move fastdwarf's teleport code to Units module

and expose in Lua API

docs/Lua API.rst

@@ -1172,13 +1172,18 @@ Units module
 
   Returns true *x,y,z* of the unit, or *nil* if invalid; may be not equal to unit.pos if caged.
 
-* ``dfhack.getUnitsInBox(x1,y1,z1,x2,y2,z2[,filter])``
+* ``dfhack.units.getUnitsInBox(x1,y1,z1,x2,y2,z2[,filter])``
 
   Returns a table of all units within the specified coordinates. If the ``filter``
   argument is given, only units where ``filter(unit)`` returns true will be included.
   Note that ``pos2xyz()`` cannot currently be used to convert coordinate objects to
   the arguments required by this function.
 
+* ``dfhack.units.teleport(unit, pos)``
+
+  Moves the specified unit and any riders to the target coordinates, setting
+  tile occupancy flags appropriately. Returns true if successful.
+
 * ``dfhack.units.getGeneralRef(unit, type)``
 
   Searches for a general_ref with the given type.

library/LuaApi.cpp

@@ -1572,6 +1572,7 @@ static const luaL_Reg dfhack_job_funcs[] = {
 /***** Units module *****/
 
 static const LuaWrapper::FunctionReg dfhack_units_module[] = {
+    WRAPM(Units, teleport),
     WRAPM(Units, getGeneralRef),
     WRAPM(Units, getSpecificRef),
     WRAPM(Units, getContainer),

library/include/modules/Units.h

@@ -82,6 +82,9 @@ DFHACK_EXPORT int32_t findIndexById(int32_t id);
 /// Returns the true position of the unit (non-trivial in case of caged).
 DFHACK_EXPORT df::coord getPosition(df::unit *unit);
 
+// moves unit and any riders to the target coordinates
+DFHACK_EXPORT bool teleport(df::unit *unit, df::coord target_pos);
+
 DFHACK_EXPORT df::general_ref *getGeneralRef(df::unit *unit, df::general_ref_type type);
 DFHACK_EXPORT df::specific_ref *getSpecificRef(df::unit *unit, df::specific_ref_type type);
 

library/modules/Units.cpp

@@ -71,6 +71,7 @@ using namespace std;
 #include "df/job.h"
 #include "df/nemesis_record.h"
 #include "df/squad.h"
+#include "df/tile_occupancy.h"
 #include "df/ui.h"
 #include "df/unit_inventory_item.h"
 #include "df/unit_misc_trait.h"
@@ -144,6 +145,49 @@ df::coord Units::getPosition(df::unit *unit)
     return unit->pos;
 }
 
+bool Units::teleport(df::unit *unit, df::coord target_pos)
+{
+    // make sure source and dest map blocks are valid
+    auto old_occ = Maps::getTileOccupancy(unit->pos);
+    auto new_occ = Maps::getTileOccupancy(target_pos);
+    if (!old_occ || !new_occ)
+        return false;
+
+    // clear appropriate occupancy flags at old tile
+    if (unit->flags1.bits.on_ground)
+        // this is potentially wrong, but the game will recompute this as needed
+        old_occ->bits.unit_grounded = 0;
+    else
+        old_occ->bits.unit = 0;
+
+    // if there's already somebody standing at the destination, then force the
+    // unit to lay down
+    if (new_occ->bits.unit)
+        unit->flags1.bits.on_ground = 1;
+
+    // set appropriate occupancy flags at new tile
+    if (unit->flags1.bits.on_ground)
+        new_occ->bits.unit_grounded = 1;
+    else
+        new_occ->bits.unit = 1;
+
+    // move unit to destination
+    unit->pos = target_pos;
+
+    // move unit's riders (including babies) to destination
+    if (unit->flags1.bits.ridden)
+    {
+        for (size_t j = 0; j < world->units.other[units_other_id::ANY_RIDER].size(); j++)
+        {
+            df::unit *rider = world->units.other[units_other_id::ANY_RIDER][j];
+            if (rider->relationship_ids[df::unit_relationship_type::RiderMount] == unit->id)
+                rider->pos = unit->pos;
+        }
+    }
+
+    return true;
+}
+
 df::general_ref *Units::getGeneralRef(df::unit *unit, df::general_ref_type type)
 {
     CHECK_NULL_POINTER(unit);

plugins/fastdwarf.cpp

@@ -54,7 +54,7 @@ DFhackCExport command_result plugin_onupdate ( color_ostream &out )
         if (!Units::isCitizen(unit))
             continue;
 
-        if (enable_teledwarf) do
+        if (enable_teledwarf)
         {
             // skip dwarves that are dragging creatures or being dragged
             if ((unit->relationship_ids[df::unit_relationship_type::Draggee] != -1) ||
@@ -74,44 +74,11 @@ DFhackCExport command_result plugin_onupdate ( color_ostream &out )
                 break;
             }
 
-            // make sure source and dest map blocks are valid
+            if (!Units::teleport(unit, unit->path.dest))
-            auto old_occ = Maps::getTileOccupancy(unit->pos);
-            auto new_occ = Maps::getTileOccupancy(unit->path.dest);
-            if (!old_occ || !new_occ)
                 break;
 
-            // clear appropriate occupancy flags at old tile
-            if (unit->flags1.bits.on_ground)
-                // this is technically wrong, but the game will recompute this as needed
-                old_occ->bits.unit_grounded = 0;
-            else
-                old_occ->bits.unit = 0;
-
-            // if there's already somebody standing at the destination, then force the unit to lay down
-            if (new_occ->bits.unit)
-                unit->flags1.bits.on_ground = 1;
-
-            // set appropriate occupancy flags at new tile
-            if (unit->flags1.bits.on_ground)
-                new_occ->bits.unit_grounded = 1;
-            else
-                new_occ->bits.unit = 1;
-
-            // move unit to destination
-            unit->pos = unit->path.dest;
             unit->path.path.clear();
-
-            //move unit's riders(including babies) to destination
-            if (unit->flags1.bits.ridden)
-            {
-                for (size_t j = 0; j < world->units.other[units_other_id::ANY_RIDER].size(); j++)
-                {
-                    df::unit *rider = world->units.other[units_other_id::ANY_RIDER][j];
-                    if (rider->relationship_ids[df::unit_relationship_type::RiderMount] == unit->id)
-                        rider->pos = unit->pos;
-                }
         }
-        } while (0);
 
         if (enable_fastdwarf)
         {