Switch from booleans to symbolic tags in a few places.

src/comp/front/parser.rs

@@ -12,13 +12,18 @@
 import util.common.span;
 import util.common.new_str_hash;
 
+tag restriction {
+    UNRESTRICTED;
+    RESTRICT_NO_CALL_EXPRS;
+}
+
 state type parser =
     state obj {
           fn peek() -> token.token;
           impure fn bump();
           impure fn err(str s);
-          impure fn restrict(bool r);
-          fn is_restricted() -> bool;
+          impure fn restrict(restriction r);
+          fn get_restriction() -> restriction;
           fn get_session() -> session.session;
           fn get_span() -> common.span;
           fn next_def_id() -> ast.def_id;
@@ -31,7 +36,7 @@
                            mutable common.pos lo,
                            mutable common.pos hi,
                            mutable ast.def_num def,
-                           mutable bool restricted,
+                           mutable restriction res,
                            ast.crate_num crate,
                            lexer.reader rdr)
         {
@@ -52,12 +57,12 @@ fn peek() -> token.token {
                 sess.span_err(span, m);
             }
 
-            impure fn restrict(bool r) {
-                restricted = r;
+            impure fn restrict(restriction r) {
+                res = r;
             }
 
-            fn is_restricted() -> bool {
-                ret restricted;
+            fn get_restriction() -> restriction {
+                ret res;
             }
 
             fn get_session() -> session.session {
@@ -78,7 +83,7 @@ fn next_def_id() -> ast.def_id {
     auto rdr = lexer.new_reader(srdr, path);
     auto npos = rdr.get_curr_pos();
     ret stdio_parser(sess, lexer.next_token(rdr),
-                     npos, npos, 0, false, crate, rdr);
+                     npos, npos, 0, UNRESTRICTED, crate, rdr);
 }
 
 impure fn unexpected(parser p, token.token t) {
@@ -283,7 +288,7 @@ fn spanned[T](&span lo, &span hi, &T node) -> ast.spanned[T] {
         }
 
         case (token.IDENT(_)) {
-            t = ast.ty_path(parse_path(p, true), none[ast.def]);
+            t = ast.ty_path(parse_path(p, GREEDY), none[ast.def]);
         }
 
         case (_) {
@@ -380,7 +385,12 @@ fn is_ident(token.token t) -> bool {
     ret false;
 }
 
-impure fn parse_path(parser p, bool greedy) -> ast.path {
+tag greed {
+    GREEDY;
+    MINIMAL;
+}
+
+impure fn parse_path(parser p, greed g) -> ast.path {
 
     auto lo = p.get_span();
     auto hi = lo;
@@ -394,7 +404,7 @@ fn is_ident(token.token t) -> bool {
                 ids += i;
                 p.bump();
                 if (p.peek() == token.DOT) {
-                    if (greedy) {
+                    if (g == GREEDY) {
                         p.bump();
                         check (is_ident(p.peek()));
                     } else {
@@ -456,7 +466,7 @@ fn is_ident(token.token t) -> bool {
     alt (p.peek()) {
 
         case (token.IDENT(_)) {
-            auto pth = parse_path(p, false);
+            auto pth = parse_path(p, MINIMAL);
             hi = pth.span;
             ex = ast.expr_path(pth, none[ast.def], ast.ann_none);
         }
@@ -521,7 +531,7 @@ fn is_ident(token.token t) -> bool {
 
         case (token.BIND) {
             p.bump();
-            auto e = parse_restricted_expr(p);
+            auto e = parse_expr_res(p, RESTRICT_NO_CALL_EXPRS);
             impure fn parse_expr_opt(parser p) -> option.t[@ast.expr] {
                 alt (p.peek()) {
                     case (token.UNDERSCORE) {
@@ -589,7 +599,7 @@ fn append_dot_ident_to_expr(span lo, span hi,
         alt (p.peek()) {
 
             case (token.LPAREN) {
-                if (p.is_restricted()) {
+                if (p.get_restriction() == RESTRICT_NO_CALL_EXPRS) {
                     ret e;
                 } else {
                     // Call expr.
@@ -983,18 +993,13 @@ fn append_dot_ident_to_expr(span lo, span hi,
     ret @spanned(lo, hi, expr);
 }
 
-
-impure fn parse_restricted_expr(parser p) -> @ast.expr {
-    ret parse_expr_res(p, true);
-}
-
 impure fn parse_expr(parser p) -> @ast.expr {
-    ret parse_expr_res(p, false);
+    ret parse_expr_res(p, UNRESTRICTED);
 }
 
-impure fn parse_expr_res(parser p, bool restrict) -> @ast.expr {
-    auto old = p.is_restricted();
-    p.restrict(restrict);
+impure fn parse_expr_res(parser p, restriction r) -> @ast.expr {
+    auto old = p.get_restriction();
+    p.restrict(r);
     auto e = parse_expr_inner(p);
     p.restrict(old);
     ret e;

src/comp/middle/trans.rs

@@ -93,10 +93,16 @@ fn next(str prefix) -> str {
     clean(fn(@block_ctxt cx) -> result);
 }
 
+
+tag block_kind {
+    SCOPE_BLOCK;
+    NON_SCOPE_BLOCK;
+}
+
 state type block_ctxt = rec(BasicBlockRef llbb,
                             builder build,
                             block_parent parent,
-                            bool is_scope,
+                            block_kind kind,
                             mutable vec[cleanup] cleanups,
                             @fn_ctxt fcx);
 
@@ -640,7 +646,7 @@ fn trans_non_gc_free(@block_ctxt cx, ValueRef v) -> result {
 }
 
 fn find_scope_cx(@block_ctxt cx) -> @block_ctxt {
-    if (cx.is_scope) {
+    if (cx.kind == SCOPE_BLOCK) {
         ret cx;
     }
     alt (cx.parent) {
@@ -1492,8 +1498,13 @@ fn memcpy_ty(@block_ctxt cx,
     }
 }
 
+tag copy_action {
+    INIT;
+    DROP_EXISTING;
+}
+
 fn copy_ty(@block_ctxt cx,
-           bool is_init,
+           copy_action action,
            ValueRef dst,
            ValueRef src,
            @ty.t t) -> result {
@@ -1505,7 +1516,7 @@ fn copy_ty(@block_ctxt cx,
 
     } else if (ty.type_is_boxed(t)) {
         auto r = incr_all_refcnts(cx, src, t);
-        if (! is_init) {
+        if (action == DROP_EXISTING) {
             r = drop_ty(r.bcx, r.bcx.build.Load(dst), t);
         }
         ret res(r.bcx, r.bcx.build.Store(src, dst));
@@ -1513,7 +1524,7 @@ fn copy_ty(@block_ctxt cx,
     } else if (ty.type_is_structural(t) ||
                ty.type_has_dynamic_size(t)) {
         auto r = incr_all_refcnts(cx, src, t);
-        if (! is_init) {
+        if (action == DROP_EXISTING) {
             r = drop_ty(r.bcx, dst, t);
         }
         ret memcpy_ty(r.bcx, dst, src, t);
@@ -1623,7 +1634,7 @@ fn trans_unary(@block_ctxt cx, ast.unop op,
                                           vec(C_int(0),
                                               C_int(abi.box_rc_field_body)));
             sub.bcx.build.Store(C_int(1), rc);
-            sub = copy_ty(sub.bcx, true, body, e_val, e_ty);
+            sub = copy_ty(sub.bcx, INIT, body, e_val, e_ty);
             ret res(sub.bcx, box);
         }
         case (ast.deref) {
@@ -1815,7 +1826,7 @@ fn inner(@block_ctxt cx,
 
         cx.build.Br(scope_cx.llbb);
         auto local_res = alloc_local(scope_cx, local);
-        auto bcx = copy_ty(local_res.bcx, true, local_res.val, curr, t).bcx;
+        auto bcx = copy_ty(local_res.bcx, INIT, local_res.val, curr, t).bcx;
         bcx = trans_block(bcx, body).bcx;
         bcx.build.Br(next_cx.llbb);
         ret res(next_cx, C_nil());
@@ -1955,7 +1966,7 @@ fn trans_pat_binding(@block_ctxt cx, @ast.pat pat, ValueRef llval)
             cx.fcx.lllocals.insert(def_id, dst);
             cx.cleanups += clean(bind drop_slot(_, dst, ty));
 
-            ret copy_ty(cx, true, dst, llval, ty);
+            ret copy_ty(cx, INIT, dst, llval, ty);
         }
         case (ast.pat_tag(_, ?subpats, _, _)) {
             if (_vec.len[@ast.pat](subpats) == 0u) { ret res(cx, llval); }
@@ -2496,7 +2507,7 @@ fn trans_bind(@block_ctxt cx, @ast.expr f,
             for (ValueRef v in bound_vals) {
                 auto bound = bcx.build.GEP(bindings,
                                            vec(C_int(0),C_int(i)));
-                bcx = copy_ty(r.bcx, true, bound, v, bound_tys.(i)).bcx;
+                bcx = copy_ty(r.bcx, INIT, bound, v, bound_tys.(i)).bcx;
                 i += 1;
             }
 
@@ -2608,7 +2619,7 @@ fn trans_tup(@block_ctxt cx, vec[ast.elt] elts,
         auto t = ty.expr_ty(e.expr);
         auto src_res = trans_expr(r.bcx, e.expr);
         auto dst_elt = r.bcx.build.GEP(tup_val, vec(C_int(0), C_int(i)));
-        r = copy_ty(src_res.bcx, true, dst_elt, src_res.val, t);
+        r = copy_ty(src_res.bcx, INIT, dst_elt, src_res.val, t);
         i += 1;
     }
     ret res(r.bcx, tup_val);
@@ -2645,7 +2656,7 @@ fn trans_vec(@block_ctxt cx, vec[@ast.expr] args,
     for (@ast.expr e in args) {
         auto src_res = trans_expr(sub.bcx, e);
         auto dst_elt = sub.bcx.build.GEP(body, vec(C_int(0), C_int(i)));
-        sub = copy_ty(src_res.bcx, true, dst_elt, src_res.val, unit_ty);
+        sub = copy_ty(src_res.bcx, INIT, dst_elt, src_res.val, unit_ty);
         i += 1;
     }
     auto fill = sub.bcx.build.GEP(vec_val,
@@ -2668,7 +2679,7 @@ fn trans_rec(@block_ctxt cx, vec[ast.field] fields,
         auto src_res = trans_expr(r.bcx, f.expr);
         auto dst_elt = r.bcx.build.GEP(rec_val, vec(C_int(0), C_int(i)));
         // FIXME: calculate copy init-ness in typestate.
-        r = copy_ty(src_res.bcx, true, dst_elt, src_res.val, t);
+        r = copy_ty(src_res.bcx, INIT, dst_elt, src_res.val, t);
         i += 1;
     }
     ret res(r.bcx, rec_val);
@@ -2727,7 +2738,8 @@ fn trans_expr(@block_ctxt cx, @ast.expr e) -> result {
             auto rhs_res = trans_expr(lhs_res.res.bcx, src);
             auto t = node_ann_type(cx.fcx.ccx, ann);
             // FIXME: calculate copy init-ness in typestate.
-            ret copy_ty(rhs_res.bcx, false, lhs_res.res.val, rhs_res.val, t);
+            ret copy_ty(rhs_res.bcx, DROP_EXISTING,
+                        lhs_res.res.val, rhs_res.val, t);
         }
 
         case (ast.expr_assign_op(?op, ?dst, ?src, ?ann)) {
@@ -2739,7 +2751,8 @@ fn trans_expr(@block_ctxt cx, @ast.expr e) -> result {
             auto rhs_res = trans_expr(lhs_res.res.bcx, src);
             auto v = trans_eager_binop(rhs_res.bcx, op, lhs_val, rhs_res.val);
             // FIXME: calculate copy init-ness in typestate.
-            ret copy_ty(rhs_res.bcx, false, lhs_res.res.val, v, t);
+            ret copy_ty(rhs_res.bcx, DROP_EXISTING,
+                        lhs_res.res.val, v, t);
         }
 
         case (ast.expr_bind(?f, ?args, ?ann)) {
@@ -2889,7 +2902,7 @@ fn trans_ret(@block_ctxt cx, &option.t[@ast.expr] e) -> result {
             alt (cx.fcx.llretptr) {
                 case (some[ValueRef](?llptr)) {
                     // Generic return via tydesc + retptr.
-                    bcx = copy_ty(bcx, true, llptr, val, t).bcx;
+                    bcx = copy_ty(bcx, INIT, llptr, val, t).bcx;
                     bcx.build.RetVoid();
                 }
                 case (none[ValueRef]) {
@@ -2921,7 +2934,7 @@ fn init_local(@block_ctxt cx, @ast.local local) -> result {
     alt (local.init) {
         case (some[@ast.expr](?e)) {
             auto sub = trans_expr(bcx, e);
-            bcx = copy_ty(sub.bcx, true, llptr, sub.val, ty).bcx;
+            bcx = copy_ty(sub.bcx, INIT, llptr, sub.val, ty).bcx;
         }
         case (_) {
             if (middle.ty.type_has_dynamic_size(ty)) {
@@ -2983,7 +2996,7 @@ fn new_builder(BasicBlockRef llbb) -> builder {
 // You probably don't want to use this one. See the
 // next three functions instead.
 fn new_block_ctxt(@fn_ctxt cx, block_parent parent,
-                  bool is_scope,
+                  block_kind kind,
                   str name) -> @block_ctxt {
     let vec[cleanup] cleanups = vec();
     let BasicBlockRef llbb =
@@ -2993,24 +3006,24 @@ fn new_block_ctxt(@fn_ctxt cx, block_parent parent,
     ret @rec(llbb=llbb,
              build=new_builder(llbb),
              parent=parent,
-             is_scope=is_scope,
+             kind=kind,
              mutable cleanups=cleanups,
              fcx=cx);
 }
 
 // Use this when you're at the top block of a function or the like.
 fn new_top_block_ctxt(@fn_ctxt fcx) -> @block_ctxt {
-    ret new_block_ctxt(fcx, parent_none, true, "function top level");
+    ret new_block_ctxt(fcx, parent_none, SCOPE_BLOCK, "function top level");
 }
 
 // Use this when you're at a curly-brace or similar lexical scope.
 fn new_scope_block_ctxt(@block_ctxt bcx, str n) -> @block_ctxt {
-    ret new_block_ctxt(bcx.fcx, parent_some(bcx), true, n);
+    ret new_block_ctxt(bcx.fcx, parent_some(bcx), SCOPE_BLOCK, n);
 }
 
 // Use this when you're making a general CFG BB within a scope.
 fn new_sub_block_ctxt(@block_ctxt bcx, str n) -> @block_ctxt {
-    ret new_block_ctxt(bcx.fcx, parent_some(bcx), false, n);
+    ret new_block_ctxt(bcx.fcx, parent_some(bcx), NON_SCOPE_BLOCK, n);
 }
 
 
@@ -3018,7 +3031,7 @@ fn trans_block_cleanups(@block_ctxt cx,
                         @block_ctxt cleanup_cx) -> @block_ctxt {
     auto bcx = cx;
 
-    if (!cleanup_cx.is_scope) {
+    if (cleanup_cx.kind != SCOPE_BLOCK) {
         check (_vec.len[cleanup](cleanup_cx.cleanups) == 0u);
     }
 
@@ -3430,7 +3443,7 @@ fn trans_obj(@crate_ctxt cx, &ast._obj ob, ast.def_id oid,
             arg = load_scalar_or_boxed(r.bcx, arg, arg_tys.(i).ty);
             auto field = r.bcx.build.GEP(body_fields,
                                          vec(C_int(0),C_int(i)));
-            r = copy_ty(r.bcx, true, field, arg, arg_tys.(i).ty);
+            r = copy_ty(r.bcx, INIT, field, arg, arg_tys.(i).ty);
             i += 1;
         }