diff --git a/src/terrain/filter.cpp b/src/terrain/filter.cpp
index 014f351098bd..5b3eab951dfa 100644
--- a/src/terrain/filter.cpp
+++ b/src/terrain/filter.cpp
@@ -33,6 +33,8 @@
 #include "formula/callable_objects.hpp"
 #include "formula/formula.hpp"
 
+#include <boost\range\adaptor\transformed.hpp>
+
 static lg::log_domain log_engine("engine");
 #define ERR_NG LOG_STREAM(err, log_engine)
 #define WRN_NG LOG_STREAM(warn, log_engine)
@@ -420,171 +422,88 @@ bool terrain_filter::match(const map_location& loc) const
 	}
 	return false;
 }
-
-void terrain_filter::get_locations(std::set<map_location>& locs, bool with_border) const
+//using a class to be able to firen it in terrain_filter
+class terrain_filterimpl
 {
-	std::set<map_location> match_set;
-
-	// See if the caller provided an override to with_border
-	with_border = cfg_["include_borders"].to_bool(with_border);
-
-	// None of the generators provided
-	if ( !cfg_.has_attribute("x") && !cfg_.has_attribute("y")
-			&& !cfg_.has_attribute("find_in")
-			&& !cfg_.has_attribute("area") ) {
+public:
+	using location_set = std::set<map_location>;
+	struct tno_start_set_yet {};
+	struct tno_filter
+	{
+		bool operator()(const map_location&) const { return true; }
+	};
 
-		//consider all locations on the map
-		int bs = fc_->get_disp_context().map().border_size();
-		int w = with_border ? fc_->get_disp_context().map().w() + bs : fc_->get_disp_context().map().w();
-		int h = with_border ? fc_->get_disp_context().map().h() + bs : fc_->get_disp_context().map().h();
-		for (int x = with_border ? 0 - bs : 0; x < w; ++x) {
-			for (int y = with_border ? 0 - bs : 0; y < h; ++y) {
-				match_set.insert(map_location(x,y));
+	template<typename T, typename F1, typename F2>
+	static void filter_final(T&& src, location_set& dest, const terrain_filter&, const F1& f1, const F2& f2)
+	{
+		for (const map_location &loc : src) {
+			if (f1(loc) && f2(loc)) {
+				dest.insert(loc);
 			}
 		}
-	} else
-
-	// Only the x,y attributes found
-	if ( (cfg_.has_attribute("x") || cfg_.has_attribute("y"))
-			&& !cfg_.has_attribute("find_in")
-			&& !cfg_.has_attribute("area") ) {
-
-		std::vector<map_location> xy_vector;
-		xy_vector = fc_->get_disp_context().map().parse_location_range(cfg_["x"], cfg_["y"], with_border);
-		match_set.insert(xy_vector.begin(), xy_vector.end());
-	} else
-
-	// Only find_in provided
-	if ( !cfg_.has_attribute("x") && !cfg_.has_attribute("y")
-			&& cfg_.has_attribute("find_in")
-			&& !cfg_.has_attribute("area") ) {
+	}
 
-		//use content of find_in as starting set
-		if (const game_data * gd = fc_->get_game_data()) {
-			try
-			{
-				variable_access_const vi = gd->get_variable_access_read(cfg_["find_in"]);
-				for (const config& cfg : vi.as_array())
-				{
-					map_location test_loc(cfg, nullptr);
-					match_set.insert(test_loc);
-				}
-			}
-			catch(const invalid_variablename_exception&)
-			{
-				//Do nothing
-			}
+	template<typename T, typename F1>
+	static void filter_area(T&& src, location_set& dest, const terrain_filter& filter, const F1& f1)
+	{
+		if (filter.cfg_.has_attribute("area")) {
+			const std::set<map_location>& area = filter.fc_->get_tod_man().get_area_by_id(filter.cfg_["area"]);
+			filter_final(src, dest, filter, f1, [&area](const map_location& loc) { return area.find(loc) != area.end(); });
 		}
-	} else
-
-	// Only area provided
-	if ( !cfg_.has_attribute("x") && !cfg_.has_attribute("y")
-			&& !cfg_.has_attribute("find_in")
-			&& cfg_.has_attribute("area") ) {
-
-		const std::set<map_location>& area = fc_->get_tod_man().get_area_by_id(cfg_["area"]);
-		match_set.insert(area.begin(), area.end());
-	} else
-
-	// find_in + xy
-	if ( (cfg_.has_attribute("x") || cfg_.has_attribute("y"))
-			&& cfg_.has_attribute("find_in")
-			&& !cfg_.has_attribute("area") ) {
-
-		std::vector<map_location> xy_vector;
-		xy_vector = fc_->get_disp_context().map().parse_location_range(cfg_["x"], cfg_["y"], with_border);
-		match_set.insert(xy_vector.begin(), xy_vector.end());
-
-		// remove any locations not found in the specified variable
-		if (const game_data * gd = fc_->get_game_data()) {
-			try
-			{
-				std::set<map_location> findin_locs;
-				variable_access_const vi = gd->get_variable_access_read(cfg_["find_in"]);
-				for (const config& cfg : vi.as_array())
-				{
-					map_location test_loc(cfg, nullptr);
-					if (match_set.count(test_loc)) {
-						findin_locs.insert(test_loc);
-					}
-				}
-				match_set.swap(findin_locs);
-			}
-			catch(const invalid_variablename_exception&)
-			{
-				match_set.clear();
-			}
+		else {
+			filter_final(src, dest, filter, f1, tno_filter());
 		}
-	} else
-
-	// xy + area
-	if ( (cfg_.has_attribute("x") || cfg_.has_attribute("y"))
-			&& !cfg_.has_attribute("find_in")
-			&& cfg_.has_attribute("area") ) {
-
-		std::vector<map_location> xy_vector;
-		xy_vector = fc_->get_disp_context().map().parse_location_range(cfg_["x"], cfg_["y"], with_border);
-		const std::set<map_location>& area = fc_->get_tod_man().get_area_by_id(cfg_["area"]);
+	}
 
-		for (const map_location& loc : xy_vector) {
-			if (area.count(loc) != 0)
-				match_set.insert(loc);
+	template<typename T>
+	static void filter_xy(T&& src, location_set& dest, const terrain_filter& filter, bool with_border)
+	{
+		if (filter.cfg_.has_attribute("x") || filter.cfg_.has_attribute("y")) {
+			std::vector<map_location> xy_vector = filter.fc_->get_disp_context().map().parse_location_range(filter.cfg_["x"], filter.cfg_["y"], with_border);
+			filter_area(src, dest, filter, [&xy_vector](const map_location& loc) { return std::find(xy_vector.begin(), xy_vector.end(), loc) != xy_vector.end(); });
 		}
-	} else
-
-	// area + find_in
-	if ( !(cfg_.has_attribute("x") && cfg_.has_attribute("y"))
-			&& cfg_.has_attribute("find_in")
-			&& cfg_.has_attribute("area") ) {
+		else {
+			filter_area(src, dest, filter, tno_filter());
+		}
+	}
+};
+void terrain_filter::get_locations(std::set<map_location>& locs, bool with_border) const
+{
+	std::set<map_location> match_set;
 
-		const std::set<map_location>& area = fc_->get_tod_man().get_area_by_id(cfg_["area"]);
+	// See if the caller provided an override to with_border
+	with_border = cfg_["include_borders"].to_bool(with_border);
 
-		//use content of find_in as starting set
+	if (cfg_.has_attribute("find_in")) {
 
 		if (const game_data * gd = fc_->get_game_data()) {
 			try
 			{
-				variable_access_const vi = gd->get_variable_access_read(cfg_["find_in"]);
-				for (const config& cfg : vi.as_array())
-				{
-					map_location test_loc(cfg, nullptr);
-					if (area.count(test_loc) != 0)
-						match_set.insert(test_loc);
-				}
+				auto ar = gd->get_variable_access_read(cfg_["find_in"]).as_array();
+				terrain_filterimpl::filter_xy(ar | boost::adaptors::transformed([](const config& cfg) { return map_location(cfg, nullptr);}), match_set, *this, with_border);
 			}
-			catch(const invalid_variablename_exception&)
+			catch (const invalid_variablename_exception&)
 			{
-				match_set.clear();
+				//Do nothing
 			}
 		}
-	} else
-
-	// area + find_in + xy
-	if ( (cfg_.has_attribute("x") && cfg_.has_attribute("y"))
-			&& cfg_.has_attribute("find_in")
-			&& cfg_.has_attribute("area") ) {
-
-		const std::vector<map_location>& xy_vector =
-				fc_->get_disp_context().map().parse_location_range(cfg_["x"], cfg_["y"], with_border);
-		std::set<map_location> xy_set(xy_vector.begin(), xy_vector.end());
-
+	}
+	else if (cfg_.has_attribute("x") || cfg_.has_attribute("y")) {
+		std::vector<map_location> xy_vector = fc_->get_disp_context().map().parse_location_range(cfg_["x"], cfg_["y"], with_border);
+		terrain_filterimpl::filter_area(xy_vector, match_set, *this, terrain_filterimpl::tno_filter());
+	}
+	else if (cfg_.has_attribute("area")) {
 		const std::set<map_location>& area = fc_->get_tod_man().get_area_by_id(cfg_["area"]);
-
-		//use content of find_in as starting set
-		if (const game_data * gd = fc_->get_game_data()) {
-			try
-			{
-				variable_access_const vi = gd->get_variable_access_read(cfg_["find_in"]);
-
-				for (const config &cfg : vi.as_array()) {
-					map_location test_loc(cfg, nullptr);
-					if (area.count(test_loc) != 0 && xy_set.count(test_loc) != 0)
-						match_set.insert(test_loc);
-				}
-			}
-			catch(const invalid_variablename_exception&)
-			{
-				//Do nothing
+		terrain_filterimpl::filter_final(area, match_set, *this, terrain_filterimpl::tno_filter(), terrain_filterimpl::tno_filter());
+	}
+	else {
+		//consider all locations on the map
+		int bs = fc_->get_disp_context().map().border_size();
+		int w = with_border ? fc_->get_disp_context().map().w() + bs : fc_->get_disp_context().map().w();
+		int h = with_border ? fc_->get_disp_context().map().h() + bs : fc_->get_disp_context().map().h();
+		for (int x = with_border ? 0 - bs : 0; x < w; ++x) {
+			for (int y = with_border ? 0 - bs : 0; y < h; ++y) {
+				match_set.insert(map_location(x, y));
 			}
 		}
 	}
diff --git a/src/terrain/filter.hpp b/src/terrain/filter.hpp
index 3c0dbf3c54e8..5f421cd10072 100644
--- a/src/terrain/filter.hpp
+++ b/src/terrain/filter.hpp
@@ -66,6 +66,7 @@ class terrain_filter : public xy_pred {
 	void flatten(const bool flat_tod=true) { flat_ = flat_tod; }
 
 	config to_config() const;
+	friend class terrain_filterimpl;
 private:
 	bool match_internal(const map_location& loc, const bool ignore_xy) const;