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c6762a6525
* fix: cancel reconnection when unsubscribing * test: remove print * feat: allow factory to return nil * perf: use `next` iteration
38 lines
1.2 KiB
Text
38 lines
1.2 KiB
Text
local atom = require(script.Parent.atom)
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local store = require(script.Parent.store)
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local types = require(script.Parent.types)
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type Atom<T> = types.Atom<T>
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type AtomOptions<T> = types.AtomOptions<T>
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type Molecule<T> = types.Molecule<T>
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--[=[
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Creates a read-only atom that derives its state from one or more atoms.
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Used to avoid unnecessary recomputations if multiple listeners depend on
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the same molecule.
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@param molecule The function that produces the state.
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@param options Optional configuration.
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@return A new read-only atom.
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]=]
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local function computed<T>(molecule: Molecule<T>, options: AtomOptions<T>?): Molecule<T>
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local dependencies, state = store.capture(molecule)
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local computedAtom = atom(state, options)
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local computedRef = setmetatable({ current = computedAtom }, { __mode = "v" })
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local function listener()
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local computedAtom = computedRef.current
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if computedAtom then
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store.disconnect(dependencies, listener)
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dependencies, state = store.capture(molecule)
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store.connect(dependencies, listener, computedAtom)
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computedAtom(state)
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end
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end
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store.connect(dependencies, listener, computedAtom)
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return computedAtom
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end
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return computed
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