napi-rs/crates/macro/src/lib.rs

#[cfg(feature = "compat-mode")]
mod compat_macro;
mod parser;

#[macro_use]
extern crate syn;
#[macro_use]
extern crate napi_derive_backend;
#[macro_use]
extern crate quote;
use napi_derive_backend::{BindgenResult, TryToTokens};

#[cfg(feature = "type-def")]
use napi_derive_backend::{ToTypeDef, TypeDef};
use parser::{attrs::BindgenAttrs, ParseNapi};
use proc_macro::TokenStream as RawStream;
use proc_macro2::{TokenStream, TokenTree};
use quote::ToTokens;
use std::env;
#[cfg(feature = "type-def")]
use std::{
  fs,
  io::{BufWriter, Result as IOResult, Write},
};
#[cfg(feature = "compat-mode")]
use syn::{fold::Fold, parse_macro_input, ItemFn};
use syn::{Attribute, Item};

/// ```ignore
/// #[napi]
/// fn test(ctx: CallContext, name: String) {
///   "hello" + name
/// }
/// ```
#[proc_macro_attribute]
pub fn napi(attr: RawStream, input: RawStream) -> RawStream {
  match expand(attr.into(), input.into()) {
    Ok(tokens) => {
      if env::var("DEBUG_GENERATED_CODE").is_ok() {
        println!("{}", tokens.to_string());
      }
      tokens.into()
    }
    Err(diagnostic) => {
      println!("`napi` macro expand failed.");

      (quote! { #diagnostic }).into()
    }
  }
}

fn expand(attr: TokenStream, input: TokenStream) -> BindgenResult<TokenStream> {
  let mut item = syn::parse2::<syn::Item>(input)?;
  let opts: BindgenAttrs = syn::parse2(attr)?;
  let mut tokens = proc_macro2::TokenStream::new();
  if let Item::Mod(mut js_mod) = item {
    let js_name = opts.js_name().map_or_else(
      || js_mod.ident.to_string(),
      |(js_name, _)| js_name.to_owned(),
    );
    if let Some((_, mut items)) = js_mod.content.clone() {
      for item in items.iter_mut() {
        let mut empty_attrs = vec![];
        if let Some(item_opts) = replace_napi_attr_in_mod(
          js_name.clone(),
          match item {
            syn::Item::Fn(ref mut function) => &mut function.attrs,
            syn::Item::Struct(ref mut struct_) => &mut struct_.attrs,
            syn::Item::Enum(ref mut enum_) => &mut enum_.attrs,
            syn::Item::Const(ref mut const_) => &mut const_.attrs,
            syn::Item::Impl(ref mut impl_) => &mut impl_.attrs,
            syn::Item::Mod(mod_) => {
              let mod_in_mod = mod_
                .attrs
                .iter()
                .enumerate()
                .find(|(_, m)| m.path.segments[0].ident == "napi");
              if mod_in_mod.is_some() {
                bail_span!(
                  mod_,
                  "napi module cannot be nested under another napi module"
                );
              } else {
                &mut empty_attrs
              }
            }
            _ => &mut empty_attrs,
          },
        ) {
          let napi = item.parse_napi(&mut tokens, item_opts)?;
          napi.try_to_tokens(&mut tokens)?;
          #[cfg(feature = "type-def")]
          if let Ok(type_def_file) = env::var("TYPE_DEF_TMP_PATH") {
            if let Err(e) = output_type_def(type_def_file, napi.to_type_def()) {
              println!("Failed to write type def file: {:?}", e);
            };
          }
        } else {
          item.to_tokens(&mut tokens);
        };
      }
      js_mod.content = None;
    };
    let js_mod_attrs: Vec<Attribute> = js_mod
      .attrs
      .clone()
      .into_iter()
      .filter(|attr| attr.path.segments[0].ident != "napi")
      .collect();
    let mod_name = js_mod.ident;
    let visible = js_mod.vis;
    let mod_tokens = quote! { #(#js_mod_attrs)* #visible mod #mod_name { #tokens } };
    Ok(mod_tokens)
  } else {
    let napi = item.parse_napi(&mut tokens, opts)?;
    napi.try_to_tokens(&mut tokens)?;

    #[cfg(feature = "type-def")]
    if let Ok(type_def_file) = env::var("TYPE_DEF_TMP_PATH") {
      if let Err(e) = output_type_def(type_def_file, napi.to_type_def()) {
        println!("Failed to write type def file: {:?}", e);
      };
    }
    Ok(tokens)
  }
}

#[cfg(feature = "type-def")]
fn output_type_def(type_def_file: String, type_def: TypeDef) -> IOResult<()> {
  let file = fs::OpenOptions::new()
    .append(true)
    .create(true)
    .open(type_def_file)?;

  let mut writer = BufWriter::<fs::File>::new(file);
  writer.write_all(type_def.to_string().as_bytes())?;
  writer.write_all("\n".as_bytes())
}

#[cfg(feature = "compat-mode")]
#[proc_macro_attribute]
pub fn contextless_function(_attr: RawStream, input: RawStream) -> RawStream {
  let input = parse_macro_input!(input as ItemFn);
  let mut js_fn = compat_macro::JsFunction::new();
  js_fn.fold_item_fn(input);
  let fn_name = js_fn.name.unwrap();
  let fn_block = js_fn.block;
  let signature = js_fn.signature.unwrap();
  let visibility = js_fn.visibility;
  let new_fn_name = signature.ident.clone();
  let execute_js_function =
    compat_macro::get_execute_js_code(new_fn_name, compat_macro::FunctionKind::Contextless);

  let expanded = quote! {
    #[inline(always)]
    #signature #(#fn_block)*

    #visibility extern "C" fn #fn_name(
      raw_env: napi::sys::napi_env,
      cb_info: napi::sys::napi_callback_info,
    ) -> napi::sys::napi_value {
      use std::ptr;
      use std::panic::{self, AssertUnwindSafe};
      use std::ffi::CString;
      use napi::{Env, NapiValue, NapiRaw, Error, Status};

      let ctx = unsafe { Env::from_raw(raw_env) };
      #execute_js_function
    }
  };
  // Hand the output tokens back to the compiler
  RawStream::from(expanded)
}

#[cfg(feature = "compat-mode")]
#[proc_macro_attribute]
pub fn js_function(attr: RawStream, input: RawStream) -> RawStream {
  let arg_len = parse_macro_input!(attr as compat_macro::ArgLength);
  let arg_len_span = arg_len.length;
  let input = parse_macro_input!(input as ItemFn);
  let mut js_fn = compat_macro::JsFunction::new();
  js_fn.fold_item_fn(input);
  let fn_name = js_fn.name.unwrap();
  let fn_block = js_fn.block;
  let signature = js_fn.signature.unwrap();
  let visibility = js_fn.visibility;
  let new_fn_name = signature.ident.clone();
  let execute_js_function =
    compat_macro::get_execute_js_code(new_fn_name, compat_macro::FunctionKind::JsFunction);
  let expanded = quote! {
    #[inline(always)]
    #signature #(#fn_block)*

    #visibility extern "C" fn #fn_name(
      raw_env: napi::sys::napi_env,
      cb_info: napi::sys::napi_callback_info,
    ) -> napi::sys::napi_value {
      use std::ptr;
      use std::panic::{self, AssertUnwindSafe};
      use std::ffi::CString;
      use napi::{Env, Error, Status, NapiValue, NapiRaw, CallContext};
      let mut argc = #arg_len_span as usize;
      #[cfg(all(target_os = "windows", target_arch = "x86"))]
      let mut raw_args = vec![ptr::null_mut(); #arg_len_span];
      #[cfg(not(all(target_os = "windows", target_arch = "x86")))]
      let mut raw_args = [ptr::null_mut(); #arg_len_span];
      let mut raw_this = ptr::null_mut();

      unsafe {
        let status = napi::sys::napi_get_cb_info(
          raw_env,
          cb_info,
          &mut argc,
          raw_args.as_mut_ptr(),
          &mut raw_this,
          ptr::null_mut(),
        );
        debug_assert!(Status::from(status) == Status::Ok, "napi_get_cb_info failed");
      }

      let mut env = unsafe { Env::from_raw(raw_env) };
      #[cfg(all(target_os = "windows", target_arch = "x86"))]
      let ctx = CallContext::new(&mut env, cb_info, raw_this, raw_args.as_slice(), argc);
      #[cfg(not(all(target_os = "windows", target_arch = "x86")))]
      let ctx = CallContext::new(&mut env, cb_info, raw_this, &raw_args, argc);
      #execute_js_function
    }
  };
  // Hand the output tokens back to the compiler
  RawStream::from(expanded)
}

#[cfg(feature = "compat-mode")]
#[proc_macro_attribute]
pub fn module_exports(_attr: RawStream, input: RawStream) -> RawStream {
  let input = parse_macro_input!(input as ItemFn);
  let mut js_fn = compat_macro::JsFunction::new();
  js_fn.fold_item_fn(input);
  let fn_block = js_fn.block;
  let fn_name = js_fn.name.unwrap();
  let signature = js_fn.signature_raw.unwrap();
  let args_len = js_fn.args.len();
  let call_expr = if args_len == 1 {
    quote! { #fn_name(exports) }
  } else if args_len == 2 {
    quote! { #fn_name(exports, env) }
  } else {
    panic!("Arguments length of #[module_exports] function must be 1 or 2");
  };

  let register = quote! {
    #[napi::bindgen_prelude::ctor]
    fn __napi__explicit_module_register() {
      unsafe fn register(raw_env: napi::sys::napi_env, raw_exports: napi::sys::napi_value) -> napi::Result<()> {
        use napi::{Env, JsObject, NapiValue};

        let env = Env::from_raw(raw_env);
        let exports = JsObject::from_raw_unchecked(raw_env, raw_exports);

        #call_expr
      }

      napi::bindgen_prelude::register_module_exports(register)
    }
  };

  (quote! {
    #[inline]
    #signature #(#fn_block)*

    #register
  })
  .into()
}

fn replace_napi_attr_in_mod(
  js_namespace: String,
  attrs: &mut Vec<syn::Attribute>,
) -> Option<BindgenAttrs> {
  let napi_attr = attrs.clone();
  let napi_attr = napi_attr
    .iter()
    .enumerate()
    .find(|(_, m)| m.path.segments[0].ident == "napi");
  if let Some((index, napi_attr)) = napi_attr {
    let attr_token_stream = napi_attr.tokens.clone();
    let raw_attr_stream = attr_token_stream.to_string();
    let raw_attr_stream = if !raw_attr_stream.is_empty() {
      raw_attr_stream
        .strip_prefix('(')
        .unwrap()
        .strip_suffix(')')
        .unwrap()
        .to_string()
    } else {
      raw_attr_stream
    };
    let raw_attr_token_stream = syn::parse_str::<TokenStream>(raw_attr_stream.as_str()).unwrap();

    let new_attr: syn::Attribute = if !raw_attr_stream.is_empty() {
      syn::parse_quote!(
        #[napi(#raw_attr_token_stream, namespace = #js_namespace)]
      )
    } else {
      syn::parse_quote!(
        #[napi(namespace = #js_namespace)]
      )
    };
    let struct_opts: BindgenAttrs;
    if let Some(TokenTree::Group(g)) = new_attr.tokens.into_iter().next() {
      struct_opts = syn::parse2(g.stream()).ok()?;
    } else {
      struct_opts = syn::parse2(quote! {}).ok()?;
    }
    attrs.remove(index);
    Some(struct_opts)
  } else {
    None
  }
}