One last refactoring of the import handling:

* Create an import resolving stage. Currently this involves a copy of the ast,
  we can probably revisit this once we revisit doing full copies of the ast in
  general.

* Don't repeat work. Once we resolve a import, put it on a hash table and use
  it next time we are asked for it. This solves a O(n^2) behaviour in
  degenerated cases.

* Once import resolution is done, the target of an import is stored on the
  import itself.

2 files changed, 4 insertions, 3 deletions

diff --git a/src/comp/front/ast.rs b/src/comp/front/ast.rs
index 1ee50c2a..1fad1c1a 100644
--- a/src/comp/front/ast.rs
+++ b/src/comp/front/ast.rs
@@ -229,7 +229,7 @@ type variant = rec(str name, vec[variant_arg] args, def_id id, ann ann);
 type view_item = spanned[view_item_];
 tag view_item_ {
     view_item_use(ident, vec[@meta_item], def_id);
-    view_item_import(vec[ident], def_id);
+    view_item_import(vec[ident], def_id, option.t[def]);
 }
 
 type item = spanned[item_];
@@ -247,7 +247,7 @@ fn index_view_item(mod_index index, @view_item it) {
         case(ast.view_item_use(?id, _, _)) {
             index.insert(id, ast.mie_view_item(it));
         }
-        case(ast.view_item_import(?ids,_)) {
+        case(ast.view_item_import(?ids,_,_)) {
             auto len = _vec.len[ast.ident](ids);
             auto last_id = ids.(len - 1u);
             index.insert(last_id, ast.mie_view_item(it));
diff --git a/src/comp/front/parser.rs b/src/comp/front/parser.rs
index c44da8f1..0e8d1dc7 100644
--- a/src/comp/front/parser.rs
+++ b/src/comp/front/parser.rs
@@ -1704,7 +1704,8 @@ impure fn parse_rest_import_name(parser p, ast.ident id) -> @ast.view_item {
         identifiers += i;
     }
     p.bump();
-    auto import_decl = ast.view_item_import(identifiers, p.next_def_id());
+    auto import_decl = ast.view_item_import(identifiers, p.next_def_id(),
+                                            none[ast.def]);
     ret @spanned(lo, hi, import_decl);
 }