Allow relative coordinates in /area_pos[12] (#77)

locale/areas.fr.tr

@@ -133,3 +133,5 @@ Set area protection region, position 1, or position 2 by punching nodes, or disp
 The area @1 does not exist.=La zone @1 n’existe pas.
 Unable to get position.=Impossible d’obtenir la position.
 Unknown subcommand: @1=Sous-commande inconnue : @1
+
+Relative coordinates is not supported on this server. Please upgrade Minetest to 5.7.0 or newer versions.=

locale/areas.it.tr

@@ -133,3 +133,5 @@ Set area protection region, position 1, or position 2 by punching nodes, or disp
 The area @1 does not exist.=L'area @1 non esiste.
 Unable to get position.=Impossibile ottenere la posizione.
 Unknown subcommand: @1=Sotto-comando sconosciuto: @1
+
+Relative coordinates is not supported on this server. Please upgrade Minetest to 5.7.0 or newer versions.=

locale/areas.ru.tr

@@ -133,3 +133,5 @@ Set area protection region, position 1, or position 2 by punching nodes, or disp
 The area @1 does not exist.=Территория @1 не существует.
 Unable to get position.=Не удалось получить позицию.
 Unknown subcommand: @1=Неизвестная под-команда/аргумент.
+
+Relative coordinates is not supported on this server. Please upgrade Minetest to 5.7.0 or newer versions.=

locale/areas.zh_CN.tr

@@ -132,4 +132,6 @@ Set area protection region, position 1, or position 2 by punching nodes, or disp
 
 The area @1 does not exist.=保护区 @1 不存在。
 Unable to get position.=无法获得座标。
-Unknown subcommand: @1=子指令不明：@1
+Unknown subcommand: @1=子指令不明：@1
+
+Relative coordinates is not supported on this server. Please upgrade Minetest to 5.7.0 or newer versions.=此服务器不支援相对座标。请更新Minetest至5.7.0或之后的版本。

locale/areas.zh_TW.tr

@@ -133,3 +133,5 @@ Set area protection region, position 1, or position 2 by punching nodes, or disp
 The area @1 does not exist.=保護區 @1 不存在。
 Unable to get position.=無法獲得座標。
 Unknown subcommand: @1=子指令不明：@1
+
+Relative coordinates is not supported on this server. Please upgrade Minetest to 5.7.0 or newer versions.=此伺服器不支援相對座標。請更新Minetest至5.7.0或之後的版本。

locale/template.txt

@@ -133,3 +133,5 @@ Set area protection region, position 1, or position 2 by punching nodes, or disp
 The area @1 does not exist.=
 Unable to get position.=
 Unknown subcommand: @1=
+
+Relative coordinates is not supported on this server. Please upgrade Minetest to 5.7.0 or newer versions.=

pos.lua

@@ -22,6 +22,37 @@ local function posLimit(pos)
 	}
 end
 
+local parse_relative_pos
+
+if minetest.parse_relative_number then
+	parse_relative_pos = function(x_str, y_str, z_str, pos)
+
+		local x = pos and minetest.parse_relative_number(x_str, pos.x)
+			or tonumber(x_str)
+		local y = pos and minetest.parse_relative_number(y_str, pos.y)
+			or tonumber(y_str)
+		local z = pos and minetest.parse_relative_number(z_str, pos.z)
+			or tonumber(z_str)
+		if x and y and z then
+			return vector.new(x, y, z)
+		end
+	end
+else
+	parse_relative_pos = function(x_str, y_str, z_str, pos)
+		local x = tonumber(x_str)
+		local y = tonumber(y_str)
+		local z = tonumber(z_str)
+		if x and y and z then
+			return vector.new(x, y, z)
+		elseif string.sub(x_str, 1, 1) == "~"
+			or string.sub(y_str, 1, 1) == "~"
+			or string.sub(z_str, 1, 1) == "~" then
+			return nil, S("Relative coordinates is not supported on this server. " ..
+				"Please upgrade Minetest to 5.7.0 or newer versions.")
+		end
+	end
+end
+
 minetest.register_chatcommand("select_area", {
 	params = S("<ID>"),
 	description = S("Select an area by ID."),
@@ -47,20 +78,25 @@ minetest.register_chatcommand("area_pos1", {
 	privs = {},
 	func = function(name, param)
 		local pos
-		local found, _, x, y, z = param:find(
-				"^(-?%d+)[, ](-?%d+)[, ](-?%d+)$")
+		local player = minetest.get_player_by_name(name)
+		if player then
+			pos = vector.round(player:get_pos())
+		end
+		local found, _, x_str, y_str, z_str = param:find(
+			"^(~?-?%d*)[, ](~?-?%d*)[, ](~?-?%d*)$")
 		if found then
-			pos = {x=tonumber(x), y=tonumber(y), z=tonumber(z)}
-		elseif param == "" then
-			local player = minetest.get_player_by_name(name)
-			if player then
-				pos = player:get_pos()
-			else
-				return false, S("Unable to get position.")
+			local get_pos, reason = parse_relative_pos(x_str, y_str, z_str, pos)
+			if get_pos then
+				pos = get_pos
+			elseif not get_pos and reason then
+				return false, reason
 			end
-		else
+		elseif param ~= "" then
 			return false, S("Invalid usage, see /help @1.", "area_pos1")
 		end
+		if not pos then
+			return false, S("Unable to get position.")
+		end
 		pos = posLimit(vector.round(pos))
 		areas:setPos1(name, pos)
 		return true, S("Area position @1 set to @2", "1",
@@ -74,20 +110,25 @@ minetest.register_chatcommand("area_pos2", {
 		.." location or the one specified", "2"),
 	func = function(name, param)
 		local pos
-		local found, _, x, y, z = param:find(
-				"^(-?%d+)[, ](-?%d+)[, ](-?%d+)$")
+		local player = minetest.get_player_by_name(name)
+		if player then
+			pos = vector.round(player:get_pos())
+		end
+		local found, _, x_str, y_str, z_str = param:find(
+			"^(~?-?%d*)[, ](~?-?%d*)[, ](~?-?%d*)$")
 		if found then
-			pos = {x=tonumber(x), y=tonumber(y), z=tonumber(z)}
-		elseif param == "" then
-			local player = minetest.get_player_by_name(name)
-			if player then
-				pos = player:get_pos()
-			else
-				return false, S("Unable to get position.")
+			local get_pos, reason = parse_relative_pos(x_str, y_str, z_str, pos)
+			if get_pos then
+				pos = get_pos
+			elseif not get_pos and reason then
+				return false, reason
 			end
-		else
+		elseif param ~= "" then
 			return false, S("Invalid usage, see /help @1.", "area_pos2")
 		end
+		if not pos then
+			return false, S("Unable to get position.")
+		end
 		pos = posLimit(vector.round(pos))
 		areas:setPos2(name, pos)
 		return true, S("Area position @1 set to @2", "2",