ast: Add trailing comma formatting option

Add an option to output trailing commas depending on the configuration
of the TokenStream.

gcc/rust/ChangeLog:

	* ast/rust-ast-tokenstream.cc (TokenStream::trailing_comma):
	Output a trailing comma to the token stream according to the
	configuration.
	* ast/rust-ast-tokenstream.h: Add function prototype.

Signed-off-by: Pierre-Emmanuel Patry <pierre-emmanuel.patry@embecosm.com>

2 files changed, 11 insertions, 0 deletions

diff --git a/gcc/rust/ast/rust-ast-tokenstream.cc b/gcc/rust/ast/rust-ast-tokenstream.cc
index a7fee13..d68c19a 100644
--- a/gcc/rust/ast/rust-ast-tokenstream.cc
+++ b/gcc/rust/ast/rust-ast-tokenstream.cc
@@ -93,6 +93,15 @@ TokenStream::visit_items_as_block (T &collection,
 }
 
 void
+TokenStream::trailing_comma ()
+{
+  if (output_trailing_commas)
+    {
+      tokens.push_back (Rust::Token::make (COMMA, Location ()));
+    }
+}
+
+void
 TokenStream::visit (FunctionParam &param)
 {
   visit (param.get_pattern ());
diff --git a/gcc/rust/ast/rust-ast-tokenstream.h b/gcc/rust/ast/rust-ast-tokenstream.h
index 70ef246..58459c6 100644
--- a/gcc/rust/ast/rust-ast-tokenstream.h
+++ b/gcc/rust/ast/rust-ast-tokenstream.h
@@ -31,6 +31,7 @@ class TokenStream : public ASTVisitor
 {
 public:
   TokenStream (std::vector<TokenPtr> &container);
+  bool output_trailing_commas = false;
 
   void go (AST::Crate &crate);
   void go (AST::Item &item);
@@ -86,6 +87,7 @@ private:
 			     TokenId left_brace = LEFT_CURLY,
 			     TokenId right_brace = RIGHT_CURLY);
 
+  void trailing_comma ();
   /**
    * Visit common items of functions: Parameters, return type, block
    */