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#!/usr/bin/env lua
--[[ expectbc.lua
-
- a somewhat less simple example for lpty, using bc via quite simplistic
- expect like functionality
-
- Gunnar Zötl <gz@tset.de>, 2010, 2011
- Released under MIT/X11 license. See file LICENSE for details.
--]]
local lpty = require "lpty"
local function start(...)
local p = lpty.new()
p:startproc(...)
while p:hasproc() and not p:readok() do end
if not p:hasproc() then
local what, code = p:exitstatus()
error("start failed: child process terminated because of " .. tostring(what) .. " " ..tostring(code))
end
return p
end
local function expect(p, what, plain, timeout)
if not p:hasproc() then return nil, "no running process." end
local res = ""
local found = false
-- consume all output from client while searching for our pattern
while not found do
local r, why = p:read(timeout)
if r ~= nil then
res = res .. r
local first, last, capture = string.find(res, what, 1, plain)
if first then
if capture then
found = capture
else
found = string.sub(res, first, last)
end
end
else
if why then
error("read failed: " .. why)
else
local what, code = p:exitstatus()
if what then
error("read failed: child process terminated because of " .. tostring(what) .. " " ..tostring(code))
end
end
end
end
return found
end
local function send(p, what)
local s = p:send(what)
-- wait for reply
while not p:readok() and p:hasproc() do end
return s
end
-- and here's how we use it
p = start("lua")
if expect(p, "> $") then
send(p, "=111+234\n")
res = expect(p, "([0-9]+)[^0-9]*> $")
print("Got '"..tostring(res).."'")
send(p, "os.exit()\n")
else
print "Whoops..."
end
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