从Python到Lua的代码转换几乎完成

Question

我找到了一个Python脚本，我正在尝试将其转换为Lua。我相信我已经转换了它，但是代码不能正常工作，所以我需要帮助，因为我根本不了解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。该表非常大，因此为了便于阅读，我将其截断。

蟒蛇代码：

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('33[48;5;%sm%s:%s' % (short, short, rgb))
sys.stdout.write("33[0m  ")
sys.stdout.write('33[38;5;%sm%s:%s' % (short, short, rgb))
sys.stdout.write("33[0mn")
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 33[38;5;%sm%s33[0m -> RGB exact 33[38;5;%sm%s33[0m' % (arg, arg, arg, rgb))
sys.stdout.write("33[0mn")
else:
short, rgb = rgb2short(arg)
sys.stdout.write('RGB %s -> xterm color approx 33[38;5;%sm%s (%s)' % (arg, short, short, rgb))
sys.stdout.write("33[0mn")

还有我几乎完成翻译的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，但我不确定这是否相关，而且我知道我翻译的一些代码根本不正确，因为否则脚本将正常工作。我得到的失败是rgb2short函数没有返回正确的equiv和res值。我的修订还有多远？我需要进行哪些更改才能使其绝对有效？

Answer 1

经过一些硬核的试验和错误，我最终自己弄清楚了。rgb2short函数应该是：

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