+///
+/// It is not necessary to call it in the same crate as the implementation, but
+/// it is required that these crates are linked together.
+///
+/// See the [crate-level documentation](crate) for more details.
+#[proc_macro]
+pub fn call_interface(item: TokenStream) -> TokenStream {
+    parse_call_interface(item)
+        .unwrap_or_else(|msg| compiler_error(Error::new(Span::call_site(), msg)))
+}
+
+fn parse_call_interface(item: TokenStream) -> Result<TokenStream, String> {
+    let mut iter = item.into_iter();
+    let tt = iter
+        .next_chunk::<4>()
+        .or(Err("expect `Trait::func`"))?
+        .map(|t| t.to_string());
+
+    let trait_name = &tt[0];
+    if tt[1] != ":" || tt[2] != ":" {
+        return Err("missing `::`".into());
+    }
+    let fn_name = &tt[3];
+    let extern_fn_name = format!("__{}_{}", trait_name, fn_name);
+
+    let mut args = iter.map(|x| x.to_string()).collect::<Vec<_>>().join("");
+    if args.starts_with(',') {
+        args.remove(0);
+    } else if args.starts_with('(') && args.ends_with(')') {
+        args.remove(0);
+        args.pop();
+    }
+
+    let call = format!("unsafe {{ {}( {} ) }}", extern_fn_name, args);
+    Ok(call
+        .parse::<TokenStream>()
+        .or(Err("expect a correct argument list"))?)
+}

tests/test_crate_interface.rs

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+use crate_interface::*;
+
+#[def_interface]
+trait SimpleIf {
+    fn foo() -> u32 {
+        123
+    }
+
+    /// Test comments
+    fn bar(&self, a: u16, b: &[u8], c: &str);
+}
+
+struct SimpleIfImpl;
+
+#[impl_interface]
+impl SimpleIf for SimpleIfImpl {
+    #[inline]
+    fn foo() -> u32 {
+        456
+    }
+
+    /// Test comments2
+    fn bar(&self, a: u16, b: &[u8], c: &str) {
+        println!("{} {:?} {}", a, b, c);
+        assert_eq!(b[1], 3);
+    }
+}
+
+#[test]
+fn test_crate_interface_call() {
+    call_interface!(SimpleIf::bar, 123, &[2, 3, 5, 7, 11], "test");
+    call_interface!(SimpleIf::bar(123, &[2, 3, 5, 7, 11], "test"));
+    assert_eq!(call_interface!(SimpleIf::foo), 456);
+}