From 877d04d0fb83b5fc602dbab22b58f26a793ec236 Mon Sep 17 00:00:00 2001 From: Lewis Russell Date: Sat, 16 Sep 2023 23:10:30 +0100 Subject: feat(lua): add vim.func._memoize 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'. --- runtime/lua/vim/func.lua | 41 +++++++++++++++++++++++++++++++++++++++++ 1 file changed, 41 insertions(+) create mode 100644 runtime/lua/vim/func.lua (limited to 'runtime/lua/vim/func.lua') diff --git a/runtime/lua/vim/func.lua b/runtime/lua/vim/func.lua new file mode 100644 index 0000000000..206d1bae95 --- /dev/null +++ b/runtime/lua/vim/func.lua @@ -0,0 +1,41 @@ +local M = {} + +-- TODO(lewis6991): 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` is completely thought out. We +-- may be able to have a good default hash by hashing each argument, +-- so basically a better 'concat'. +-- - Need to support multi level caches. Can be done by allow `hash` to +-- return multiple values. +-- +--- Memoizes a function {fn} using {hash} to hash the arguments. +--- +--- Internally uses a |lua-weaktable| to cache the results of {fn} meaning the +--- cache will be invalidated whenever Lua does garbage collection. +--- +--- The memoized function returns shared references so be wary about +--- mutating return values. +--- +--- @generic F: function +--- @param hash integer|string|function Hash function to create a hash to use as a key to +--- store results. Possible values: +--- - When integer, refers to the index of an argument of {fn} to hash. +--- This argument can have any type. +--- - When function, is evaluated using the same arguments passed to {fn}. +--- - When `concat`, the hash is determined by string concatenating all the +--- arguments passed to {fn}. +--- - When `concat-n`, the hash is determined by string concatenating the +--- first n arguments passed to {fn}. +--- +--- @param fn F Function to memoize. +--- @return F # Memoized version of {fn} +--- @nodoc +function M._memoize(hash, fn) + return require('vim.func._memoize')(hash, fn) +end + +return M -- cgit