An iterator for going through all level_id values.

It's a travesty something like this is even needed.  Really, all the
level_type nonsense and portal levels inaccessible except for parsing their
description should be regular branches.

For now, here's a crutch.

1 files changed, 10 insertions, 0 deletions

diff --git a/crawl-ref/source/travel.h b/crawl-ref/source/travel.h
index 69f10f51bc..dc67372bc2 100644
--- a/crawl-ref/source/travel.h
+++ b/crawl-ref/source/travel.h
@@ -621,4 +621,14 @@ int click_travel(const coord_def &gc, bool force);
 bool check_for_interesting_features();
 void clear_level_target();
 
+class level_id_iterator : public std::iterator<std::forward_iterator_tag, level_id>
+{
+public:
+    level_id_iterator();
+    operator bool() const;
+    level_id operator *() const;
+    void operator++();
+private:
+    level_id cur;
+};
 #endif // TRAVEL_H