path: root/modules/lua/lua.luadoc

---
-- Issues an error when the value of its argument `v` is false (i.e.,
-- nil or false); otherwise, returns all its arguments. `message` is an error
-- message; when absent, it defaults to "assertion failed!"
function assert(v [, message]) end

---
-- This function is a generic interface to the garbage collector. It
-- performs different functions according to its first argument, `opt`:
--   "stop": stops the garbage collector.
--   "restart": restarts the garbage collector.
--   "collect": performs a full garbage-collection cycle.
--   "count": returns the total memory in use by Lua (in Kbytes).
--   "step": performs a garbage-collection step. The step "size" is controlled
--   by `arg` (larger values mean more steps) in a non-specified way. If you
--   want to control the step size you must experimentally tune the value of
--   `arg`. Returns true if the step finished a collection cycle.
--   "setpause": sets `arg` as the new value for the *pause* of the collector
--   (see §2.10). Returns the previous value for *pause*.
--   "setstepmul": sets `arg` as the new value for the *step multiplier*
--   of the collector (see §2.10). Returns the previous value for *step*.
function collectgarbage(opt [, arg]) end

---
-- Opens the named file and executes its contents as a Lua chunk. When
-- called without arguments,
-- `dofile` executes the contents of the standard input (`stdin`). Returns
-- all values returned by the chunk. In case of errors, `dofile` propagates
-- the error to its caller (that is, `dofile` does not run in protected mode).
function dofile(filename) end

---
-- Terminates the last protected function called and returns `message`
-- as the error message. Function `error` never returns.
-- Usually, `error` adds some information about the error position at the
-- beginning of the message. The `level` argument specifies how to get the
-- error position. With level 1 (the default), the error position is where the
-- `error` function was called. Level 2 points the error to where the function
-- that called `error` was called; and so on. Passing a level 0 avoids the
-- addition of error position information to the message.
function error(message [, level]) end

-- * `_G._G`: A global variable (not a function) that holds the global
--   environment (that is, `_G._G = _G`). Lua itself does not use this variable;
--   changing its value does not affect any environment, nor vice-versa. (Use
--   `setfenv` to change environments.)

---
-- Returns the current environment in use by the function.
-- `f` can be a Lua function or a number that specifies the function at that
-- stack level: Level 1 is the function calling `getfenv`. If the given
-- function is not a Lua function, or if `f` is 0, `getfenv` returns the
-- global environment. The default for `f` is 1.
function getfenv([f]) end

---
-- If `object` does not have a metatable, returns nil. Otherwise, if the
-- object's metatable has a `"__metatable"` field, returns the associated
-- value. Otherwise, returns the metatable of the given object.
function getmetatable(object) end

---
-- Returns three values: an iterator function, the table `t`, and 0,
-- so that the construction
--   for i,v in ipairs(t) do *body* end
-- will iterate over the pairs (`1,t[1]`), (`2,t[2]`), ···, up to the
-- first integer key absent from the table.
function ipairs(t) end

---
-- Loads a chunk using function `func` to get its pieces. Each call to
-- `func` must return a string that concatenates with previous results. A
-- return of an empty string, nil, or no value signals the end of the chunk.
-- If there are no errors, returns the compiled chunk as a function; otherwise,
-- returns nil plus the error message. The environment of the returned function
-- is the global environment.
-- `chunkname` is used as the chunk name for error messages and debug
-- information. When absent, it defaults to "`=(load)`".
function load(func [, chunkname]) end

---
-- Similar to `load`, but gets the chunk from file `filename` or from the
-- standard input, if no file name is given.
function loadfile([filename]) end

---
-- Similar to `load`, but gets the chunk from the given string.
-- To load and run a given string, use the idiom
--   assert(loadstring(s))()
-- When absent, `chunkname` defaults to the given string.
function loadstring(string [, chunkname]) end

---
-- Allows a program to traverse all fields of a table. Its first argument is
-- a table and its second argument is an index in this table. `next` returns
-- the next index of the table and its associated value. When called with nil
-- as its second argument, `next` returns an initial index and its associated
-- value. When called with the last index, or with nil in an empty table, `next`
-- returns nil. If the second argument is absent, then it is interpreted as
-- nil. In particular, you can use `next(t)` to check whether a table is empty.
-- The order in which the indices are enumerated is not specified, *even for
-- numeric indices*. (To traverse a table in numeric order, use a numerical
-- for or the `ipairs` function.)
-- The behavior of `next` is *undefined* if, during the traversal, you assign
-- any value to a non-existent field in the table. You may however modify
-- existing fields. In particular, you may clear existing fields.
function next(table [, index]) end

---
-- Returns three values: the `next` function, the table `t`, and nil,
-- so that the construction
--   for k,v in pairs(t) do *body* end
-- will iterate over all key–value pairs of table `t`.
-- See function `next` for the caveats of modifying the table during its
-- traversal.
function pairs(t) end

---
-- Calls function `f` with the given arguments in *protected mode*. This
-- means that any error inside `f` is not propagated; instead, `pcall` catches
-- the error and returns a status code. Its first result is the status code (a
-- boolean), which is true if the call succeeds without errors. In such case,
-- `pcall` also returns all results from the call, after this first result. In
-- case of any error, `pcall` returns false plus the error message.
function pcall(f, arg1, ···) end

---
-- Receives any number of arguments, and prints their values to `stdout`,
-- using the `tostring` function to convert them to strings. `print` is not
-- intended for formatted output, but only as a quick way to show a value,
-- typically for debugging. For formatted output, use `string.format`.
function print(···) end

---
-- Checks whether `v1` is equal to `v2`, without invoking any
-- metamethod. Returns a boolean.
function rawequal(v1, v2) end

---
-- Gets the real value of `table[index]`, without invoking any
-- metamethod. `table` must be a table; `index` may be any value.
function rawget(table, index) end

---
-- Sets the real value of `table[index]` to `value`, without invoking any
-- metamethod. `table` must be a table, `index` any value different from nil,
-- and `value` any Lua value.
-- This function returns `table`.
function rawset(table, index, value) end

---
-- If `index` is a number, returns all arguments after argument number
-- `index`. Otherwise, `index` must be the string `"#"`, and `select` returns
-- the total number of extra arguments it received.
function select(index, ···) end

---
-- Sets the environment to be used by the given function. `f` can be a Lua
-- function or a number that specifies the function at that stack level: Level
-- 1 is the function calling `setfenv`. `setfenv` returns the given function.
-- As a special case, when `f` is 0 `setfenv` changes the environment of the
-- running thread. In this case, `setfenv` returns no values.
function setfenv(f, table) end

---
-- Sets the metatable for the given table. (You cannot change the metatable
-- of other types from Lua, only from C.) If `metatable` is nil, removes the
-- metatable of the given table. If the original metatable has a `"__metatable"`
-- field, raises an error.
-- This function returns `table`.
function setmetatable(table, metatable) end

---
-- Tries to convert its argument to a number. If the argument is already
-- a number or a string convertible to a number, then `tonumber` returns this
-- number; otherwise, it returns nil.
-- An optional argument specifies the base to interpret the numeral. The base
-- may be any integer between 2 and 36, inclusive. In bases above 10, the
-- letter '`A`' (in either upper or lower case) represents 10, '`B`' represents
-- 11, and so forth, with '`Z`' representing 35. In base 10 (the default),
-- the number can have a decimal part, as well as an optional exponent part
-- (see §2.1). In other bases, only unsigned integers are accepted.
function tonumber(e [, base]) end

---
-- Receives an argument of any type and converts it to a string in a
-- reasonable format. For complete control of how numbers are converted, use
-- `string.format`.
-- If the metatable of `e` has a `"__tostring"` field, then `tostring` calls
-- the corresponding value with `e` as argument, and uses the result of the
-- call as its result.
function tostring(e) end

---
-- Returns the type of its only argument, coded as a string. The possible
-- results of this function are "
-- `nil`" (a string, not the value nil), "`number`", "`string`", "`boolean`",
-- "`table`", "`function`", "`thread`", and "`userdata`".
function type(v) end

---
-- Returns the elements from the given table. This function is equivalent to
--   return list[i], list[i+1], ···, list[j]
-- except that the above code can be written only for a fixed number of
-- elements. By default, `i` is 1 and `j` is the length of the list, as
-- defined by the length operator (see §2.5.5).
function unpack(list [, i [, j]]) end

-- * `_G._VERSION`: A global variable (not a function) that holds a string
--   containing the current interpreter version. The current contents of this
--   variable is "`Lua 5.1`".

---
-- This function is similar to `pcall`, except that you can set a new
-- error handler.
-- `xpcall` calls function `f` in protected mode, using `err` as the error
-- handler. Any error inside `f` is not propagated; instead, `xpcall` catches
-- the error, calls the `err` function with the original error object, and
-- returns a status code. Its first result is the status code (a boolean),
-- which is true if the call succeeds without errors. In this case, `xpcall`
-- also returns all results from the call, after this first result. In case
-- of any error, `xpcall` returns false plus the result from `err`.
function xpcall(f, err) end

---
-- Creates a new coroutine, with body `f`. `f` must be a Lua
-- function. Returns this new coroutine, an object with type `"thread"`.
function coroutine.create(f) end

---
-- Starts or continues the execution of coroutine `co`. The first time
-- you resume a coroutine, it starts running its body. The values `val1`,
-- ··· are passed as the arguments to the body function. If the coroutine
-- has yielded, `resume` restarts it; the values `val1`, ··· are passed
-- as the results from the yield.
-- If the coroutine runs without any errors, `resume` returns true plus any
-- values passed to `yield` (if the coroutine yields) or any values returned
-- by the body function (if the coroutine terminates). If there is any error,
-- `resume` returns false plus the error message.
function coroutine.resume(co [, val1, ···]) end

---
-- Returns the running coroutine, or nil when called by the main thread.
function coroutine.running() end

---
-- Returns the status of coroutine `co`, as a string: `"running"`, if
-- the coroutine is running (that is, it called `status`); `"suspended"`, if
-- the coroutine is suspended in a call to `yield`, or if it has not started
-- running yet; `"normal"` if the coroutine is active but not running (that
-- is, it has resumed another coroutine); and `"dead"` if the coroutine has
-- finished its body function, or if it has stopped with an error.
function coroutine.status(co) end

---
-- Creates a new coroutine, with body `f`. `f` must be a Lua
-- function. Returns a function that resumes the coroutine each time it is
-- called. Any arguments passed to the function behave as the extra arguments to
-- `resume`. Returns the same values returned by `resume`, except the first
-- boolean. In case of error, propagates the error.
function coroutine.wrap(f) end

---
-- Suspends the execution of the calling coroutine. The coroutine cannot
-- be running a C function, a metamethod, or an iterator. Any arguments to
-- `yield` are passed as extra results to `resume`.
function coroutine.yield(···) end

---
-- Creates a module. If there is a table in `package.loaded[name]`,
-- this table is the module. Otherwise, if there is a global table `t`
-- with the given name, this table is the module. Otherwise creates a new
-- table `t` and sets it as the value of the global `name` and the value of
-- `package.loaded[name]`. This function also initializes `t._NAME` with the
-- given name, `t._M` with the module (`t` itself), and `t._PACKAGE` with the
-- package name (the full module name minus last component; see below). Finally,
-- `module` sets `t` as the new environment of the current function and the
-- new value of `package.loaded[name]`, so that `require` returns `t`.
-- If `name` is a compound name (that is, one with components separated by
-- dots), `module` creates (or reuses, if they already exist) tables for each
-- component. For instance, if `name` is `a.b.c`, then `module` stores the
-- module table in field `c` of field `b` of global `a`.
-- This function can receive optional *options* after the module name, where
-- each option is a function to be applied over the module.
function module(name [, ···]) end

---
-- Loads the given module. The function starts by looking into the
-- `package.loaded` table to determine whether `modname` is already
-- loaded. If it is, then `require` returns the value stored at
-- `package.loaded[modname]`. Otherwise, it tries to find a *loader* for
-- the module.
-- To find a loader, `require` is guided by the `package.loaders` array. By
-- changing this array, we can change how `require` looks for a module. The
-- following explanation is based on the default configuration for
-- `package.loaders`.
-- First `require` queries `package.preload[modname]`. If it has a value,
-- this value (which should be a function) is the loader. Otherwise `require`
-- searches for a Lua loader using the path stored in `package.path`. If
-- that also fails, it searches for a C loader using the path stored in
-- `package.cpath`. If that also fails, it tries an *all-in-one* loader (see
-- `package.loaders`).
-- Once a loader is found, `require` calls the loader with a single argument,
-- `modname`. If the loader returns any value, `require` assigns the returned
-- value to `package.loaded[modname]`. If the loader returns no value and
-- has not assigned any value to `package.loaded[modname]`, then `require`
-- assigns true to this entry. In any case, `require` returns the final value
-- of `package.loaded[modname]`.
-- If there is any error loading or running the module, or if it cannot find
-- any loader for the module, then `require` signals an error.
function require(modname) end

-- * `package.cpath`: The path used by `require` to search for a C loader.
--   Lua initializes the C path `package.cpath` in the same way it initializes
--   the Lua path `package.path`, using the environment variable `LUA_CPATH`
--   or a default path defined in `luaconf.h`.

-- * `package.loaded`: A table used by `require` to control which modules are
--   already loaded. When you require a module `modname` and
--   `package.loaded[modname]` is not false, `require` simply returns the value
--   stored there.

-- * `package.loaders`: A table used by `require` to control how to load
--   modules. Each entry in this table is a *searcher function*. When looking
--   for a module, `require` calls each of these searchers in ascending order,
--   with the module name (the argument given to `require`) as its sole
--   parameter. The function can return another function (the module *loader*)
--   or a string explaining why it did not find that module (or nil if it has
--   nothing to say). Lua initializes this table with four functions.
--   The first searcher simply looks for a loader in the `package.preload`
--   table.
--   The second searcher looks for a loader as a Lua library, using the path
--   stored at `package.path`. A path is a sequence of *templates* separated by
--   semicolons. For each template, the searcher will change each interrogation
--   mark in the template by `filename`, which is the module name with each dot
--   replaced by a "directory separator" (such as "`/`" in Unix); then it will
--   try to open the resulting file name. So, for instance, if the Lua path is
--   the string
--     "./?.lua;./?.lc;/usr/local/?/init.lua"
--   the search for a Lua file for module `foo` will try to open the files
--   `./foo.lua`, `./foo.lc`, and `/usr/local/foo/init.lua`, in that order.
--   The third searcher looks for a loader as a C library, using the path given
--   by the variable `package.cpath`. For instance, if the C path is the string
--     "./?.so;./?.dll;/usr/local/?/init.so"
--   the searcher for module `foo` will try to open the files `./foo.so`,
--   `./foo.dll`, and `/usr/local/foo/init.so`, in that order. Once it finds
--   a C library, this searcher first uses a dynamic link facility to link the
--   application with the library. Then it tries to find a C function inside the
--   library to be used as the loader. The name of this C function is the string
--   "`luaopen_`" concatenated with a copy of the module name where each dot
--   is replaced by an underscore. Moreover, if the module name has a hyphen,
--   its prefix up to (and including) the first hyphen is removed. For instance,
--   if the module name is `a.v1-b.c`, the function name will be `luaopen_b_c`.
--   The fourth searcher tries an *all-in-one loader*. It searches the C
--   path for a library for the root name of the given module. For instance,
--   when requiring `a.b.c`, it will search for a C library for `a`. If found,
--   it looks into it for an open function for the submodule; in our example,
--   that would be `luaopen_a_b_c`. With this facility, a package can pack
--   several C submodules into one single library, with each submodule keeping
--   its original open function.

---
-- Dynamically links the host program with the C library `libname`. Inside
-- this library, looks for a function `funcname` and returns this function as a
-- C function. (So, `funcname` must follow the protocol (see `lua_CFunction`)).
-- This is a low-level function. It completely bypasses the package and module
-- system. Unlike `require`, it does not perform any path searching and does
-- not automatically adds extensions. `libname` must be the complete file name
-- of the C library, including if necessary a path and extension. `funcname`
-- must be the exact name exported by the C library (which may depend on the
-- C compiler and linker used).
-- This function is not supported by ANSI C. As such, it is only available
-- on some platforms (Windows, Linux, Mac OS X, Solaris, BSD, plus other Unix
-- systems that support the `dlfcn` standard).
function package.loadlib(libname, funcname) end

-- * `package.path`: The path used by `require` to search for a Lua loader.
--   At start-up, Lua initializes this variable with the value of the
--   environment variable `LUA_PATH` or with a default path defined in
--   `luaconf.h`, if the environment variable is not defined. Any "`;;`" in the
--   value of the environment variable is replaced by the default path.

-- * `package.preload`: A table to store loaders for specific modules (see
--   `require`).

---
-- Sets a metatable for `module` with its `__index` field referring to the
-- global environment, so that this module inherits values from the global
-- environment. To be used as an option to function `module`.
function package.seeall(module) end

---
-- Returns the internal numerical codes of the characters `s[i]`, `s[i+1]`,
-- ···, `s[j]`. The default value for `i` is 1; the default value for `j`
-- is `i`.
-- Note that numerical codes are not necessarily portable across platforms.
function string.byte(s [, i [, j]]) end

---
-- Receives zero or more integers. Returns a string with length equal to
-- the number of arguments, in which each character has the internal numerical
-- code equal to its corresponding argument.
-- Note that numerical codes are not necessarily portable across platforms.
function string.char(···) end

---
-- Returns a string containing a binary representation of the given
-- function, so that a later `loadstring` on this string returns a copy of
-- the function. `function` must be a Lua function without upvalues.
function string.dump(function) end

---
-- Looks for the first match of `pattern` in the string `s`. If it finds a
-- match, then `find` returns the indices of `s` where this occurrence starts
-- and ends; otherwise, it returns nil. A third, optional numerical argument
-- `init` specifies where to start the search; its default value is 1 and
-- can be negative. A value of true as a fourth, optional argument `plain`
-- turns off the pattern matching facilities, so the function does a plain
-- "find substring" operation, with no characters in `pattern` being considered
-- "magic". Note that if `plain` is given, then `init` must be given as well.
-- If the pattern has captures, then in a successful match the captured values
-- are also returned, after the two indices.
function string.find(s, pattern [, init [, plain]]) end

---
-- Returns a formatted version of its variable number of arguments following
-- the description given in its first argument (which must be a string). The
-- format string follows the same rules as the `printf` family of standard C
-- functions. The only differences are that the options/modifiers `*`, `l`,
-- `L`, `n`, `p`, and `h` are not supported and that there is an extra option,
-- `q`. The `q` option formats a string in a form suitable to be safely read
-- back by the Lua interpreter: the string is written between double quotes,
-- and all double quotes, newlines, embedded zeros, and backslashes in the
-- string are correctly escaped when written. For instance, the call
--   string.format('%q', 'a string with "quotes" and \n new line')
-- will produce the string:
--   "a string with \"quotes\" and \
--       new line"
-- The options `c`, `d`, `E`, `e`, `f`, `g`, `G`, `i`, `o`, `u`, `X`, and
-- `x` all expect a number as argument, whereas `q` and `s` expect a string.
-- This function does not accept string values containing embedded zeros,
-- except as arguments to the `q` option.
function string.format(formatstring, ···) end

---
-- Returns an iterator function that, each time it is called, returns the
-- next captures from `pattern` over string `s`. If `pattern` specifies no
-- captures, then the whole match is produced in each call.
-- As an example, the following loop
--   s = "hello world from Lua"
--   for w in string.gmatch(s, "%a+") do
--     print(w)
--   end
-- will iterate over all the words from string `s`, printing one per line. The
-- next example collects all pairs `key=value` from the given string into
-- a table:
--   t = {}
--   s = "from=world, to=Lua"
--   for k, v in string.gmatch(s, "(%w+)=(%w+)") do
--     t[k] = v
--   end
-- For this function, a '`^`' at the start of a pattern does not work as an
-- anchor, as this would prevent the iteration.
function string.gmatch(s, pattern) end

---
-- Returns a copy of `s` in which all (or the first `n`, if given)
-- occurrences of the `pattern` have been replaced by a replacement string
-- specified by `repl`, which can be a string, a table, or a function. `gsub`
-- also returns, as its second value, the total number of matches that occurred.
-- If `repl` is a string, then its value is used for replacement. The character
-- `%` works as an escape character: any sequence in `repl` of the form `%n`,
-- with *n* between 1 and 9, stands for the value of the *n*-th captured
-- substring (see below). The sequence `%0` stands for the whole match. The
-- sequence `%%` stands for a single `%`.
-- If `repl` is a table, then the table is queried for every match, using
-- the first capture as the key; if the pattern specifies no captures, then
-- the whole match is used as the key.
-- If `repl` is a function, then this function is called every time a match
-- occurs, with all captured substrings passed as arguments, in order; if
-- the pattern specifies no captures, then the whole match is passed as a
-- sole argument.
-- If the value returned by the table query or by the function call is a
-- string or a number, then it is used as the replacement string; otherwise,
-- if it is false or nil, then there is no replacement (that is, the original
-- match is kept in the string).
-- Here are some examples:
--   x = string.gsub("hello world", "(%w+)", "%1 %1")
--   --> x="hello hello world world"
--   x = string.gsub("hello world", "%w+", "%0 %0", 1)
--   --> x="hello hello world"
--   x = string.gsub("hello world from Lua", "(%w+)%s*(%w+)", "%2 %1")
--   --> x="world hello Lua from"
--   x = string.gsub("home = $HOME, user = $USER", "%$(%w+)", os.getenv)
--   --> x="home = /home/roberto, user = roberto"
--   x = string.gsub("4+5 = $return 4+5$", "%$(.-)%$", function (s)
--         return loadstring(s)()
--       end)
--   --> x="4+5 = 9"
--   local t = {name="lua", version="5.1"}
--   x = string.gsub("$name-$version.tar.gz", "%$(%w+)", t)
--   --> x="lua-5.1.tar.gz"
function string.gsub(s, pattern, repl [, n]) end

---
-- Receives a string and returns its length. The empty string `""` has
-- length 0. Embedded zeros are counted, so `"a\000bc\000"` has length 5.
function string.len(s) end

---
-- Receives a string and returns a copy of this string with all uppercase
-- letters changed to lowercase. All other characters are left unchanged. The
-- definition of what an uppercase letter is depends on the current locale.
function string.lower(s) end

---
-- Looks for the first *match* of `pattern` in the string `s`. If it
-- finds one, then `match` returns the captures from the pattern; otherwise
-- it returns nil. If `pattern` specifies no captures, then the whole match
-- is returned. A third, optional numerical argument `init` specifies where
-- to start the search; its default value is 1 and can be negative.
function string.match(s, pattern [, init]) end

---
-- Returns a string that is the concatenation of `n` copies of the string
-- `s`.
function string.rep(s, n) end

---
-- Returns a string that is the string `s` reversed.
function string.reverse(s) end

---
-- Returns the substring of `s` that starts at `i` and continues until
-- `j`; `i` and `j` can be negative. If `j` is absent, then it is assumed to
-- be equal to -1 (which is the same as the string length). In particular,
-- the call `string.sub(s,1,j)` returns a prefix of `s` with length `j`, and
-- `string.sub(s, -i)` returns a suffix of `s` with length `i`.
function string.sub(s, i [, j]) end

---
-- Receives a string and returns a copy of this string with all lowercase
-- letters changed to uppercase. All other characters are left unchanged. The
-- definition of what a lowercase letter is depends on the current locale.
function string.upper(s) end

---
-- Given an array where all elements are strings or numbers, returns
-- `table[i]..sep..table[i+1] ··· sep..table[j]`. The default value for
-- `sep` is the empty string, the default for `i` is 1, and the default for
-- `j` is the length of the table. If `i` is greater than `j`, returns the
-- empty string.
function table.concat(table [, sep [, i [, j]]]) end

---
-- Inserts element `value` at position `pos` in `table`, shifting up
-- other elements to open space, if necessary. The default value for `pos` is
-- `n+1`, where `n` is the length of the table (see §2.5.5), so that a call
-- `table.insert(t,x)` inserts `x` at the end of table `t`.
function table.insert(table, [pos,] value) end

---
-- Returns the largest positive numerical index of the given table, or
-- zero if the table has no positive numerical indices. (To do its job this
-- function does a linear traversal of the whole table.)
function table.maxn(table) end

---
-- Removes from `table` the element at position `pos`, shifting down other
-- elements to close the space, if necessary. Returns the value of the removed
-- element. The default value for `pos` is `n`, where `n` is the length of the
-- table, so that a call `table.remove(t)` removes the last element of table
-- `t`.
function table.remove(table [, pos]) end

---
-- Sorts table elements in a given order,
-- *in-place*, from `table[1]` to `table[n]`, where `n` is the length of the
-- table. If `comp` is given, then it must be a function that receives two
-- table elements, and returns true when the first is less than the second
-- (so that `not comp(a[i+1],a[i])` will be true after the sort). If `comp`
-- is not given, then the standard Lua operator ``io.lines`, this function
-- does not close the file when the loop ends.)
function table.sort(table [, comp]) end

---
-- Returns the absolute value of `x`.
function math.abs(x) end

---
-- Returns the arc cosine of `x` (in radians).
function math.acos(x) end

---
-- Returns the arc sine of `x` (in radians).
function math.asin(x) end

---
-- Returns the arc tangent of `x` (in radians).
function math.atan(x) end

---
-- Returns the arc tangent of `y/x` (in radians), but uses the signs
-- of both parameters to find the quadrant of the result. (It also handles
-- correctly the case of `x` being zero.)
function math.atan2(y, x) end

---
-- Returns the smallest integer larger than or equal to `x`.
function math.ceil(x) end

---
-- Returns the cosine of `x` (assumed to be in radians).
function math.cos(x) end

---
-- Returns the hyperbolic cosine of `x`.
function math.cosh(x) end

---
-- Returns the angle `x` (given in radians) in degrees.
function math.deg(x) end

---
-- Returns the value *e^x*.
function math.exp(x) end

---
-- Returns the largest integer smaller than or equal to `x`.
function math.floor(x) end

---
-- Returns the remainder of the division of `x` by `y` that rounds the
-- quotient towards zero.
function math.fmod(x, y) end

---
-- Returns `m` and `e` such that *x = m2^e*, `e` is an integer and the
-- absolute value of `m` is in the range *[0.5, 1)* (or zero when `x` is zero).
function math.frexp(x) end

-- * `math.HUGE_VAL`: The value `HUGE_VAL`, a value larger than or equal to any
--   other numerical value.

---
-- Returns *m2^e* (`e` should be an integer).
function math.ldexp(m, e) end

---
-- Returns the natural logarithm of `x`.
function math.log(x) end

---
-- Returns the base-10 logarithm of `x`.
function math.log10(x) end

---
-- Returns the maximum value among its arguments.
function math.max(x, ···) end

---
-- Returns the minimum value among its arguments.
function math.min(x, ···) end

---
-- Returns two numbers, the integral part of `x` and the fractional part of
-- `x`.
function math.modf(x) end

-- * `math.pi`: The value of *pi*.

---
-- Returns *x^y*. (You can also use the expression `x^y` to compute this
-- value.)
function math.pow(x, y) end

---
-- Returns the angle `x` (given in degrees) in radians.
function math.rad(x) end

---
-- This function is an interface to the simple pseudo-random generator
-- function `rand` provided by ANSI C. (No guarantees can be given for its
-- statistical properties.)
-- When called without arguments, returns a uniform pseudo-random real
-- number in the range *[0,1)*. When called with an integer number `m`,
-- `math.random` returns a uniform pseudo-random integer in the range *[1,
-- m]*. When called with two integer numbers `m` and `n`, `math.random`
-- returns a uniform pseudo-random integer in the range *[m, n]*.
function math.random([m [, n]]) end

---
-- Sets `x` as the "seed" for the pseudo-random generator: equal seeds
-- produce equal sequences of numbers.
function math.randomseed(x) end

---
-- Returns the sine of `x` (assumed to be in radians).
function math.sin(x) end

---
-- Returns the hyperbolic sine of `x`.
function math.sinh(x) end

---
-- Returns the square root of `x`. (You can also use the expression `x^0.5`
-- to compute this value.)
function math.sqrt(x) end

---
-- Returns the tangent of `x` (assumed to be in radians).
function math.tan(x) end

---
-- Returns the hyperbolic tangent of `x`.
function math.tanh(x) end

---
-- Equivalent to `file:close()`. Without a `file`, closes the default
-- output file.
function io.close([file]) end

---
-- Equivalent to `file:flush` over the default output file.
function io.flush() end

---
-- When called with a file name, it opens the named file (in text mode),
-- and sets its handle as the default input file. When called with a file
-- handle, it simply sets this file handle as the default input file. When
-- called without parameters, it returns the current default input file.
-- In case of errors this function raises the error, instead of returning an
-- error code.
function io.input([file]) end

---
-- Opens the given file name in read mode and returns an iterator function
-- that, each time it is called, returns a new line from the file. Therefore,
-- the construction
--   for line in io.lines(filename) do *body* end
-- will iterate over all lines of the file. When the iterator function detects
-- the end of file, it returns nil (to finish the loop) and automatically
-- closes the file.
-- The call `io.lines()` (with no file name) is equivalent to
-- `io.input():lines()`; that is, it iterates over the lines of the default
-- input file. In this case it does not close the file when the loop ends.
function io.lines([filename]) end

---
-- This function opens a file, in the mode specified in the string `mode`. It
-- returns a new file handle, or, in case of errors, nil plus an error message.
-- The `mode` string can be any of the following:
--   "r": read mode (the default);
--   "w": write mode;
--   "a": append mode;
--   "r+": update mode, all previous data is preserved;
--   "w+": update mode, all previous data is erased;
--   "a+": append update mode, previous data is preserved, writing is only
--   allowed at the end of file.
-- The `mode` string can also have a '`b`' at the end, which is needed in
-- some systems to open the file in binary mode. This string is exactly what
-- is used in the standard C function `fopen`.
function io.open(filename [, mode]) end

---
-- Similar to `io.input`, but operates over the default output file.
function io.output([file]) end

---
-- Starts program `prog` in a separated process and returns a file handle
-- that you can use to read data from this program (if `mode` is `"r"`,
-- the default) or to write data to this program (if `mode` is `"w"`).
-- This function is system dependent and is not available on all platforms.
function io.popen(prog [, mode]) end

---
-- Equivalent to `io.input():read`.
function io.read(···) end

-- * `io.stderr`: Standard error.
-- * `io.stdin`: Standard in.
-- * `io.stdout`: Standard out.

---
-- Returns a handle for a temporary file. This file is opened in update
-- mode and it is automatically removed when the program ends.
function io.tmpfile() end

---
-- Checks whether `obj` is a valid file handle. Returns the string `"file"`
-- if `obj` is an open file handle, `"closed file"` if `obj` is a closed file
-- handle, or nil if `obj` is not a file handle.
function io.type(obj) end

---
-- Equivalent to `io.output():write`.
function io.write(···) end

---
-- Closes `file`. Note that files are automatically closed when their
-- handles are garbage collected, but that takes an unpredictable amount of
-- time to happen.
function file:close() end

---
-- Saves any written data to `file`.
function file:flush() end

---
-- Returns an iterator function that, each time it is called, returns a
-- new line from the file. Therefore, the construction
--   for line in file:lines() do *body* end
-- will iterate over all lines of the file. (Unlike `io.lines`, this function
-- does not close the file when the loop ends.)
function file:lines() end

---
-- Reads the file `file`, according to the given formats, which specify
-- what to read. For each format, the function returns a string (or a number)
-- with the characters read, or nil if it cannot read data with the specified
-- format. When called without formats, it uses a default format that reads
-- the entire next line (see below).
-- The available formats are
--   "*n": reads a number; this is the only format that returns a number
--   instead of a string.
--   "*a": reads the whole file, starting at the current position. On end of
--   file, it returns the empty string.
--   "*l": reads the next line (skipping the end of line), returning nil on
--   end of file. This is the default format.
--   *number*: reads a string with up to this number of characters, returning
--   nil on end of file. If number is zero, it reads nothing and returns an
--   empty string, or nil on end of file.
function file:read(···) end

---
-- Sets and gets the file position, measured from the beginning of the
-- file, to the position given by `offset` plus a base specified by the string
-- `whence`, as follows:
--   "set": base is position 0 (beginning of the file);
--   "cur": base is current position;
--   "end": base is end of file;
-- In case of success, function `seek` returns the final file position,
-- measured in bytes from the beginning of the file. If this function fails,
-- it returns nil, plus a string describing the error.
-- The default value for `whence` is `"cur"`, and for `offset` is 0. Therefore,
-- the call `file:seek()` returns the current file position, without changing
-- it; the call `file:seek("set")` sets the position to the beginning of the
-- file (and returns 0); and the call `file:seek("end")` sets the position
-- to the end of the file, and returns its size.
function file:seek([whence] [, offset]) end

---
-- Sets the buffering mode for an output file. There are three available
-- modes:
--   "no": no buffering; the result of any output operation appears immediately.
--   "full": full buffering; output operation is performed only when the
--   buffer is full (or when you explicitly `flush` the file (see `io.flush`)).
--   "line": line buffering; output is buffered until a newline is output or
--   there is any input from some special files (such as a terminal device).
-- For the last two cases, `size` specifies the size of the buffer, in
-- bytes. The default is an appropriate size.
function file:setvbuf(mode [, size]) end

---
-- Writes the value of each of its arguments to the `file`. The arguments
-- must be strings or numbers. To write other values, use `tostring` or
-- `string.format` before `write`.
function file:write(···) end

---
-- Returns an approximation of the amount in seconds of CPU time used by
-- the program.
function os.clock() end

---
-- Returns a string or a table containing date and time, formatted according
-- to the given string `format`.
-- If the `time` argument is present, this is the time to be formatted
-- (see the `os.time` function for a description of this value). Otherwise,
-- `date` formats the current time.
-- If `format` starts with '`!`', then the date is formatted in Coordinated
-- Universal Time. After this optional character, if `format` is the string
-- "`*t`", then `date` returns a table with the following fields: `year` (four
-- digits), `month` (1--12), `day` (1--31), `hour` (0--23), `min` (0--59),
-- `sec` (0--61), `wday` (weekday, Sunday is 1), `yday` (day of the year),
-- and `isdst` (daylight saving flag, a boolean).
-- If `format` is not "`*t`", then `date` returns the date as a string,
-- formatted according to the same rules as the C function `strftime`.
-- When called without arguments, `date` returns a reasonable date and time
-- representation that depends on the host system and on the current locale
-- (that is, `os.date()` is equivalent to `os.date("%c")`).
function os.date([format [, time]]) end

---
-- Returns the number of seconds from time `t1` to time `t2`. In POSIX,
-- Windows, and some other systems, this value is exactly `t2`*-*`t1`.
function os.difftime(t2, t1) end

---
-- This function is equivalent to the C function `system`. It passes
-- `command` to be executed by an operating system shell. It returns a status
-- code, which is system-dependent. If `command` is absent, then it returns
-- nonzero if a shell is available and zero otherwise.
function os.execute([command]) end

---
-- Calls the C function `exit`, with an optional `code`, to terminate the
-- host program. The default value for `code` is the success code.
function os.exit([code]) end

---
-- Returns the value of the process environment variable `varname`, or
-- nil if the variable is not defined.
function os.getenv(varname) end

---
-- Deletes the file or directory with the given name. Directories must be
-- empty to be removed. If this function fails, it returns nil, plus a string
-- describing the error.
function os.remove(filename) end

---
-- Renames file or directory named `oldname` to `newname`. If this function
-- fails, it returns nil, plus a string describing the error.
function os.rename(oldname, newname) end

---
-- Sets the current locale of the program. `locale` is a string specifying
-- a locale; `category` is an optional string describing which category to
-- change: `"all"`, `"collate"`, `"ctype"`, `"monetary"`, `"numeric"`, or
-- `"time"`; the default category is `"all"`. The function returns the name
-- of the new locale, or nil if the request cannot be honored.
-- If `locale` is the empty string, the current locale is set to an
-- implementation-defined native locale. If `locale` is the string "`C`",
-- the current locale is set to the standard C locale.
-- When called with nil as the first argument, this function only returns
-- the name of the current locale for the given category.
function os.setlocale(locale [, category]) end

---
-- Returns the current time when called without arguments, or a time
-- representing the date and time specified by the given table. This table
-- must have fields `year`, `month`, and `day`, and may have fields `hour`,
-- `min`, `sec`, and `isdst` (for a description of these fields, see the
-- `os.date` function).
-- The returned value is a number, whose meaning depends on your system. In
-- POSIX, Windows, and some other systems, this number counts the number
-- of seconds since some given start time (the "epoch"). In other systems,
-- the meaning is not specified, and the number returned by `time` can be
-- used only as an argument to `date` and `difftime`.
function os.time([table]) end

---
-- Returns a string with a file name that can be used for a temporary
-- file. The file must be explicitly opened before its use and explicitly
-- removed when no longer needed.
-- On some systems (POSIX), this function also creates a file with that
-- name, to avoid security risks. (Someone else might create the file with
-- wrong permissions in the time between getting the name and creating the
-- file.) You still have to open the file to use it and to remove it (even
-- if you do not use it).
-- When possible, you may prefer to use `io.tmpfile`, which automatically
-- removes the file when the program ends.
function os.tmpname() end

---
-- Enters an interactive mode with the user, running each string that
-- the user enters. Using simple commands and other debug facilities,
-- the user can inspect global and local variables, change their values,
-- evaluate expressions, and so on. A line containing only the word `cont`
-- finishes this function, so that the caller continues its execution.
-- Note that commands for `debug.debug` are not lexically nested within any
-- function, and so have no direct access to local variables.
function debug.debug() end

---
-- Returns the environment of object `o`.
function debug.getfenv(o) end

---
-- Returns the current hook settings of the thread, as three values: the
-- current hook function, the current hook mask, and the current hook count
-- (as set by the `debug.sethook` function).
function debug.gethook([thread]) end

---
-- Returns a table with information about a function. You can give the
-- function directly, or you can give a number as the value of `function`,
-- which means the function running at level `function` of the call stack
-- of the given thread: level 0 is the current function (`getinfo` itself);
-- level 1 is the function that called `getinfo`; and so on. If `function`
-- is a number larger than the number of active functions, then `getinfo`
-- returns nil.
-- The returned table can contain all the fields returned by `lua_getinfo`,
-- with the string `what` describing which fields to fill in. The default for
-- `what` is to get all information available, except the table of valid
-- lines. If present, the option '`f`' adds a field named `func` with
-- the function itself. If present, the option '`L`' adds a field named
-- `activelines` with the table of valid lines.
-- For instance, the expression `debug.getinfo(1,"n").name` returns a table
-- with a name for the current function, if a reasonable name can be found,
-- and the expression `debug.getinfo(print)` returns a table with all available
-- information about the `print` function.
function debug.getinfo([thread,] function [, what]) end

---
-- This function returns the name and the value of the local variable with
-- index `local` of the function at level `level` of the stack. (The first
-- parameter or local variable has index 1, and so on, until the last active
-- local variable.) The function returns nil if there is no local variable
-- with the given index, and raises an error when called with a `level` out
-- of range. (You can call `debug.getinfo` to check whether the level is valid.)
-- Variable names starting with '`(`' (open parentheses) represent internal
-- variables (loop control variables, temporaries, and C function locals).
function debug.getlocal([thread,] level, local) end

---
-- Returns the metatable of the given `object` or nil if it does not have
-- a metatable.
function debug.getmetatable(object) end

---
-- Returns the registry table (see §3.5).
function debug.getregistry() end

---
-- This function returns the name and the value of the upvalue with index
-- `up` of the function `func`. The function returns nil if there is no
-- upvalue with the given index.
function debug.getupvalue(func, up) end

---
-- Sets the environment of the given `object` to the given `table`. Returns
-- `object`.
function debug.setfenv(object, table) end

---
-- Sets the given function as a hook. The string `mask` and the number
-- `count` describe when the hook will be called. The string mask may have
-- the following characters, with the given meaning:
--   `"c"`: the hook is called every time Lua calls a function;
--   `"r"`: the hook is called every time Lua returns from a function;
--   `"l"`: the hook is called every time Lua enters a new line of code.
-- With a `count` different from zero, the hook is called after every `count`
-- instructions.
-- When called without arguments, `debug.sethook` turns off the hook.
-- When the hook is called, its first parameter is a string describing
-- the event that has triggered its call: `"call"`, `"return"` (or `"tail
-- return"`, when simulating a return from a tail call), `"line"`, and
-- `"count"`. For line events, the hook also gets the new line number as its
-- second parameter. Inside a hook, you can call `getinfo` with level 2 to
-- get more information about the running function (level 0 is the `getinfo`
-- function, and level 1 is the hook function), unless the event is `"tail
-- return"`. In this case, Lua is only simulating the return, and a call to
-- `getinfo` will return invalid data.
function debug.sethook([thread,] hook, mask [, count]) end

---
-- This function assigns the value `value` to the local variable with
-- index `local` of the function at level `level` of the stack. The function
-- returns nil if there is no local variable with the given index, and raises
-- an error when called with a `level` out of range. (You can call `getinfo`
-- to check whether the level is valid.) Otherwise, it returns the name of
-- the local variable.
function debug.setlocal([thread,] level, local, value) end

---
-- Sets the metatable for the given `object` to the given `table` (which
-- can be nil).
function debug.setmetatable(object, table) end

---
-- This function assigns the value `value` to the upvalue with index `up`
-- of the function `func`. The function returns nil if there is no upvalue
-- with the given index. Otherwise, it returns the name of the upvalue.
function debug.setupvalue(func, up, value) end

-- External libraries.

-- LPeg.

---
-- The matching function. It attempts to match the given pattern against the
-- subject string. If the match succeeds, returns the index in the subject of
-- the first character after the match, or the captured values (if the pattern
-- captured any value).
-- An optional numeric argument init makes the match starts at that position in
-- the subject string. As usual in Lua libraries, a negative value counts from
-- the end.
-- Unlike typical pattern-matching functions, match works only in anchored mode;
-- that is, it tries to match the pattern with a prefix of the given subject
-- string (at position init), not with an arbitrary substring of the subject.
-- So, if we want to find a pattern anywhere in a string, we must either write a
-- loop in Lua or write a pattern that matches anywhere. This second approach is
-- easy and quite efficient; see examples.
function lpeg.match(pattern, subject [, init]) end

---
-- If the given value is a pattern, returns the string "pattern". Otherwise
-- returns nil.
function lpeg.type(value) end

---
-- Returns a string with the running version of LPeg.
function lpeg.version() end

---
-- Sets the maximum size for the backtrack stack used by LPeg to track calls and
-- choices. Most well-written patterns need little backtrack levels and
-- therefore you seldom need to change this maximum; but a few useful patterns
-- may need more space. Before changing this maximum you should try to rewrite
-- your pattern to avoid the need for extra space.
function lpeg.setmaxstack(max) end

---
-- Converts the given value into a proper pattern, according to the following
-- rules:
--   * If the argument is a pattern, it is returned unmodified.
--   * If the argument is a string, it is translated to a pattern that matches
--     literally the string.
--   * If the argument is a non-negative number n, the result is a pattern that
--     matches exactly n characters.
--   * If the argument is a negative number -n, the result is a pattern that
--     succeeds only if the input string does not have n characters: lpeg.P(-n)
--     is equivalent to -lpeg.P(n) (see the unary minus operation).
--   * If the argument is a boolean, the result is a pattern that always
--     succeeds or always fails (according to the boolean value), without
--     consuming any input.
--   * If the argument is a table, it is interpreted as a grammar (see
--     Grammars).
--   * If the argument is a function, returns a pattern equivalent to a
--     match-time capture over the empty string.
function lpeg.P(value) end

---
-- Returns a pattern that matches any single character belonging to one of the
-- given ranges. Each range is a string xy of length 2, representing all
-- characters with code between the codes of x and y (both inclusive).
-- As an example, the pattern lpeg.R("09") matches any digit, and lpeg.R("az",
-- "AZ") matches any ASCII letter.
function lpeg.R({range}) end

---
-- Returns a pattern that matches any single character that appears in the given
-- string. (The S stands for Set.)
-- As an example, the pattern lpeg.S("+-*/") matches any arithmetic operator.
-- Note that, if s is a character (that is, a string of length 1), then
-- lpeg.P(s) is equivalent to lpeg.S(s) which is equivalent to lpeg.R(s..s).
-- Note also that both lpeg.S("") and lpeg.R() are patterns that always fail.
function lpeg.S(string) end

---
-- This operation creates a non-terminal (a variable) for a grammar. The created
-- non-terminal refers to the rule indexed by v in the enclosing grammar. (See
-- Grammars for details.)
function lpeg.V(v) end

---
-- Returns a table with patterns for matching some character classes according
-- to the current locale. The table has fields named alnum, alpha, cntrl, digit,
-- graph, lower, print, punct, space, upper, and xdigit, each one containing a
-- correspondent pattern. Each pattern matches any single character that belongs
-- to its class.
-- If called with an argument table, then it creates those fields inside the
-- given table and returns that table.
function lpeg.locale([table]) end

---
-- Creates a simple capture, which captures the substring of the subject that
-- matches patt. The captured value is a string. If patt has other captures,
-- their values are returned after this one.
function lpeg.C(patt) end

---
-- Creates an argument capture. This pattern matches the empty string and
-- produces the value given as the nth extra argument given in the call to
-- lpeg.match.
function lpeg.Carg(n) end

---
-- Creates a back capture. This pattern matches the empty string and produces
-- the values produced by the most recent group capture named name.
-- Most recent means the last complete outermost group capture with the given
-- name. A Complete capture means that the entire pattern corresponding to the
-- capture has matched. An Outermost capture means that the capture is not
-- inside another complete capture.
function lpeg.Cb(name) end

---
-- Creates a constant capture. This pattern matches the empty string and
-- produces all given values as its captured values.
function lpeg.Cc([value, ...]) end

---
-- Creates a fold capture. If patt produces a list of captures C1 C2 ... Cn,
-- this capture will produce the value func(...func(func(C1, C2), C3)..., Cn),
-- that is, it will fold (or accumulate, or reduce) the captures from patt using
-- function func.
-- This capture assumes that patt should produce at least one capture with at
-- least one value (of any type), which becomes the initial value of an
-- accumulator. (If you need a specific initial value, you may prefix a constant
-- capture to patt.) For each subsequent capture LPeg calls func with this
-- accumulator as the first argument and all values produced by the capture as
-- extra arguments; the value returned by this call becomes the new value for
-- the accumulator. The final value of the accumulator becomes the captured
-- value.
-- As an example, the following pattern matches a list of numbers separated by
-- commas and returns their addition:
--   -- matches a numeral and captures its value
--   number = lpeg.R"09"^1 / tonumber
--   -- matches a list of numbers, captures their values
--   list = number * ("," * number)^0
--   -- auxiliary function to add two numbers
--   function add (acc, newvalue) return acc + newvalue end
--   -- folds the list of numbers adding them
--   sum = lpeg.Cf(list, add)
--   -- example of use
--   print(sum:match("10,30,43"))   --> 83
function lpeg.Cf(patt, func) end

---
-- Creates a group capture. It groups all values returned by patt into a single
-- capture. The group may be anonymous (if no name is given) or named with the
-- given name.
-- An anonymous group serves to join values from several captures into a single
-- capture. A named group has a different behavior. In most situations, a named
-- group returns no values at all. Its values are only relevant for a following
-- back capture or when used inside a table capture.
function lpeg.Cg(patt [, name]) end

---
-- Creates a position capture. It matches the empty string and captures the
-- position in the subject where the match occurs. The captured value is a
-- number.
function lpeg.Cp() end

---
-- Creates a substitution capture, which captures the substring of the subject
-- that matches patt, with substitutions. For any capture inside patt with a
-- value, the substring that matched the capture is replaced by the capture
-- value (which should be a string). The final captured value is the string
-- resulting from all replacements.
function lpeg.Cs(patt) end

---
-- Creates a table capture. This capture creates a table and puts all values
-- from all anonymous captures made by patt inside this table in successive
-- integer keys, starting at 1. Moreover, for each named capture group created
-- by patt, the first value of the group is put into the table with the group
-- name as its key. The captured value is only the table.
function lpeg.Ct(patt) end

---
-- Creates a match-time capture. Unlike all other captures, this one is
-- evaluated immediately when a match occurs. It forces the immediate evaluation
-- of all its nested captures and then calls function.
-- The given function gets as arguments the entire subject, the current position
-- (after the match of patt), plus any capture values produced by patt.
-- The first value returned by function defines how the match happens. If the
-- call returns a number, the match succeeds and the returned number becomes the
-- new current position. (Assuming a subject s and current position i, the
-- returned number must be in the range [i, len(s) + 1].) If the call returns
-- true, the match succeeds without consuming any input. (So, to return true is
-- equivalent to return i.) If the call returns false, nil, or no value, the
-- match fails.
-- Any extra values returned by the function become the values produced by the
-- capture.
function lpeg.Cmt(patt, function) end

-- LuaFileSystem.

---
-- Returns a table with the file attributes corresponding to filepath (or nil
-- followed by an error message in case of error). If the second optional
-- argument is given, then only the value of the named attribute is returned
-- (this use is equivalent to lfs.attributes(filepath).aname, but the table is
-- not created and only one attribute is retrieved from the O.S.). The
-- attributes are described as follows; attribute mode is a string, all the
-- others are numbers, and the time related attributes use the same time
-- reference of os.time:
--   dev: on Unix systems, this represents the device that the inode resides on.
--        On Windows systems, represents the drive number of the disk containing
--        the file
--   ino: on Unix systems, this represents the inode number. On Windows systems
--        this has no meaning
--   mode: string representing the associated protection mode (the values could
--         be file, directory, link, socket, named pipe, char device, block
--         device or other)
--   nlink: number of hard links to the file
--   uid: user-id of owner (Unix only, always 0 on Windows)
--   gid: group-id of owner (Unix only, always 0 on Windows)
--   rdev: on Unix systems, represents the device type, for special file inodes.
--         On Windows systems represents the same as dev
--   access: time of last access
--   modification: time of last data modification
--   change: time of last file status change
--   size: file size, in bytes
--   blocks: block allocated for file; (Unix only)
--   blksize: optimal file system I/O blocksize; (Unix only)
-- This function uses stat internally thus if the given filepath is a symbolic
-- link, it is followed (if it points to another link the chain is followed
-- recursively) and the information is about the file it refers to. To obtain
-- information about the link itself, see function lfs.symlinkattributes.
function lfs.attributes(filepath [, aname]) end

---
-- Changes the current working directory to the given path.
-- Returns true in case of success or nil plus an error string.
function lfs.chdir(path) end

---
-- Creates a lockfile (called lockfile.lfs) in path if it does not exist and
-- returns the lock. If the lock already exists checks it it's stale, using the
-- second parameter (default for the second parameter is INT_MAX, which in
-- practice means the lock will never be stale. To free the the lock call
-- lock:free().
-- In case of any errors it returns nil and the error message. In particular,
-- if the lock exists and is not stale it returns the "File exists" message.
function lfs.lock_dir(path, [seconds_stale]) end

---
-- Returns a string with the current working directory or nil plus an error
-- string.
function lfs.currentdir() end

---
-- Lua iterator over the entries of a given directory. Each time the iterator is
-- called with dir_obj it returns a directory entry's name as a string, or nil
-- if there are no more entries. You can also iterate by calling dir_obj:next(),
-- and explicitly close the directory before the iteration finished with
-- dir_obj:close(). Raises an error if path is not a directory.
function lfs.dir(path) end

---
-- Locks a file or a part of it. This function works on open files; the file
-- handle should be specified as the first argument. The string mode could be
-- either r (for a read/shared lock) or w (for a write/exclusive lock). The
-- optional arguments start and length can be used to specify a starting point
-- and its length; both should be numbers.
-- Returns true if the operation was successful; in case of error, it returns
-- nil plus an error string.
function lfs.lock(filehandle, mode[, start[, length]])

---
-- Creates a new directory. The argument is the name of the new directory.
-- Returns true if the operation was successful; in case of error, it returns
-- nil plus an error string.
function lfs.mkdir(dirname) end

---
-- Removes an existing directory. The argument is the name of the directory.
-- Returns true if the operation was successful; in case of error, it returns
-- nil plus an error string.
function lfs.rmdir(dirname) end

---
-- Sets the writing mode for a file. The mode string can be either binary or
-- text. Returns the previous mode string for the file. This function is only
-- available in Windows, so you may want to make sure that lfs.setmode exists
-- before using it.
function lfs.setmode(file, mode) end

---
-- Identical to lfs.attributes except that it obtains information about the link
-- itself (not the file it refers to). This function is not available in Windows
-- so you may want to make sure that lfs.symlinkattributes exists before using
-- it.
function lfs.symlinkattributes(filepath [, aname]) end

---
-- Set access and modification times of a file. This function is a bind to utime
-- function. The first argument is the filename, the second argument (atime) is
-- the access time, and the third argument (mtime) is the modification time.
-- Both times are provided in seconds (which should be generated with Lua
-- standard function os.time). If the modification time is omitted, the access
-- time provided is used; if both times are omitted, the current time is used.
-- Returns true if the operation was successful; in case of error, it returns
-- nil plus an error string.
function lfs.touch(filepath [, atime [, mtime]]) end

---
-- Unlocks a file or a part of it. This function works on open files; the file
-- handle should be specified as the first argument. The optional arguments
-- start and length can be used to specify a starting point and its length; both
-- should be numbers.
-- Returns true if the operation was successful; in case of error, it returns
-- nil plus an error string.
function lfs.unlock(filehandle[, start[, length]]) end