auto merge of #15732 : bgamari/rust/to-tokens, r=alexcrichton

Here I add a `ToTokens` impl for `Attribute_` and `Option<T>`, as well as generalize the impl for `Vec<T>`

Author: bors

src/libsyntax/ext/base.rs

@@ -371,6 +371,9 @@ pub fn syntax_expander_table() -> SyntaxEnv {
     syntax_expanders.insert(intern("quote_ty"),
                        builtin_normal_expander(
                             ext::quote::expand_quote_ty));
+    syntax_expanders.insert(intern("quote_method"),
+                       builtin_normal_expander(
+                            ext::quote::expand_quote_method));
     syntax_expanders.insert(intern("quote_item"),
                        builtin_normal_expander(
                             ext::quote::expand_quote_item));

src/libsyntax/ext/quote.rs

@@ -54,9 +54,10 @@ pub mod rt {
         }
     }
 
-    impl ToTokens for Vec<TokenTree> {
-        fn to_tokens(&self, _cx: &ExtCtxt) -> Vec<TokenTree> {
-            (*self).clone()
+    impl<T: ToTokens> ToTokens for Vec<T> {
+        fn to_tokens(&self, cx: &ExtCtxt) -> Vec<TokenTree> {
+            let a = self.iter().flat_map(|t| t.to_tokens(cx).move_iter());
+            FromIterator::from_iter(a)
         }
     }
 
@@ -67,6 +68,15 @@ pub mod rt {
         }
     }
 
+    impl<T: ToTokens> ToTokens for Option<T> {
+        fn to_tokens(&self, cx: &ExtCtxt) -> Vec<TokenTree> {
+            match self {
+                &Some(ref t) => t.to_tokens(cx),
+                &None => Vec::new(),
+            }
+        }
+    }
+
     /* Should be (when bugs in default methods are fixed):
 
     trait ToSource : ToTokens {
@@ -133,11 +143,18 @@ pub mod rt {
     impl_to_source!(ast::Arg, arg_to_string)
     impl_to_source!(Generics, generics_to_string)
     impl_to_source!(Gc<ast::Item>, item_to_string)
+    impl_to_source!(Gc<ast::Method>, method_to_string)
     impl_to_source!(Gc<ast::Expr>, expr_to_string)
     impl_to_source!(Gc<ast::Pat>, pat_to_string)
     impl_to_source_slice!(ast::Ty, ", ")
     impl_to_source_slice!(Gc<ast::Item>, "\n\n")
 
+    impl ToSource for ast::Attribute_ {
+        fn to_source(&self) -> String {
+            pprust::attribute_to_string(&dummy_spanned(*self))
+        }
+    }
+
     impl<'a> ToSource for &'a str {
         fn to_source(&self) -> String {
             let lit = dummy_spanned(ast::LitStr(
@@ -222,13 +239,15 @@ pub mod rt {
     impl_to_tokens!(ast::Ident)
     impl_to_tokens!(Gc<ast::Item>)
     impl_to_tokens!(Gc<ast::Pat>)
+    impl_to_tokens!(Gc<ast::Method>)
     impl_to_tokens_lifetime!(&'a [Gc<ast::Item>])
     impl_to_tokens!(ast::Ty)
     impl_to_tokens_lifetime!(&'a [ast::Ty])
     impl_to_tokens!(Generics)
     impl_to_tokens!(Gc<ast::Expr>)
     impl_to_tokens!(ast::Block)
     impl_to_tokens!(ast::Arg)
+    impl_to_tokens!(ast::Attribute_)
     impl_to_tokens_lifetime!(&'a str)
     impl_to_tokens!(())
     impl_to_tokens!(char)
@@ -336,6 +355,16 @@ pub fn expand_quote_ty(cx: &mut ExtCtxt,
     base::MacExpr::new(expanded)
 }
 
+pub fn expand_quote_method(cx: &mut ExtCtxt,
+                           sp: Span,
+                           tts: &[ast::TokenTree])
+                           -> Box<base::MacResult> {
+    let e_param_colons = cx.expr_none(sp);
+    let expanded = expand_parse_call(cx, sp, "parse_method",
+                                     vec!(e_param_colons), tts);
+    base::MacExpr::new(expanded)
+}
+
 pub fn expand_quote_stmt(cx: &mut ExtCtxt,
                          sp: Span,
                          tts: &[ast::TokenTree])