write something there

mods/unified_inventory/group.lua

@@ -0,0 +1,146 @@
+local S = minetest.get_translator("unified_inventory")
+local ui = unified_inventory
+
+function unified_inventory.extract_groupnames(groupname)
+	local specname = ItemStack(groupname):get_name()
+	if specname:sub(1, 6) ~= "group:" then
+		return nil, 0
+	end
+	local group_names = specname:sub(7):split(",")
+	return table.concat(group_names, S(" and ")), #group_names
+end
+
+
+-- This is used when displaying craft recipes, where an ingredient is
+-- specified by group rather than as a specific item.  A single-item group
+-- is represented by that item, with the single-item status signalled
+-- in the "sole" field.  If the group contains no items at all, the item
+-- field will be nil.
+--
+-- Within a multiple-item group, we prefer to use an item that has the
+-- same specific name as the group, and if there are more than one of
+-- those items we prefer the one registered for the group by a mod.
+-- Among equally-preferred items, we just pick the one with the
+-- lexicographically earliest name.
+--
+-- The parameter to this function isn't just a single group name.
+-- 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 = {}
+	for itemname, itemdef in pairs(minetest.registered_items) do
+		if (itemdef.groups.not_in_creative_inventory or 0) == 0 then
+			local all = true
+			for _, group_name in ipairs(group_names) do
+				if (itemdef.groups[group_name] or 0) == 0 then
+					all = false
+				end
+			end
+			if all then table.insert(candidate_items, itemname) end
+		end
+	end
+	local num_candidates = #candidate_items
+	if num_candidates == 0 then
+		return {sole = true}
+	elseif num_candidates == 1 then
+		return {item = candidate_items[1], sole = true}
+	end
+	local is_group = {}
+	local registered_rep = {}
+	for _, group_name in ipairs(group_names) do
+		is_group[group_name] = true
+		local rep = unified_inventory.registered_group_items[group_name]
+		if rep then registered_rep[rep] = true end
+	end
+	local bestitem = ""
+	local bestpref = 0
+	for _, item in ipairs(candidate_items) do
+		local pref
+		if registered_rep[item] then
+			pref = 4
+		elseif string.sub(item, 1, 8) == "default:" and is_group[string.sub(item, 9)] then
+			pref = 3
+		elseif is_group[item:gsub("^[^:]*:", "")] then
+			pref = 2
+		else
+			pref = 1
+		end
+		if pref > bestpref or (pref == bestpref and item < bestitem) then
+			bestitem = item
+			bestpref = pref
+		end
+	end
+	return {item = bestitem, sole = false}
+end
+
+
+local group_item_cache = {}
+
+function unified_inventory.get_group_item(group_name)
+	if not group_item_cache[group_name] then
+		group_item_cache[group_name] = compute_group_item(group_name)
+	end
+	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