Auto merge of #443 - scoopr:objc, r=emilio

Add initial Objective C support

Hi! I made an attempt to support parsing objective c headers. This is very much incomplete,
and likely not quite yet ready for merging, but I thought I'd share the progress so far.

Comments appreciated, I'm still very much a newbie in just about everything related to this change (rust as a language, rust ast, libclang, rust-bindgen), and there were many parts of code I wasn't quite sure about.

Commit message:
It parses interfaces and protocol but ignores base classes,
methods that don’t have arguments, the arguments are currently ignored.
Also you can pass objc class instances to C functions.

Next steps are inheritance/base classes, method signatures,
properties, categories.
Then check with system headers what is missing.

Author: bors-servo

src/clang.rs

@@ -696,7 +696,8 @@ impl Type {
             CXType_Pointer |
             CXType_RValueReference |
             CXType_LValueReference |
-            CXType_MemberPointer => {
+            CXType_MemberPointer |
+            CXType_ObjCObjectPointer => {
                 let ret = Type {
                     x: unsafe { clang_getPointeeType(self.x) },
                 };

src/codegen/mod.rs

@@ -13,6 +13,7 @@ use ir::item::{Item, ItemAncestors, ItemCanonicalName, ItemCanonicalPath};
 use ir::item_kind::ItemKind;
 use ir::layout::Layout;
 use ir::module::Module;
+use ir::objc::ObjCInterface;
 use ir::ty::{Type, TypeKind};
 use ir::type_collector::ItemSet;
 use ir::var::Var;
@@ -87,6 +88,9 @@ struct CodegenResult<'a> {
     /// Whether an incomplete array has been generated at least once.
     saw_incomplete_array: bool,
 
+    /// Whether Objective C types have been seen at least once.
+    saw_objc: bool,
+
     items_seen: HashSet<ItemId>,
     /// The set of generated function/var names, needed because in C/C++ is
     /// legal to do something like:
@@ -119,6 +123,7 @@ impl<'a> CodegenResult<'a> {
             items: vec![],
             saw_union: false,
             saw_incomplete_array: false,
+            saw_objc: false,
             codegen_id: codegen_id,
             items_seen: Default::default(),
             functions_seen: Default::default(),
@@ -140,6 +145,10 @@ impl<'a> CodegenResult<'a> {
         self.saw_incomplete_array = true;
     }
 
+    fn saw_objc(&mut self) {
+        self.saw_objc = true;
+    }
+
     fn seen(&self, item: ItemId) -> bool {
         self.items_seen.contains(&item)
     }
@@ -184,6 +193,7 @@ impl<'a> CodegenResult<'a> {
 
         self.saw_union |= new.saw_union;
         self.saw_incomplete_array |= new.saw_incomplete_array;
+        self.saw_objc |= new.saw_objc;
 
         new.items
     }
@@ -359,6 +369,9 @@ impl CodeGenerator for Module {
                 if ctx.need_bindegen_complex_type() {
                     utils::prepend_complex_type(ctx, &mut *result);
                 }
+                if result.saw_objc {
+                    utils::prepend_objc_header(ctx, &mut *result);
+                }
             }
         };
 
@@ -623,6 +636,9 @@ impl CodeGenerator for Type {
             TypeKind::Enum(ref ei) => {
                 ei.codegen(ctx, result, whitelisted_items, item)
             }
+            TypeKind::ObjCInterface(ref interface) => {
+                interface.codegen(ctx, result, whitelisted_items, item)
+            }
             ref u @ TypeKind::UnresolvedTypeRef(..) => {
                 unreachable!("Should have been resolved after parsing {:?}!", u)
             }
@@ -2111,6 +2127,9 @@ impl ToRustTy for Type {
                 let ident = ctx.rust_ident(&name);
                 quote_ty!(ctx.ext_cx(), $ident)
             }
+            TypeKind::ObjCInterface(..) => {
+                quote_ty!(ctx.ext_cx(), id)
+            },
             ref u @ TypeKind::UnresolvedTypeRef(..) => {
                 unreachable!("Should have been resolved after parsing {:?}!", u)
             }
@@ -2144,10 +2163,22 @@ impl ToRustTy for FunctionSig {
             //     the array type derivation.
             //
             // [1]: http://c0x.coding-guidelines.com/6.7.5.3.html
-            let arg_ty = if let TypeKind::Array(t, _) = *arg_ty.canonical_type(ctx).kind() {
-                t.to_rust_ty(ctx).to_ptr(arg_ty.is_const(), ctx.span())
-            } else {
-                arg_item.to_rust_ty(ctx)
+            let arg_ty = match *arg_ty.canonical_type(ctx).kind() {
+                TypeKind::Array(t, _) => {
+                    t.to_rust_ty(ctx).to_ptr(arg_ty.is_const(), ctx.span())
+                },
+                TypeKind::Pointer(inner) => {
+                    let inner = ctx.resolve_item(inner);
+                    let inner_ty = inner.expect_type();
+                    if let TypeKind::ObjCInterface(_) = *inner_ty.canonical_type(ctx).kind() {
+                        quote_ty!(ctx.ext_cx(), id)
+                    } else {
+                        arg_item.to_rust_ty(ctx)
+                    }
+                },
+                _ => {
+                    arg_item.to_rust_ty(ctx)
+                }
             };
 
             let arg_name = match *name {
@@ -2263,6 +2294,85 @@ impl CodeGenerator for Function {
     }
 }
 
+impl CodeGenerator for ObjCInterface {
+    type Extra = Item;
+    fn codegen<'a>(&self,
+                   ctx: &BindgenContext,
+                   result: &mut CodegenResult<'a>,
+                   _whitelisted_items: &ItemSet,
+                   _: &Item) {
+        let mut impl_items = vec![];
+        let mut trait_items = vec![];
+
+        for method in self.methods() {
+            let method_name = ctx.rust_ident(method.name());
+
+            let body = quote_stmt!(ctx.ext_cx(), msg_send![self, $method_name])
+                .unwrap();
+            let block = ast::Block {
+                stmts: vec![body],
+                id: ast::DUMMY_NODE_ID,
+                rules: ast::BlockCheckMode::Default,
+                span: ctx.span(),
+            };
+
+            let sig = aster::AstBuilder::new()
+                .method_sig()
+                .unsafe_()
+                .fn_decl()
+                .self_()
+                .build(ast::SelfKind::Value(ast::Mutability::Immutable))
+                .build(ast::FunctionRetTy::Default(ctx.span()));
+            let attrs = vec![];
+
+            let impl_item = ast::ImplItem {
+                id: ast::DUMMY_NODE_ID,
+                ident: ctx.rust_ident(method.rust_name()),
+                vis: ast::Visibility::Inherited, // Public,
+                attrs: attrs.clone(),
+                node: ast::ImplItemKind::Method(sig.clone(), P(block)),
+                defaultness: ast::Defaultness::Final,
+                span: ctx.span(),
+            };
+
+            let trait_item = ast::TraitItem {
+                id: ast::DUMMY_NODE_ID,
+                ident: ctx.rust_ident(method.rust_name()),
+                attrs: attrs,
+                node: ast::TraitItemKind::Method(sig, None),
+                span: ctx.span(),
+            };
+
+            impl_items.push(impl_item);
+            trait_items.push(trait_item)
+        }
+
+
+        let trait_block = aster::AstBuilder::new()
+            .item()
+            .pub_()
+            .trait_(self.name())
+            .with_items(trait_items)
+            .build();
+
+        let ty_for_impl = quote_ty!(ctx.ext_cx(), id);
+        let impl_block = aster::AstBuilder::new()
+            .item()
+            .impl_()
+            .trait_()
+            .id(self.name())
+            .build()
+            .with_items(impl_items)
+            .build_ty(ty_for_impl);
+
+        result.push(trait_block);
+        result.push(impl_block);
+        result.saw_objc();
+    }
+}
+
+
+
 pub fn codegen(context: &mut BindgenContext) -> Vec<P<ast::Item>> {
     context.gen(|context| {
         let counter = Cell::new(0);
@@ -2296,6 +2406,32 @@ mod utils {
     use syntax::ast;
     use syntax::ptr::P;
 
+
+    pub fn prepend_objc_header(ctx: &BindgenContext,
+                               result: &mut Vec<P<ast::Item>>) {
+        let use_objc = if ctx.options().objc_extern_crate {
+            quote_item!(ctx.ext_cx(),
+                use objc;
+            ).unwrap()
+        } else {
+            quote_item!(ctx.ext_cx(),
+                #[macro_use]
+                extern crate objc;
+            ).unwrap()
+        };
+
+
+        let id_type = quote_item!(ctx.ext_cx(),
+            #[allow(non_camel_case_types)]
+            pub type id = *mut objc::runtime::Object;
+        )
+            .unwrap();
+
+        let items = vec![use_objc, id_type];
+        let old_items = mem::replace(result, items);
+        result.extend(old_items.into_iter());
+    }
+
     pub fn prepend_union_types(ctx: &BindgenContext,
                                result: &mut Vec<P<ast::Item>>) {
         let prefix = ctx.trait_prefix();

src/ir/mod.rs

@@ -17,3 +17,4 @@ pub mod module;
 pub mod ty;
 pub mod type_collector;
 pub mod var;
+pub mod objc;

src/ir/objc.rs

@@ -0,0 +1,99 @@
+//! Objective C types
+
+use clang;
+use clang_sys::CXChildVisit_Continue;
+use clang_sys::CXCursor_ObjCInstanceMethodDecl;
+// use clang_sys::CXCursor_ObjCSuperClassRef;
+use super::context::BindgenContext;
+
+/// Objective C interface as used in TypeKind
+///
+/// Also protocols are parsed as this type
+#[derive(Debug)]
+pub struct ObjCInterface {
+    /// The name
+    /// like, NSObject
+    name: String,
+
+    /// List of the methods defined in this interfae
+    methods: Vec<ObjCInstanceMethod>,
+}
+
+/// The objective c methods
+#[derive(Debug)]
+pub struct ObjCInstanceMethod {
+    /// The original method selector name
+    /// like, dataWithBytes:length:
+    name: String,
+
+    /// Method name as converted to rust
+    /// like, dataWithBytes_length_
+    rust_name: String,
+}
+
+impl ObjCInterface {
+    fn new(name: &str) -> ObjCInterface {
+        ObjCInterface {
+            name: name.to_owned(),
+            methods: Vec::new(),
+        }
+    }
+
+    /// The name
+    /// like, NSObject
+    pub fn name(&self) -> &str {
+        self.name.as_ref()
+    }
+
+    /// List of the methods defined in this interfae
+    pub fn methods(&self) -> &Vec<ObjCInstanceMethod> {
+        &self.methods
+    }
+
+    /// Parses the Objective C interface from the cursor
+    pub fn from_ty(cursor: &clang::Cursor,
+                   _ctx: &mut BindgenContext)
+                   -> Option<Self> {
+        let name = cursor.spelling();
+        let mut interface = Self::new(&name);
+
+        cursor.visit(|cursor| {
+            match cursor.kind() {
+                CXCursor_ObjCInstanceMethodDecl => {
+                    let name = cursor.spelling();
+                    let method = ObjCInstanceMethod::new(&name);
+
+                    interface.methods.push(method);
+                }
+                _ => {}
+            }
+            CXChildVisit_Continue
+        });
+        Some(interface)
+    }
+}
+
+impl ObjCInstanceMethod {
+    fn new(name: &str) -> ObjCInstanceMethod {
+        let split_name: Vec<&str> = name.split(':').collect();
+
+        let rust_name = split_name.join("_");
+
+        ObjCInstanceMethod {
+            name: name.to_owned(),
+            rust_name: rust_name.to_owned(),
+        }
+    }
+
+    /// The original method selector name
+    /// like, dataWithBytes:length:
+    pub fn name(&self) -> &str {
+        self.name.as_ref()
+    }
+
+    /// Method name as converted to rust
+    /// like, dataWithBytes_length_
+    pub fn rust_name(&self) -> &str {
+        self.rust_name.as_ref()
+    }
+}