Introduce the wasm-bindgen-webidl frontend

This is still a work in progress. Parse WebIDL source text and convert it into
wasm-bindgen AST, so that we can automatically emit bindings for the types and
functions described in the WebIDL.

Cargo.toml

@@ -37,6 +37,7 @@ wasm-bindgen-cli-support = { path = "crates/cli-support", version = '=0.2.11' }
 [workspace]
 members = [
   "crates/cli",
+  "crates/webidl",
   "examples/hello_world",
   "examples/smorgasboard",
   "examples/console_log",

crates/webidl/Cargo.toml

@@ -0,0 +1,18 @@
+[package]
+name = "wasm-bindgen-webidl"
+version = "0.1.0"
+authors = ["Nick Fitzgerald <fitzgen@gmail.com>"]
+
+[[test]]
+name = "webidl-all"
+path = "tests/all/lib.rs"
+
+[dev-dependencies]
+wasm-bindgen-backend = { version = "=0.2.11", path = "../backend", features = ["extra-traits"] }
+
+[dependencies]
+failure = "0.1"
+proc-macro2 = "0.4"
+syn = { version = '0.14', features = ['full'] }
+wasm-bindgen-backend = { version = "=0.2.11", path = "../backend" }
+webidl = "0.6.0"

crates/webidl/src/lib.rs

@@ -0,0 +1,102 @@
+/*!
+# `wasm_bindgen_webidl`
+
+Converts WebIDL into wasm-bindgen's internal AST form, so that bindings can be
+emitted for the types and methods described in the WebIDL.
+ */
+
+#![deny(missing_docs)]
+#![deny(missing_debug_implementations)]
+
+extern crate failure;
+extern crate proc_macro2;
+extern crate syn;
+extern crate wasm_bindgen_backend as backend;
+extern crate webidl;
+
+use failure::ResultExt;
+use proc_macro2::Ident;
+use std::fs;
+use std::io::{self, Read};
+use std::path::Path;
+
+/// Either `Ok(t)` or `Err(failure::Error)`.
+pub type Result<T> = ::std::result::Result<T, failure::Error>;
+
+/// Parse the WebIDL at the given path into a wasm-bindgen AST.
+pub fn parse_file(webidl_path: &Path) -> Result<backend::ast::Program> {
+    let file = fs::File::open(webidl_path).context("opening WebIDL file")?;
+    let mut file = io::BufReader::new(file);
+    let mut source = String::new();
+    file.read_to_string(&mut source)
+        .context("reading WebIDL file")?;
+    parse(&source)
+}
+
+/// Parse a string of WebIDL source text into a wasm-bindgen AST.
+pub fn parse(webidl_source: &str) -> Result<backend::ast::Program> {
+    let definitions = webidl::parse_string(webidl_source).context("parsing WebIDL source text")?;
+
+    let mut program = backend::ast::Program::default();
+    definitions.webidl_parse(&mut program)?;
+
+    Ok(program)
+}
+
+trait WebidlParse {
+    fn webidl_parse(&self, program: &mut backend::ast::Program) -> Result<()>;
+}
+
+impl WebidlParse for Vec<webidl::ast::Definition> {
+    fn webidl_parse(&self, program: &mut backend::ast::Program) -> Result<()> {
+        for def in self {
+            def.webidl_parse(program)?;
+        }
+        Ok(())
+    }
+}
+
+impl WebidlParse for webidl::ast::Definition {
+    fn webidl_parse(&self, program: &mut backend::ast::Program) -> Result<()> {
+        match *self {
+            webidl::ast::Definition::Interface(ref interface) => interface.webidl_parse(program),
+            // TODO
+            webidl::ast::Definition::Callback(..)
+            | webidl::ast::Definition::Dictionary(..)
+            | webidl::ast::Definition::Enum(..)
+            | webidl::ast::Definition::Implements(..)
+            | webidl::ast::Definition::Includes(..)
+            | webidl::ast::Definition::Mixin(..)
+            | webidl::ast::Definition::Namespace(..)
+            | webidl::ast::Definition::Typedef(..) => Ok(()),
+        }
+    }
+}
+
+impl WebidlParse for webidl::ast::Interface {
+    fn webidl_parse(&self, program: &mut backend::ast::Program) -> Result<()> {
+        match *self {
+            webidl::ast::Interface::NonPartial(ref interface) => interface.webidl_parse(program),
+            // TODO
+            webidl::ast::Interface::Callback(..) | webidl::ast::Interface::Partial(..) => Ok(()),
+        }
+    }
+}
+
+impl WebidlParse for webidl::ast::NonPartialInterface {
+    fn webidl_parse(&self, program: &mut backend::ast::Program) -> Result<()> {
+        program.imports.push(backend::ast::Import {
+            module: None,
+            version: None,
+            js_namespace: None,
+            kind: backend::ast::ImportKind::Type(backend::ast::ImportType {
+                vis: syn::Visibility::Public(syn::VisPublic {
+                    pub_token: syn::token::Pub(proc_macro2::Span::call_site()),
+                }),
+                name: Ident::new(&self.name, proc_macro2::Span::call_site()),
+            }),
+        });
+        println!("{:#?}", self);
+        Ok(())
+    }
+}

crates/webidl/tests/all/Event.webidl

@@ -0,0 +1,59 @@
+/* -*- Mode: IDL; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this file,
+ * You can obtain one at http://mozilla.org/MPL/2.0/.
+ *
+ * The origin of this IDL file is
+ * http://www.w3.org/TR/2012/WD-dom-20120105/
+ *
+ * Copyright © 2012 W3C® (MIT, ERCIM, Keio), All Rights Reserved. W3C
+ * liability, trademark and document use rules apply.
+ */
+
+[Constructor(DOMString type, optional EventInit eventInitDict),
+ Exposed=(Window,Worker,System), ProbablyShortLivingWrapper]
+interface Event {
+  [Pure]
+  readonly attribute DOMString type;
+  [Pure]
+  readonly attribute EventTarget? target;
+  [Pure]
+  readonly attribute EventTarget? currentTarget;
+
+  sequence<EventTarget> composedPath();
+
+  const unsigned short NONE = 0;
+  const unsigned short CAPTURING_PHASE = 1;
+  const unsigned short AT_TARGET = 2;
+  const unsigned short BUBBLING_PHASE = 3;
+  [Pure]
+  readonly attribute unsigned short eventPhase;
+
+  void stopPropagation();
+  void stopImmediatePropagation();
+
+  [Pure]
+  readonly attribute boolean bubbles;
+  [Pure]
+  readonly attribute boolean cancelable;
+  [NeedsCallerType]
+  void preventDefault();
+  [Pure, NeedsCallerType]
+  readonly attribute boolean defaultPrevented;
+  [ChromeOnly, Pure]
+  readonly attribute boolean defaultPreventedByChrome;
+  [ChromeOnly, Pure]
+  readonly attribute boolean defaultPreventedByContent;
+  [Pure]
+  readonly attribute boolean composed;
+
+  [Unforgeable, Pure]
+  readonly attribute boolean isTrusted;
+  [Pure]
+  readonly attribute DOMHighResTimeStamp timeStamp;
+
+  void initEvent(DOMString type,
+                 optional boolean bubbles = false,
+                 optional boolean cancelable = false);
+  attribute boolean cancelBubble;
+};

crates/webidl/tests/all/event.rs

@@ -0,0 +1,24 @@
+use super::backend;
+use proc_macro2;
+use syn;
+
+assert_parse!(
+    event,
+    include_str!("./Event.webidl"),
+    backend::ast::Program {
+        exports: vec![],
+        imports: vec![backend::ast::Import {
+            module: None,
+            version: None,
+            js_namespace: None,
+            kind: backend::ast::ImportKind::Type(backend::ast::ImportType {
+                vis: syn::Visibility::Public(syn::VisPublic {
+                    pub_token: syn::token::Pub(proc_macro2::Span::call_site()),
+                }),
+                name: syn::Ident::new("Event", proc_macro2::Span::call_site()),
+            }),
+        }],
+        enums: vec![],
+        structs: vec![],
+    }
+);

crates/webidl/tests/all/lib.rs

@@ -0,0 +1,21 @@
+extern crate proc_macro2;
+extern crate syn;
+extern crate wasm_bindgen_backend as backend;
+extern crate wasm_bindgen_webidl as wb_webidl;
+
+pub fn assert_parse(webidl: &str, expected: backend::ast::Program) {
+    let actual = wb_webidl::parse(webidl).expect("should parse the webidl source OK");
+    assert_eq!(expected, actual);
+}
+
+macro_rules! assert_parse {
+    ($test_name:ident, $webidl_source:expr, $expected_ast:expr) => {
+        #[test]
+        fn $test_name() {
+            $crate::assert_parse($webidl_source, $expected_ast);
+        }
+    };
+}
+
+mod event;
+mod simple;

crates/webidl/tests/all/simple.rs

@@ -0,0 +1,3 @@
+use super::backend;
+
+assert_parse!(empty, "", backend::ast::Program::default());