New Reactive system (#89)
Simplify Move out shared code Wrap render functions and event functions in transactions Rename
This commit is contained in:
Sabine Lim
165
Basalt/libraries/reactivePrimitives.lua
Normal file
165
Basalt/libraries/reactivePrimitives.lua
Normal file
@@ -0,0 +1,165 @@
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local NodeStatus = {
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CURRENT = 0,
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STALE = 1,
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MAYBE_STALE = 2
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}
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local Node = {}
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Node.new = function()
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return {
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fn = nil,
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value = nil,
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status = NodeStatus.STALE,
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parents = {},
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children = {},
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cleanup = function(self)
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for _, parentNode in ipairs(self.parents) do
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for index, childNode in ipairs(parentNode.children) do
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if (childNode == self) then
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table.remove(parentNode.children, index)
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break
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end
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end
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end
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self.parents = {}
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end
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}
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end
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local ReactiveState = {
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listeningNode = nil,
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sourceNodes = {},
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effectNodes = {},
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transaction = false
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}
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local Reactive = {}
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Reactive.pushUpdates = function()
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for _, sourceNode in ipairs(ReactiveState.sourceNodes) do
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Reactive.pushSourceNodeUpdate(sourceNode)
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end
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Reactive.pullUpdates()
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end
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Reactive.pushSourceNodeUpdate = function(sourceNode)
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if (sourceNode.status == NodeStatus.CURRENT) then
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return
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end
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Reactive.pushNodeUpdate(sourceNode)
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for _, childNode in ipairs(sourceNode.children) do
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childNode.status = NodeStatus.STALE
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end
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sourceNode.status = NodeStatus.CURRENT
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end
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Reactive.pushNodeUpdate = function(node)
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if (node == nil) then
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return
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end
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node.status = NodeStatus.MAYBE_STALE
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for _, childNode in ipairs(node.children) do
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Reactive.pushNodeUpdate(childNode)
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end
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end
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Reactive.pullUpdates = function()
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for _, effectNode in ipairs(ReactiveState.effectNodes) do
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Reactive.pullNodeUpdates(effectNode)
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end
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end
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Reactive.pullNodeUpdates = function(node)
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if (node.status == NodeStatus.CURRENT) then
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return
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end
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if (node.status == NodeStatus.MAYBE_STALE) then
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for _, parentNode in ipairs(node.parents) do
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Reactive.pullNodeUpdates(parentNode)
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end
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end
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if (node.status == NodeStatus.STALE) then
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node:cleanup()
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local prevListeningNode = ReactiveState.listeningNode
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ReactiveState.listeningNode = node
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local oldValue = node.value
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node.value = node.fn()
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ReactiveState.listeningNode = prevListeningNode
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for _, childNode in ipairs(node.children) do
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if (oldValue == node.value) then
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childNode.status = NodeStatus.CURRENT
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else
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childNode.status = NodeStatus.STALE
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end
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end
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end
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node.status = NodeStatus.CURRENT
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end
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Reactive.subscribe = function(node)
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local listeningNode = ReactiveState.listeningNode
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if (listeningNode ~= nil) then
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table.insert(node.children, listeningNode)
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table.insert(listeningNode.parents, node)
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end
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end
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Reactive.observable = function(initialValue)
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local node = Node.new()
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node.value = initialValue
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node.status = NodeStatus.CURRENT
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local get = function()
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Reactive.subscribe(node)
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return node.value
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end
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local set = function(newValue)
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if (node.value == newValue) then
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return
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end
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node.value = newValue
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node.status = ReactiveState.STALE
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if (not ReactiveState.transaction) then
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Reactive.pushUpdates()
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end
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end
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table.insert(ReactiveState.sourceNodes, node)
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return get, set
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end
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Reactive.derived = function(fn)
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local node = Node.new()
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node.fn = fn
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return function()
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if (node.status ~= NodeStatus.CURRENT) then
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Reactive.pullNodeUpdates(node)
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end
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Reactive.subscribe(node)
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return node.value
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end
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end
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Reactive.effect = function(fn)
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local node = Node.new()
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node.fn = fn
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table.insert(ReactiveState.effectNodes, node)
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Reactive.pushUpdates()
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end
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Reactive.transaction = function(fn)
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ReactiveState.transaction = true
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fn()
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ReactiveState.transaction = false
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Reactive.pushUpdates()
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end
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Reactive.untracked = function(fn)
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local prevListeningNode = ReactiveState.listeningNode
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ReactiveState.listeningNode = nil
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local value = fn()
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ReactiveState.listeningNode = prevListeningNode
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return value
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end
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return Reactive
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@@ -1,72 +1,6 @@
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local Reactive = require("reactivePrimitives")
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local XMLParser = require("xmlParser")
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local Reactive = {}
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Reactive.currentEffect = nil
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Reactive.observable = function(initialValue)
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local value = initialValue
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local observerEffects = {}
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local get = function()
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if (Reactive.currentEffect ~= nil) then
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table.insert(observerEffects, Reactive.currentEffect)
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table.insert(Reactive.currentEffect.dependencies, observerEffects)
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end
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return value
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end
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local set = function(newValue)
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value = newValue
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local observerEffectsCopy = {}
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for index, effect in ipairs(observerEffects) do
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observerEffectsCopy[index] = effect
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end
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for _, effect in ipairs(observerEffectsCopy) do
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effect.execute()
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end
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end
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return get, set
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end
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Reactive.untracked = function(getter)
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local parentEffect = Reactive.currentEffect
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Reactive.currentEffect = nil
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local value = getter()
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Reactive.currentEffect = parentEffect
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return value
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end
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Reactive.effect = function(effectFn)
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local effect = {dependencies = {}}
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local execute = function()
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Reactive.clearEffectDependencies(effect)
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local parentEffect = Reactive.currentEffect
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Reactive.currentEffect = effect
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effectFn()
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Reactive.currentEffect = parentEffect
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end
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effect.execute = execute
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effect.execute()
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end
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Reactive.derived = function(computeFn)
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local getValue, setValue = Reactive.observable();
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Reactive.effect(function()
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setValue(computeFn())
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end)
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return getValue;
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end
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Reactive.clearEffectDependencies = function(effect)
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for _, dependency in ipairs(effect.dependencies) do
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for index, backlink in ipairs(dependency) do
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if (backlink == effect) then
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table.remove(dependency, index)
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end
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end
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end
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effect.dependencies = {};
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end
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local Layout = {
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fromXML = function(text)
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local nodes = XMLParser.parseText(text)
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@@ -91,7 +25,9 @@ end
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local registerFunctionEvent = function(object, event, script, env)
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event(object, function(...)
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local success, msg = pcall(load(script, nil, "t", env))
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local success, msg = pcall(function()
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Reactive.transaction(load(script, nil, "t", env))
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end)
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if not success then
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error("XML Error: "..msg)
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end
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@@ -116,11 +52,10 @@ return {
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if (attribute:sub(1, 2) == "on") then
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registerFunctionEvent(object, object[attribute], expression .. "()", env)
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else
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local update = function()
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Reactive.effect(function()
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local value = load("return " .. expression, nil, "t", env)()
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object:setProperty(attribute, value)
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end
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basalt.effect(update)
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end)
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end
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end
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for _, child in ipairs(node.children) do
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@@ -134,9 +69,10 @@ return {
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local object = {
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observable = Reactive.observable,
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untracked = Reactive.untracked,
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effect = Reactive.effect,
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derived = Reactive.derived,
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effect = Reactive.effect,
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transaction = Reactive.transaction,
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untracked = Reactive.untracked,
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layout = function(path)
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if (not fs.exists(path)) then
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@@ -163,7 +99,9 @@ return {
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end
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})
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if (layout.script ~= nil) then
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executeScript(layout.script, env)
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Reactive.transaction(function()
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executeScript(layout.script, env)
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end)
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end
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local objects = {}
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for _, node in ipairs(layout.nodes) do
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