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36 lines
859 B
Text
36 lines
859 B
Text
local source = require "./source"
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local derive = require "./derive"
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local effect = require "./effect"
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local untrack = require "./untrack"
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local switch = require "./switch"
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type Array<T> = { T }
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type Source<T> = () -> T
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local function show<T, Obj>(
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input: Source<T?>,
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component: (Source<T>, Source<boolean>) -> (Obj, ...number),
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fallback: ((Source<boolean>) -> (Obj, ...number))?
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): Source<nil | Obj | Array<Obj>>
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local filtered_input = source()
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effect(function()
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local v = input()
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if v then
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filtered_input(v)
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end
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end)
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local input_is_truthy = derive(function()
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return not not input()
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end)
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return switch(input_is_truthy) {
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[true] = function(present)
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return component(filtered_input, present)
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end,
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[false] = fallback
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}
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end
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return show
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