awesome/lib/lain/helpers.lua

--[[

     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