menu_iterator: generic menu creator function

A simple example usage is given over on the amh project~[1]

[1]: dcf101c8ef/exec/mpv.lua (L32)

util/menu_iterator.lua

@@ -10,6 +10,7 @@
 -- Menu iterator using naughty.notify
 
 local naughty = require("naughty")
+local util = require("lain.util")
 
 local state = { cid = nil }
 
@@ -63,4 +64,76 @@ local function iterate(menu, timeout, icon)
     }).id
 end
 
-return { iterate = iterate }
+-- Generates a menu compatible with the iterate function argument and suitable
+-- for the following cases:
+-- * all possible choices individually.
+-- * all possible choices are all the possible subsets of the set of individual
+--   choices (the powerset)
+--
+-- The following describes the function arguments:
+-- * args: an array containing the following members:
+--   * choices:       the list of choices from which to generate the menu
+--   * name:          the displayed name of the menu (in the form "name: choices")
+--   * selected_cb:   the callback to execute for each selected choice. Takes
+--                    the choice as a string argument. The function
+--                    menu_iterator.naughty_destroy_callback will handle nil
+--                    callbacks. It is then fine to pass nil callbacks.
+--   * rejected_cb:   the callback to execute for each rejected choice (in the
+--                    set of possible choices, but not selected). Takes the
+--                    choice as a string argument. The function
+--                    menu_iterator.naughty_destroy_callback will handle nil
+--                    callbacks. It is then fine to pass nil callbacks.
+--   * extra_choices: an array of pairs { choice_text, cb } for extra choices to
+--                    be added to the menu. The function
+--                    menu_iterator.naughty_destroy_callback will handle nil
+--                    callbacks. It is then fine to pass nil callbacks.
+--   * combination:   the combination of choice to generate. Possible choices
+--                    are "powerset" and "single" (the default).
+local function menu(args)
+    local choices     = assert(args.choices or args[1])
+    local name        = assert(args.name or args[2])
+    local selected_cb = args.selected_cb
+    local rejected_cb = args.rejected_cb
+    local extra_choices = args.extra_choices or {}
+
+    local ch_combinations = args.combination == "powerset" and helpers.powerset(choices) or helpers.trivial_partition_set(choices)
+    for _,c in pairs(extra_choices) do
+        ch_combinations = awful.util.table.join(ch_combinations, {{c[1]}})
+    end
+
+    local m = {}
+    for _,c in pairs(ch_combinations) do
+        if #c > 0 then
+            local cbs = {}
+            -- selected choices
+            for _,ch in pairs(c) do
+                if awful.util.table.hasitem(choices, ch) then
+                    cbs[#cbs + 1] = selected_cb and function() selected_cb(ch) end or nil
+                end
+            end
+
+            -- rejected choices
+            for _,ch in pairs(choices) do
+                if not awful.util.table.hasitem(c, ch) and awful.util.table.hasitem(choices, ch) then
+                    cbs[#cbs + 1] = rejected_cb and function() rejected_cb(ch) end or nil
+                end
+            end
+
+            -- add user extra choices (like the choice "None" for e.g.)
+            for _,x in pairs(extra_choices) do
+                if x[1] == c[1] then
+                    cbs[#cbs + 1] = x[2]
+                end
+            end
+
+            m[#m + 1] = { name .. ": " .. table.concat(c, " + "), cbs }
+        end
+    end
+
+    return m
+end
+
+return {
+    iterate = iterate,
+    menu    = menu
+}