Coroutines and Read()

local line = 1
local cursorPos = 1
local input = ""
local length = 0
local keys = {}
keys[14] = function() -- Backspace
  if cursorPos~=1 then
   input = string.sub(input,0,cursorPos-2)..(string.sub(input,cursorPos) or "")
   cursorPos = cursorPos - 1
   length = length - 1
   term.setCursorPos(cursorPos+2,line)
   term.write(string.sub(input,cursorPos).." ")
  end
end
keys[203] = function() -- Left Arrow
  if cursorPos~=1 then cursorPos = cursorPos - 1 end
end
keys[205] = function() -- Right Arrow
  if cursorPos~=length+1 then cursorPos = cursorPos + 1 end
end
keys[28] = function() -- Enter
  -- replace this with whatever you want to do with your input.
  term.setCursorPos(cursorPos+2,line+1)
  term.write(" ")
  term.setCursorPos(1,line+1)
  shell.run(input)
  _,line = term.getCursorPos()
  input=""
  length=0
  cursorPos=1
  term.setCursorPos(1,line)
  term.write(">")
  term.setCursorPos(3,line+1)
  term.write("^")
  timer = os.startTimer(0.25)
end

term.clear()
term.setCursorPos(1,1)
term.write(">")
term.setCursorPos(3,2)
term.write("^")
local timer = os.startTimer(0.25)
while true do
local eventType, p1 = os.pullEvent()
if eventType=="char" then
  term.setCursorPos(cursorPos+2,line+1)
  term.write(" ")
  if cursorPos-1==length then
   input = input..p1
   term.setCursorPos(cursorPos+2,line)
   term.write(p1)
  elseif cursorPos==1 then
   input = p1..input
  else
   input = string.sub(input,0,cursorPos-1)..p1..string.sub(input,cursorPos)
   term.setCursorPos(cursorPos+2,line)
   term.write(string.sub(input,cursorPos))
  end
  cursorPos = cursorPos + 1
  length = length + 1
  if cursorPos<length then
   term.setCursorPos(cursorPos+2,line)
   print(string.sub(input,cursorPos))
  end
  term.setCursorPos(cursorPos+2,line+1)
  print("^")
elseif eventType=="key" then
  local f = keys[p1]
  if type(f) == "function" then
   term.setCursorPos(cursorPos+2,line+1)
   term.write(" ")
   f()
  end
elseif eventType=="timer" and p1==timer then
  term.setCursorPos(42,1)
  print("		")
  term.setCursorPos(42,1)
  print(textutils.formatTime(os.time(), false))
  timer = os.startTimer(0.25)
end
end

local function read( _sReplaceChar, _tHistory )
term.setCursorBlink( true )
local timer = os.startTimer(0.25) -- OminousPenguin
	local sLine = ""
local nHistoryPos = nil
local nPos = 0
	if _sReplaceChar then
  _sReplaceChar = string.sub( _sReplaceChar, 1, 1 )
end

local w, h = term.getSize()
local sx, sy = term.getCursorPos()
local function redraw()
  local nScroll = 0
  if sx + nPos >= w then
   nScroll = (sx + nPos) - w
  end
  
  term.setCursorPos( sx, sy )
  term.write( string.rep(" ", w - sx + 1) )
  term.setCursorPos( sx, sy )
  if _sReplaceChar then
   term.write( string.rep(_sReplaceChar, string.len(sLine) - nScroll) )
  else
   term.write( string.sub( sLine, nScroll + 1 ) )
  end
  term.setCursorPos( sx + nPos - nScroll, sy )
end

while true do
  local sEvent, param = os.pullEvent()
  if sEvent == "char" then
   sLine = string.sub( sLine, 1, nPos ) .. param .. string.sub( sLine, nPos + 1 )
   nPos = nPos + 1
   redraw()
  
  elseif sEvent == "key" then
	  if param == 28 then
	-- Enter
	break
  
   elseif param == 203 then
	-- Left
	if nPos > 0 then
	 nPos = nPos - 1
	 redraw()
	end
  
   elseif param == 205 then
	-- Right  
	if nPos < string.len(sLine) then
	 nPos = nPos + 1
	 redraw()
	end
  
   elseif param == 200 or param == 208 then
				-- Up or down
	if _tHistory then
	 if param == 200 then
	  -- Up
	  if nHistoryPos == nil then
	   if #_tHistory > 0 then
		nHistoryPos = #_tHistory
	   end
	  elseif nHistoryPos > 1 then
	   nHistoryPos = nHistoryPos - 1
	  end
	 else
	  -- Down
	  if nHistoryPos == #_tHistory then
	   nHistoryPos = nil
	  elseif nHistoryPos ~= nil then
	   nHistoryPos = nHistoryPos + 1
	  end	
	 end
	
	 if nHistoryPos then
					 sLine = _tHistory[nHistoryPos]
					 nPos = string.len( sLine )
					else
	  sLine = ""
	  nPos = 0
	 end
	 redraw()
				end
   elseif param == 14 then
	-- Backspace
	if nPos > 0 then
	 sLine = string.sub( sLine, 1, nPos - 1 ) .. string.sub( sLine, nPos + 1 )
	 nPos = nPos - 1	
	 redraw()
	end
   end
  elseif sEvent == "timer" and param==timer then  -- OminousPenguin
   term.setCursorPos(42,1)
   print("		")
   term.setCursorPos(42,1)
   print(textutils.formatTime(os.time(), false))
   timer = os.startTimer(0.25)
   redraw()
  end
end

term.setCursorBlink( false )
term.setCursorPos( w + 1, sy )
print()

return sLine
end