asyncshell.lua

--[[
                                                  
     Licensed under GNU General Public License v2 
      * (c) 2015, worron                          
      * (c) 2013, Alexander Yakushev              
                                                  
--]]

-- Asynchronous io.popen for Awesome WM.
-- How to use:
-- asyncshell.request('wscript -Kiev', function(output) wwidget.text = output end)

-- Grab environment
local awful = require('awful')

-- Avoid discrepancies across multiple shells
awful.util.shell = '/bin/sh'

-- Initialize tables for module
asyncshell = { request_table = {}, id_counter = 0 }

-- Request counter
local function next_id()
    asyncshell.id_counter = (asyncshell.id_counter + 1) % 10000
    return asyncshell.id_counter
end

-- Remove given request
function asyncshell.clear(id)
    if asyncshell.request_table[id] then
        if asyncshell.request_table[id].timer then
            asyncshell.request_table[id].timer:stop()
            asyncshell.request_table[id].timer = nil
        end
        asyncshell.request_table[id] = nil
    end
end

-- Sends an asynchronous request for an output of the shell command
-- @param command Command to be executed and taken output from
-- @param callback Function to be called when the command finishes
-- @param timeout Maximum amount of time to wait for the result (optional)
function asyncshell.request(command, callback, timeout)
    local id = next_id()
    asyncshell.request_table[id] = { callback = callback }

    local formatted_command = string.gsub(command, '"','\"')

    local req = string.format(
        "echo \"asyncshell.deliver(%s, [[\\\"$(%s)\\\"]])\" | awesome-client &",
        id, formatted_command
    )

    if type(awful.spawn) == 'table' and awful.spawn.with_shell then
        awful.spawn.with_shell(req)
    else
        awful.util.spawn_with_shell(req)
    end

    if timeout then
        asyncshell.request_table[id].timer = timer({ timeout = timeout })
        asyncshell.request_table[id].timer:connect_signal("timeout", function() asyncshell.clear(id) end)
        asyncshell.request_table[id].timer:start()
    end
end

-- Calls the remembered callback function on the output of the shell command
-- @param id Request ID
-- @param output Shell command output to be delievered
function asyncshell.deliver(id, output)
    local output = string.sub(output, 2, -2)
    if asyncshell.request_table[id] then
        asyncshell.request_table[id].callback(output)
        asyncshell.clear(id)
    end
end

return asyncshell