Add an API for search filters

API.md

@@ -22,6 +22,8 @@ craftguide.register_craft({
 })
 ```
 
+---
+
 ### Recipe filters
 
 Recipe filters can be used to filter the recipes shown to players. Progressive
@@ -61,6 +63,57 @@ Removes all recipe filters and adds a new one.
 
 Returns a map of recipe filters, indexed by name.
 
+---
+
+### Search filters
+
+Search filters are used to perform specific searches inside the search field.
+They can be used like so: `<optional name>+<filter name>=<value1>,<value2>,<...>`
+
+Notes:
+- If `optional name` is omitted, the search filter will apply to all items, without pre-filtering.
+- Filters can be combined.
+- The `+groups=` filter is currently implemented by default.
+
+#### `craftguide.add_search_filter(name, function(item, values))`
+
+Adds a search filter with the given name.
+The search function should return a boolean value (whether the given item should be listed or not).
+
+Example function to show items which contain at least a recipe of given width(s):
+
+```lua
+craftguide.add_search_filter("widths", function(item, widths)
+	local has_width
+	local recipes = recipes_cache[item]
+
+	if recipes then
+		for i = 1, #recipes do
+			local recipe_width = recipes[i].width
+			for j = 1, #widths do
+				local width = tonumber(widths[j])
+				if width == recipe_width then
+					has_width = true
+					break
+				end
+			end
+		end
+	end
+
+	return has_width
+end)
+```
+
+#### `craftguide.remove_search_filter(name)`
+
+Removes the search filter with the given name.
+
+#### `craftguide.get_search_filters()`
+
+Returns a map of search filters, indexed by name.
+
+---
+
 ### Custom formspec elements
 
 #### `craftguide.add_formspec_element(name, def)`
@@ -102,6 +155,8 @@ Removes the formspec element with the given name.
 
 Returns a map of formspec elements, indexed by name.
 
+---
+
 ### Miscellaneous
 
 #### `craftguide.show(player_name, item, show_usages)`

init.lua

@@ -27,9 +27,9 @@ local maxn, sort, concat, insert, copy =
 	table.maxn, table.sort, table.concat, table.insert,
 	table.copy
 
-local fmt, find, match, sub, split, lower =
-	string.format, string.find, string.match, string.sub,
-	string.split, string.lower
+local fmt, find, gmatch, match, sub, split, lower =
+	string.format, string.find, string.gmatch, string.match,
+	string.sub, string.split, string.lower
 
 local min, max, floor, ceil = math.min, math.max, math.floor, math.ceil
 local pairs, next, unpack = pairs, next, unpack
@@ -102,17 +102,17 @@ local function table_diff(t, t2)
 		hash[v] = nil
 	end
 
-	local ret, c = {}, 0
+	local diff, c = {}, 0
 
 	for i = 1, #t do
 		local v = t[i]
 		if hash[v] then
 			c = c + 1
-			ret[c] = v
+			diff[c] = v
 		end
 	end
 
-	return ret
+	return diff
 end
 
 local function __func()
@@ -142,16 +142,24 @@ end
 
 local recipe_filters = {}
 
-function craftguide.add_recipe_filter(name, func)
-	recipe_filters[name] = func
+function craftguide.add_recipe_filter(name, f)
+	local func = "craftguide." .. __func() .. "(): "
+	assert(name, func .. "filter name missing")
+	assert(f and type(f) == "function", func .. "filter function missing")
+
+	recipe_filters[name] = f
 end
 
 function craftguide.remove_recipe_filter(name)
 	recipe_filters[name] = nil
 end
 
-function craftguide.set_recipe_filter(name, func)
-	recipe_filters = {[name] = func}
+function craftguide.set_recipe_filter(name, f)
+	local func = "craftguide." .. __func() .. "(): "
+	assert(name, func .. "filter name missing")
+	assert(f and type(f) == "function", func .. "filter function missing")
+
+	recipe_filters = {[name] = f}
 end
 
 function craftguide.get_recipe_filters()
@@ -166,6 +174,24 @@ local function apply_recipe_filters(recipes, player)
 	return recipes
 end
 
+local search_filters = {}
+
+function craftguide.add_search_filter(name, f)
+	local func = "craftguide." .. __func() .. "(): "
+	assert(name, func .. "filter name missing")
+	assert(f and type(f) == "function", func .. "filter function missing")
+
+	search_filters[name] = f
+end
+
+function craftguide.remove_search_filter(name)
+	search_filters[name] = nil
+end
+
+function craftguide.get_search_filters()
+	return search_filters
+end
+
 local formspec_elements = {}
 
 function craftguide.add_formspec_element(name, def)
@@ -649,6 +675,21 @@ local show_fs = function(player, name)
 	end
 end
 
+craftguide.add_search_filter("groups", function(item, groups)
+	local itemdef = reg_items[item]
+	local has_groups = true
+
+	for i = 1, #groups do
+		local group = groups[i]
+		if not itemdef.groups[group] then
+			has_groups = nil
+			break
+		end
+	end
+
+	return has_groups
+end)
+
 local function search(data)
 	local filter = data.filter
 
@@ -663,27 +704,20 @@ local function search(data)
 		local item = data.items_raw[i]
 		local def  = reg_items[item]
 		local desc = lower(def.description)
-
-		local to_add
 		local search_in = item .. desc
-		local subfilter, search_groups, group_filters =
-			match(filter, "(.*)(:groups=)([%w_,]+)$")
+		local pattern = "%+([%w_]+)=([%w_,]+)"
+		local to_add
 
-		if search_groups then
-			local groups = split(group_filters, ",")
-			local has_groups = true
-
-			for j = 1, #groups do
-				local group = groups[j]
-				if not def.groups[group] then
-					has_groups = nil
-					break
+		if find(filter, pattern) then
+			local prepend = match(filter, "^(.-)%+")
+			for filter_name, values in gmatch(filter, pattern) do
+				local func = search_filters[filter_name]
+				if func then
+					values = split(values, ",")
+					to_add = func(item, values) and (not prepend or
+						find(search_in, prepend, 1, true))
 				end
 			end
-
-			if has_groups then
-				to_add = not subfilter or find(search_in, subfilter, 1, true)
-			end
 		else
 			to_add = find(search_in, filter, 1, true)
 		end