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https://github.com/rojo-rbx/rojo.git
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Factor out reconciliation into separate module
This commit is contained in:
Lucien Greathouse
256
plugin/src/Reconciler.lua
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256
plugin/src/Reconciler.lua
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@@ -0,0 +1,256 @@
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local Logging = require(script.Parent.Logging)
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local function makeInstanceMap()
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local self = {
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fromIds = {},
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fromInstances = {},
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}
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function self:insert(id, instance)
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self.fromIds[id] = instance
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self.fromInstances[instance] = id
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end
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function self:removeId(id)
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local instance = self.fromIds[id]
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if instance ~= nil then
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self.fromIds[id] = nil
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self.fromInstances[instance] = nil
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else
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Logging.warn("Attempted to remove nonexistant ID %s", tostring(id))
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end
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end
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function self:removeInstance(instance)
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local id = self.fromInstances[instance]
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if id ~= nil then
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self.fromInstances[instance] = nil
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self.fromIds[id] = nil
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else
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Logging.warn("Attempted to remove nonexistant instance %s", tostring(instance))
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end
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end
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function self:destroyId(id)
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local instance = self.fromIds[id]
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self:removeId(id)
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if instance ~= nil then
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local descendantsToDestroy = {}
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for otherInstance in pairs(self.fromInstances) do
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if otherInstance:IsDescendantOf(instance) then
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table.insert(descendantsToDestroy, otherInstance)
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end
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end
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for _, otherInstance in ipairs(descendantsToDestroy) do
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self:removeInstance(otherInstance)
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end
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instance:Destroy()
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else
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Logging.warn("Attempted to destroy nonexistant ID %s", tostring(id))
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end
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end
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return self
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end
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local function setProperty(instance, key, value)
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local ok, err = pcall(function()
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if instance[key] ~= value then
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instance[key] = value
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end
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end)
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if not ok then
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error(("Cannot set property %s on class %s: %s"):format(tostring(key), instance.ClassName, err), 2)
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end
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end
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local Reconciler = {}
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Reconciler.__index = Reconciler
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function Reconciler.new(instanceMetadataMap)
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local self = {
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instanceMap = makeInstanceMap(),
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instanceMetadataMap = instanceMetadataMap,
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}
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return setmetatable(self, Reconciler)
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end
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function Reconciler:applyUpdate(requestedIds, virtualInstancesById)
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-- This function may eventually be asynchronous; it will require calls to
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-- the server to resolve instances that don't exist yet.
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local visitedIds = {}
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for _, id in ipairs(requestedIds) do
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self:__applyUpdatePiece(id, visitedIds, virtualInstancesById)
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end
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end
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--[[
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Update an existing instance, including its properties and children, to match
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the given information.
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]]
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function Reconciler:reconcile(virtualInstancesById, id, instance)
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local virtualInstance = virtualInstancesById[id]
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-- If an instance changes ClassName, we assume it's very different. That's
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-- not always the case!
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if virtualInstance.ClassName ~= instance.ClassName then
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-- TODO: Preserve existing children instead?
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local parent = instance.Parent
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self.instanceMap:destroyId(id)
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return self:__reify(virtualInstancesById, id, parent)
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end
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self.instanceMap:insert(id, instance)
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-- Some instances don't like being named, even if their name already matches
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setProperty(instance, "Name", virtualInstance.Name)
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for key, value in pairs(virtualInstance.Properties) do
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setProperty(instance, key, value.Value)
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end
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local existingChildren = instance:GetChildren()
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local unvisitedExistingChildren = {}
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for _, child in ipairs(existingChildren) do
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unvisitedExistingChildren[child] = true
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end
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for _, childId in ipairs(virtualInstance.Children) do
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local childData = virtualInstancesById[childId]
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local existingChildInstance
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for instance in pairs(unvisitedExistingChildren) do
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local ok, name, className = pcall(function()
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return instance.Name, instance.ClassName
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end)
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if ok then
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if name == childData.Name and className == childData.ClassName then
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existingChildInstance = instance
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break
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end
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end
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end
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if existingChildInstance ~= nil then
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unvisitedExistingChildren[existingChildInstance] = nil
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self:reconcile(virtualInstancesById, childId, existingChildInstance)
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else
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self:__reify(virtualInstancesById, childId, instance)
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end
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end
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if self:__shouldClearUnknownInstances(id) then
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for existingChildInstance in pairs(unvisitedExistingChildren) do
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self.instanceMap:removeInstance(existingChildInstance)
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existingChildInstance:Destroy()
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end
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end
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-- The root instance of a project won't have a parent, like the DataModel,
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-- so we need to be careful here.
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if virtualInstance.Parent ~= nil then
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local parent = self.instanceMap.fromIds[virtualInstance.Parent]
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if parent == nil then
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Logging.info("Instance %s wanted parent of %s", tostring(id), tostring(virtualInstance.Parent))
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error("Rojo bug: During reconciliation, an instance referred to an instance ID as parent that does not exist.")
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end
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-- Some instances, like services, don't like having their Parent
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-- property poked, even if we're setting it to the same value.
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setProperty(instance, "Parent", parent)
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if instance.Parent ~= parent then
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instance.Parent = parent
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end
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end
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return instance
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end
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function Reconciler:__shouldClearUnknownInstances(id)
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if self.instanceMetadataMap[id] then
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return not self.instanceMetadataMap[id].ignoreUnknownInstances
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else
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return true
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end
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end
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function Reconciler:__reify(virtualInstancesById, id, parent)
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local virtualInstance = virtualInstancesById[id]
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local instance = Instance.new(virtualInstance.ClassName)
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for key, value in pairs(virtualInstance.Properties) do
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-- TODO: Branch on value.Type
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setProperty(instance, key, value.Value)
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end
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instance.Name = virtualInstance.Name
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for _, childId in ipairs(virtualInstance.Children) do
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self:__reify(virtualInstancesById, childId, instance)
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end
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setProperty(instance, "Parent", parent)
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self.instanceMap:insert(id, instance)
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return instance
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end
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function Reconciler:__applyUpdatePiece(id, visitedIds, virtualInstancesById)
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if visitedIds[id] then
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return
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end
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visitedIds[id] = true
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local virtualInstance = virtualInstancesById[id]
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local instance = self.instanceMap.fromIds[id]
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-- The instance was deleted in this update
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if virtualInstance == nil then
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self.instanceMap:destroyId(id)
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return
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end
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-- An instance we know about was updated
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if instance ~= nil then
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self:reconcile(virtualInstancesById, id, instance)
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return instance
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end
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-- If the instance's parent already exists, we can stick it there
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local parentInstance = self.instanceMap.fromIds[virtualInstance.Parent]
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if parentInstance ~= nil then
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self:__reify(virtualInstancesById, id, parentInstance)
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return
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end
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-- Otherwise, we can check if this response payload contained the parent and
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-- work from there instead.
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local parentData = virtualInstancesById[virtualInstance.Parent]
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if parentData ~= nil then
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if visitedIds[virtualInstance.Parent] then
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error("Rojo bug: An instance was present and marked as visited but its instance was missing")
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end
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self:__applyUpdatePiece(virtualInstance.Parent, visitedIds, virtualInstancesById)
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return
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end
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Logging.trace("Instance ID %s, parent ID %s", tostring(id), tostring(virtualInstance.Parent))
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error("Rojo NYI: Instances with parents that weren't mentioned in an update payload")
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end
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return Reconciler
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