add place-schematic variant that aborts if the schematic doesn't fit

bounding_boxes.lua

@@ -38,4 +38,17 @@ end
 mapgen_helper.intersect_exists_xz = function(minpos1, maxpos1, minpos2, maxpos2)
 	return (minpos1.x <= maxpos2.x and maxpos1.x >= minpos2.x and
 		minpos1.z <= maxpos2.z and maxpos1.z >= minpos2.z)
+end
+
+-- Simply tests whether pos is within the bounding box defined by minpos and maxpos
+local intersect_exists = mapgen_helper.intersect_exists
+mapgen_helper.is_pos_within_box = function(pos, minpos, maxpos)
+	return intersect_exists(pos, pos, minpos, maxpos)
+end
+
+-- Tests whether box 1 is entirely contained within box 2
+mapgen_helper.is_box_within_box = function(minpos1, maxpos1, minpos2, maxpos2)
+	return (minpos1.x >= minpos2.x and maxpos1.x <= maxpos2.x and
+		minpos1.z >= minpos2.z and maxpos1.z <= maxpos2.z and
+		minpos1.y >= minpos2.y and maxpos1.y <= maxpos2.y)
 end

place_schematic.lua

@@ -292,6 +292,16 @@ mapgen_helper.place_schematic_on_data = function(data, data_param2, area, pos, s
 	return contained_in_area
 end
 
+-- aborts schematic placement if it won't fit into the provided data
+mapgen_helper.place_schematic_on_data_if_it_fits = function(data, data_param2, area, pos, schematic, rotation, replacements, force_placement, flags)
+	local minbound, maxbound = mapgen_helper.get_schematic_bounding_box(pos, schematic, rotation, flags)
+	if mapgen_helper.is_box_within_box(minbound, maxbound, area.MinEdge, area.MaxEdge) then
+		return mapgen_helper.place_schematic_on_data(data, data_param2, area, pos, schematic, rotation, replacements, force_placement, flags)
+	end
+	return false
+end
+
+
 -- wraps the above for convenience, so you can use this style of schematic in non-mapgen contexts as well
 mapgen_helper.place_schematic = function(pos, schematic, rotation, replacements, force_placement, flags)
 	local minpos, maxpos = mapgen_helper.get_schematic_bounding_box(pos, schematic, rotation, flags)