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877d04d0fb
Memoizes a function, using a custom function to hash the arguments. Private for now until: - There are other places in the codebase that could benefit from this (e.g. LSP), but might require other changes to accommodate. - Invalidation of the cache needs to be controllable. Using weak tables is an acceptable invalidation policy, but it shouldn't be the only one. - I don't think the story around `hash_fn` is completely thought out. We may be able to have a good default hash_fn by hashing each argument, so basically a better 'concat'.
60 lines
1.3 KiB
Lua
60 lines
1.3 KiB
Lua
--- Module for private utility functions
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--- @param argc integer?
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--- @return fun(...): any
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local function concat_hash(argc)
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return function(...)
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return table.concat({ ... }, '%%', 1, argc)
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end
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end
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--- @param idx integer
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--- @return fun(...): any
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local function idx_hash(idx)
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return function(...)
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return select(idx, ...)
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end
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end
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--- @param hash integer|string|fun(...): any
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--- @return fun(...): any
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local function resolve_hash(hash)
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if type(hash) == 'number' then
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hash = idx_hash(hash)
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elseif type(hash) == 'string' then
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local c = hash == 'concat' or hash:match('^concat%-(%d+)')
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if c then
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hash = concat_hash(tonumber(c))
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else
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error('invalid value for hash: ' .. hash)
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end
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end
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--- @cast hash -integer
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return hash
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end
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--- @generic F: function
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--- @param hash integer|string|fun(...): any
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--- @param fn F
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--- @return F
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return function(hash, fn)
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vim.validate({
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hash = { hash, { 'number', 'string', 'function' } },
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fn = { fn, 'function' },
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})
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---@type table<any,table<any,any>>
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local cache = setmetatable({}, { __mode = 'kv' })
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hash = resolve_hash(hash)
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return function(...)
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local key = hash(...)
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if cache[key] == nil then
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cache[key] = vim.F.pack_len(fn(...))
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end
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return vim.F.unpack_len(cache[key])
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end
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end
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