filter cages by whether they are occupied

docs/changelog.txt

@@ -74,6 +74,7 @@ Template for new versions:
 - `orders`: ``recheck`` command now only resets orders that have conditions that can be rechecked
 - `sort`: added help button for squad assignment search/filter/sort
 - `zone`: animals trained for war or hunting are now labeled as such in animal assignment screens
+- `buildingplan`: support filtering cages by whether they are occupied
 
 ## Documentation
 - unavailable tools are no longer listed in the tag indices in the online docs

plugins/buildingplan/buildingplan_cycle.cpp

@@ -119,6 +119,11 @@ bool matchesFilters(df::item * item, const df::job_item * jitem, HeatSafety heat
         && static_cast<df::item_slabst *>(item)->engraving_type != df::slab_engraving_type::Memorial)
         return false;
 
+    if (item->getType() == df::item_type::CAGE && specials.count("empty")
+        && (Items::getGeneralRef(item, df::general_ref_type::CONTAINS_UNIT)
+            || Items::getGeneralRef(item, df::general_ref_type::CONTAINS_ITEM)))
+        return false;
+
     if (!matchesHeatSafety(item->getMaterial(), item->getMaterialIndex(), heat))
         return false;
 

plugins/lua/buildingplan/planneroverlay.lua

@@ -162,6 +162,10 @@ local function is_slab()
     return uibs.building_type == df.building_type.Slab
 end
 
+local function is_cage()
+    return uibs.building_type == df.building_type.Cage
+end
+
 local function is_stairs()
     return is_construction()
             and uibs.building_subtype == df.construction_type.UpDownStair
@@ -477,6 +481,16 @@ function PlannerOverlay:init()
                 buildingplan.setSpecial(uibs.building_type, uibs.building_subtype, uibs.custom_type, 'engraved', val)
             end,
         },
+        widgets.ToggleHotkeyLabel {
+            view_id='empty',
+            frame={b=4, l=1, w=22},
+            key='CUSTOM_T',
+            label='Empty only:',
+            visible=is_cage,
+            on_change=function(val)
+                buildingplan.setSpecial(uibs.building_type, uibs.building_subtype, uibs.custom_type, 'empty', val)
+            end,
+        },
         widgets.Label{
             frame={b=4, l=23},
             text_pen=COLOR_DARKGREY,
@@ -847,6 +861,8 @@ function PlannerOverlay:onRenderFrame(dc, rect)
         local buildingplan = require('plugins.buildingplan')
         self.subviews.engraved:setOption(buildingplan.getSpecials(
             uibs.building_type, uibs.building_subtype, uibs.custom_type).engraved or false)
+        self.subviews.empty:setOption(buildingplan.getSpecials(
+            uibs.building_type, uibs.building_subtype, uibs.custom_type).empty or false)
         self.subviews.choose:setOption(buildingplan.getChooseItems(
             uibs.building_type, uibs.building_subtype, uibs.custom_type))
         self.subviews.safety:setOption(buildingplan.getHeatSafetyFilter(