expose if buildingplan is enabled to lua

docs/Lua API.rst

@@ -3616,8 +3616,9 @@ buildingplan
 
 Native functions:
 
-* ``bool isPlannableBuilding(df::building_type type)`` returns whether the building type is handled by buildingplan
-* ``void addPlannedBuilding(df::building *bld)`` suspends the building jobs and adds the building to the monitor list
+* ``bool isEnabled()`` returns whether the plugin is enabled.
+* ``bool isPlannableBuilding(df::building_type type)`` returns whether the building type is handled by buildingplan.
+* ``void addPlannedBuilding(df::building *bld)`` suspends the building jobs and adds the building to the monitor list.
 * ``void doCycle()`` runs a check for whether buildlings in the monitor list can be assigned items and unsuspended. This method runs automatically twice a game day, so you only need to call it directly if you want buildingplan to do a check right now.
 
 burrows

plugins/buildingplan.cpp

@@ -418,6 +418,10 @@ DFhackCExport command_result plugin_onstatechange(color_ostream &out, state_chan
 
 // Lua API section
 
+static bool isEnabled() {
+    return is_enabled;
+}
+
 static bool isPlannableBuilding(df::building_type type) {
     return planner.isPlanableBuilding(type);
 }
@@ -431,6 +435,7 @@ static void doCycle() {
 }
 
 DFHACK_PLUGIN_LUA_FUNCTIONS {
+    DFHACK_LUA_FUNCTION(isEnabled),
     DFHACK_LUA_FUNCTION(isPlannableBuilding),
     DFHACK_LUA_FUNCTION(addPlannedBuilding),
     DFHACK_LUA_FUNCTION(doCycle),

plugins/lua/buildingplan.lua

@@ -4,6 +4,7 @@ local _ENV = mkmodule('plugins.buildingplan')
 
  Native functions:
 
+ * bool isEnabled()
  * bool isPlannableBuilding(df::building_type type)
  * void addPlannedBuilding(df::building *bld)
  * void doCycle()