rustc: Add bind expressions to the AST

src/comp/front/ast.rs

@@ -139,6 +139,7 @@
     expr_tup(vec[elt], ann);
     expr_rec(vec[field], ann);
     expr_call(@expr, vec[@expr], ann);
+    expr_bind(@expr, vec[option.t[@expr]], ann);
     expr_binary(binop, @expr, @expr, ann);
     expr_unary(unop, @expr, ann);
     expr_lit(@lit, ann);

src/comp/middle/fold.rs

@@ -74,6 +74,10 @@
          @expr f, vec[@expr] args,
          ann a) -> @expr)                         fold_expr_call,
 
+     (fn(&ENV e, &span sp,
+         @expr f, vec[option.t[@expr]] args,
+         ann a) -> @expr)                         fold_expr_bind,
+
      (fn(&ENV e, &span sp,
          ast.binop,
          @expr lhs, @expr rhs,
@@ -417,6 +421,20 @@ fn fold_expr[ENV](&ENV env, ast_fold[ENV] fld, &@expr e) -> @expr {
             ret fld.fold_expr_call(env_, e.span, ff, aargs, t);
         }
 
+        case (ast.expr_bind(?f, ?args_opt, ?t)) {
+            auto ff = fold_expr(env_, fld, f);
+            let vec[option.t[@ast.expr]] aargs_opt = vec();
+            for (option.t[@ast.expr] t_opt in args_opt) {
+                alt (t_opt) {
+                    case (some[@ast.expr](?e)) {
+                        aargs_opt += vec(some(fold_expr(env_, fld, e)));
+                    }
+                    case (none[@ast.expr]) { /* empty */ }
+                }
+            }
+            ret fld.fold_expr_bind(env_, e.span, ff, aargs_opt, t);
+        }
+
         case (ast.expr_binary(?op, ?a, ?b, ?t)) {
             auto aa = fold_expr(env_, fld, a);
             auto bb = fold_expr(env_, fld, b);
@@ -807,6 +825,12 @@ fn identity_fold_expr_call[ENV](&ENV env, &span sp, @expr f,
     ret @respan(sp, ast.expr_call(f, args, a));
 }
 
+fn identity_fold_expr_bind[ENV](&ENV env, &span sp, @expr f,
+                                vec[option.t[@expr]] args_opt, ann a)
+        -> @expr {
+    ret @respan(sp, ast.expr_bind(f, args_opt, a));
+}
+
 fn identity_fold_expr_binary[ENV](&ENV env, &span sp, ast.binop b,
                                   @expr lhs, @expr rhs,
                                   ann a) -> @expr {
@@ -1075,6 +1099,7 @@ fn new_identity_fold[ENV]() -> ast_fold[ENV] {
          fold_expr_tup    = bind identity_fold_expr_tup[ENV](_,_,_,_),
          fold_expr_rec    = bind identity_fold_expr_rec[ENV](_,_,_,_),
          fold_expr_call   = bind identity_fold_expr_call[ENV](_,_,_,_,_),
+         fold_expr_bind   = bind identity_fold_expr_bind[ENV](_,_,_,_,_),
          fold_expr_binary = bind identity_fold_expr_binary[ENV](_,_,_,_,_,_),
          fold_expr_unary  = bind identity_fold_expr_unary[ENV](_,_,_,_,_),
          fold_expr_lit    = bind identity_fold_expr_lit[ENV](_,_,_,_),