rustc: Add patterns to fold

3 files changed, 98 insertions, 9 deletions

diff --git a/src/comp/front/ast.rs b/src/comp/front/ast.rs
index 954440dd..cc0f2961 100644
--- a/src/comp/front/ast.rs
+++ b/src/comp/front/ast.rs
@@ -41,13 +41,11 @@ type block_ = rec(vec[@stmt] stmts,
 
 type pat = spanned[pat_];
 tag pat_ {
-    pat_wild;
-    pat_bind(ident);
-    pat_tag(ident, vec[@pat]);
+    pat_wild(ann);
+    pat_bind(ident, ann);
+    pat_tag(ident, vec[@pat], ann);
 }
 
-type arm = rec(@pat pat, block block);
-
 tag binop {
     add;
     sub;
@@ -100,6 +98,8 @@ tag decl_ {
     decl_item(@item);
 }
 
+type arm = rec(@pat pat, block block);
+
 type expr = spanned[expr_];
 tag expr_ {
     expr_vec(vec[@expr], ann);
diff --git a/src/comp/front/parser.rs b/src/comp/front/parser.rs
index 16c6ed11..a3cc00a0 100644
--- a/src/comp/front/parser.rs
+++ b/src/comp/front/parser.rs
@@ -815,13 +815,19 @@ impure fn parse_initializer(parser p) -> option.t[@ast.expr] {
 impure fn parse_pat(parser p) -> @ast.pat {
     auto lo = p.get_span();
 
-    auto pat = ast.pat_wild;    // FIXME: typestate bug
+    auto pat = ast.pat_wild(ast.ann_none);  // FIXME: typestate bug
     alt (p.peek()) {
-        case (token.UNDERSCORE) { p.bump(); pat = ast.pat_wild; }
+        case (token.UNDERSCORE) {
+            p.bump();
+            pat = ast.pat_wild(ast.ann_none);
+        }
         case (token.QUES) {
             p.bump();
             alt (p.peek()) {
-                case (token.IDENT(?id)) { p.bump(); pat = ast.pat_bind(id); }
+                case (token.IDENT(?id)) {
+                    p.bump();
+                    pat = ast.pat_bind(id, ast.ann_none);
+                }
                 case (?tok) {
                     p.err("expected identifier after '?' in pattern but " +
                           "found " + token.to_str(tok));
@@ -842,7 +848,7 @@ impure fn parse_pat(parser p) -> @ast.pat {
                 case (_) { args = vec(); }
             }
 
-            pat = ast.pat_tag(id, args);
+            pat = ast.pat_tag(id, args, ast.ann_none);
         }
         case (?tok) {
             p.err("expected pattern but found " + token.to_str(tok));
diff --git a/src/comp/middle/fold.rs b/src/comp/middle/fold.rs
index f32eddae..eea114ac 100644
--- a/src/comp/middle/fold.rs
+++ b/src/comp/middle/fold.rs
@@ -19,7 +19,9 @@ import front.ast.stmt;
 import front.ast.block;
 import front.ast.item;
 import front.ast.arg;
+import front.ast.pat;
 import front.ast.decl;
+import front.ast.arm;
 import front.ast.def;
 import front.ast.def_id;
 import front.ast.ann;
@@ -95,6 +97,10 @@ type ast_fold[ENV] =
          ann a) -> @expr)                         fold_expr_do_while,
 
      (fn(&ENV e, &span sp,
+         @expr e, vec[arm] arms,
+         ann a) -> @expr)                         fold_expr_alt,
+
+     (fn(&ENV e, &span sp,
          &block blk, ann a) -> @expr)             fold_expr_block,
 
      (fn(&ENV e, &span sp,
@@ -122,6 +128,18 @@ type ast_fold[ENV] =
          @item item) -> @decl)                    fold_decl_item,
 
 
+     // Pat folds.
+     (fn(&ENV e, &span sp,
+         ann a) -> @pat)                          fold_pat_wild,
+
+     (fn(&ENV e, &span sp,
+         ident i, ann a) -> @pat)                 fold_pat_bind,
+
+     (fn(&ENV e, &span sp,
+         ident i, vec[@pat] args,
+         ann a) -> @pat)                          fold_pat_tag,
+
+
      // Stmt folds.
      (fn(&ENV e, &span sp,
          @decl decl) -> @stmt)                    fold_stmt_decl,
@@ -170,6 +188,7 @@ type ast_fold[ENV] =
      (fn(&ENV e, &block b) -> ENV) update_env_for_block,
      (fn(&ENV e, @stmt s) -> ENV) update_env_for_stmt,
      (fn(&ENV e, @decl i) -> ENV) update_env_for_decl,
+     (fn(&ENV e, @pat p) -> ENV) update_env_for_pat,
      (fn(&ENV e, @expr x) -> ENV) update_env_for_expr,
      (fn(&ENV e, @ty t) -> ENV) update_env_for_ty,
 
@@ -275,6 +294,28 @@ fn fold_decl[ENV](&ENV env, ast_fold[ENV] fld, @decl d) -> @decl {
     fail;
 }
 
+fn fold_pat[ENV](&ENV env, ast_fold[ENV] fld, @ast.pat p) -> @ast.pat {
+    let ENV env_ = fld.update_env_for_pat(env, p);
+
+    if (!fld.keep_going(env_)) {
+        ret p;
+    }
+
+    alt (p.node) {
+        case (ast.pat_wild(?t)) { ret fld.fold_pat_wild(env_, p.span, t); }
+        case (ast.pat_bind(?id, ?t)) {
+            ret fld.fold_pat_bind(env_, p.span, id, t);
+        }
+        case (ast.pat_tag(?id, ?pats, ?t)) {
+            let vec[@ast.pat] ppats = vec();
+            for (@ast.pat pat in pats) {
+                ppats += vec(fold_pat(env_, fld, pat));
+            }
+            ret fld.fold_pat_tag(env_, p.span, id, ppats, t);
+        }
+    }
+}
+
 fn fold_exprs[ENV](&ENV env, ast_fold[ENV] fld, vec[@expr] es) -> vec[@expr] {
     let vec[@expr] exprs = vec();
     for (@expr e in es) {
@@ -368,6 +409,17 @@ fn fold_expr[ENV](&ENV env, ast_fold[ENV] fld, &@expr e) -> @expr {
             ret fld.fold_expr_do_while(env_, e.span, bbody, ccnd, t);
         }
 
+        case (ast.expr_alt(?expr, ?arms, ?t)) {
+            auto eexpr = fold_expr(env_, fld, expr);
+            let vec[ast.arm] aarms = vec();
+            for (ast.arm arm in arms) {
+                auto ppat = fold_pat(env_, fld, arm.pat);
+                auto bblock = fold_block(env_, fld, arm.block);
+                aarms += vec(rec(pat=ppat, block=bblock));
+            }
+            ret fld.fold_expr_alt(env_, e.span, eexpr, aarms, t);
+        }
+
         case (ast.expr_block(?b, ?t)) {
             auto bb = fold_block(env_, fld, b);
             ret fld.fold_expr_block(env_, e.span, bb, t);
@@ -658,6 +710,11 @@ fn identity_fold_expr_do_while[ENV](&ENV env, &span sp,
     ret @respan(sp, ast.expr_do_while(body, cond, a));
 }
 
+fn identity_fold_expr_alt[ENV](&ENV env, &span sp,
+                               @expr e, vec[arm] arms, ann a) -> @expr {
+    ret @respan(sp, ast.expr_alt(e, arms, a));
+}
+
 fn identity_fold_expr_block[ENV](&ENV env, &span sp, &block blk,
                                  ann a) -> @expr {
     ret @respan(sp, ast.expr_block(blk, a));
@@ -698,6 +755,22 @@ fn identity_fold_decl_item[ENV](&ENV e, &span sp, @item i) -> @decl {
 }
 
 
+// Pat identities.
+
+fn identity_fold_pat_wild[ENV](&ENV e, &span sp, ann a) -> @pat {
+    ret @respan(sp, ast.pat_wild(a));
+}
+
+fn identity_fold_pat_bind[ENV](&ENV e, &span sp, ident i, ann a) -> @pat {
+    ret @respan(sp, ast.pat_bind(i, a));
+}
+
+fn identity_fold_pat_tag[ENV](&ENV e, &span sp, ident i, vec[@pat] args,
+                              ann a) -> @pat {
+    ret @respan(sp, ast.pat_tag(i, args, a));
+}
+
+
 // Stmt identities.
 
 fn identity_fold_stmt_decl[ENV](&ENV env, &span sp, @decl d) -> @stmt {
@@ -790,6 +863,10 @@ fn identity_update_env_for_decl[ENV](&ENV e, @decl d) -> ENV {
     ret e;
 }
 
+fn identity_update_env_for_pat[ENV](&ENV e, @pat p) -> ENV {
+    ret e;
+}
+
 fn identity_update_env_for_expr[ENV](&ENV e, @expr x) -> ENV {
     ret e;
 }
@@ -835,6 +912,7 @@ fn new_identity_fold[ENV]() -> ast_fold[ENV] {
          fold_expr_while  = bind identity_fold_expr_while[ENV](_,_,_,_,_),
          fold_expr_do_while
                           = bind identity_fold_expr_do_while[ENV](_,_,_,_,_),
+         fold_expr_alt    = bind identity_fold_expr_alt[ENV](_,_,_,_,_),
          fold_expr_block  = bind identity_fold_expr_block[ENV](_,_,_,_),
          fold_expr_assign = bind identity_fold_expr_assign[ENV](_,_,_,_,_),
          fold_expr_field  = bind identity_fold_expr_field[ENV](_,_,_,_,_),
@@ -844,6 +922,10 @@ fn new_identity_fold[ENV]() -> ast_fold[ENV] {
          fold_decl_local  = bind identity_fold_decl_local[ENV](_,_,_),
          fold_decl_item   = bind identity_fold_decl_item[ENV](_,_,_),
 
+         fold_pat_wild    = bind identity_fold_pat_wild[ENV](_,_,_),
+         fold_pat_bind    = bind identity_fold_pat_bind[ENV](_,_,_,_),
+         fold_pat_tag     = bind identity_fold_pat_tag[ENV](_,_,_,_,_),
+
          fold_stmt_decl   = bind identity_fold_stmt_decl[ENV](_,_,_),
          fold_stmt_ret    = bind identity_fold_stmt_ret[ENV](_,_,_),
          fold_stmt_log    = bind identity_fold_stmt_log[ENV](_,_,_),
@@ -866,6 +948,7 @@ fn new_identity_fold[ENV]() -> ast_fold[ENV] {
          update_env_for_block = bind identity_update_env_for_block[ENV](_,_),
          update_env_for_stmt = bind identity_update_env_for_stmt[ENV](_,_),
          update_env_for_decl = bind identity_update_env_for_decl[ENV](_,_),
+         update_env_for_pat = bind identity_update_env_for_pat[ENV](_,_),
          update_env_for_expr = bind identity_update_env_for_expr[ENV](_,_),
          update_env_for_ty = bind identity_update_env_for_ty[ENV](_,_),