Observerable/observer-ish pattern for Lua markers

A new framework for Lua markers, similar to the observable/observer
design pattern, which decouples the thing being activated from the thing
watching for the activating condition.  This makes it easier to create
new types of Lua markers which are triggered by dungeon events, and
easier to add new triggering conditions to already existing marker
types.  Currently only ChangeFlags (clua/lm_flags.lua) and
MonsterOnTrigger (clua/lm_monst.lua) use it.

1 files changed, 25 insertions, 1 deletions

diff --git a/crawl-ref/source/l_dgnevt.cc b/crawl-ref/source/l_dgnevt.cc
index c379bad317..f6d1b56aeb 100644
--- a/crawl-ref/source/l_dgnevt.cc
+++ b/crawl-ref/source/l_dgnevt.cc
@@ -119,9 +119,33 @@ static int dgn_dgn_event(lua_State *ls)
     return (retvals);
 }
 
+static dgn_event_type dgn_param_to_event_type(lua_State *ls, int n)
+{
+    if (lua_isnumber(ls, n))
+        return (static_cast<dgn_event_type>(luaL_checkint(ls, n)));
+    else if (lua_isstring(ls, n))
+        return dgn_event_type_by_name(lua_tostring(ls, n));
+    else
+        return (DET_NONE);
+}
+
+static int dgn_dgn_event_is_global(lua_State *ls)
+{
+    lua_pushboolean(ls, dgn_param_to_event_type(ls, 1) & DET_GLOBAL_MASK);
+    return (1);
+}
+
+static int dgn_dgn_event_is_position(lua_State *ls)
+{
+    lua_pushboolean(ls, dgn_param_to_event_type(ls, 1) & DET_POSITION_MASK);
+    return (1);
+}
+
 const struct luaL_reg dgn_event_dlib[] =
 {
-{ "dgn_event_type", dgn_dgn_event },
+{ "dgn_event_type",        dgn_dgn_event },
+{ "dgn_event_is_global",   dgn_dgn_event_is_global },
+{ "dgn_event_is_position", dgn_dgn_event_is_position},
 
 { NULL, NULL }
 };