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77 lines
2.1 KiB
Lua
77 lines
2.1 KiB
Lua
--[[
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identifier generation
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uuid is version 4, ulid is an alternative to uuid (see
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https://github.com/ulid/spec).
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todo:
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this ulid isn't guaranteed to be sortable for ulids generated
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within the same second yet
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]]
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local path = (...):gsub("identifier", "")
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local identifier = {}
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--(internal; use a provided random generator object, or not)
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local function _random(rng, ...)
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if rng then return rng:random(...) end
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if love then return love.math.random(...) end
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return math.random(...)
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end
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local uuid4_template = "xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx"
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--generate a UUID version 4
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function identifier.uuid4(rng)
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--x should be 0x0-0xf, the single y should be 0x8-0xb
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--4 should always just be 4 (denoting uuid version)
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local out = uuid4_template:gsub("[xy]", function (c)
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return string.format(
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"%x",
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c == "x" and _random(rng, 0x0, 0xf) or _random(rng, 0x8, 0xb)
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)
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end)
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return out
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end
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--crockford's base32 https://en.wikipedia.org/wiki/Base32
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local _encoding = {
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"0", "1", "2", "3", "4", "5", "6", "7", "8", "9",
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"A", "B", "C", "D", "E", "F", "G", "H", "J", "K", "M",
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"N", "P", "Q", "R", "S", "T", "V", "W", "X", "Y", "Z"
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}
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--since ulid needs time since unix epoch with miliseconds, we can just
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--use socket. if that's not loaded, they'll have to provide their own
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local function _now(time_func, ...)
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if package.loaded.socket then return package.loaded.socket.gettime(...) end
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if require("socket") then return require("socket").gettime(...) end
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if time_func then return time_func(...) end
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error("assertion failed: socket can't be found and no time function provided")
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end
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--generate an ULID using this rng at this time (now by default)
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--implementation based on https://github.com/Tieske/ulid.lua
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function identifier.ulid(rng, time)
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time = math.floor((time or _now()) * 1000)
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local time_part = {}
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local random_part = {}
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for i = 10, 1, -1 do
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local mod = time % #_encoding
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time_part[i] = _encoding[mod + 1]
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time = (time - mod) / #_encoding
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end
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for i = 1, 16 do
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random_part[i] = _encoding[math.floor(_random(rng) * #_encoding) + 1]
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end
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return table.concat(time_part) .. table.concat(random_part)
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end
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return identifier
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