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 rawget     = rawget
local table      = { sort  = table.sort }

-- 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(table, key)
    local module = rawget(table, key)
    return module or require(table._NAME .. '.' .. key)
end

-- }}}

-- {{{ File operations

-- see if the file exists and is readable
function helpers.file_exists(file)
  local f = io.open(file)
  if f then
      local s = f:read()
      f:close()
      f = s
  end
  return f ~= nil
end

-- get all lines from a file, returns an empty
-- list/table if the file does not exist
function helpers.lines_from(file)
  if not helpers.file_exists(file) then return {} end
  local lines = {}
  for line in io.lines(file) do
    lines[#lines + 1] = line
  end
  return lines
end

-- match all lines from a file, returns an empty
-- list/table if the file or match does not exist
function helpers.lines_match(regexp, file)
	local lines = {}
	for index,line in pairs(helpers.lines_from(file)) do
		if string.match(line, regexp) then
			lines[index] = line
		end
	end
	return lines
end

-- get first line of a file, return nil if
-- the file does not exist
function helpers.first_line(file)
    return helpers.lines_from(file)[1]
end

-- get first non empty line from a file,
-- returns nil otherwise
function helpers.first_nonempty_line(file)
  for k,v in pairs(helpers.lines_from(file)) do
    if #v then return v 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, stderr, reason, 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, stderr, reason, 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

    table.sort(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 trivial partition of a set. The trivial partition set is the simplest
-- partition of a set. For e.g., the trivial partition set of {a, b, c}, is
-- simply {{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

-- creates 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