Implement //airapply

For #56, but the docs aren't written yet so we'll wait on closing it 
until I've written them.

worldeditadditions/init.lua

@@ -55,6 +55,7 @@ dofile(worldeditadditions.modpath.."/lib/bonemeal.lua")
 dofile(worldeditadditions.modpath.."/lib/forest.lua")
 
 dofile(worldeditadditions.modpath.."/lib/ellipsoidapply.lua")
+dofile(worldeditadditions.modpath.."/lib/airapply.lua")
 
 dofile(worldeditadditions.modpath.."/lib/subdivide.lua")
 dofile(worldeditadditions.modpath.."/lib/selection/stack.lua")

worldeditadditions/lib/airapply.lua

@@ -35,12 +35,13 @@ function worldeditadditions.airapply(pos1, pos2, func)
 	for z = pos2.z, pos1.z, -1 do
 		for y = pos2.y, pos1.y, -1 do
 			for x = pos2.x, pos1.x, -1 do
-				local i = area:index(x, y, z)
+				local i_before = area_before:index(x, y, z)
-				local old_is_airlike = worldeditadditions.is_airlike(data_before[i])
+				local i_after = area_after:index(x, y, z)
+				local old_is_airlike = worldeditadditions.is_airlike(data_before[i_before])
 				
 				-- Roll everything that replaces nodes that aren't airlike
 				if not old_is_airlike then
-					data_after[area_after:index(x, y, z)] = data_before[area_before:index(x, y, z)]
+					data_after[i_after] = data_before[i_before]
 				end
 			end
 		end

worldeditadditions_commands/commands/meta/airapply.lua

@@ -0,0 +1,69 @@
+-- ███████ ██      ██      ██ ██████  ███████ ███████  █████  ██████  ██████  ██   ██    ██
+-- ██      ██      ██      ██ ██   ██ ██      ██      ██   ██ ██   ██ ██   ██ ██    ██  ██
+-- █████   ██      ██      ██ ██████  ███████ █████   ███████ ██████  ██████  ██     ████
+-- ██      ██      ██      ██ ██           ██ ██      ██   ██ ██      ██      ██      ██
+-- ███████ ███████ ███████ ██ ██      ███████ ███████ ██   ██ ██      ██      ███████ ██
+
+worldedit.register_command("airapply", {
+	params = "<command_name> <args>",
+	description = "Executes the given command (automatically prepending '//'), but only on non-air nodes within the defined region.",
+	privs = { worldedit = true },
+	require_pos = 2,
+	parse = function(params_text)
+		if params_text == "" then return false, "Error: No command specified." end
+		
+		local cmd_name, args_text = params_text:match("([^%s]+)%s+(.+)")
+		if not cmd_name then
+			cmd_name = params_text
+			args_text = ""
+		end
+		
+		-- Note that we search the worldedit commands here, not the minetest ones
+		local cmd_we = worldedit.registered_commands[cmd_name]
+		if cmd_we == nil then
+			return false, "Error: "..cmd_name.." isn't a valid command."
+		end
+		if cmd_we.require_pos ~= 2 then
+			return false, "Error: The command "..cmd_name.." exists, but doesn't take 2 positions and so can't be used with //airapply."
+		end
+		
+		-- Run parsing of target command
+		-- Lifted from cubeapply in WorldEdit
+		local args_parsed = {cmd_we.parse(args_text)}
+		if not table.remove(args_parsed, 1) then
+			return false, args_parsed[1]
+		end
+		
+		return true, cmd_we, args_parsed
+	end,
+	nodes_needed = function(name)
+		local pos1, pos2 = worldedit.sort_pos(worldedit.pos1[name], worldedit.pos2[name])
+		return math.ceil(4/3 * math.pi * (pos2.x - pos1.x)/2 * (pos2.y - pos1.y)/2 * (pos2.z - pos1.z)/2)
+	end,
+	func = function(name, cmd, args_parsed)
+		if not minetest.check_player_privs(name, cmd.privs) then
+			return false, "Your privileges are insufficient to execute the command '"..cmd_name.."'."
+		end
+		
+		local pos1, pos2 = worldeditadditions.Vector3.sort(
+			worldedit.pos1[name],
+			worldedit.pos2[name]
+		)
+		
+		
+		local success, stats_time = worldeditadditions.airapply(
+			pos1, pos2,
+			function()
+				cmd.func(name, worldeditadditions.table.unpack(args_parsed))
+			end, args
+		)
+		
+		
+		local time_overhead = 100 - worldeditadditions.round((stats_time.fn / stats_time.all) * 100, 3)
+		local text_time_all = worldeditadditions.format.human_time(stats_time.all)
+		local text_time_fn = worldeditadditions.format.human_time(stats_time.fn)
+		
+		minetest.log("action", name.." used //airapply at "..pos1.." - "..pos2.." in "..text_time_all)
+		return true, "Complete in "..text_time_all.." ("..text_time_fn.." fn, "..time_overhead.."% airapply overhead)"
+	end
+})

worldeditadditions_commands/init.lua

@@ -41,6 +41,7 @@ dofile(we_c.modpath.."/commands/meta/multi.lua")
 dofile(we_c.modpath.."/commands/meta/many.lua")
 dofile(we_c.modpath.."/commands/meta/subdivide.lua")
 dofile(we_c.modpath.."/commands/meta/ellipsoidapply.lua")
+dofile(we_c.modpath.."/commands/meta/airapply.lua")
 
 -- Selection Tools
 dofile(we_c.modpath.."/commands/selectors/init.lua")