mirror of
https://github.com/luau-lang/luau.git
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131 lines
2.8 KiB
Lua
131 lines
2.8 KiB
Lua
-- @original: https://gist.github.com/Reselim/40d62b17d138cc74335a1b0709e19ce2
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local Alphabet = {}
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local Indexes = {}
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-- A-Z
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for Index = 65, 90 do
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table.insert(Alphabet, Index)
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end
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-- a-z
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for Index = 97, 122 do
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table.insert(Alphabet, Index)
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end
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-- 0-9
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for Index = 48, 57 do
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table.insert(Alphabet, Index)
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end
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table.insert(Alphabet, 43) -- +
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table.insert(Alphabet, 47) -- /
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for Index, Character in ipairs(Alphabet) do
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Indexes[Character] = Index
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end
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local Base64 = {}
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local bit32_rshift = bit32.rshift
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local bit32_lshift = bit32.lshift
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local bit32_band = bit32.band
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--[[**
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Encodes a string in Base64.
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@param [t:string] Input The input string to encode.
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@returns [t:string] The string encoded in Base64.
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**--]]
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function Base64.Encode(Input)
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local Output = {}
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local Length = 0
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for Index = 1, #Input, 3 do
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local C1, C2, C3 = string.byte(Input, Index, Index + 2)
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local A = bit32_rshift(C1, 2)
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local B = bit32_lshift(bit32_band(C1, 3), 4) + bit32_rshift(C2 or 0, 4)
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local C = bit32_lshift(bit32_band(C2 or 0, 15), 2) + bit32_rshift(C3 or 0, 6)
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local D = bit32_band(C3 or 0, 63)
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Length = Length + 1
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Output[Length] = Alphabet[A + 1]
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Length = Length + 1
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Output[Length] = Alphabet[B + 1]
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Length = Length + 1
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Output[Length] = C2 and Alphabet[C + 1] or 61
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Length = Length + 1
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Output[Length] = C3 and Alphabet[D + 1] or 61
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end
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local NewOutput = {}
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local NewLength = 0
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local IndexAdd4096Sub1
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for Index = 1, Length, 4096 do
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NewLength = NewLength + 1
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IndexAdd4096Sub1 = Index + 4096 - 1
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NewOutput[NewLength] = string.char(
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table.unpack(Output, Index, IndexAdd4096Sub1 > Length and Length or IndexAdd4096Sub1)
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)
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end
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return table.concat(NewOutput)
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end
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--[[**
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Decodes a string from Base64.
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@param [t:string] Input The input string to decode.
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@returns [t:string] The newly decoded string.
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**--]]
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function Base64.Decode(Input)
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local Output = {}
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local Length = 0
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for Index = 1, #Input, 4 do
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local C1, C2, C3, C4 = string.byte(Input, Index, Index + 3)
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local I1 = Indexes[C1] - 1
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local I2 = Indexes[C2] - 1
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local I3 = (Indexes[C3] or 1) - 1
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local I4 = (Indexes[C4] or 1) - 1
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local A = bit32_lshift(I1, 2) + bit32_rshift(I2, 4)
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local B = bit32_lshift(bit32_band(I2, 15), 4) + bit32_rshift(I3, 2)
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local C = bit32_lshift(bit32_band(I3, 3), 6) + I4
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Length = Length + 1
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Output[Length] = A
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if C3 ~= 61 then
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Length = Length + 1
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Output[Length] = B
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end
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if C4 ~= 61 then
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Length = Length + 1
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Output[Length] = C
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end
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end
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local NewOutput = {}
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local NewLength = 0
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local IndexAdd4096Sub1
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for Index = 1, Length, 4096 do
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NewLength = NewLength + 1
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IndexAdd4096Sub1 = Index + 4096 - 1
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NewOutput[NewLength] = string.char(
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table.unpack(Output, Index, IndexAdd4096Sub1 > Length and Length or IndexAdd4096Sub1)
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)
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end
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return table.concat(NewOutput)
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end
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return Base64
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