webidl: refactor method/getter/getter generation

crates/backend/src/ast.rs

@@ -41,6 +41,7 @@ pub enum ImportKind {
 pub struct ImportFunction {
     pub function: Function,
     pub rust_name: Ident,
+    pub js_ret: Option<syn::Type>,
     pub kind: ImportFunctionKind,
     pub shim: Ident,
 }
@@ -70,11 +71,10 @@ pub struct ImportType {
 #[cfg_attr(feature = "extra-traits", derive(Debug, PartialEq, Eq))]
 pub struct Function {
     pub name: Ident,
-    pub arguments: Vec<syn::Type>,
+    pub arguments: Vec<syn::ArgCaptured>,
     pub ret: Option<syn::Type>,
     pub opts: BindgenAttrs,
     pub rust_attrs: Vec<syn::Attribute>,
-    pub rust_decl: Box<syn::FnDecl>,
     pub rust_vis: syn::Visibility,
 }
 
@@ -139,7 +139,8 @@ impl Program {
             syn::Item::Fn(mut f) => {
                 let opts = opts.unwrap_or_else(|| BindgenAttrs::find(&mut f.attrs));
 
-                let no_mangle = f.attrs
+                let no_mangle = f
+                    .attrs
                     .iter()
                     .enumerate()
                     .filter_map(|(i, m)| m.interpret_meta().map(|m| (i, m)))
@@ -268,7 +269,8 @@ impl Program {
             _ => panic!("only public enums are allowed"),
         }
 
-        let variants = item.variants
+        let variants = item
+            .variants
             .iter()
             .enumerate()
             .map(|(i, v)| {
@@ -345,8 +347,8 @@ impl Program {
 
     pub fn push_foreign_fn(&mut self, f: syn::ForeignItemFn, opts: BindgenAttrs) -> ImportKind {
         let js_name = opts.js_name().unwrap_or(&f.ident).clone();
-        let mut wasm = Function::from_decl(&js_name, f.decl, f.attrs, opts, f.vis, false).0;
+        let wasm = Function::from_decl(&js_name, f.decl, f.attrs, opts, f.vis, false).0;
-        if wasm.opts.catch() {
+        let js_ret = if wasm.opts.catch() {
             // TODO: this assumes a whole bunch:
             //
             // * The outer type is actually a `Result`
@@ -354,15 +356,18 @@ impl Program {
             // * The actual type is the first type parameter
             //
             // should probably fix this one day...
-            wasm.ret = extract_first_ty_param(wasm.ret.as_ref())
+            extract_first_ty_param(wasm.ret.as_ref())
-                .expect("can't `catch` without returning a Result");
+                .expect("can't `catch` without returning a Result")
-        }
+        } else {
+            wasm.ret.clone()
+        };
 
         let kind = if wasm.opts.method() {
-            let class = wasm.arguments
+            let class = wasm
+                .arguments
                 .get(0)
                 .expect("methods must have at least one argument");
-            let class = match *class {
+            let class = match class.ty {
                 syn::Type::Reference(syn::TypeReference {
                     mutability: None,
                     ref elem,
@@ -418,6 +423,7 @@ impl Program {
         ImportKind::Function(ImportFunction {
             function: wasm,
             kind,
+            js_ret,
             rust_name: f.ident.clone(),
             shim: Ident::new(&shim, Span::call_site()),
         })
@@ -501,11 +507,13 @@ impl Function {
 
         assert_no_lifetimes(&mut decl);
 
+        let syn::FnDecl { inputs, output, .. } = { *decl };
+
         let mut mutable = None;
-        let arguments = decl.inputs
+        let arguments = inputs
-            .iter()
+            .into_iter()
-            .filter_map(|arg| match *arg {
+            .filter_map(|arg| match arg {
-                syn::FnArg::Captured(ref c) => Some(c),
+                syn::FnArg::Captured(c) => Some(c),
                 syn::FnArg::SelfValue(_) => {
                     panic!("by-value `self` not yet supported");
                 }
@@ -516,12 +524,11 @@ impl Function {
                 }
                 _ => panic!("arguments cannot be `self` or ignored"),
             })
-            .map(|arg| arg.ty.clone())
             .collect::<Vec<_>>();
 
-        let ret = match decl.output {
+        let ret = match output {
             syn::ReturnType::Default => None,
-            syn::ReturnType::Type(_, ref t) => Some((**t).clone()),
+            syn::ReturnType::Type(_, ty) => Some(*ty),
         };
 
         (
@@ -531,7 +538,6 @@ impl Function {
                 ret,
                 opts,
                 rust_vis: vis,
-                rust_decl: decl,
                 rust_attrs: attrs,
             },
             mutable,

crates/backend/src/codegen.rs

@@ -1,10 +1,10 @@
 use std::borrow::Cow;
 use std::collections::HashSet;
 use std::env;
-use std::sync::atomic::{ATOMIC_USIZE_INIT, AtomicUsize, Ordering};
+use std::sync::atomic::{AtomicUsize, Ordering, ATOMIC_USIZE_INIT};
 
 use ast;
-use proc_macro2::{Span, Ident, TokenStream};
+use proc_macro2::{Ident, Span, TokenStream};
 use quote::ToTokens;
 use serde_json;
 use shared;
@@ -50,7 +50,7 @@ impl ToTokens for ast::Program {
                 if types.contains(ns) && i.kind.fits_on_impl() {
                     let kind = &i.kind;
                     (quote! { impl #ns { #kind } }).to_tokens(tokens);
-                    continue
+                    continue;
                 }
             }
 
@@ -240,7 +240,10 @@ impl ToTokens for ast::StructField {
         let ty = &self.ty;
         let getter = &self.getter;
         let setter = &self.setter;
-        let desc = Ident::new(&format!("__wbindgen_describe_{}", getter), Span::call_site());
+        let desc = Ident::new(
+            &format!("__wbindgen_describe_{}", getter),
+            Span::call_site(),
+        );
         (quote! {
             #[no_mangle]
             #[cfg(all(target_arch = "wasm32", not(target_os = "emscripten")))]
@@ -270,7 +273,7 @@ impl ToTokens for ast::StructField {
         }).to_tokens(tokens);
 
         if self.opts.readonly() {
-            return
+            return;
         }
 
         (quote! {
@@ -315,7 +318,7 @@ impl ToTokens for ast::Export {
             offset = 1;
         }
 
-        for (i, ty) in self.function.arguments.iter().enumerate() {
+        for (i, syn::ArgCaptured { ty, .. }) in self.function.arguments.iter().enumerate() {
             let i = i + offset;
             let ident = Ident::new(&format!("arg{}", i), Span::call_site());
             match *ty {
@@ -377,8 +380,8 @@ impl ToTokens for ast::Export {
                 };
             }
             None => {
-                ret_ty = quote!{};
+                ret_ty = quote!();
-                convert_ret = quote!{};
+                convert_ret = quote!();
             }
         }
         let describe_ret = match &self.function.ret {
@@ -406,7 +409,7 @@ impl ToTokens for ast::Export {
         let descriptor_name = format!("__wbindgen_describe_{}", export_name);
         let descriptor_name = Ident::new(&descriptor_name, Span::call_site());
         let nargs = self.function.arguments.len() as u32;
-        let argtys = self.function.arguments.iter();
+        let argtys = self.function.arguments.iter().map(|arg| &arg.ty);
 
         let tokens = quote! {
             #[export_name = #export_name]
@@ -559,37 +562,27 @@ impl ToTokens for ast::ImportFunction {
             ast::ImportFunctionKind::Normal => {}
         }
         let vis = &self.function.rust_vis;
-        let ret = &self.function.rust_decl.output;
+        let ret = match &self.function.ret {
-        let fn_token = &self.function.rust_decl.fn_token;
+            Some(ty) => quote! { -> #ty },
+            None => quote!(),
+        };
 
         let mut abi_argument_names = Vec::new();
         let mut abi_arguments = Vec::new();
         let mut arg_conversions = Vec::new();
         let ret_ident = Ident::new("_ret", Span::call_site());
 
-        let names = self.function
+        for (i, syn::ArgCaptured { pat, ty, .. }) in self.function.arguments.iter().enumerate() {
-            .rust_decl
+            let name = match pat {
-            .inputs
+                syn::Pat::Ident(syn::PatIdent {
-            .iter()
+                    by_ref: None,
-            .map(|arg| {
+                    ident,
-                match arg {
+                    subpat: None,
-                    syn::FnArg::Captured(c) => c,
+                    ..
-                    _ => panic!("arguments cannot be `self` or ignored"),
+                }) => ident.clone(),
-                }
+                _ => panic!("unsupoported pattern in foreign function"),
-            })
+            };
-            .map(|arg| {
-                match &arg.pat {
-                    syn::Pat::Ident(syn::PatIdent {
-                        by_ref: None,
-                        ident,
-                        subpat: None,
-                        ..
-                    }) => ident.clone(),
-                    _ => panic!("unsupported pattern in foreign function"),
-                }
-            });
 
-        for (i, (ty, name)) in self.function.arguments.iter().zip(names).enumerate() {
             abi_argument_names.push(name.clone());
             abi_arguments.push(quote! {
                 #name: <#ty as ::wasm_bindgen::convert::IntoWasmAbi>::Abi
@@ -606,7 +599,7 @@ impl ToTokens for ast::ImportFunction {
         }
         let abi_ret;
         let mut convert_ret;
-        match self.function.ret {
+        match &self.js_ret {
             Some(syn::Type::Reference(_)) => {
                 panic!("cannot return references in imports yet");
             }
@@ -628,7 +621,7 @@ impl ToTokens for ast::ImportFunction {
             }
         }
 
-        let mut exceptional_ret = quote!{};
+        let mut exceptional_ret = quote!();
         let exn_data = if self.function.opts.catch() {
             let exn_data = Ident::new("exn_data", Span::call_site());
             let exn_data_ptr = Ident::new("exn_data_ptr", Span::call_site());
@@ -649,20 +642,18 @@ impl ToTokens for ast::ImportFunction {
                 let #exn_data_ptr = #exn_data.as_mut_ptr();
             }
         } else {
-            quote! {}
+            quote!()
         };
 
         let rust_name = &self.rust_name;
         let import_name = &self.shim;
         let attrs = &self.function.rust_attrs;
 
-        let arguments = self.function
+        let arguments = if is_method {
-            .rust_decl
+            &self.function.arguments[1..]
-            .inputs
+        } else {
-            .iter()
+            &self.function.arguments[..]
-            .skip(if is_method { 1 } else { 0 })
+        };
-            .collect::<Vec<_>>();
-        let arguments = &arguments[..];
 
         let me = if is_method {
             quote! { &self, }
@@ -674,7 +665,7 @@ impl ToTokens for ast::ImportFunction {
             #(#attrs)*
             #[allow(bad_style)]
             #[cfg(all(target_arch = "wasm32", not(target_os = "emscripten")))]
-            #vis extern #fn_token #rust_name(#me #(#arguments),*) #ret {
+            #vis extern fn #rust_name(#me #(#arguments),*) #ret {
                 ::wasm_bindgen::__rt::link_this_library();
                 #[wasm_import_module = "__wbindgen_placeholder__"]
                 extern {
@@ -695,7 +686,7 @@ impl ToTokens for ast::ImportFunction {
             #(#attrs)*
             #[allow(bad_style, unused_variables)]
             #[cfg(not(all(target_arch = "wasm32", not(target_os = "emscripten"))))]
-            #vis extern #fn_token #rust_name(#me #(#arguments),*) #ret {
+            #vis extern fn #rust_name(#me #(#arguments),*) #ret {
                 panic!("cannot call wasm-bindgen imported functions on \
                         non-wasm targets");
             }
@@ -726,9 +717,9 @@ impl<'a> ToTokens for DescribeImport<'a> {
         };
         let describe_name = format!("__wbindgen_describe_{}", f.shim);
         let describe_name = Ident::new(&describe_name, Span::call_site());
-        let argtys = f.function.arguments.iter();
+        let argtys = f.function.arguments.iter().map(|arg| &arg.ty);
         let nargs = f.function.arguments.len() as u32;
-        let inform_ret = match f.function.ret {
+        let inform_ret = match &f.js_ret {
             Some(ref t) => quote! { inform(1); <#t as WasmDescribe>::describe(); },
             None => quote! { inform(0); },
         };

crates/webidl/src/lib.rs

@@ -18,15 +18,19 @@ extern crate syn;
 extern crate wasm_bindgen_backend as backend;
 extern crate webidl;
 
-use failure::ResultExt;
-use heck::SnakeCase;
-use proc_macro2::Ident;
-use quote::ToTokens;
 use std::fs;
 use std::io::{self, Read};
-use std::iter::FromIterator;
+use std::iter;
 use std::path::Path;
 
+use failure::ResultExt;
+use heck::CamelCase;
+use quote::ToTokens;
+
+mod util;
+
+use util::{create_function, ident_ty, raw_ident, rust_ident, webidl_ty_to_syn_ty, TypePosition};
+
 /// Either `Ok(t)` or `Err(failure::Error)`.
 pub type Result<T> = ::std::result::Result<T, failure::Error>;
 
@@ -70,43 +74,11 @@ fn compile_ast(ast: &backend::ast::Program) -> String {
     tokens.to_string()
 }
 
-fn is_rust_keyword(name: &str) -> bool {
+trait WebidlParse<Ctx> {
-    match name {
+    fn webidl_parse(&self, program: &mut backend::ast::Program, context: Ctx) -> Result<()>;
-        "abstract" | "alignof" | "as" | "become" | "box" | "break" | "const" | "continue"
-        | "crate" | "do" | "else" | "enum" | "extern" | "false" | "final" | "fn" | "for" | "if"
-        | "impl" | "in" | "let" | "loop" | "macro" | "match" | "mod" | "move" | "mut"
-        | "offsetof" | "override" | "priv" | "proc" | "pub" | "pure" | "ref" | "return"
-        | "Self" | "self" | "sizeof" | "static" | "struct" | "super" | "trait" | "true"
-        | "type" | "typeof" | "unsafe" | "unsized" | "use" | "virtual" | "where" | "while"
-        | "yield" | "bool" | "_" => true,
-        _ => false,
-    }
 }
 
-// Create an `Ident`, possibly mangling it if it conflicts with a Rust keyword.
+impl WebidlParse<()> for Vec<webidl::ast::Definition> {
-fn rust_ident(name: &str) -> Ident {
-    if is_rust_keyword(name) {
-        Ident::new(&format!("{}_", name), proc_macro2::Span::call_site())
-    } else {
-        raw_ident(name)
-    }
-}
-
-// Create an `Ident` without checking to see if it conflicts with a Rust
-// keyword.
-fn raw_ident(name: &str) -> Ident {
-    Ident::new(name, proc_macro2::Span::call_site())
-}
-
-trait WebidlParse<'a> {
-    type Extra;
-
-    fn webidl_parse(&self, program: &mut backend::ast::Program, extra: Self::Extra) -> Result<()>;
-}
-
-impl<'a> WebidlParse<'a> for Vec<webidl::ast::Definition> {
-    type Extra = ();
-
     fn webidl_parse(&self, program: &mut backend::ast::Program, _: ()) -> Result<()> {
         for def in self {
             def.webidl_parse(program, ())?;
@@ -115,9 +87,7 @@ impl<'a> WebidlParse<'a> for Vec<webidl::ast::Definition> {
     }
 }
 
-impl<'a> WebidlParse<'a> for webidl::ast::Definition {
+impl WebidlParse<()> for webidl::ast::Definition {
-    type Extra = ();
-
     fn webidl_parse(&self, program: &mut backend::ast::Program, _: ()) -> Result<()> {
         match *self {
             webidl::ast::Definition::Interface(ref interface) => {
@@ -139,9 +109,7 @@ impl<'a> WebidlParse<'a> for webidl::ast::Definition {
     }
 }
 
-impl<'a> WebidlParse<'a> for webidl::ast::Interface {
+impl WebidlParse<()> for webidl::ast::Interface {
-    type Extra = ();
-
     fn webidl_parse(&self, program: &mut backend::ast::Program, _: ()) -> Result<()> {
         match *self {
             webidl::ast::Interface::NonPartial(ref interface) => {
@@ -156,9 +124,7 @@ impl<'a> WebidlParse<'a> for webidl::ast::Interface {
     }
 }
 
-impl<'a> WebidlParse<'a> for webidl::ast::Typedef {
+impl WebidlParse<()> for webidl::ast::Typedef {
-    type Extra = ();
-
     fn webidl_parse(&self, program: &mut backend::ast::Program, _: ()) -> Result<()> {
         let dest = rust_ident(&self.name);
         let src = match webidl_ty_to_syn_ty(&self.type_, TypePosition::Return) {
@@ -184,9 +150,7 @@ impl<'a> WebidlParse<'a> for webidl::ast::Typedef {
     }
 }
 
-impl<'a> WebidlParse<'a> for webidl::ast::NonPartialInterface {
+impl WebidlParse<()> for webidl::ast::NonPartialInterface {
-    type Extra = ();
-
     fn webidl_parse(&self, program: &mut backend::ast::Program, _: ()) -> Result<()> {
         program.imports.push(backend::ast::Import {
             module: None,
@@ -208,9 +172,7 @@ impl<'a> WebidlParse<'a> for webidl::ast::NonPartialInterface {
     }
 }
 
-impl<'a> WebidlParse<'a> for webidl::ast::InterfaceMember {
+impl<'a> WebidlParse<&'a str> for webidl::ast::InterfaceMember {
-    type Extra = &'a str;
-
     fn webidl_parse(&self, program: &mut backend::ast::Program, self_name: &'a str) -> Result<()> {
         match *self {
             webidl::ast::InterfaceMember::Attribute(ref attr) => {
@@ -229,9 +191,7 @@ impl<'a> WebidlParse<'a> for webidl::ast::InterfaceMember {
     }
 }
 
-impl<'a> WebidlParse<'a> for webidl::ast::Attribute {
+impl<'a> WebidlParse<&'a str> for webidl::ast::Attribute {
-    type Extra = &'a str;
-
     fn webidl_parse(&self, program: &mut backend::ast::Program, self_name: &'a str) -> Result<()> {
         match *self {
             webidl::ast::Attribute::Regular(ref attr) => attr.webidl_parse(program, self_name),
@@ -244,9 +204,7 @@ impl<'a> WebidlParse<'a> for webidl::ast::Attribute {
     }
 }
 
-impl<'a> WebidlParse<'a> for webidl::ast::Operation {
+impl<'a> WebidlParse<&'a str> for webidl::ast::Operation {
-    type Extra = &'a str;
-
     fn webidl_parse(&self, program: &mut backend::ast::Program, self_name: &'a str) -> Result<()> {
         match *self {
             webidl::ast::Operation::Regular(ref op) => op.webidl_parse(program, self_name),
@@ -261,192 +219,39 @@ impl<'a> WebidlParse<'a> for webidl::ast::Operation {
     }
 }
 
-fn simple_path_ty<I>(segments: I) -> syn::Type
+impl<'a> WebidlParse<&'a str> for webidl::ast::RegularAttribute {
-where
-    I: IntoIterator<Item = Ident>,
-{
-    let segments: Vec<_> = segments
-        .into_iter()
-        .map(|i| syn::PathSegment {
-            ident: i,
-            arguments: syn::PathArguments::None,
-        })
-        .collect();
-
-    syn::TypePath {
-        qself: None,
-        path: syn::Path {
-            leading_colon: None,
-            segments: syn::punctuated::Punctuated::from_iter(segments),
-        },
-    }.into()
-}
-
-fn ident_ty(ident: Ident) -> syn::Type {
-    simple_path_ty(Some(ident))
-}
-
-fn shared_ref(ty: syn::Type) -> syn::Type {
-    syn::TypeReference {
-        and_token: Default::default(),
-        lifetime: None,
-        mutability: None,
-        elem: Box::new(ty),
-    }.into()
-}
-
-#[derive(Copy, Clone, Debug, PartialEq, Eq)]
-enum TypePosition {
-    Argument,
-    Return,
-}
-
-fn webidl_ty_to_syn_ty(ty: &webidl::ast::Type, pos: TypePosition) -> Option<syn::Type> {
-    // nullable types are not yet supported (see issue #14)
-    if ty.nullable {
-        return None;
-    }
-    Some(match ty.kind {
-        // `any` becomes `::wasm_bindgen::JsValue`.
-        webidl::ast::TypeKind::Any => {
-            simple_path_ty(vec![rust_ident("wasm_bindgen"), rust_ident("JsValue")])
-        }
-
-        // A reference to a type by name becomes the same thing in the
-        // bindings.
-        webidl::ast::TypeKind::Identifier(ref id) => ident_ty(rust_ident(id)),
-
-        // Scalars.
-        webidl::ast::TypeKind::Boolean => ident_ty(raw_ident("bool")),
-        webidl::ast::TypeKind::Byte => ident_ty(raw_ident("i8")),
-        webidl::ast::TypeKind::Octet => ident_ty(raw_ident("u8")),
-        webidl::ast::TypeKind::RestrictedDouble | webidl::ast::TypeKind::UnrestrictedDouble => {
-            ident_ty(raw_ident("f64"))
-        }
-        webidl::ast::TypeKind::RestrictedFloat | webidl::ast::TypeKind::UnrestrictedFloat => {
-            ident_ty(raw_ident("f32"))
-        }
-        webidl::ast::TypeKind::SignedLong => ident_ty(raw_ident("i32")),
-        webidl::ast::TypeKind::SignedLongLong => ident_ty(raw_ident("i64")),
-        webidl::ast::TypeKind::SignedShort => ident_ty(raw_ident("i16")),
-        webidl::ast::TypeKind::UnsignedLong => ident_ty(raw_ident("u32")),
-        webidl::ast::TypeKind::UnsignedLongLong => ident_ty(raw_ident("u64")),
-        webidl::ast::TypeKind::UnsignedShort => ident_ty(raw_ident("u16")),
-
-        // `DOMString -> `&str` for arguments
-        webidl::ast::TypeKind::DOMString if pos == TypePosition::Argument => {
-            shared_ref(ident_ty(raw_ident("str")))
-        }
-        // `DOMString` is not supported yet in other positions.
-        webidl::ast::TypeKind::DOMString => return None,
-
-        // Support for these types is not yet implemented, so skip
-        // generating any bindings for this function.
-        webidl::ast::TypeKind::ArrayBuffer
-        | webidl::ast::TypeKind::ByteString
-        | webidl::ast::TypeKind::DataView
-        | webidl::ast::TypeKind::Error
-        | webidl::ast::TypeKind::Float32Array
-        | webidl::ast::TypeKind::Float64Array
-        | webidl::ast::TypeKind::FrozenArray(_)
-        | webidl::ast::TypeKind::Int16Array
-        | webidl::ast::TypeKind::Int32Array
-        | webidl::ast::TypeKind::Int8Array
-        | webidl::ast::TypeKind::Object
-        | webidl::ast::TypeKind::Promise(_)
-        | webidl::ast::TypeKind::Record(..)
-        | webidl::ast::TypeKind::Sequence(_)
-        | webidl::ast::TypeKind::Symbol
-        | webidl::ast::TypeKind::USVString
-        | webidl::ast::TypeKind::Uint16Array
-        | webidl::ast::TypeKind::Uint32Array
-        | webidl::ast::TypeKind::Uint8Array
-        | webidl::ast::TypeKind::Uint8ClampedArray
-        | webidl::ast::TypeKind::Union(_) => {
-            return None;
-        }
-    })
-}
-
-fn simple_fn_arg(ident: Ident, ty: syn::Type) -> syn::FnArg {
-    syn::FnArg::Captured(syn::ArgCaptured {
-        pat: syn::Pat::Ident(syn::PatIdent {
-            by_ref: None,
-            mutability: None,
-            ident,
-            subpat: None,
-        }),
-        colon_token: Default::default(),
-        ty,
-    })
-}
-
-impl<'a> WebidlParse<'a> for webidl::ast::RegularAttribute {
-    type Extra = &'a str;
-
     fn webidl_parse(&self, program: &mut backend::ast::Program, self_name: &'a str) -> Result<()> {
         fn create_getter(
             this: &webidl::ast::RegularAttribute,
             self_name: &str,
         ) -> Option<backend::ast::Import> {
-            let name = raw_ident(&this.name);
+            let ret = match webidl_ty_to_syn_ty(&this.type_, TypePosition::Return) {
-            let rust_name = rust_ident(&this.name.to_snake_case());
-
-            let (output, ret) = match webidl_ty_to_syn_ty(&this.type_, TypePosition::Return) {
                 None => {
                     warn!("Attribute's type does not yet support reading: {:?}. Skipping getter binding for {:?}",
                         this.type_, this);
                     return None;
                 }
-                Some(ty) => (
+                Some(ty) => Some(ty),
-                    syn::ReturnType::Type(Default::default(), Box::new(ty.clone())),
-                    Some(ty),
-                ),
             };
 
-            let self_ty = ident_ty(rust_ident(self_name));
+            let kind = backend::ast::ImportFunctionKind::Method {
-            let self_ref_ty = shared_ref(self_ty.clone());
+                class: self_name.to_string(),
+                ty: ident_ty(rust_ident(self_name)),
+            };
 
-            let shim = rust_ident(&format!("__wbg_f_{}_{}_{}", name, rust_name, self_name));
+            create_function(
-
+                &this.name,
-            Some(backend::ast::Import {
+                iter::empty(),
+                kind,
+                ret,
+                vec![backend::ast::BindgenAttr::Getter(Some(raw_ident(
+                    &this.name,
+                )))],
+            ).map(|function| backend::ast::Import {
                 module: None,
                 version: None,
                 js_namespace: None,
-                kind: backend::ast::ImportKind::Function(backend::ast::ImportFunction {
+                kind: backend::ast::ImportKind::Function(function),
-                    function: backend::ast::Function {
-                        name: name.clone(),
-                        arguments: vec![self_ref_ty.clone()],
-                        ret,
-                        opts: backend::ast::BindgenAttrs {
-                            attrs: vec![
-                                backend::ast::BindgenAttr::Method,
-                                backend::ast::BindgenAttr::Getter(Some(name.clone())),
-                            ],
-                        },
-                        rust_attrs: vec![],
-                        rust_decl: Box::new(syn::FnDecl {
-                            fn_token: Default::default(),
-                            generics: Default::default(),
-                            paren_token: Default::default(),
-                            inputs: syn::punctuated::Punctuated::from_iter(vec![simple_fn_arg(
-                                raw_ident("self_"),
-                                self_ref_ty,
-                            )]),
-                            variadic: None,
-                            output,
-                        }),
-                        rust_vis: syn::Visibility::Public(syn::VisPublic {
-                            pub_token: Default::default(),
-                        }),
-                    },
-                    rust_name,
-                    kind: backend::ast::ImportFunctionKind::Method {
-                        class: self_name.to_string(),
-                        ty: self_ty,
-                    },
-                    shim,
-                }),
             })
         }
 
@@ -454,65 +259,24 @@ impl<'a> WebidlParse<'a> for webidl::ast::RegularAttribute {
             this: &webidl::ast::RegularAttribute,
             self_name: &str,
         ) -> Option<backend::ast::Import> {
-            let name = raw_ident(&this.name);
+            let kind = backend::ast::ImportFunctionKind::Method {
-            let rust_attr_name = rust_ident(&this.name.to_snake_case());
+                class: self_name.to_string(),
-            let rust_name = rust_ident(&format!("set_{}", rust_attr_name));
+                ty: ident_ty(rust_ident(self_name)),
-
-            let self_ty = ident_ty(rust_ident(self_name));
-
-            let (inputs, arguments) = match webidl_ty_to_syn_ty(&this.type_, TypePosition::Argument)
-            {
-                None => {
-                    warn!("Attribute's type does not yet support writing: {:?}. Skipping setter binding for {:?}",
-                        this.type_, this);
-                    return None;
-                }
-                Some(ty) => {
-                    let self_ref_ty = shared_ref(self_ty.clone());
-                    let mut inputs = syn::punctuated::Punctuated::new();
-                    inputs.push(simple_fn_arg(raw_ident("self_"), self_ref_ty.clone()));
-                    inputs.push(simple_fn_arg(rust_attr_name, ty.clone()));
-                    (inputs, vec![self_ref_ty, ty])
-                }
             };
 
-            let shim = rust_ident(&format!("__wbg_f_{}_{}_{}", name, rust_name, self_name));
+            create_function(
-
+                &format!("set_{}", this.name.to_camel_case()),
-            Some(backend::ast::Import {
+                iter::once((&*this.name, &*this.type_, false)),
+                kind,
+                None,
+                vec![backend::ast::BindgenAttr::Setter(Some(raw_ident(
+                    &this.name,
+                )))],
+            ).map(|function| backend::ast::Import {
                 module: None,
                 version: None,
                 js_namespace: None,
-                kind: backend::ast::ImportKind::Function(backend::ast::ImportFunction {
+                kind: backend::ast::ImportKind::Function(function),
-                    function: backend::ast::Function {
-                        name: name.clone(),
-                        arguments,
-                        ret: None,
-                        opts: backend::ast::BindgenAttrs {
-                            attrs: vec![
-                                backend::ast::BindgenAttr::Method,
-                                backend::ast::BindgenAttr::Setter(Some(name)),
-                            ],
-                        },
-                        rust_attrs: vec![],
-                        rust_decl: Box::new(syn::FnDecl {
-                            fn_token: Default::default(),
-                            generics: Default::default(),
-                            paren_token: Default::default(),
-                            inputs,
-                            variadic: None,
-                            output: syn::ReturnType::Default,
-                        }),
-                        rust_vis: syn::Visibility::Public(syn::VisPublic {
-                            pub_token: Default::default(),
-                        }),
-                    },
-                    rust_name,
-                    kind: backend::ast::ImportFunctionKind::Method {
-                        class: self_name.to_string(),
-                        ty: self_ty,
-                    },
-                    shim,
-                }),
             })
         }
 
@@ -526,9 +290,7 @@ impl<'a> WebidlParse<'a> for webidl::ast::RegularAttribute {
     }
 }
 
-impl<'a> WebidlParse<'a> for webidl::ast::RegularOperation {
+impl<'a> WebidlParse<&'a str> for webidl::ast::RegularOperation {
-    type Extra = &'a str;
-
     fn webidl_parse(&self, program: &mut backend::ast::Program, self_name: &'a str) -> Result<()> {
         let name = match self.name {
             None => {
@@ -541,11 +303,13 @@ impl<'a> WebidlParse<'a> for webidl::ast::RegularOperation {
             Some(ref name) => name,
         };
 
-        let rust_name = rust_ident(&name.to_snake_case());
+        let kind = backend::ast::ImportFunctionKind::Method {
-        let name = raw_ident(name);
+            class: self_name.to_string(),
+            ty: ident_ty(rust_ident(self_name)),
+        };
 
-        let (output, ret) = match self.return_type {
+        let ret = match self.return_type {
-            webidl::ast::ReturnType::Void => (syn::ReturnType::Default, None),
+            webidl::ast::ReturnType::Void => None,
             webidl::ast::ReturnType::NonVoid(ref ty) => {
                 match webidl_ty_to_syn_ty(ty, TypePosition::Return) {
                     None => {
@@ -555,80 +319,26 @@ impl<'a> WebidlParse<'a> for webidl::ast::RegularOperation {
                     );
                         return Ok(());
                     }
-                    Some(ty) => (
+                    Some(ty) => Some(ty),
-                        syn::ReturnType::Type(Default::default(), Box::new(ty.clone())),
-                        Some(ty),
-                    ),
                 }
             }
         };
 
-        let mut inputs = Vec::with_capacity(self.arguments.len() + 1);
+        create_function(
-        let mut arguments = Vec::with_capacity(self.arguments.len() + 1);
+            &name,
-
+            self.arguments
-        let self_ty = ident_ty(rust_ident(self_name));
+                .iter()
-        let self_ref_ty = shared_ref(self_ty.clone());
+                .map(|arg| (&*arg.name, &*arg.type_, arg.variadic)),
-        inputs.push(simple_fn_arg(raw_ident("self_"), self_ref_ty.clone()));
+            kind,
-        arguments.push(self_ref_ty);
+            ret,
-
+            Vec::new(),
-        for arg in &self.arguments {
+        ).map(|function| {
-            if arg.variadic {
+            program.imports.push(backend::ast::Import {
-                warn!(
+                module: None,
-                    "Variadic arguments are not supported yet. Skipping bindings for {:?}",
+                version: None,
-                    self
+                js_namespace: None,
-                );
+                kind: backend::ast::ImportKind::Function(function),
-                return Ok(());
+            })
-            }
-
-            match webidl_ty_to_syn_ty(&arg.type_, TypePosition::Argument) {
-                None => {
-                    warn!(
-                        "Argument's type is not yet supported: {:?}. Skipping bindings for {:?}",
-                        arg.type_, self
-                    );
-                    return Ok(());
-                }
-                Some(ty) => {
-                    inputs.push(simple_fn_arg(rust_ident(&arg.name), ty.clone()));
-                    arguments.push(ty);
-                }
-            }
-        }
-
-        let shim = rust_ident(&format!("__wbg_f_{}_{}_{}", name, rust_name, self_name));
-
-        program.imports.push(backend::ast::Import {
-            module: None,
-            version: None,
-            js_namespace: None,
-            kind: backend::ast::ImportKind::Function(backend::ast::ImportFunction {
-                function: backend::ast::Function {
-                    name,
-                    arguments,
-                    ret,
-                    opts: backend::ast::BindgenAttrs {
-                        attrs: vec![backend::ast::BindgenAttr::Method],
-                    },
-                    rust_attrs: vec![],
-                    rust_decl: Box::new(syn::FnDecl {
-                        fn_token: Default::default(),
-                        generics: Default::default(),
-                        paren_token: Default::default(),
-                        inputs: syn::punctuated::Punctuated::from_iter(inputs),
-                        variadic: None,
-                        output,
-                    }),
-                    rust_vis: syn::Visibility::Public(syn::VisPublic {
-                        pub_token: Default::default(),
-                    }),
-                },
-                rust_name,
-                kind: backend::ast::ImportFunctionKind::Method {
-                    class: self_name.to_string(),
-                    ty: self_ty,
-                },
-                shim,
-            }),
         });
 
         Ok(())

crates/webidl/src/util.rs

@@ -0,0 +1,241 @@
+use std::iter::FromIterator;
+
+use backend;
+use heck::SnakeCase;
+use proc_macro2::{self, Ident};
+use syn;
+use webidl;
+
+fn is_rust_keyword(name: &str) -> bool {
+    match name {
+        "abstract" | "alignof" | "as" | "become" | "box" | "break" | "const" | "continue"
+        | "crate" | "do" | "else" | "enum" | "extern" | "false" | "final" | "fn" | "for" | "if"
+        | "impl" | "in" | "let" | "loop" | "macro" | "match" | "mod" | "move" | "mut"
+        | "offsetof" | "override" | "priv" | "proc" | "pub" | "pure" | "ref" | "return"
+        | "Self" | "self" | "sizeof" | "static" | "struct" | "super" | "trait" | "true"
+        | "type" | "typeof" | "unsafe" | "unsized" | "use" | "virtual" | "where" | "while"
+        | "yield" | "bool" | "_" => true,
+        _ => false,
+    }
+}
+
+// Create an `Ident`, possibly mangling it if it conflicts with a Rust keyword.
+pub fn rust_ident(name: &str) -> Ident {
+    if is_rust_keyword(name) {
+        Ident::new(&format!("{}_", name), proc_macro2::Span::call_site())
+    } else {
+        raw_ident(name)
+    }
+}
+
+// Create an `Ident` without checking to see if it conflicts with a Rust
+// keyword.
+pub fn raw_ident(name: &str) -> Ident {
+    Ident::new(name, proc_macro2::Span::call_site())
+}
+
+fn simple_path_ty<I>(segments: I) -> syn::Type
+where
+    I: IntoIterator<Item = Ident>,
+{
+    let segments: Vec<_> = segments
+        .into_iter()
+        .map(|i| syn::PathSegment {
+            ident: i,
+            arguments: syn::PathArguments::None,
+        })
+        .collect();
+
+    syn::TypePath {
+        qself: None,
+        path: syn::Path {
+            leading_colon: None,
+            segments: syn::punctuated::Punctuated::from_iter(segments),
+        },
+    }.into()
+}
+
+pub fn ident_ty(ident: Ident) -> syn::Type {
+    simple_path_ty(Some(ident))
+}
+
+fn shared_ref(ty: syn::Type) -> syn::Type {
+    syn::TypeReference {
+        and_token: Default::default(),
+        lifetime: None,
+        mutability: None,
+        elem: Box::new(ty),
+    }.into()
+}
+
+#[derive(Copy, Clone, Debug, PartialEq, Eq)]
+pub enum TypePosition {
+    Argument,
+    Return,
+}
+
+pub fn webidl_ty_to_syn_ty(ty: &webidl::ast::Type, pos: TypePosition) -> Option<syn::Type> {
+    // nullable types are not yet supported (see issue #14)
+    if ty.nullable {
+        return None;
+    }
+    Some(match ty.kind {
+        // `any` becomes `::wasm_bindgen::JsValue`.
+        webidl::ast::TypeKind::Any => {
+            simple_path_ty(vec![rust_ident("wasm_bindgen"), rust_ident("JsValue")])
+        }
+
+        // A reference to a type by name becomes the same thing in the
+        // bindings.
+        webidl::ast::TypeKind::Identifier(ref id) => ident_ty(rust_ident(id)),
+
+        // Scalars.
+        webidl::ast::TypeKind::Boolean => ident_ty(raw_ident("bool")),
+        webidl::ast::TypeKind::Byte => ident_ty(raw_ident("i8")),
+        webidl::ast::TypeKind::Octet => ident_ty(raw_ident("u8")),
+        webidl::ast::TypeKind::RestrictedDouble | webidl::ast::TypeKind::UnrestrictedDouble => {
+            ident_ty(raw_ident("f64"))
+        }
+        webidl::ast::TypeKind::RestrictedFloat | webidl::ast::TypeKind::UnrestrictedFloat => {
+            ident_ty(raw_ident("f32"))
+        }
+        webidl::ast::TypeKind::SignedLong => ident_ty(raw_ident("i32")),
+        webidl::ast::TypeKind::SignedLongLong => ident_ty(raw_ident("i64")),
+        webidl::ast::TypeKind::SignedShort => ident_ty(raw_ident("i16")),
+        webidl::ast::TypeKind::UnsignedLong => ident_ty(raw_ident("u32")),
+        webidl::ast::TypeKind::UnsignedLongLong => ident_ty(raw_ident("u64")),
+        webidl::ast::TypeKind::UnsignedShort => ident_ty(raw_ident("u16")),
+
+        // `DOMString -> `&str` for arguments
+        webidl::ast::TypeKind::DOMString if pos == TypePosition::Argument => {
+            shared_ref(ident_ty(raw_ident("str")))
+        }
+        // `DOMString` is not supported yet in other positions.
+        webidl::ast::TypeKind::DOMString => return None,
+
+        // Support for these types is not yet implemented, so skip
+        // generating any bindings for this function.
+        webidl::ast::TypeKind::ArrayBuffer
+        | webidl::ast::TypeKind::ByteString
+        | webidl::ast::TypeKind::DataView
+        | webidl::ast::TypeKind::Error
+        | webidl::ast::TypeKind::Float32Array
+        | webidl::ast::TypeKind::Float64Array
+        | webidl::ast::TypeKind::FrozenArray(_)
+        | webidl::ast::TypeKind::Int16Array
+        | webidl::ast::TypeKind::Int32Array
+        | webidl::ast::TypeKind::Int8Array
+        | webidl::ast::TypeKind::Object
+        | webidl::ast::TypeKind::Promise(_)
+        | webidl::ast::TypeKind::Record(..)
+        | webidl::ast::TypeKind::Sequence(_)
+        | webidl::ast::TypeKind::Symbol
+        | webidl::ast::TypeKind::USVString
+        | webidl::ast::TypeKind::Uint16Array
+        | webidl::ast::TypeKind::Uint32Array
+        | webidl::ast::TypeKind::Uint8Array
+        | webidl::ast::TypeKind::Uint8ClampedArray
+        | webidl::ast::TypeKind::Union(_) => {
+            return None;
+        }
+    })
+}
+
+fn simple_fn_arg(ident: Ident, ty: syn::Type) -> syn::ArgCaptured {
+    syn::ArgCaptured {
+        pat: syn::Pat::Ident(syn::PatIdent {
+            by_ref: None,
+            mutability: None,
+            ident,
+            subpat: None,
+        }),
+        colon_token: Default::default(),
+        ty,
+    }
+}
+
+fn webidl_arguments_to_syn_arg_captured<'a, I>(
+    arguments: I,
+    kind: &backend::ast::ImportFunctionKind,
+) -> Option<Vec<syn::ArgCaptured>>
+where
+    I: Iterator<Item = (&'a str, &'a webidl::ast::Type, bool)>,
+{
+    let estimate = arguments.size_hint();
+    let len = estimate.1.unwrap_or(estimate.0);
+    let mut res = if let backend::ast::ImportFunctionKind::Method { ty, .. } = kind {
+        let mut res = Vec::with_capacity(len + 1);
+        res.push(simple_fn_arg(raw_ident("self_"), shared_ref(ty.clone())));
+        res
+    } else {
+        Vec::with_capacity(len)
+    };
+
+    for (name, ty, variadic) in arguments {
+        if variadic {
+            warn!("Variadic arguments are not supported yet",);
+            return None;
+        }
+
+        match webidl_ty_to_syn_ty(ty, TypePosition::Argument) {
+            None => {
+                warn!("Argument's type is not yet supported: {:?}", ty);
+                return None;
+            }
+            Some(ty) => res.push(simple_fn_arg(rust_ident(&name.to_snake_case()), ty)),
+        }
+    }
+
+    Some(res)
+}
+
+pub fn create_function<'a, 'b, I>(
+    name: &str,
+    arguments: I,
+    kind: backend::ast::ImportFunctionKind,
+    ret: Option<syn::Type>,
+    mut attrs: Vec<backend::ast::BindgenAttr>,
+) -> Option<backend::ast::ImportFunction>
+where
+    I: Iterator<Item = (&'a str, &'a webidl::ast::Type, bool)>,
+{
+    let rust_name = rust_ident(&name.to_snake_case());
+    let name = raw_ident(name);
+
+    let arguments = webidl_arguments_to_syn_arg_captured(arguments, &kind)?;
+
+    let js_ret = ret.clone();
+
+    if let backend::ast::ImportFunctionKind::Method { .. } = kind {
+        attrs.push(backend::ast::BindgenAttr::Method);
+    }
+
+    let opts = backend::ast::BindgenAttrs { attrs };
+
+    let shim = {
+        let ns = match kind {
+            backend::ast::ImportFunctionKind::Normal => "",
+            backend::ast::ImportFunctionKind::Method { ref class, .. } => class,
+            backend::ast::ImportFunctionKind::JsConstructor { ref class, .. } => class,
+        };
+
+        raw_ident(&format!("__widl_f_{}_{}", rust_name, ns))
+    };
+
+    Some(backend::ast::ImportFunction {
+        function: backend::ast::Function {
+            name,
+            arguments,
+            ret,
+            opts,
+            rust_attrs: vec![],
+            rust_vis: syn::Visibility::Public(syn::VisPublic {
+                pub_token: Default::default(),
+            }),
+        },
+        rust_name,
+        js_ret,
+        kind,
+        shim,
+    })
+}