add static const members ZERO, default_dirs, of map_location

Replace local constants appearing elsewhere with these.
The definitions are inlined.

src/ai/default/contexts.cpp

@@ -175,7 +175,7 @@ std::vector<target> default_ai_context_impl::find_targets(const move_map& enemy_
 		}
 	}
 
-	double corner_distance = distance_between(map_location(0,0), map_location(map_.w(),map_.h()));
+	double corner_distance = distance_between(map_location::ZERO(), map_location(map_.w(),map_.h()));
 	double village_value = get_village_value();
 	if(has_leader && village_value > 0.0) {
 		std::map<map_location,pathfind::paths> friends_possible_moves;

src/editor/action/action.hpp

@@ -224,7 +224,7 @@ class editor_action_area : public editor_action_extendable
 class editor_action_paste : public editor_action_extendable
 {
 	public:
-		editor_action_paste(const map_fragment& paste, const map_location& offset = map_location(0,0))
+		editor_action_paste(const map_fragment& paste, const map_location& offset = map_location::ZERO())
 		: offset_(offset), paste_(paste)
 		{
 		}

src/editor/map/map_fragment.cpp

@@ -103,7 +103,7 @@ void map_fragment::rotate_60_cw()
 {
 	area_.clear();
 	BOOST_FOREACH(tile_info& ti, items_) {
-		map_location l(0,0);
+		map_location l = map_location::ZERO();
 		int x = ti.offset.x;
 		int y = ti.offset.y;
 		// rotate the X-Y axes to SOUTH/SOUTH_EAST - SOUTH_WEST axes
@@ -123,7 +123,7 @@ void map_fragment::rotate_60_ccw()
 {
 	area_.clear();
 	BOOST_FOREACH(tile_info& ti, items_) {
-		map_location l(0,0);
+		map_location l = map_location::ZERO();
 		int x = ti.offset.x;
 		int y = ti.offset.y;
 		// rotate the X-Y axes to NORTH/NORTH_EAST - SOUTH_EAST axes'

src/halo.cpp

@@ -119,9 +119,8 @@ effect::effect(int xpos, int ypos, const animated<image::locator>::anim_descript
 
 void effect::set_location(int x, int y)
 {
-	const map_location zero_loc(0,0);
-	int new_x = x - disp->get_location_x(zero_loc);
-	int new_y = y - disp->get_location_y(zero_loc);
+	int new_x = x - disp->get_location_x(map_location::ZERO());
+	int new_y = y - disp->get_location_y(map_location::ZERO());
 	if (new_x != x_ || new_y != y_) {
 		x_ = new_x;
 		y_ = new_y;
@@ -165,9 +164,8 @@ bool effect::render()
 		surf_.assign(flop_surface(surf_));
 	}
 
-	const map_location zero_loc(0,0);
-	const int screenx = disp->get_location_x(zero_loc);
-	const int screeny = disp->get_location_y(zero_loc);
+	const int screenx = disp->get_location_x(map_location::ZERO());
+	const int screeny = disp->get_location_y(map_location::ZERO());
 
 	const int xpos = x_ + screenx - surf_->w/2;
 	const int ypos = y_ + screeny - surf_->h/2;
@@ -231,9 +229,8 @@ void effect::unrender()
 
 	// Due to scrolling, the location of the rendered halo
 	// might have changed; recalculate
-	const map_location zero_loc(0,0);
-	const int screenx = disp->get_location_x(zero_loc);
-	const int screeny = disp->get_location_y(zero_loc);
+	const int screenx = disp->get_location_x(map_location::ZERO());
+	const int screeny = disp->get_location_y(map_location::ZERO());
 
 	const int xpos = x_ + screenx - surf_->w/2;
 	const int ypos = y_ + screeny - surf_->h/2;

src/map.cpp

@@ -645,7 +645,7 @@ const std::map<t_translation::t_terrain, size_t>& gamemap::get_weighted_terrain_
 
 	const map_location center(w()/2,h()/2);
 
-	const size_t furthest_distance = distance_between(map_location(0,0),center);
+	const size_t furthest_distance = distance_between(map_location::ZERO(),center);
 
 	const size_t weight_at_edge = 100;
 	const size_t additional_weight_at_center = 200;

src/map_location.cpp

@@ -29,7 +29,6 @@
 #include "resources.hpp"
 #include "util.hpp"
 
-
 #define ERR_CF LOG_STREAM(err, config)
 #define LOG_G LOG_STREAM(info, general)
 #define DBG_G LOG_STREAM(debug, general)

src/map_location.hpp

@@ -24,6 +24,7 @@ class variable_set;
 #include <vector>
 #include <set>
 #include <boost/unordered_map.hpp>
+#include <boost/assign/list_of.hpp>
 
 /**
  * Encapsulates the map of the game.
@@ -38,6 +39,15 @@ struct map_location {
 	enum DIRECTION { NORTH=0, NORTH_EAST=1, SOUTH_EAST=2, SOUTH=3,
 					 SOUTH_WEST=4, NORTH_WEST=5, NDIRECTIONS=6 };
 
+	static const std::vector<DIRECTION> & default_dirs() {
+		static const std::vector<map_location::DIRECTION> dirs = boost::assign::list_of(map_location::NORTH)(map_location::NORTH_EAST)(map_location::SOUTH_EAST)(map_location::SOUTH)(map_location::SOUTH_WEST)(map_location::NORTH_WEST);
+		return dirs;
+	}
+
+	static const map_location & ZERO() {
+		static const map_location z(0,0);
+		return z;
+	}
 
 	static inline DIRECTION rotate_right(DIRECTION d, unsigned int k = 1u) {
 		return (d == NDIRECTIONS) ? NDIRECTIONS : static_cast<map_location::DIRECTION>((d + (k%6u)) % 6u);
@@ -105,7 +115,7 @@ struct map_location {
 	// Rotates the map_location clockwise in 60 degree increments around a center point. Negative numbers of steps are permitted.
 	map_location rotate_right_around_center(const map_location & center, int k) const;
 
-	static const map_location null_location;
+	static const map_location null_location;	
 
 	friend std::size_t hash_value(map_location const &a);
 };

src/terrain_filter.cpp

@@ -185,10 +185,8 @@ bool terrain_filter::match_internal(const map_location& loc, const bool ignore_x
 		for (i = i_begin, i_end = adj_cfgs.end(); i != i_end; ++i) {
 			int match_count = 0;
 			vconfig::child_list::difference_type index = i - i_begin;
-			static std::vector<map_location::DIRECTION> default_dirs
-				= map_location::parse_directions("n,ne,se,s,sw,nw");
 			std::vector<map_location::DIRECTION> dirs = (*i).has_attribute("adjacent")
-				? map_location::parse_directions((*i)["adjacent"]) : default_dirs;
+				? map_location::parse_directions((*i)["adjacent"]) : map_location::default_dirs();
 			std::vector<map_location::DIRECTION>::const_iterator j, j_end = dirs.end();
 			for (j = dirs.begin(); j != j_end; ++j) {
 				map_location &adj = adjacent[*j];

src/tests/test_map_location.cpp

@@ -38,7 +38,7 @@ struct MLFixture
 		va = map_location(3,4);
 		vb = map_location(10,8);
 		vc = map_location(0,9);
-		vz = map_location(0,0);
+		vz = map_location::ZERO();
 		vt1 = map_location(va.vector_negation());
 		vt2 = map_location(vb.vector_sum(vc));
 		vt3 = map_location(va.vector_sum(vc.vector_negation()));

src/unit.cpp

@@ -1609,11 +1609,9 @@ bool unit::internal_matches_filter(const vconfig& cfg, const map_location& loc,
 		const vconfig::child_list& adj_filt = cfg.get_children("filter_adjacent");
 		for (i = adj_filt.begin(), i_end = adj_filt.end(); i != i_end; ++i) {
 			int match_count=0;
-			static std::vector<map_location::DIRECTION> default_dirs
-				= map_location::parse_directions("n,ne,se,s,sw,nw");
 			config::attribute_value i_adjacent = (*i)["adjacent"];
 			std::vector<map_location::DIRECTION> dirs = !i_adjacent.blank() ?
-				map_location::parse_directions(i_adjacent) : default_dirs;
+				map_location::parse_directions(i_adjacent) : map_location::default_dirs();
 			std::vector<map_location::DIRECTION>::const_iterator j, j_end = dirs.end();
 			for (j = dirs.begin(); j != j_end; ++j) {
 				unit_map::const_iterator unit_itor = units.find(adjacent[*j]);