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