Enable nested namespace (#951) (#2105)

* Enable nested namespace (#951)

* Specify the namespace as array (#951)

* added an example to the document

Co-authored-by: Alex Crichton <alex@alexcrichton.com>

crates/backend/src/ast.rs

@@ -75,7 +75,7 @@ pub enum MethodSelf {
 #[derive(Clone)]
 pub struct Import {
     pub module: ImportModule,
-    pub js_namespace: Option<Ident>,
+    pub js_namespace: Option<Vec<String>>,
     pub kind: ImportKind,
 }
 

crates/backend/src/codegen.rs

@@ -4,7 +4,7 @@ use crate::util::ShortHash;
 use crate::Diagnostic;
 use proc_macro2::{Ident, Literal, Span, TokenStream};
 use quote::{quote, ToTokens};
-use std::collections::HashSet;
+use std::collections::{HashMap, HashSet};
 use std::sync::atomic::{AtomicUsize, Ordering};
 use std::sync::Mutex;
 use syn;
@@ -32,10 +32,10 @@ impl TryToTokens for ast::Program {
         for s in self.structs.iter() {
             s.to_tokens(tokens);
         }
-        let mut types = HashSet::new();
+        let mut types = HashMap::new();
         for i in self.imports.iter() {
             if let ast::ImportKind::Type(t) = &i.kind {
-                types.insert(t.rust_name.clone());
+                types.insert(t.rust_name.to_string(), t.rust_name.clone());
             }
         }
         for i in self.imports.iter() {
@@ -43,8 +43,10 @@ impl TryToTokens for ast::Program {
 
             // If there is a js namespace, check that name isn't a type. If it is,
             // this import might be a method on that type.
-            if let Some(ns) = &i.js_namespace {
-                if types.contains(ns) && i.kind.fits_on_impl() {
+            if let Some(nss) = &i.js_namespace {
+                // When the namespace is `A.B`, the type name should be `B`.
+                if let Some(ns) = nss.last().and_then(|t| types.get(t)) {
+                    if i.kind.fits_on_impl() {
                         let kind = match i.kind.try_to_token_stream() {
                             Ok(kind) => kind,
                             Err(e) => {
@@ -56,6 +58,7 @@ impl TryToTokens for ast::Program {
                         continue;
                     }
                 }
+            }
 
             if let Err(e) = i.kind.try_to_tokens(tokens) {
                 errors.push(e);

crates/backend/src/encode.rs

@@ -241,7 +241,7 @@ fn shared_import<'a>(i: &'a ast::Import, intern: &'a Interner) -> Result<Import<
             ast::ImportModule::Inline(idx, _) => ImportModule::Inline(*idx as u32),
             ast::ImportModule::None => ImportModule::None,
         },
-        js_namespace: i.js_namespace.as_ref().map(|s| intern.intern(s)),
+        js_namespace: i.js_namespace.clone(),
         kind: shared_import_kind(&i.kind, intern)?,
     })
 }

crates/cli-support/src/js/mod.rs

@@ -1998,7 +1998,7 @@ impl<'a> Context<'a> {
 
             JsImportName::VendorPrefixed { name, prefixes } => {
                 self.imports_post.push_str("const l");
-                self.imports_post.push_str(&name);
+                self.imports_post.push_str(name);
                 self.imports_post.push_str(" = ");
                 switch(&mut self.imports_post, name, "", prefixes);
                 self.imports_post.push_str(";\n");

crates/cli-support/src/wit/mod.rs

@@ -898,7 +898,7 @@ impl<'a> Context<'a> {
                     "import of `{}` through js namespace `{}` isn't supported \
                      right now when it lists a polyfill",
                     item,
-                    ns
+                    ns.join(".")
                 );
             }
             return Ok(JsImport {
@@ -911,8 +911,12 @@ impl<'a> Context<'a> {
         }
 
         let (name, fields) = match import.js_namespace {
-            Some(ns) => (ns, vec![item.to_string()]),
-            None => (item, Vec::new()),
+            Some(ref ns) => {
+                let mut tail = (&ns[1..]).to_owned();
+                tail.push(item.to_string());
+                (ns[0].to_owned(), tail)
+            }
+            None => (item.to_owned(), Vec::new()),
         };
 
         let name = match import.module {

crates/macro-support/Cargo.toml

@@ -17,7 +17,7 @@ extra-traits = ["syn/extra-traits"]
 strict-macro = []
 
 [dependencies]
-syn = { version = '1.0.27', features = ['visit'] }
+syn = { version = '1.0.27', features = ['visit', 'full'] }
 quote = '1.0'
 proc-macro2 = "1.0"
 wasm-bindgen-backend = { path = "../backend", version = "=0.2.63" }

crates/macro-support/src/parser.rs

@@ -11,6 +11,7 @@ use quote::ToTokens;
 use shared;
 use syn;
 use syn::parse::{Parse, ParseStream, Result as SynResult};
+use syn::spanned::Spanned;
 
 thread_local!(static ATTRS: AttributeParseState = Default::default());
 
@@ -34,7 +35,7 @@ macro_rules! attrgen {
             (constructor, Constructor(Span)),
             (method, Method(Span)),
             (static_method_of, StaticMethodOf(Span, Ident)),
-            (js_namespace, JsNamespace(Span, Ident)),
+            (js_namespace, JsNamespace(Span, Vec<String>, Vec<Span>)),
             (module, Module(Span, String, Span)),
             (raw_module, RawModule(Span, String, Span)),
             (inline_js, InlineJs(Span, String, Span)),
@@ -116,6 +117,21 @@ macro_rules! methods {
         }
     };
 
+    (@method $name:ident, $variant:ident(Span, Vec<String>, Vec<Span>)) => {
+        fn $name(&self) -> Option<(&[String], &[Span])> {
+            self.attrs
+                .iter()
+                .filter_map(|a| match &a.1 {
+                    BindgenAttr::$variant(_, ss, spans) => {
+                        a.0.set(true);
+                        Some((&ss[..], &spans[..]))
+                    }
+                    _ => None,
+                })
+                .next()
+        }
+    };
+
     (@method $name:ident, $variant:ident(Span, $($other:tt)*)) => {
         #[allow(unused)]
         fn $name(&self) -> Option<&$($other)*> {
@@ -280,6 +296,36 @@ impl Parse for BindgenAttr {
                 };
                 return Ok(BindgenAttr::$variant(attr_span, val, span))
             });
+
+            (@parser $variant:ident(Span, Vec<String>, Vec<Span>)) => ({
+                input.parse::<Token![=]>()?;
+                let input_before_parse = input.fork();
+                let (vals, spans) = match input.parse::<syn::ExprArray>() {
+                    Ok(exprs) => {
+                        let mut vals = vec![];
+                        let mut spans = vec![];
+
+                        for expr in exprs.elems.iter() {
+                            if let syn::Expr::Lit(syn::ExprLit {
+                                lit: syn::Lit::Str(ref str),
+                                ..
+                            }) = expr {
+                                vals.push(str.value());
+                                spans.push(str.span());
+                            } else {
+                                return Err(syn::Error::new(expr.span(), "expected string literals"));
+                            }
+                        }
+
+                        (vals, spans)
+                    },
+                    Err(_) => {
+                        let ident = input_before_parse.parse::<AnyIdent>()?.0;
+                        (vec![ident.to_string()], vec![ident.span()])
+                    }
+                };
+                return Ok(BindgenAttr::$variant(attr_span, vals, spans))
+            });
         }
 
         attrgen!(parsers);
@@ -1270,7 +1316,7 @@ impl MacroParse<ast::ImportModule> for syn::ForeignItem {
             };
             BindgenAttrs::find(attrs)?
         };
-        let js_namespace = item_opts.js_namespace().cloned();
+        let js_namespace = item_opts.js_namespace().map(|(s, _)| s.to_owned());
         let kind = match self {
             syn::ForeignItem::Fn(f) => f.convert((item_opts, &module))?,
             syn::ForeignItem::Type(t) => t.convert(item_opts)?,

crates/shared/src/lib.rs

@@ -22,7 +22,7 @@ macro_rules! shared_api {
 
         struct Import<'a> {
             module: ImportModule<'a>,
-            js_namespace: Option<&'a str>,
+            js_namespace: Option<Vec<String>>,
             kind: ImportKind<'a>,
         }
 

guide/src/reference/attributes/on-js-imports/js_namespace.md

@@ -24,3 +24,18 @@ Foo::new();
 This is an example of how to bind namespaced items in Rust. The `log` and `Foo::new` functions will
 be available in the Rust module and will be invoked as `console.log` and `new Bar.Foo` in
 JavaScript.
+
+It is also possible to access the JavaScript object under the nested namespace.
+`js_namespace` also accepts the array of the string to specify the namespace.
+
+```rust
+#[wasm_bindgen]
+extern "C" {
+    #[wasm_bindgen(js_namespace = ["window", "document"])]
+    fn write(s: &str);
+}
+
+write("hello, document!");
+```
+
+This example shows how to bind `window.document.write` in Rust.

tests/wasm/import_class.js

@@ -140,3 +140,31 @@ exports.StaticStructural = class {
     return x + 3;
   }
 };
+
+class InnerClass {
+  static inner_static_function(x) {
+    return x + 5;
+  }
+
+  static create_inner_instance() {
+    const ret = new InnerClass();
+    ret.internal_int = 3;
+    return ret;
+  }
+
+  get_internal_int() {
+    return this.internal_int;
+  }
+
+  append_to_internal_int(i) {
+    this.internal_int += i;
+  }
+
+  assert_internal_int(i) {
+    assert.strictEqual(this.internal_int, i);
+  }
+}
+
+exports.nestedNamespace = {
+  InnerClass: InnerClass
+}

tests/wasm/import_class.rs

@@ -96,6 +96,19 @@ extern "C" {
     type StaticStructural;
     #[wasm_bindgen(static_method_of = StaticStructural, structural)]
     fn static_structural(a: u32) -> u32;
+
+    #[derive(Clone)]
+    type InnerClass;
+    #[wasm_bindgen(js_namespace = ["nestedNamespace", "InnerClass"])]
+    fn inner_static_function(a: u32) -> u32;
+    #[wasm_bindgen(js_namespace = ["nestedNamespace", "InnerClass"])]
+    fn create_inner_instance() -> InnerClass;
+    #[wasm_bindgen(method)]
+    fn get_internal_int(this: &InnerClass) -> u32;
+    #[wasm_bindgen(method)]
+    fn append_to_internal_int(this: &InnerClass, i: u32);
+    #[wasm_bindgen(method)]
+    fn assert_internal_int(this: &InnerClass, i: u32);
 }
 
 #[wasm_bindgen]
@@ -237,3 +250,14 @@ fn catch_constructors() {
 fn static_structural() {
     assert_eq!(StaticStructural::static_structural(30), 33);
 }
+
+#[wasm_bindgen_test]
+fn nested_namespace() {
+    assert_eq!(InnerClass::inner_static_function(15), 20);
+
+    let f = InnerClass::create_inner_instance();
+    assert_eq!(f.get_internal_int(), 3);
+    assert_eq!(f.clone().get_internal_int(), 3);
+    f.append_to_internal_int(5);
+    f.assert_internal_int(8);
+}