add an output field, that is being filled with the crafting result and can be used for quickly emptying or filling the crafting grid with the last registered recipe

some of the recipes are still treated wrongly due to minetest/minetest#2222 but are failling gracefully

autocrafter.lua

@@ -22,22 +22,12 @@ local function get_craft(pos, inventory, hash)
 	local hash = hash or minetest.hash_node_position(pos)
 	local craft = autocrafterCache[hash]
 	if not craft then
-		if inventory:is_empty("recipe") then
-			set_infotext(pos, nil)
-			return
-		end
 		local recipe = inventory:get_list("recipe")
 		local output, decremented_input = minetest.get_craft_result({method = "normal", width = 3, items = recipe})
 		craft = {recipe = recipe, consumption=count_index(recipe), output = output, decremented_input = decremented_input}
 		autocrafterCache[hash] = craft
-		set_infotext(pos, "Autocrafter: " .. output.item:get_name())
-	end
-	-- only return crafts that have an actual result
-	if not craft.output.item:is_empty() then
-		return craft
-	else
-		set_infotext(pos, "Autocrafter: unknown recipe")
 	end
+	return craft
 end
 
 local function start_crafter(pos)
@@ -78,6 +68,11 @@ local function after_recipe_change(pos, inventory)
 		end
 	end
 
+	craft = craft or get_craft(pos, inventory, hash)
+	local output_item = craft.output.item
+	set_infotext(pos, "Autocrafter: " .. output_item:get_name())
+	inventory:set_stack("output", 1, output_item)
+
 	start_crafter(pos)
 end
 
@@ -119,6 +114,12 @@ local function run_autocrafter(pos, elapsed)
 	local inventory = meta:get_inventory()
 	local craft = get_craft(pos, inventory)
 
+	-- only use crafts that have an actual result
+	if craft.output.item:is_empty() then
+		set_infotext(pos, "Autocrafter: unknown recipe")
+		return false
+	end
+
 	for step = 1, math.floor(elapsed/craft_time) do
 		local continue = autocraft(inventory, craft)
 		if not continue then return false end
@@ -146,6 +147,8 @@ local function set_formspec(meta, enabled)
 	meta:set_string("formspec",
 			"size[8,11]"..
 			"list[context;recipe;0,0;3,3;]"..
+			"image[3,1;1,1;gui_hb_bg.png^[colorize:#141318:255]"..
+			"list[context;output;3,1;1,1;]"..
 			"image_button[3,2;1,1;pipeworks_button_" .. state .. ".png;" .. state .. ";;;false;pipeworks_button_interm.png]" ..
 			"list[context;src;0,3.5;8,3;]"..
 			"list[context;dst;4,0;4,3;]"..
@@ -162,6 +165,19 @@ local function add_virtual_item(inv, listname, index, stack)
 	inv:set_stack(listname, index, stack_copy)
 end
 
+local function on_output_change(pos, inventory, stack)
+	if not stack then
+		inventory:set_list("output", {})
+		inventory:set_list("recipe", {})
+	else
+		local input = minetest.get_craft_recipe(stack:get_name())
+		if not input.items or input.type ~= "normal" then return end
+		inventory:set_list("recipe", input.items)
+		add_virtual_item(inventory, "output", 1, stack)
+	end
+	after_recipe_change(pos, inventory)
+end
+
 minetest.register_node("pipeworks:autocrafter", {
 	description = "Autocrafter", 
 	drawtype = "normal", 
@@ -190,6 +206,7 @@ minetest.register_node("pipeworks:autocrafter", {
 		inv:set_size("src", 3*8)
 		inv:set_size("recipe", 3*3)
 		inv:set_size("dst", 4*3)
+		inv:set_size("output", 1)
 	end,
 	on_receive_fields = function(pos, formname, fields, sender)
 		local meta = minetest.get_meta(pos)
@@ -227,10 +244,12 @@ minetest.register_node("pipeworks:autocrafter", {
 			add_virtual_item(inv, listname, index, stack)
 			after_recipe_change(pos, inv)
 			return 0
-		else
+		elseif listname == "output" then
-			after_inventory_change(pos, inv)
+			on_output_change(pos, inv, stack)
-			return stack:get_count()
+			return 0
 		end
+		after_inventory_change(pos, inv)
+		return stack:get_count()
 	end,
 	allow_metadata_inventory_take = function(pos, listname, index, stack, player)
 		update_autocrafter(pos)
@@ -239,23 +258,33 @@ minetest.register_node("pipeworks:autocrafter", {
 			inv:set_stack(listname, index, ItemStack(""))
 			after_recipe_change(pos, inv)
 			return 0
-		else
+		elseif listname == "output" then
-			after_inventory_change(pos, inv)
+			on_output_change(pos, inv, nil)
-			return stack:get_count()
+			return 0
 		end
+		after_inventory_change(pos, inv)
+		return stack:get_count()
 	end,
 	allow_metadata_inventory_move = function(pos, from_list, from_index, to_list, to_index, count, player)
 		update_autocrafter(pos)
 		local inv = minetest.get_meta(pos):get_inventory()
 		local stack = inv:get_stack(from_list, from_index)
 		stack:set_count(count)
+
+		if to_list == "output" then
+			on_output_change(pos, inv, stack)
+			return 0
+		elseif from_list == "output" then
+			on_output_change(pos, inv, nil)
+			return 0
+		end
+
 		if from_list == "recipe" then
 			inv:set_stack(from_list, from_index, ItemStack(""))
 		end
 		if to_list == "recipe" then
 			add_virtual_item(inv, to_list, to_index, stack)
 		end
-
 		if from_list == "recipe" or to_list == "recipe" then
 			after_recipe_change(pos, inv)
 			return 0