Add AreaStore custom ID API

5 files changed, 14 insertions, 7 deletions

diff --git a/builtin/game/features.lua b/builtin/game/features.lua
index a5f17e540..2aad458da 100644
--- a/builtin/game/features.lua
+++ b/builtin/game/features.lua
@@ -8,6 +8,7 @@ core.features = {
 	use_texture_alpha = true,
 	no_legacy_abms = true,
 	texture_names_parens = true,
+	area_store_custom_ids = true,
 }
 
 function core.has_feature(arg)
diff --git a/doc/lua_api.txt b/doc/lua_api.txt
index 50fa25273..65af51578 100644
--- a/doc/lua_api.txt
+++ b/doc/lua_api.txt
@@ -2727,7 +2727,7 @@ If you chose the parameter-less constructor, a fast implementation will be autom
 * `get_area(id, include_borders, include_data)`: returns the area with the id `id`. (optional) Boolean values `include_borders` and `include_data` control what's copied.
 * `get_areas_for_pos(pos, include_borders, include_data)`: returns all areas that contain the position `pos`. (optional) Boolean values `include_borders` and `include_data` control what's copied.
 * `get_areas_in_area(edge1, edge2, accept_overlap, include_borders, include_data)`: returns all areas that contain all nodes inside the area specified by `edge1` and `edge2` (inclusive). If `accept_overlap` is true, also areas are returned that have nodes in common with the specified area. (optional) Boolean values `include_borders` and `include_data` control what's copied.
-* `insert_area(edge1, edge2, data)`: inserts an area into the store. Returns the new area's ID, or nil if the insertion failed. The (inclusive) positions `edge1` and `edge2` describe the area, `data` is a string stored with the area.
+* `insert_area(edge1, edge2, data, [id])`: inserts an area into the store. Returns the new area's ID, or nil if the insertion failed. The (inclusive) positions `edge1` and `edge2` describe the area. `data` is a string stored with the area.  If passed, `id` will be used as the internal area ID, it must be a unique number between 0 and 2^32-2. If you use the `id` parameter you must always use it, or insertions are likely to fail due to conflicts.
 * `reserve(count)`: reserves resources for at most `count` many contained areas. Only needed for efficiency, and only some implementations profit.
 * `remove_area(id)`: removes the area with the given id from the store, returns success.
 * `set_cache_params(params)`: sets params for the included prefiltering cache. Calling invalidates the cache, so that its elements have to be newly generated.
diff --git a/src/script/lua_api/l_areastore.cpp b/src/script/lua_api/l_areastore.cpp
index 261baf6c9..20e7875c7 100644
--- a/src/script/lua_api/l_areastore.cpp
+++ b/src/script/lua_api/l_areastore.cpp
@@ -164,7 +164,7 @@ int LuaAreaStore::l_get_areas_in_area(lua_State *L)
 	return 1;
 }
 
-// insert_area(edge1, edge2, data)
+// insert_area(edge1, edge2, data, id)
 int LuaAreaStore::l_insert_area(lua_State *L)
 {
 	NO_MAP_LOCK_REQUIRED;
@@ -179,6 +179,9 @@ int LuaAreaStore::l_insert_area(lua_State *L)
 
 	a.data = std::string(data, d_len);
 
+	if (lua_isnumber(L, 5))
+		a.id = lua_tonumber(L, 5);
+
 	if (!ast->insertArea(&a))
 		return 0;
 
diff --git a/src/util/areastore.cpp b/src/util/areastore.cpp
index 17addb3af..58f08a8c2 100644
--- a/src/util/areastore.cpp
+++ b/src/util/areastore.cpp
@@ -160,7 +160,8 @@ void AreaStore::getAreasForPos(std::vector<Area *> *result, v3s16 pos)
 
 bool VectorAreaStore::insertArea(Area *a)
 {
-	a->id = getNextId();
+	if (a->id == U32_MAX)
+		a->id = getNextId();
 	std::pair<AreaMap::iterator, bool> res =
 			areas_map.insert(std::make_pair(a->id, *a));
 	if (!res.second)
@@ -232,7 +233,8 @@ static inline SpatialIndex::Point get_spatial_point(const v3s16 pos)
 
 bool SpatialAreaStore::insertArea(Area *a)
 {
-	a->id = getNextId();
+	if (a->id == U32_MAX)
+		a->id = getNextId();
 	if (!areas_map.insert(std::make_pair(a->id, *a)).second)
 		// ID is not unique
 		return false;
diff --git a/src/util/areastore.h b/src/util/areastore.h
index ab6bd76a3..bebecfd78 100644
--- a/src/util/areastore.h
+++ b/src/util/areastore.h
@@ -38,9 +38,9 @@ with this program; if not, write to the Free Software Foundation, Inc.,
 
 
 struct Area {
-	Area() {}
+	Area() : id(U32_MAX) {}
 	Area(const v3s16 &mine, const v3s16 &maxe) :
-		minedge(mine), maxedge(maxe)
+		id(U32_MAX), minedge(mine), maxedge(maxe)
 	{
 		sortBoxVerticies(minedge, maxedge);
 	}
@@ -68,7 +68,8 @@ public:
 	size_t size() const { return areas_map.size(); }
 
 	/// Add an area to the store.
-	/// Updates the area's ID.
+	/// Updates the area's ID if it hasn't already been set.
+	/// @return Whether the area insertion was successful.
 	virtual bool insertArea(Area *a) = 0;
 
 	/// Removes an area from the store by ID.