mlua-socket 0.2.7

-- https://github.com/lunarmodules/luasocket/blob/v3.1.0/src/ltn12.lua
-----------------------------------------------------------------------------
-- LTN12 - Filters, sources, sinks and pumps.
-- LuaSocket toolkit.
-- Author: Diego Nehab
-----------------------------------------------------------------------------

-----------------------------------------------------------------------------
-- Declare module
-----------------------------------------------------------------------------
local string = require("string")
local table = require("table")
local unpack = unpack or table.unpack
local base = _G
local select = select

local _M = {}
if module then
    -- heuristic for exporting a global package table
    ltn12 = _M  -- luacheck: ignore
end
local filter, source, sink, pump = {}, {}, {}, {}

_M.filter = filter
_M.source = source
_M.sink = sink
_M.pump = pump

-- 2048 seems to be better in windows...
_M.BLOCKSIZE = 2048
_M._VERSION = "LTN12 1.0.3"

-----------------------------------------------------------------------------
-- Filter stuff
-----------------------------------------------------------------------------
-- returns a high level filter that cycles a low-level filter
function filter.cycle(low, ctx, extra)
    base.assert(low)
    return function(chunk)
        local ret
        ret, ctx = low(ctx, chunk, extra)
        return ret
    end
end

-- chains a bunch of filters together
-- (thanks to Wim Couwenberg)
function filter.chain(...)
    local arg = { ... }
    local n = select('#', ...)
    local top, index = 1, 1
    local retry = ""
    return function(chunk)
        retry = chunk and retry
        while true do
            if index == top then
                chunk = arg[index](chunk)
                if chunk == "" or top == n then
                    return chunk
                elseif chunk then
                    index = index + 1
                else
                    top = top + 1
                    index = top
                end
            else
                chunk = arg[index](chunk or "")
                if chunk == "" then
                    index = index - 1
                    chunk = retry
                elseif chunk then
                    if index == n then
                        return chunk
                    else
                        index = index + 1
                    end
                else
                    base.error("filter returned inappropriate nil")
                end
            end
        end
    end
end

-----------------------------------------------------------------------------
-- Source stuff
-----------------------------------------------------------------------------
-- create an empty source
local function empty()
    return nil
end

function source.empty()
    return empty
end

-- returns a source that just outputs an error
function source.error(err)
    return function()
        return nil, err
    end
end

-- creates a file source
function source.file(handle, io_err)
    if handle then
        return function()
            local chunk = handle:read(_M.BLOCKSIZE)
            if not chunk then
                handle:close()
            end
            return chunk
        end
    else
        return source.error(io_err or "unable to open file")
    end
end

-- turns a fancy source into a simple source
function source.simplify(src)
    base.assert(src)
    return function()
        local chunk, err_or_new = src()
        src = err_or_new or src
        if not chunk then
            return nil, err_or_new
        else
            return chunk
        end
    end
end

-- creates string source
function source.string(s)
    if s then
        local i = 1
        return function()
            local chunk = string.sub(s, i, i + _M.BLOCKSIZE - 1)
            i = i + _M.BLOCKSIZE
            if chunk ~= "" then
                return chunk
            else
                return nil
            end
        end
    else
        return source.empty()
    end
end

-- creates table source
function source.table(t)
    base.assert('table' == type(t))
    local i = 0
    return function()
        i = i + 1
        return t[i]
    end
end

-- creates rewindable source
function source.rewind(src)
    base.assert(src)
    local t = {}
    return function(chunk)
        if not chunk then
            chunk = table.remove(t)
            if not chunk then
                return src()
            else
                return chunk
            end
        else
            table.insert(t, chunk)
        end
    end
end

-- chains a source with one or several filter(s)
function source.chain(src, f, ...)
    if ... then
        f = filter.chain(f, ...)
    end
    base.assert(src and f)
    local last_in, last_out = "", ""
    local state = "feeding"
    local err
    return function()
        if not last_out then
            base.error('source is empty!', 2)
        end
        while true do
            if state == "feeding" then
                last_in, err = src()
                if err then
                    return nil, err
                end
                last_out = f(last_in)
                if not last_out then
                    if last_in then
                        base.error('filter returned inappropriate nil')
                    else
                        return nil
                    end
                elseif last_out ~= "" then
                    state = "eating"
                    if last_in then
                        last_in = ""
                    end
                    return last_out
                end
            else
                last_out = f(last_in)
                if last_out == "" then
                    if last_in == "" then
                        state = "feeding"
                    else
                        base.error('filter returned ""')
                    end
                elseif not last_out then
                    if last_in then
                        base.error('filter returned inappropriate nil')
                    else
                        return nil
                    end
                else
                    return last_out
                end
            end
        end
    end
end

-- creates a source that produces contents of several sources, one after the
-- other, as if they were concatenated
-- (thanks to Wim Couwenberg)
function source.cat(...)
    local arg = { ... }
    local src = table.remove(arg, 1)
    return function()
        while src do
            local chunk, err = src()
            if chunk then
                return chunk
            end
            if err then
                return nil, err
            end
            src = table.remove(arg, 1)
        end
    end
end

-----------------------------------------------------------------------------
-- Sink stuff
-----------------------------------------------------------------------------
-- creates a sink that stores into a table
function sink.table(t)
    t = t or {}
    local f = function(chunk, err)
        if chunk then
            table.insert(t, chunk)
        end
        return 1
    end
    return f, t
end

-- turns a fancy sink into a simple sink
function sink.simplify(snk)
    base.assert(snk)
    return function(chunk, err)
        local ret, err_or_new = snk(chunk, err)
        if not ret then
            return nil, err_or_new
        end
        snk = err_or_new or snk
        return 1
    end
end

-- creates a file sink
function sink.file(handle, io_err)
    if handle then
        return function(chunk, err)
            if not chunk then
                handle:close()
                return 1
            else
                return handle:write(chunk)
            end
        end
    else
        return sink.error(io_err or "unable to open file")
    end
end

-- creates a sink that discards data
local function null()
    return 1
end

function sink.null()
    return null
end

-- creates a sink that just returns an error
function sink.error(err)
    return function()
        return nil, err
    end
end

-- chains a sink with one or several filter(s)
function sink.chain(f, snk, ...)
    if ... then
        local args = { f, snk, ... }
        snk = table.remove(args, #args)
        f = filter.chain(unpack(args))
    end
    base.assert(f and snk)
    return function(chunk, err)
        if chunk ~= "" then
            local filtered = f(chunk)
            local done = chunk and ""
            while true do
                local ret, snkerr = snk(filtered, err)
                if not ret then
                    return nil, snkerr
                end
                if filtered == done then
                    return 1
                end
                filtered = f(done)
            end
        else
            return 1
        end
    end
end

-----------------------------------------------------------------------------
-- Pump stuff
-----------------------------------------------------------------------------
-- pumps one chunk from the source to the sink
function pump.step(src, snk)
    local chunk, src_err = src()
    local ret, snk_err = snk(chunk, src_err)
    if chunk and ret then
        return 1
    else
        return nil, src_err or snk_err
    end
end

-- pumps all data from a source to a sink, using a step function
function pump.all(src, snk, step)
    base.assert(src and snk)
    step = step or pump.step
    while true do
        local ret, err = step(src, snk)
        if not ret then
            if err then
                return nil, err
            else
                return 1
            end
        end
    end
end

return _M