MarkdownPreviewer/lua/MarkdownPreviewer/msgpack.lua

module = {}

local bit8 = 256
local bit16 = 65535
local bit32 = 4294967295
local bit64 = 18446744070000001024

local function ToUint16(length)
    local len = length
    t = {}
    for i=2,1,-1 do
        t[i] = math.fmod(len,256)
        len = math.floor(len / 256)
    end
    return string.char(unpack(t))
end

local function ToUint32(length)
    local len = length
    t = {}
    for i=4,1,-1 do
        t[i] = math.fmod(len,256)
        len = math.floor(len / 256)
    end
    return string.char(unpack(t))
end

local function ToUint64(length)
    local len = length
    t = {}
    for i=8,1,-1 do
        t[i] = math.fmod(len,256)
        len = math.floor(len / 256)
    end
    return string.char(unpack(t))
end

local function is_array(t)
    return type(t) == 'table' and (#t > 0 or next(t) == nil)
end

local function NilToMsgPack()
    return string.char(0xc0)
end

local function StringToMsgPack(operand)
    local str_len = #operand

    if str_len <= 31 then
        local header = string.char(0xa0 + str_len)
        return header .. operand
    elseif str_len <= bit8 - 1 then
        local header = string.char(0xd9)
        return header .. string.char(str_len) .. operand
    elseif str_len <= bit16 - 1 then
        local header = string.char(0xda)
        return header .. ToUint16(str_len) .. operand
    elseif str_len <= bit32 - 1 then
        local header = string.char(0xdb)
        return header .. ToUint32(str_len) .. operand
    else
        print("String too large")
        return nil
    end
end

local function NumberToMsgPack(operand)
    if operand > 0 then
        if operand <= 127 then
            return string.char(operand)
        elseif operand <= bit8 - 1 then
            return string.char(0xcc) .. string.char(operand)
        elseif operand <= bit16 - 1 then
            return string.char(0xcd) .. ToUint16(operand)
        elseif operand <= bit32 - 1 then
            return string.char(0xce) .. ToUint32(operand)
        elseif operand <= bit64 - 1 then
            return string.char(0xcf) .. ToUint64(operand)
        end
    end

    return nil
end

local function ArrayToMsgPack(operand)
    local len = #operand

    local data = ""

    if len <= 15 then
        data = data .. string.char(0x90 + len)
    elseif len <= bit16 - 1 then
        data = data .. string.char(0xdc) .. ToUint16(len)
    elseif len <= bit32 - 1 then
        data = data .. string.char(0xdd) .. ToUint32(len)
    end

    for i=1,len do
        local element = operand[i]
        if type(element) == 'nil' then
            data = data .. NilToMsgPack()
        elseif type(element) == 'number' then
            data = data .. NumberToMsgPack(element)
        elseif type(element) == 'string' then
            data = data .. StringToMsgPack(element)
        elseif type(element) == 'table' then
            if is_array(element) then
                data = data .. ArrayToMsgPack(element)
            else
                data = data .. TableToMsgPack(element)
            end
        end
    end

    return data
end

local function TableToMsgPack(operand)
    local len = 0
    for _,v in pairs(operand) do
        len = len + 1
    end

    local data = ""

    if len <= 15 then
        data = data .. string.char(0x80 + len)
    elseif len <= bit16 - 1 then
        data = data .. string.char(0xde) .. ToUint16(len)
    elseif len <= bit32 - 1 then
        data = data .. string.char(0xdf) .. ToUint32(len)
    end

    for k,v in pairs(operand) do
        if type(k) == 'nil' then
            data = data .. NilToMsgPack()
        elseif type(k) == 'number' then
            data = data .. NumberToMsgPack(k)
        elseif type(k) == 'string' then
            data = data .. StringToMsgPack(k)
        elseif type(k) == 'table' then
            if is_array(k) then
                data = data .. ArrayToMsgPack(k)
            else
                data = data .. TableToMsgPack(k)
            end
        end

        if type(v) == 'nil' then
            data = data .. NilToMsgPack()
        elseif type(v) == 'number' then
            data = data .. NumberToMsgPack(v)
        elseif type(v) == 'string' then
            data = data .. StringToMsgPack(v)
        elseif type(v) == 'table' then
            if is_array(v) then
                data = data .. ArrayToMsgPack(v)
            else
                data = data .. TableToMsgPack(v)
            end
        end
    end

    return data
end

function module.ToMsgPack(operand)
    if type(operand) == 'nil' then
        return NilToMsgPack()
    elseif type(operand) == 'number' then
        return NumberToMsgPack()
    elseif type(operand) == 'string' then
        return StringToMsgPack()
    elseif type(operand) == 'table' then
        if is_array(operand) then
            return ArrayToMsgPack(operand)
        else
            return TableToMsgPack(operand)
        end
    end
end

return module