Initial commit

lib/lain/helpers.lua

@@ -0,0 +1,210 @@
+--[[
+
+     Licensed under GNU General Public License v2
+      * (c) 2013, Luca CPZ
+
+--]]
+
+local spawn = require('awful.spawn')
+local timer = require('gears.timer')
+local debug = require('debug')
+local io = { lines = io.lines, open = io.open }
+local pairs = pairs
+local rawget = rawget
+local tsort = table.sort
+local unpack = unpack or table.unpack -- lua 5.1 retro-compatibility
+
+-- Lain helper functions for internal use
+-- lain.helpers
+local helpers = {}
+
+helpers.lain_dir = debug.getinfo(1, 'S').source:match([[^@(.*/).*$]])
+helpers.icons_dir = helpers.lain_dir .. 'icons/'
+helpers.scripts_dir = helpers.lain_dir .. 'scripts/'
+
+-- {{{ Modules loader
+
+function helpers.wrequire(t, k)
+	return rawget(t, k) or require(t._NAME .. '.' .. k)
+end
+
+-- }}}
+
+-- {{{ File operations
+
+-- check if the file exists and is readable
+function helpers.file_exists(path)
+	local file = io.open(path, 'rb')
+	if file then
+		file:close()
+	end
+	return file ~= nil
+end
+
+-- get a table with all lines from a file
+function helpers.lines_from(path)
+	local lines = {}
+	for line in io.lines(path) do
+		lines[#lines + 1] = line
+	end
+	return lines
+end
+
+-- get a table with all lines from a file matching regexp
+function helpers.lines_match(regexp, path)
+	local lines = {}
+	for line in io.lines(path) do
+		if string.match(line, regexp) then
+			lines[#lines + 1] = line
+		end
+	end
+	return lines
+end
+
+-- get first line of a file
+function helpers.first_line(path)
+	local file, first = io.open(path, 'rb'), nil
+	if file then
+		first = file:read('*l')
+		file:close()
+	end
+	return first
+end
+
+-- get first non empty line from a file
+function helpers.first_nonempty_line(path)
+	for line in io.lines(path) do
+		if #line then
+			return line
+		end
+	end
+	return nil
+end
+
+-- }}}
+
+-- {{{ Timer maker
+
+helpers.timer_table = {}
+
+function helpers.newtimer(name, timeout, fun, nostart, stoppable)
+	if not name or #name == 0 then
+		return
+	end
+	name = (stoppable and name) or timeout
+	if not helpers.timer_table[name] then
+		helpers.timer_table[name] = timer({ timeout = timeout })
+		helpers.timer_table[name]:start()
+	end
+	helpers.timer_table[name]:connect_signal('timeout', fun)
+	if not nostart then
+		helpers.timer_table[name]:emit_signal('timeout')
+	end
+	return stoppable and helpers.timer_table[name]
+end
+
+-- }}}
+
+-- {{{ Pipe operations
+
+-- run a command and execute a function on its output (asynchronous pipe)
+-- @param cmd the input command
+-- @param callback function to execute on cmd output
+-- @return cmd PID
+function helpers.async(cmd, callback)
+	return spawn.easy_async(cmd, function(stdout, _, _, exit_code)
+		callback(stdout, exit_code)
+	end)
+end
+
+-- like above, but call spawn.easy_async with a shell
+function helpers.async_with_shell(cmd, callback)
+	return spawn.easy_async_with_shell(cmd, function(stdout, _, _, exit_code)
+		callback(stdout, exit_code)
+	end)
+end
+
+-- run a command and execute a function on its output line by line
+function helpers.line_callback(cmd, callback)
+	return spawn.with_line_callback(cmd, {
+		stdout = function(line)
+			callback(line)
+		end,
+	})
+end
+
+-- }}}
+
+-- {{{ A map utility
+
+helpers.map_table = {}
+
+function helpers.set_map(element, value)
+	helpers.map_table[element] = value
+end
+
+function helpers.get_map(element)
+	return helpers.map_table[element]
+end
+
+-- }}}
+
+-- {{{ Misc
+
+-- check if an element exist on a table
+function helpers.element_in_table(element, tbl)
+	for _, i in pairs(tbl) do
+		if i == element then
+			return true
+		end
+	end
+	return false
+end
+
+-- iterate over table of records sorted by keys
+function helpers.spairs(t)
+	-- collect the keys
+	local keys = {}
+	for k in pairs(t) do
+		keys[#keys + 1] = k
+	end
+
+	tsort(keys)
+
+	-- return the iterator function
+	local i = 0
+	return function()
+		i = i + 1
+		if keys[i] then
+			return keys[i], t[keys[i]]
+		end
+	end
+end
+
+-- create the partition of singletons of a given set
+-- example: the trivial partition set of {a, b, c}, is {{a}, {b}, {c}}
+function helpers.trivial_partition_set(set)
+	local ss = {}
+	for _, e in pairs(set) do
+		ss[#ss + 1] = { e }
+	end
+	return ss
+end
+
+-- create the powerset of a given set
+function helpers.powerset(s)
+	if not s then
+		return {}
+	end
+	local t = { {} }
+	for i = 1, #s do
+		for j = 1, #t do
+			t[#t + 1] = { s[i], unpack(t[j]) }
+		end
+	end
+	return t
+end
+
+-- }}}
+
+return helpers