Vendor things

third-party/vendor/wasm-bindgen-macro-support/src/lib.rs

@@ -0,0 +1,166 @@
+//! 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::check_unused_attrs(&mut tokens);
+
+    Ok(tokens)
+}
+
+/// Takes the parsed input from a `wasm_bindgen::link_to` macro and returns the generated link
+pub fn expand_link_to(input: TokenStream) -> Result<TokenStream, Diagnostic> {
+    parser::reset_attrs_used();
+    let opts = syn::parse2(input)?;
+
+    let mut tokens = proc_macro2::TokenStream::new();
+    let link = parser::link_to(opts)?;
+    link.try_to_tokens(&mut tokens)?;
+
+    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::ImplItemFn>(input)?;
+    let opts: ClassMarker = syn::parse2(attr)?;
+
+    let mut program = backend::ast::Program::default();
+    item.macro_parse(&mut program, &opts)?;
+
+    // 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 ImplItemFn` 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| matches!(attr.style, syn::AttrStyle::Outer)),
+    );
+    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);
+        }
+        parser::check_unused_attrs(tokens); // same as above
+        tokens.append_all(
+            item.attrs
+                .iter()
+                .filter(|attr| matches!(attr.style, syn::AttrStyle::Inner(_))),
+        );
+        tokens.append_all(&item.block.stmts);
+    });
+
+    if let Some(err) = err {
+        return Err(err);
+    }
+
+    Ok(tokens)
+}
+
+struct ClassMarker {
+    class: syn::Ident,
+    js_class: String,
+    wasm_bindgen: syn::Path,
+    wasm_bindgen_futures: syn::Path,
+}
+
+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();
+
+        let mut wasm_bindgen = None;
+        let mut wasm_bindgen_futures = None;
+
+        loop {
+            if input.parse::<Option<Token![,]>>()?.is_some() {
+                let ident = input.parse::<syn::Ident>()?;
+
+                if ident == "wasm_bindgen" {
+                    if wasm_bindgen.is_some() {
+                        return Err(syn::Error::new(
+                            ident.span(),
+                            "found duplicate `wasm_bindgen`",
+                        ));
+                    }
+
+                    input.parse::<Token![=]>()?;
+                    wasm_bindgen = Some(input.parse::<syn::Path>()?);
+                } else if ident == "wasm_bindgen_futures" {
+                    if wasm_bindgen_futures.is_some() {
+                        return Err(syn::Error::new(
+                            ident.span(),
+                            "found duplicate `wasm_bindgen_futures`",
+                        ));
+                    }
+
+                    input.parse::<Token![=]>()?;
+                    wasm_bindgen_futures = Some(input.parse::<syn::Path>()?);
+                } else {
+                    return Err(syn::Error::new(
+                        ident.span(),
+                        "expected `wasm_bindgen` or `wasm_bindgen_futures`",
+                    ));
+                }
+            } else {
+                break;
+            }
+        }
+
+        Ok(ClassMarker {
+            class,
+            js_class,
+            wasm_bindgen: wasm_bindgen.unwrap_or_else(|| syn::parse_quote! { wasm_bindgen }),
+            wasm_bindgen_futures: wasm_bindgen_futures
+                .unwrap_or_else(|| syn::parse_quote! { wasm_bindgen_futures }),
+        })
+    }
+}