ComputerCraft: File System Iterator

--[[
  File System Iterator v1.0 [Updated: 14 Jan 2013]

  Copyright © 2013-2014 Joshua Asbury a.k.a. theoriginalbit [theoriginalbit@gmail.com]

  Permission is hereby granted, free of charge, to any person obtaining a copy
  of this software and associated documentation files (the "Software"), to deal
  in the Software without restriction, including without limitation the rights
  to use, copy, modify, merge, publish, distribute, and/or sublicense copies
  of the Software, and to permit persons to whom the Software is furnished to
  do so, subject to the following conditions:

  - The above copyright notice and this permission notice shall be included in
    all copies or substantial portions of the Software;
  - Visible credit is given to the original author;
  - The software is distributed in a non-profit way;

  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
  AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
  OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
  THE SOFTWARE.
--]]

local function str_contains( str, seq )
  return (str:find( seq, 1 )) ~= nil
end

local function contains( ignore, line )
  if type( ignore ) == "table" then
    for _, v in pairs( ignore ) do
      if line == v or str_contains( line, v ) then
        return true
      end
    end
    return false
  end
  return str_contains( line, ignore )
end

local function yieldFileSystem(startPath, ignorePaths, debug)
  local fsList = fs.list(startPath)
  for _, file in ipairs(fsList) do
    local path = fs.combine(startPath, file)
    if not contains(ignorePaths, path) then
      if fs.isDir(path) then
        yieldFileSystem(path, ignorePaths, debug)
      else
        coroutine.yield(path, file)
      end
    elseif debug then
      print( "Ignoring: "..path )
    end
  end
end

function fileSystemIter(startPath, ignorePaths, debug)
  startPath = startPath or "/"
  ignorePaths = ignorePaths or {}
  debug = debug == true
  return coroutine.wrap(function()
    yieldFileSystem(startPath, ignorePaths, debug)
  end)
end