Module:HLFan/Toolkit

Documentation

local p = {}
local bit32 = require("bit32")
local keyStr = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789-_"

-- for base64-LZW-encoding Overpass queries
function p.lzw_encode(data)
    local dict = {}
    local out = {}
    local currChar
    local phrase = data:sub(1, 1)
    local code = 256
    local i = 1
    while i <= #data do
        currChar = data:sub(i + 1, i + 1)
        if dict[phrase .. currChar] then
            phrase = phrase .. currChar
        else
            table.insert(out, #phrase > 1 and dict[phrase] or phrase:byte())
            dict[phrase .. currChar] = code
            code = code + 1
            phrase = currChar
        end
        i = i + 1
    end
    return out
end
function p.utf8_encode(bytesArr)
    local utf = {}
    for i = 1, #bytesArr do
        local c = bytesArr[i]
        if c < 128 then
            table.insert(utf, c)
        elseif c < 2048 then
            table.insert(utf, bit32.bor(bit32.rshift(c, 6), 192))
            table.insert(utf, bit32.bor(bit32.band(c, 63), 128))
        else
            table.insert(utf, bit32.bor(bit32.rshift(c, 12), 224))
            table.insert(utf, bit32.bor(bit32.band(bit32.rshift(c, 6), 63), 128))
            table.insert(utf, bit32.bor(bit32.band(c, 63), 128))
        end
    end
    return utf
end
function p.base64_encode(inputArr)
    local output = ""
    local i = 1
    while i <= #inputArr do
        local chr1 = inputArr[i] or 0
        local chr2 = inputArr[i + 1] or 0
        local chr3 = inputArr[i + 2] or 0

        local enc1 = bit32.rshift(chr1, 2)
        local enc2 = bit32.bor(bit32.lshift(bit32.band(chr1, 3), 4), bit32.rshift(chr2, 4))
        local enc3 = bit32.bor(bit32.lshift(bit32.band(chr2, 15), 2), bit32.rshift(chr3, 6))
        local enc4 = bit32.band(chr3, 63)

        if i + 1 > #inputArr then
            enc3, enc4 = 64, 64
        elseif i + 2 > #inputArr then
            enc4 = 64
        end

        output = output ..
                 keyStr:sub(enc1 + 1, enc1 + 1) ..
                 keyStr:sub(enc2 + 1, enc2 + 1) ..
                 keyStr:sub(enc3 + 1, enc3 + 1) ..
                 keyStr:sub(enc4 + 1, enc4 + 1)

        i = i + 3
    end
    return output
end
function p.compress_query(input)
	return p.base64_encode(p.utf8_encode(p.lzw_encode(input)))
end



return p