| //! This crate contains the part of the implementation of the `#[wasm_bindgen]` optsibute that is |
| //! not in the shared backend crate. |
| |
| #![doc(html_root_url = "https://docs.rs/wasm-bindgen-macro-support/0.2")] |
| |
| extern crate proc_macro2; |
| extern crate quote; |
| #[macro_use] |
| extern crate syn; |
| #[macro_use] |
| extern crate wasm_bindgen_backend as backend; |
| extern crate wasm_bindgen_shared as shared; |
| |
| pub use crate::parser::BindgenAttrs; |
| use crate::parser::MacroParse; |
| use backend::{Diagnostic, TryToTokens}; |
| use proc_macro2::TokenStream; |
| use quote::ToTokens; |
| use quote::TokenStreamExt; |
| use syn::parse::{Parse, ParseStream, Result as SynResult}; |
| |
| mod parser; |
| |
| /// Takes the parsed input from a `#[wasm_bindgen]` macro and returns the generated bindings |
| pub fn expand(attr: TokenStream, input: TokenStream) -> Result<TokenStream, Diagnostic> { |
| parser::reset_attrs_used(); |
| let item = syn::parse2::<syn::Item>(input)?; |
| let opts = syn::parse2(attr)?; |
| |
| let mut tokens = proc_macro2::TokenStream::new(); |
| let mut program = backend::ast::Program::default(); |
| item.macro_parse(&mut program, (Some(opts), &mut tokens))?; |
| program.try_to_tokens(&mut tokens)?; |
| |
| // If we successfully got here then we should have used up all attributes |
| // and considered all of them to see if they were used. If one was forgotten |
| // that's a bug on our end, so sanity check here. |
| parser::assert_all_attrs_checked(); |
| |
| Ok(tokens) |
| } |
| |
| /// Takes the parsed input from a `#[wasm_bindgen]` macro and returns the generated bindings |
| pub fn expand_class_marker( |
| attr: TokenStream, |
| input: TokenStream, |
| ) -> Result<TokenStream, Diagnostic> { |
| parser::reset_attrs_used(); |
| let mut item = syn::parse2::<syn::ImplItemMethod>(input)?; |
| let opts: ClassMarker = syn::parse2(attr)?; |
| |
| let mut program = backend::ast::Program::default(); |
| item.macro_parse(&mut program, (&opts.class, &opts.js_class))?; |
| parser::assert_all_attrs_checked(); // same as above |
| |
| // This is where things are slightly different, we are being expanded in the |
| // context of an impl so we can't inject arbitrary item-like tokens into the |
| // output stream. If we were to do that then it wouldn't parse! |
| // |
| // Instead what we want to do is to generate the tokens for `program` into |
| // the header of the function. This'll inject some no_mangle functions and |
| // statics and such, and they should all be valid in the context of the |
| // start of a function. |
| // |
| // We manually implement `ToTokens for ImplItemMethod` here, injecting our |
| // program's tokens before the actual method's inner body tokens. |
| let mut tokens = proc_macro2::TokenStream::new(); |
| tokens.append_all(item.attrs.iter().filter(|attr| match attr.style { |
| syn::AttrStyle::Outer => true, |
| _ => false, |
| })); |
| item.vis.to_tokens(&mut tokens); |
| item.sig.to_tokens(&mut tokens); |
| let mut err = None; |
| item.block.brace_token.surround(&mut tokens, |tokens| { |
| if let Err(e) = program.try_to_tokens(tokens) { |
| err = Some(e); |
| } |
| tokens.append_all(item.attrs.iter().filter(|attr| match attr.style { |
| syn::AttrStyle::Inner(_) => true, |
| _ => false, |
| })); |
| tokens.append_all(&item.block.stmts); |
| }); |
| |
| if let Some(err) = err { |
| return Err(err); |
| } |
| |
| Ok(tokens) |
| } |
| |
| struct ClassMarker { |
| class: syn::Ident, |
| js_class: String, |
| } |
| |
| impl Parse for ClassMarker { |
| fn parse(input: ParseStream) -> SynResult<Self> { |
| let class = input.parse::<syn::Ident>()?; |
| input.parse::<Token![=]>()?; |
| let js_class = input.parse::<syn::LitStr>()?.value(); |
| Ok(ClassMarker { class, js_class }) |
| } |
| } |