Purge recipes with invalid ingredients

api.lua

@@ -145,50 +145,18 @@ minetest.after(0.01, function()
 		end
 	end
 
-	-- Step 1: group-indexed lookup table for items
-	local spec_matcher = {}
-	for _, name in ipairs(ui.items_list) do
-		-- we only need to care about groups, exact items are handled separately
-		for group, value in pairs(minetest.registered_items[name].groups) do
-			if value and value ~= 0 then
-				if not spec_matcher[group] then
-					spec_matcher[group] = {}
-				end
-				spec_matcher[group][name] = true
-			end
-		end
-	end
+	-- Step 1: Initialize cache for looking up groups
+	unified_inventory.init_matching_cache()
 
 	-- Step 2: Find all matching items for the given spec (groups)
-	local function get_matching_spec_items(specname)
-		if specname:sub(1,6) ~= "group:" then
-			return { [specname] = true }
-		end
+	local get_matching_spec_items = unified_inventory.get_matching_items
 
-		local accepted = {}
-		for i, group in ipairs(specname:sub(7):split(",")) do
-			if i == 1 then
-				-- First step: Copy all possible item names in this group
-				for name, _ in pairs(spec_matcher[group] or {}) do
-					accepted[name] = true
-				end
-			else
-				-- Perform filtering
-				if spec_matcher[group] then
-					for name, _ in pairs(accepted) do
-						accepted[name] = spec_matcher[group][name]
-					end
-				else
-					-- No matching items
-					return {}
-				end
-			end
-		end
-		return accepted
-	end
-
-	for _, recipes in pairs(ui.crafts_for.recipe) do
+	for outputitemname, recipes in pairs(ui.crafts_for.recipe) do
 		-- List of crafts that return this item string (variable "_")
+
+		-- Problem: The group cache must be initialized after all mods finished loading
+		-- thus, invalid recipes might be indexed. Hence perform filtering with `new_recipe_list`
+		local new_recipe_list = {}
 		for _, recipe in ipairs(recipes) do
 			local ingredient_items = {}
 			for _, spec in pairs(recipe.items) do
@@ -204,7 +172,14 @@ minetest.after(0.01, function()
 				end
 				table.insert(ui.crafts_for.usage[name], recipe)
 			end
+
+			if next(ingredient_items) then
+				-- There's at least one known ingredient: mark as good recipe
+				-- PS: What whatll be done about partially incomplete recipes?
+				table.insert(new_recipe_list, recipe)
+			end
 		end
+		ui.crafts_for.recipe[outputitemname] = new_recipe_list
 	end
 
 	for _, callback in ipairs(ui.initialized_callbacks) do

doc/mod_api.txt

@@ -24,7 +24,9 @@ Grouped by use-case, afterwards sorted alphabetically.
 Callbacks
 ---------
 
-Register a callback that will be run whenever a craft is registered via unified_inventory.register_craft:
+Register a callback that will be run whenever a craft is registered via unified_inventory.register_craft.
+This callback is run before any recipe ingredients checks, hence it is also executed on recipes that are
+purged after all mods finished loading.
 
 	unified_inventory.register_on_craft_registered(
 		function (item_name, options)

group.lua

@@ -1,4 +1,5 @@
 local S = minetest.get_translator("unified_inventory")
+local ui = unified_inventory
 
 function unified_inventory.extract_groupnames(groupname)
 	local specname = ItemStack(groupname):get_name()
@@ -26,6 +27,7 @@ end
 -- It may be a comma-separated list of group names.  This is really a
 -- "group:..." ingredient specification, minus the "group:" prefix.
 
+-- TODO Replace this with the more efficient spec matcher (below)
 local function compute_group_item(group_name_list)
 	local group_names = group_name_list:split(",")
 	local candidate_items = {}
@@ -84,3 +86,61 @@ function unified_inventory.get_group_item(group_name)
 	return group_item_cache[group_name]
 end
 
+
+--[[
+This is for filtering known items by groups
+e.g. find all items that match "group:flower,yellow" (flower AND yellow groups)
+]]
+local spec_matcher = {}
+function unified_inventory.init_matching_cache()
+	for _, name in ipairs(ui.items_list) do
+		-- we only need to care about groups, exact items are handled separately
+		for group, value in pairs(minetest.registered_items[name].groups) do
+			if value and value ~= 0 then
+				if not spec_matcher[group] then
+					spec_matcher[group] = {}
+				end
+				spec_matcher[group][name] = true
+			end
+		end
+	end
+end
+
+--[[
+Retrieves all matching items
+
+Arguments:
+	specname (string): Item name or group(s) to filter
+
+Output:
+	{
+		matchingitem1 = true,
+		...
+	}
+]]
+function unified_inventory.get_matching_items(specname)
+	if specname:sub(1,6) ~= "group:" then
+		return { [specname] = true }
+	end
+
+	local accepted = {}
+	for i, group in ipairs(specname:sub(7):split(",")) do
+		if i == 1 then
+			-- First step: Copy all possible item names in this group
+			for name, _ in pairs(spec_matcher[group] or {}) do
+				accepted[name] = true
+			end
+		else
+			-- Perform filtering
+			if spec_matcher[group] then
+				for name, _ in pairs(accepted) do
+					accepted[name] = spec_matcher[group][name]
+				end
+			else
+				-- No matching items
+				return {}
+			end
+		end
+	end
+	return accepted
+end

match_craft.lua

@@ -126,25 +126,18 @@ Example output:
 	}
 --]]
 function unified_inventory.find_usable_items(inv_items, craft_items)
-	local get_group = minetest.get_item_group
 	local result = {}
 
 	for craft_item in pairs(craft_items) do
-		local group = craft_item:match("^group:(.+)")
-		local found = {}
+		-- may specify group:type1,type2
+		local items = unified_inventory.get_matching_items(craft_item)
 
-		if group ~= nil then
-			for inv_item in pairs(inv_items) do
-				if get_group(inv_item, group) > 0 then
-					found[inv_item] = true
-				end
-			end
-		else
-			if inv_items[craft_item] ~= nil then
-				found[craft_item] = true
+		local found = {}
+		for itemname, _ in pairs(items) do
+			if inv_items[itemname] then
+				found[itemname] = true
 			end
 		end
-
 		result[craft_item] = found
 	end