From 38846e39c4be0f12241ab0df2e94cbb366ae34ba Mon Sep 17 00:00:00 2001
From: Graydon Hoare <graydon@mozilla.com>
Date: Mon, 29 Nov 2010 12:29:57 -0800
Subject: [PATCH] Add ast.ty_mutable.

---
 src/comp/front/ast.rs     |  1 +
 src/comp/front/parser.rs  | 14 +++++++++++++-
 src/comp/middle/fold.rs   | 12 ++++++++++++
 src/comp/middle/typeck.rs | 14 +++++++++++++-
 4 files changed, 39 insertions(+), 2 deletions(-)

diff --git a/src/comp/front/ast.rs b/src/comp/front/ast.rs
index 3c2af3c85d3..a177f30187f 100644
--- a/src/comp/front/ast.rs
+++ b/src/comp/front/ast.rs
@@ -150,6 +150,7 @@ tag ty_ {
     ty_tup(vec[tup(bool /* mutability */, @ty)]);
     ty_fn(vec[rec(mode mode, @ty ty)], @ty);        // TODO: effect
     ty_path(path, option.t[def]);
+    ty_mutable(@ty);
 }
 
 tag mode {
diff --git a/src/comp/front/parser.rs b/src/comp/front/parser.rs
index 261ea1ad7dc..ab0f795d6dd 100644
--- a/src/comp/front/parser.rs
+++ b/src/comp/front/parser.rs
@@ -174,7 +174,12 @@ impure fn parse_ty(parser p) -> @ast.ty {
             }
         }
 
-        case (token.AT) { p.bump(); t = ast.ty_box(parse_ty(p)); }
+        case (token.AT) {
+            p.bump();
+            auto t0 = parse_ty(p);
+            hi = t0.span;
+            t = ast.ty_box(t0);
+        }
 
         case (token.VEC) {
             p.bump();
@@ -193,6 +198,13 @@ impure fn parse_ty(parser p) -> @ast.ty {
             t = ast.ty_tup(elems.node);
         }
 
+        case (token.MUTABLE) {
+            p.bump();
+            auto t0 = parse_ty(p);
+            hi = p.get_span();
+            t = ast.ty_mutable(t0);
+        }
+
         case (token.FN) {
             t = parse_ty_fn(p);
             alt (t) {
diff --git a/src/comp/middle/fold.rs b/src/comp/middle/fold.rs
index de2fd87ae0e..1caaa00e7d3 100644
--- a/src/comp/middle/fold.rs
+++ b/src/comp/middle/fold.rs
@@ -55,6 +55,8 @@ type ast_fold[ENV] =
      (fn(&ENV e, &span sp, ast.path p,
          &option.t[def] d) -> @ty)                fold_ty_path,
 
+     (fn(&ENV e, &span sp, @ty t) -> @ty)         fold_ty_mutable,
+
      // Expr folds.
      (fn(&ENV e, &span sp,
          vec[@expr] es, ann a) -> @expr)          fold_expr_vec,
@@ -258,6 +260,11 @@ fn fold_ty[ENV](&ENV env, ast_fold[ENV] fld, @ty t) -> @ty {
             ret fld.fold_ty_path(env_, t.span, path, ref_opt);
         }
 
+        case (ast.ty_mutable(?ty)) {
+            auto ty_ = fold_ty(env, fld, ty);
+            ret fld.fold_ty_mutable(env_, t.span, ty_);
+        }
+
         case (ast.ty_fn(?inputs, ?output)) {
             ret fld.fold_ty_fn(env_, t.span, inputs, output);
         }
@@ -659,6 +666,10 @@ fn identity_fold_ty_path[ENV](&ENV env, &span sp, ast.path p,
     ret @respan(sp, ast.ty_path(p, d));
 }
 
+fn identity_fold_ty_mutable[ENV](&ENV env, &span sp, @ty t) -> @ty {
+    ret @respan(sp, ast.ty_mutable(t));
+}
+
 
 // Expr identities.
 
@@ -908,6 +919,7 @@ fn new_identity_fold[ENV]() -> ast_fold[ENV] {
          fold_ty_tup     = bind identity_fold_ty_tup[ENV](_,_,_),
          fold_ty_fn      = bind identity_fold_ty_fn[ENV](_,_,_,_),
          fold_ty_path    = bind identity_fold_ty_path[ENV](_,_,_,_),
+         fold_ty_mutable = bind identity_fold_ty_mutable[ENV](_,_,_),
 
          fold_expr_vec    = bind identity_fold_expr_vec[ENV](_,_,_,_),
          fold_expr_tup    = bind identity_fold_expr_tup[ENV](_,_,_,_),
diff --git a/src/comp/middle/typeck.rs b/src/comp/middle/typeck.rs
index a0aec16f654..0fd72d9e66f 100644
--- a/src/comp/middle/typeck.rs
+++ b/src/comp/middle/typeck.rs
@@ -122,6 +122,10 @@ fn ast_ty_to_str(&@ast.ty ty) -> str {
             s = path_to_str(path);
         }
 
+        case (ast.ty_mutable(?t)) {
+            s = "mutable " + ast_ty_to_str(t);
+        }
+
         case (_) {
             fail;   // FIXME: typestate bug
         }
@@ -213,6 +217,7 @@ fn ast_ty_to_ty(ty_getter getter, &@ast.ty ast_ty) -> @ty {
         ret rec(mode=arg.mode, ty=ast_ty_to_ty(getter, arg.ty));
     }
 
+    auto mut = false;
     auto sty;
     auto cname = none[str];
     alt (ast_ty.node) {
@@ -252,12 +257,19 @@ fn ast_ty_to_ty(ty_getter getter, &@ast.ty ast_ty) -> @ty {
             cname = some(path_to_str(path));
         }
 
+        case (ast.ty_mutable(?t)) {
+            mut = true;
+            auto t0 = ast_ty_to_ty(getter, t);
+            sty = t0.struct;
+            cname = t0.cname;
+        }
+
         case (_) {
             fail;
         }
     }
 
-    ret @rec(struct=sty, mut=false, cname=cname);
+    ret @rec(struct=sty, mut=mut, cname=cname);
 }
 
 // A convenience function to use a crate_ctxt to resolve names for