Copy doc comments from Rust to JS (#265)

* backend comments complete

* better matching

* gen comments

* Add example

* Move test bindings gen to own fn

* move build step into build fn

* add fn to read js, refactor gen_bindings/test to allow for this

* Add comments test

* Update readmes

* add comments to travis

* fix broken tests

* +x on build.sh

* fix wbg cmd in build.sh

* Address fitzgen's comments

Author: FreeMasen

.travis.yml

@@ -61,6 +61,8 @@ matrix:
           (cd examples/char && sed -i 's/: "webpack-dev-server"/: "webpack"/' package.json && ./build.sh)
         - |
           (cd examples/closures && sed -i 's/: "webpack-dev-server"/: "webpack"/' package.json && ./build.sh)
+        - |
+          (cd examples/comments && sed -i 's/: "webpack-dev-server"/: "webpack"/' package.json && ./build.sh)
 
 
 install:

Cargo.toml

@@ -52,6 +52,7 @@ members = [
   "examples/asm.js",
   "examples/char",
   "examples/import_js",
+  "examples/comments"
 ]
 
 [profile.release]

crates/backend/src/ast.rs

@@ -20,6 +20,7 @@ pub struct Export {
     pub mutable: bool,
     pub constructor: Option<String>,
     pub function: Function,
+    pub comments: Vec<String>,
 }
 
 #[cfg_attr(feature = "extra-traits", derive(Debug, PartialEq, Eq))]
@@ -82,6 +83,7 @@ pub struct Function {
 pub struct Struct {
     pub name: Ident,
     pub fields: Vec<StructField>,
+    pub comments: Vec<String>,
 }
 
 #[cfg_attr(feature = "extra-traits", derive(Debug, PartialEq, Eq))]
@@ -92,12 +94,14 @@ pub struct StructField {
     pub ty: syn::Type,
     pub getter: Ident,
     pub setter: Ident,
+    pub comments: Vec<String>,
 }
 
 #[cfg_attr(feature = "extra-traits", derive(Debug, PartialEq, Eq))]
 pub struct Enum {
     pub name: Ident,
     pub variants: Vec<Variant>,
+    pub comments: Vec<String>,
 }
 
 #[cfg_attr(feature = "extra-traits", derive(Debug, PartialEq, Eq))]
@@ -150,13 +154,15 @@ impl Program {
                     }
                     _ => {}
                 }
+                let comments = extract_doc_comments(&f.attrs);
                 f.to_tokens(tokens);
                 self.exports.push(Export {
                     class: None,
                     method: false,
                     mutable: false,
                     constructor: None,
                     function: Function::from(f, opts),
+                    comments,
                 });
             }
             syn::Item::Struct(mut s) => {
@@ -237,6 +243,7 @@ impl Program {
         }
 
         let opts = BindgenAttrs::find(&mut method.attrs);
+        let comments = extract_doc_comments(&method.attrs);
         let is_constructor = opts.constructor();
         let constructor = if is_constructor {
             Some(method.sig.ident.to_string())
@@ -259,6 +266,7 @@ impl Program {
             mutable: mutable.unwrap_or(false),
             constructor,
             function,
+            comments,
         });
     }
 
@@ -299,9 +307,11 @@ impl Program {
                 }
             })
             .collect();
+        let comments = extract_doc_comments(&item.attrs);
         self.enums.push(Enum {
             name: item.ident,
             variants,
+            comments,
         });
     }
 
@@ -585,6 +595,7 @@ impl Export {
             method: self.method,
             constructor: self.constructor.clone(),
             function: self.function.shared(),
+            comments: self.comments.clone(),
         }
     }
 }
@@ -594,6 +605,7 @@ impl Enum {
         shared::Enum {
             name: self.name.to_string(),
             variants: self.variants.iter().map(|v| v.shared()).collect(),
+            comments: self.comments.clone(),
         }
     }
 }
@@ -750,26 +762,31 @@ impl Struct {
                 let getter = shared::struct_field_get(&ident, &name_str);
                 let setter = shared::struct_field_set(&ident, &name_str);
                 let opts = BindgenAttrs::find(&mut field.attrs);
+                let comments = extract_doc_comments(&field.attrs);
                 fields.push(StructField {
                     opts,
                     name: name.clone(),
                     struct_name: s.ident.clone(),
                     ty: field.ty.clone(),
                     getter: Ident::new(&getter, Span::call_site()),
                     setter: Ident::new(&setter, Span::call_site()),
+                    comments
                 });
             }
         }
+        let comments: Vec<String> = extract_doc_comments(&s.attrs);
         Struct {
             name: s.ident.clone(),
             fields,
+            comments,
         }
     }
 
     fn shared(&self) -> shared::Struct {
         shared::Struct {
             name: self.name.to_string(),
             fields: self.fields.iter().map(|s| s.shared()).collect(),
+            comments: self.comments.clone(),
         }
     }
 }
@@ -779,6 +796,7 @@ impl StructField {
         shared::StructField {
             name: self.name.to_string(),
             readonly: self.opts.readonly(),
+            comments: self.comments.clone(),
         }
     }
 }
@@ -1072,3 +1090,30 @@ fn replace_self(name: &Ident, item: &mut syn::ImplItem) {
 
     syn::visit_mut::VisitMut::visit_impl_item_mut(&mut Walk(name), item);
 }
+
+/// Extract the documentation comments from a Vec of attributes
+fn extract_doc_comments(attrs: &[syn::Attribute]) -> Vec<String> {
+    attrs
+    .iter()
+    .filter_map(|a| {
+        // if the path segments include an ident of "doc" we know this
+        // this is a doc comment
+        if a.path.segments.iter().any(|s| s.ident.to_string() == "doc") {
+            Some(
+                // We want to filter out any Puncts so just grab the Literals
+                a.tts.clone().into_iter().filter_map(|t| match t {
+                    TokenTree::Literal(lit) => {
+                        // this will always return the quoted string, we deal with 
+                        // that in the cli when we read in the comments
+                        Some(lit.to_string())
+                    },
+                    _ => None,
+                })
+            )
+        } else {
+            None
+        }
+    })
+    //Fold up the [[String]] iter we created into Vec<String>
+    .fold(vec![], |mut acc, a| {acc.extend(a); acc})
+}

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

@@ -35,13 +35,15 @@ pub struct Context<'a> {
 
 #[derive(Default)]
 pub struct ExportedClass {
+    comments: String,
     contents: String,
     typescript: String,
     constructor: Option<String>,
     fields: Vec<ClassField>,
 }
 
 struct ClassField {
+    comments: String,
     name: String,
     readonly: bool,
 }
@@ -52,9 +54,12 @@ pub struct SubContext<'a, 'b: 'a> {
 }
 
 impl<'a> Context<'a> {
-    fn export(&mut self, name: &str, contents: &str) {
+    fn export(&mut self, name: &str, contents: &str, comments: Option<String>) {
         let contents = deindent(contents);
         let contents = contents.trim();
+        if let Some(ref c) = comments {
+            self.globals.push_str(c);
+        }
         let global = if self.config.nodejs {
             if contents.starts_with("class") {
                 format!("{1}\nmodule.exports.{0} = {0};\n", name, contents)
@@ -396,7 +401,7 @@ impl<'a> Context<'a> {
             .with_context(|_| {
                 format!("failed to generate internal JS function `{}`", name)
             })?;
-        self.export(name, &contents);
+        self.export(name, &contents, None);
         Ok(())
     }
 
@@ -461,7 +466,7 @@ impl<'a> Context<'a> {
                 function(ptr) {{
                     return addHeapObject({}.__construct(ptr));
                 }}
-            ", name));
+            ", name), None);
         }
 
         for field in class.fields.iter() {
@@ -484,7 +489,10 @@ impl<'a> Context<'a> {
                 .method(true)
                 .ret(&Some(descriptor))?
                 .finish("", &format!("wasm.{}", wasm_getter));
-
+            if !dst.ends_with("\n") {
+                dst.push_str("\n");
+            }
+            dst.push_str(&field.comments);
             dst.push_str("get ");
             dst.push_str(&field.name);
             dst.push_str(&get);
@@ -504,13 +512,12 @@ impl<'a> Context<'a> {
             }}
         ", shared::free_function(&name)));
         ts_dst.push_str("free(): void;\n");
-
         dst.push_str(&class.contents);
         ts_dst.push_str(&class.typescript);
         dst.push_str("}\n");
         ts_dst.push_str("}\n");
 
-        self.export(&name, &dst);
+        self.export(&name, &dst, Some(class.comments.clone()));
         self.typescript.push_str(&ts_dst);
 
         Ok(())
@@ -534,7 +541,7 @@ impl<'a> Context<'a> {
 
     fn rewrite_imports(&mut self, module_name: &str) {
         for (name, contents) in self._rewrite_imports(module_name) {
-            self.export(&name, &contents);
+            self.export(&name, &contents, None);
         }
     }
 
@@ -691,7 +698,7 @@ impl<'a> Context<'a> {
                         return;
                     throw new Error('stack is not currently empty');
                 }
-            ");
+            ", None);
         }
     }
 
@@ -715,7 +722,7 @@ impl<'a> Context<'a> {
                         throw new Error('slab is not currently empty');
                     }}
                 }}
-            ", initial_values.len()));
+            ", initial_values.len()), None);
         }
     }
 
@@ -1406,7 +1413,7 @@ impl<'a> Context<'a> {
 
         // Ensure a blank line between adjacent items, and ensure everything is
         // terminated with a newline.
-        while !self.globals.ends_with("\n\n\n") {
+        while !self.globals.ends_with("\n\n\n") && !self.globals.ends_with("*/\n") {
             self.globals.push_str("\n");
         }
         self.globals.push_str(s);
@@ -1452,14 +1459,16 @@ impl<'a, 'b> SubContext<'a, 'b> {
             self.generate_enum(e);
         }
         for s in self.program.structs.iter() {
-            self.cx.exported_classes
+            let mut class = self.cx.exported_classes
                 .entry(s.name.clone())
-                .or_insert_with(Default::default)
-                .fields
-                .extend(s.fields.iter().map(|s| {
+                .or_insert_with(Default::default);
+            class.comments = format_doc_comments(&s.comments);
+            class.fields
+                .extend(s.fields.iter().map(|f| {
                     ClassField {
-                        name: s.name.clone(),
-                        readonly: s.readonly,
+                        name: f.name.clone(),
+                        readonly: f.readonly,
+                        comments: format_doc_comments(&f.comments),
                     }
                 }));
         }
@@ -1477,7 +1486,7 @@ impl<'a, 'b> SubContext<'a, 'b> {
         let (js, ts) = Js2Rust::new(&export.function.name, self.cx)
             .process(descriptor.unwrap_function())?
             .finish("function", &format!("wasm.{}", export.function.name));
-        self.cx.export(&export.function.name, &js);
+        self.cx.export(&export.function.name, &js, Some(format_doc_comments(&export.comments)));
         self.cx.globals.push_str("\n");
         self.cx.typescript.push_str("export ");
         self.cx.typescript.push_str(&ts);
@@ -1498,6 +1507,7 @@ impl<'a, 'b> SubContext<'a, 'b> {
             .finish("", &format!("wasm.{}", wasm_name));
         let class = self.cx.exported_classes.entry(class_name.to_string())
             .or_insert(ExportedClass::default());
+        class.contents.push_str(&format_doc_comments(&export.comments));
         if !export.method {
             class.contents.push_str("static ");
             class.typescript.push_str("static ");
@@ -1514,7 +1524,6 @@ impl<'a, 'b> SubContext<'a, 'b> {
             1 => Some(constructors[0].clone()),
             x @ _ => bail!("there must be only one constructor, not {}", x),
         };
-
         class.contents.push_str(&export.function.name);
         class.contents.push_str(&js);
         class.contents.push_str("\n");
@@ -1593,7 +1602,7 @@ impl<'a, 'b> SubContext<'a, 'b> {
             function() {{
                 return addHeapObject({});
             }}
-        ", obj));
+        ", obj), None);
         Ok(())
     }
 
@@ -1688,7 +1697,7 @@ impl<'a, 'b> SubContext<'a, 'b> {
             .catch(import.catch)
             .process(descriptor.unwrap_function())?
             .finish(&target);
-        self.cx.export(&import.shim, &js);
+        self.cx.export(&import.shim, &js, None);
         Ok(())
     }
 
@@ -1698,7 +1707,7 @@ impl<'a, 'b> SubContext<'a, 'b> {
         for variant in enum_.variants.iter() {
             variants.push_str(&format!("{}:{},", variant.name, variant.value));
         }
-        self.cx.export(&enum_.name, &format!("Object.freeze({{ {} }})", variants));
+        self.cx.export(&enum_.name, &format!("Object.freeze({{ {} }})", variants), Some(format_doc_comments(&enum_.comments)));
         self.cx.typescript.push_str(&format!("export enum {} {{", enum_.name));
 
         variants.clear();
@@ -1764,3 +1773,9 @@ fn deindent(s: &str) -> String {
     }
     ret
 }
+
+
+fn format_doc_comments(comments: &Vec<String>) -> String {
+    let body: String = comments.iter().map(|c| format!("*{}\n", c.trim_matches('"'))).collect();
+    format!("/**\n{}*/\n", body)
+}