从Python到Lua的代码转换几乎完成

Question

我发现了一个Python脚本，我正在尝试将其转换为Lua。我相信我只是转换了，但代码工作不正常，所以我需要帮助，因为我根本不懂Python，只能猜测意图。这只是一个将RGB颜色转换为xterm 256的颜色转换器。该表非常庞大，因此我将其截断以便于阅读。

Python代码：

import sys, re

CLUT = [  # color look-up table
#    8-bit, RGB hex

    # Primary 3-bit (8 colors). Unique representation!
    ('00',  '000000'),
    ('01',  '800000'),
    ('02',  '008000'),
    ('03',  '808000'),
    ('04',  '000080'),
    ('05',  '800080'),
    ('06',  '008080'),
    ('07',  'c0c0c0'),
]

def _str2hex(hexstr):
    return int(hexstr, 16)

def _strip_hash(rgb):
    # Strip leading `#` if exists.
    if rgb.startswith('#'):
        rgb = rgb.lstrip('#')
    return rgb

def _create_dicts():
    short2rgb_dict = dict(CLUT)
    rgb2short_dict = {}
    for k, v in short2rgb_dict.items():
        rgb2short_dict[v] = k
    return rgb2short_dict, short2rgb_dict

def short2rgb(short):
    return SHORT2RGB_DICT[short]

def print_all():
    """ Print all 256 xterm color codes.
    """
    for short, rgb in CLUT:
        sys.stdout.write('\033[48;5;%sm%s:%s' % (short, short, rgb))
        sys.stdout.write("\033[0m  ")
        sys.stdout.write('\033[38;5;%sm%s:%s' % (short, short, rgb))
        sys.stdout.write("\033[0m\n")
    print "Printed all codes."
    print "You can translate a hex or 0-255 code by providing an argument."

def rgb2short(rgb):
    """ Find the closest xterm-256 approximation to the given RGB value.
    @param rgb: Hex code representing an RGB value, eg, 'abcdef'
    @returns: String between 0 and 255, compatible with xterm.
    >>> rgb2short('123456')
    ('23', '005f5f')
    >>> rgb2short('ffffff')
    ('231', 'ffffff')
    >>> rgb2short('0DADD6') # vimeo logo
    ('38', '00afd7')
    """
    rgb = _strip_hash(rgb)
    incs = (0x00, 0x5f, 0x87, 0xaf, 0xd7, 0xff)
    # Break 6-char RGB code into 3 integer vals.
    parts = [ int(h, 16) for h in re.split(r'(..)(..)(..)', rgb)[1:4] ]
    res = []
    for part in parts:
        i = 0
        while i < len(incs)-1:
            s, b = incs[i], incs[i+1]  # smaller, bigger
            if s <= part <= b:
                s1 = abs(s - part)
                b1 = abs(b - part)
                if s1 < b1: closest = s
                else: closest = b
                res.append(closest)
                break
            i += 1
    #print '***', res
    res = ''.join([ ('%02.x' % i) for i in res ])
    equiv = RGB2SHORT_DICT[ res ]
    #print '***', res, equiv
    return equiv, res

RGB2SHORT_DICT, SHORT2RGB_DICT = _create_dicts()

#---------------------------------------------------------------------

if __name__ == '__main__':
    import doctest
    doctest.testmod()
    if len(sys.argv) == 1:
        print_all()
        raise SystemExit
    arg = sys.argv[1]
    if len(arg) < 4 and int(arg) < 256:
        rgb = short2rgb(arg)
        sys.stdout.write('xterm color \033[38;5;%sm%s\033[0m -> RGB exact \033[38;5;%sm%s\033[0m' % (arg, arg, arg, rgb))
        sys.stdout.write("\033[0m\n")
    else:
        short, rgb = rgb2short(arg)
        sys.stdout.write('RGB %s -> xterm color approx \033[38;5;%sm%s (%s)' % (arg, short, short, rgb))
        sys.stdout.write("\033[0m\n")

我几乎完整翻译了Lua代码：

CLUT = {
    -- Primary 3-bit (8 colors). Unique representation!
    ['00'] = '000000',
    ['01'] = '800000',
    ['02'] = '008000',
    ['03'] = '808000',
    ['04'] = '000080',
    ['05'] = '800080',
    ['06'] = '008080',
    ['07'] = 'c0c0c0',
}

function _str2hex(hexstr)
    return tonumber(hexstr, 16)
end

function _strip_hash(rgb)
    -- Strip leading # if exists
    return rgb:gsub("^#", "")
end

function _create_dicts()
    short2rgb_dict = CLUT
    rgb2short_dict = {}

    for k,v in pairs(short2rgb_dict) do
        rgb2short_dict[v] = k
    end
    return rgb2short_dict, short2rgb_dict
end

function short2rgb(short)
    return short2rgb_dict[short]
end

function rgb2short(rgb)
    -- Find closest xterm-256 approximation to the given RGB value
    _create_dicts()
    rgb = _strip_hash(rgb)
    local res = ""
    local equiv = ""

    local incs = {"0x00", "0x5f", "0x87", "0xaf", "0xd7", "0xff"}

    for part in string.gmatch(rgb, "(..)") do
        part = tonumber(part, 16)
        i = 1
        while i < #incs - 1 do
            s, b = tonumber(incs[i]), tonumber(incs[i+1])
            if s <= part and part <= b then
                s1 = math.abs(s - part)
                b1 = math.abs(b - part)
            end

            if s1 < b1 then
               closest = s
            else
                closest = b
                res = res .. closest
                break
            end
            i = i + 1
        end
    end

    equiv = rgb2short_dict[res]

    return equiv, res
end

我意识到我错过了代码的打印部分，但我不确定这是否完全相关，我知道我翻译的一些代码根本不正确，因为脚本会工作除此以外。我得到的失败是rgb2short函数，它没有返回正确的equiv和res值。我的修订版有多远？我需要做些什么改变才能使它绝对有效？

Answer 1

经过一些铁杆的试验和错误后，我自己搞清楚了。功能rgb2short应该是：

 function rgb2short(rgb)
     -- Find closest xterm-256 approximation to the given RGB value
     _create_dicts()
     rgb = _strip_hash(rgb)
     local res = ""
     local equiv = ""

     local incs = {"0x00", "0x5f", "0x87", "0xaf", "0xd7", "0xff"}

     for part in string.gmatch(rgb, "(..)") do
         part = tonumber(part, 16)
         i = 1
         while i < #incs-1 do
             s, b = tonumber(incs[i]), tonumber(incs[i+1])
             if s <= part and part <= b then
                 s1 = math.abs(s - part)
                 b1 = math.abs(b - part)
                 --break
             --end

                 if s1 < b1 then
                     closest = s
                 else
                     closest = b
                 end
                 res = res .. string.format("%02x", closest)
                 break
             end
             i = i + 1
         end
     end


     equiv = rgb2short_dict[res]

     return equiv, res
 end