61 lines
1.2 KiB
Lua
61 lines
1.2 KiB
Lua
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local byte = string.byte
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local max = 0x7fffffff
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---@class SDBMHash
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local mt = {}
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mt.__index = mt
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mt.cache = nil
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---@param str string
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---@return integer
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function mt:rawHash(str)
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local id = 0
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for i = 1, #str do
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local b = byte(str, i, i)
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id = id * 65599 + b
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end
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return id & max
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end
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---@param str string
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---@return integer
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function mt:hash(str)
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local id = self:rawHash(str)
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local other = self.cache[id]
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if other == nil or str == other then
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self.cache[id] = str
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self.cache[str] = id
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return id
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else
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log.warn(('哈希碰撞：[%s] -> [%s]: [%d]'):format(str, other, id))
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for i = 1, max do
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local newId = (id + i) % max
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if not self.cache[newId] then
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self.cache[newId] = str
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self.cache[str] = newId
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return newId
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end
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end
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error(('哈希碰撞解决失败：[%s] -> [%s]: [%d]'):format(str, other, id))
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end
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end
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function mt:setCache(t)
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self.cache = t
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end
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function mt:getCache()
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return self.cache
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end
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mt.__call = mt.hash
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---@return SDBMHash
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return function ()
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local self = setmetatable({
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cache = {}
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}, mt)
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return self
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end
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