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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'.
42 lines
1.7 KiB
Lua
42 lines
1.7 KiB
Lua
local M = {}
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-- TODO(lewis6991): Private for now until:
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-- - There are other places in the codebase that could benefit from this
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-- (e.g. LSP), but might require other changes to accommodate.
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-- - Invalidation of the cache needs to be controllable. Using weak tables
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-- is an acceptable invalidation policy, but it shouldn't be the only
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-- one.
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-- - I don't think the story around `hash` is completely thought out. We
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-- may be able to have a good default hash by hashing each argument,
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-- so basically a better 'concat'.
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-- - Need to support multi level caches. Can be done by allow `hash` to
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-- return multiple values.
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--
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--- Memoizes a function {fn} using {hash} to hash the arguments.
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---
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--- Internally uses a |lua-weaktable| to cache the results of {fn} meaning the
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--- cache will be invalidated whenever Lua does garbage collection.
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---
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--- The memoized function returns shared references so be wary about
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--- mutating return values.
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---
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--- @generic F: function
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--- @param hash integer|string|function Hash function to create a hash to use as a key to
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--- store results. Possible values:
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--- - When integer, refers to the index of an argument of {fn} to hash.
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--- This argument can have any type.
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--- - When function, is evaluated using the same arguments passed to {fn}.
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--- - When `concat`, the hash is determined by string concatenating all the
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--- arguments passed to {fn}.
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--- - When `concat-n`, the hash is determined by string concatenating the
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--- first n arguments passed to {fn}.
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---
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--- @param fn F Function to memoize.
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--- @return F # Memoized version of {fn}
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--- @nodoc
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function M._memoize(hash, fn)
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return require('vim.func._memoize')(hash, fn)
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end
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return M
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