在纯LUA中将UTF-8字符串转换为ASCII

Question

我对使用特殊字符发送和接收数据有疑问。 （德语变音符号）

当我用下面的代码发送字符串“CaféZeezicht”时，在服务器端字符串是oke。

但是，我怎样才能接收和解码包含相同字符的接收数据？现在它看起来像“Caf？Zeezicht”

我正在寻找一个纯LUA函数，因为我没有能力加载库。

------------------------------------------------------------ 
-- Function voor converting ASCII naar UTF8 
------------------------------------------------------------ 

-- return char as utf8 string 
local function CodeToUTF8 (Unicode) 
    if (Unicode == nil) then 
    return "" 
    end 

    if (Unicode < 0x20) then return ' '; end; 

    if (Unicode <= 0x7F) then return string.char(Unicode); end; 

    if (Unicode <= 0x7FF) then 
     local Byte0 = 0xC0 + math.floor(Unicode/0x40); 
     local Byte1 = 0x80 + (Unicode % 0x40); 
     return string.char(Byte0, Byte1); 
    end; 

    if (Unicode <= 0xFFFF) then 
     local Byte0 = 0xE0 + math.floor(Unicode/0x1000); 
     local Byte1 = 0x80 + (math.floor(Unicode/0x40) % 0x40); 
     local Byte2 = 0x80 + (Unicode % 0x40); 
     return string.char(Byte0, Byte1, Byte2); 
    end; 

    return ""; -- ignore UTF-32 for the moment 
end; 


-- convert ascii string to utf8 string 
function AsciiToUTF8(str) 
    result = "" 
    for i = 1, #str do 
    result = result .. CodeToUTF8(string.byte(str, i, i+1)) 
    end 
    return result 
end 
------------------------------------------------------------ 
-- Einde Function voor converting ASCII naar UTF8 
------------------------------------------------------------ 

Answer 1

local char, byte, pairs, floor = string.char, string.byte, pairs, math.floor 
local table_insert, table_concat = table.insert, table.concat 
local unpack = table.unpack or unpack 

local function unicode_to_utf8(code) 
    -- converts numeric UTF code (U+code) to UTF-8 string 
    local t, h = {}, 128 
    while code >= h do 
     t[#t+1] = 128 + code%64 
     code = floor(code/64) 
     h = h > 32 and 32 or h/2 
    end 
    t[#t+1] = 256 - 2*h + code 
    return char(unpack(t)):reverse() 
end 

local function utf8_to_unicode(utf8str, pos) 
    -- pos = starting byte position inside input string (default 1) 
    pos = pos or 1 
    local code, size = utf8str:byte(pos), 1 
    if code >= 0xC0 and code < 0xFE then 
     local mask = 64 
     code = code - 128 
     repeat 
     local next_byte = utf8str:byte(pos + size) or 0 
     if next_byte >= 0x80 and next_byte < 0xC0 then 
      code, size = (code - mask - 2) * 64 + next_byte, size + 1 
     else 
      code, size = utf8str:byte(pos), 1 
     end 
     mask = mask * 32 
     until code < mask 
    end 
    -- returns code, number of bytes in this utf8 char 
    return code, size 
end 

local map_1252_to_unicode = { 
    [0x80] = 0x20AC, 
    [0x81] = 0x81, 
    [0x82] = 0x201A, 
    [0x83] = 0x0192, 
    [0x84] = 0x201E, 
    [0x85] = 0x2026, 
    [0x86] = 0x2020, 
    [0x87] = 0x2021, 
    [0x88] = 0x02C6, 
    [0x89] = 0x2030, 
    [0x8A] = 0x0160, 
    [0x8B] = 0x2039, 
    [0x8C] = 0x0152, 
    [0x8D] = 0x8D, 
    [0x8E] = 0x017D, 
    [0x8F] = 0x8F, 
    [0x90] = 0x90, 
    [0x91] = 0x2018, 
    [0x92] = 0x2019, 
    [0x93] = 0x201C, 
    [0x94] = 0x201D, 
    [0x95] = 0x2022, 
    [0x96] = 0x2013, 
    [0x97] = 0x2014, 
    [0x98] = 0x02DC, 
    [0x99] = 0x2122, 
    [0x9A] = 0x0161, 
    [0x9B] = 0x203A, 
    [0x9C] = 0x0153, 
    [0x9D] = 0x9D, 
    [0x9E] = 0x017E, 
    [0x9F] = 0x0178, 
    [0xA0] = 0x00A0, 
    [0xA1] = 0x00A1, 
    [0xA2] = 0x00A2, 
    [0xA3] = 0x00A3, 
    [0xA4] = 0x00A4, 
    [0xA5] = 0x00A5, 
    [0xA6] = 0x00A6, 
    [0xA7] = 0x00A7, 
    [0xA8] = 0x00A8, 
    [0xA9] = 0x00A9, 
    [0xAA] = 0x00AA, 
    [0xAB] = 0x00AB, 
    [0xAC] = 0x00AC, 
    [0xAD] = 0x00AD, 
    [0xAE] = 0x00AE, 
    [0xAF] = 0x00AF, 
    [0xB0] = 0x00B0, 
    [0xB1] = 0x00B1, 
    [0xB2] = 0x00B2, 
    [0xB3] = 0x00B3, 
    [0xB4] = 0x00B4, 
    [0xB5] = 0x00B5, 
    [0xB6] = 0x00B6, 
    [0xB7] = 0x00B7, 
    [0xB8] = 0x00B8, 
    [0xB9] = 0x00B9, 
    [0xBA] = 0x00BA, 
    [0xBB] = 0x00BB, 
    [0xBC] = 0x00BC, 
    [0xBD] = 0x00BD, 
    [0xBE] = 0x00BE, 
    [0xBF] = 0x00BF, 
    [0xC0] = 0x00C0, 
    [0xC1] = 0x00C1, 
    [0xC2] = 0x00C2, 
    [0xC3] = 0x00C3, 
    [0xC4] = 0x00C4, 
    [0xC5] = 0x00C5, 
    [0xC6] = 0x00C6, 
    [0xC7] = 0x00C7, 
    [0xC8] = 0x00C8, 
    [0xC9] = 0x00C9, 
    [0xCA] = 0x00CA, 
    [0xCB] = 0x00CB, 
    [0xCC] = 0x00CC, 
    [0xCD] = 0x00CD, 
    [0xCE] = 0x00CE, 
    [0xCF] = 0x00CF, 
    [0xD0] = 0x00D0, 
    [0xD1] = 0x00D1, 
    [0xD2] = 0x00D2, 
    [0xD3] = 0x00D3, 
    [0xD4] = 0x00D4, 
    [0xD5] = 0x00D5, 
    [0xD6] = 0x00D6, 
    [0xD7] = 0x00D7, 
    [0xD8] = 0x00D8, 
    [0xD9] = 0x00D9, 
    [0xDA] = 0x00DA, 
    [0xDB] = 0x00DB, 
    [0xDC] = 0x00DC, 
    [0xDD] = 0x00DD, 
    [0xDE] = 0x00DE, 
    [0xDF] = 0x00DF, 
    [0xE0] = 0x00E0, 
    [0xE1] = 0x00E1, 
    [0xE2] = 0x00E2, 
    [0xE3] = 0x00E3, 
    [0xE4] = 0x00E4, 
    [0xE5] = 0x00E5, 
    [0xE6] = 0x00E6, 
    [0xE7] = 0x00E7, 
    [0xE8] = 0x00E8, 
    [0xE9] = 0x00E9, 
    [0xEA] = 0x00EA, 
    [0xEB] = 0x00EB, 
    [0xEC] = 0x00EC, 
    [0xED] = 0x00ED, 
    [0xEE] = 0x00EE, 
    [0xEF] = 0x00EF, 
    [0xF0] = 0x00F0, 
    [0xF1] = 0x00F1, 
    [0xF2] = 0x00F2, 
    [0xF3] = 0x00F3, 
    [0xF4] = 0x00F4, 
    [0xF5] = 0x00F5, 
    [0xF6] = 0x00F6, 
    [0xF7] = 0x00F7, 
    [0xF8] = 0x00F8, 
    [0xF9] = 0x00F9, 
    [0xFA] = 0x00FA, 
    [0xFB] = 0x00FB, 
    [0xFC] = 0x00FC, 
    [0xFD] = 0x00FD, 
    [0xFE] = 0x00FE, 
    [0xFF] = 0x00FF, 
} 
local map_unicode_to_1252 = {} 
for code1252, code in pairs(map_1252_to_unicode) do 
    map_unicode_to_1252[code] = code1252 
end 

function string.fromutf8(utf8str) 
    local pos, result_1252 = 1, {} 
    while pos <= #utf8str do 
     local code, size = utf8_to_unicode(utf8str, pos) 
     pos = pos + size 
     code = code < 128 and code or map_unicode_to_1252[code] or ('?'):byte() 
     table_insert(result_1252, char(code)) 
    end 
    return table_concat(result_1252) 
end 

function string.toutf8(str1252) 
    local result_utf8 = {} 
    for pos = 1, #str1252 do 
     local code = str1252:byte(pos) 
     table_insert(result_utf8, unicode_to_utf8(map_1252_to_unicode[code] or code)) 
    end 
    return table_concat(result_utf8) 
end 

---

用法：

local str1252 = "1\128" -- "one euro" in latin-1 
local str_utf8 = str1252:toutf8()  -- "1\226\130\172" -- one euro in utf-8 
local str1252_2 = str_utf8:fromutf8()