forked from rojo-rbx/rojo
Break apart plugin reconciler (#332)
* Start splitting apart reconciler, with tests * Reify children in reify * Baseline hydrate implementation * Remove debug print * Scaffold out diff implementation, just supporting name changes * invariant -> error in decodeValue * Flesh out diff and add getProperty * Clear out top-level reconciler interface, start updating code that touches it * Address review feedback * Add (experimental) Selene configuration * Add emptiness checks to PatchSet, remove unimplement invert method * Improve descendant destruction behavior in InstanceMap * Track instanceId on all reify errors * Base implementation of applyPatch, returning partial patches on failure * Change reify to accept InstanceMap and insert instances into it * Start testing applyPatch for removals * Add test for applyPatch adding instances successfully and not * Add , which is just error with formatting * Correctly use new diff and applyPatch APIs * Improve applyPatch logging and fix field name typo * Better debug output when reify fails * Print out unapplied patch in debug mode * Don't write properties if their values are not different. This was exposed trying to sync the Rojo plugin, which has a gigantic ModuleScript in it with the reflection database. This workaround was present in some form in many versions of Rojo, and I guess we still need it. This time, I actually documented why it's here so that I don't forget for the umpteenth time... * Add placeholder test that needs to happen still * Introduce easier plugin testing, write applyPatch properties test * Delete legacy get/setCanonicalProperty files * Fix trying to remove numbers instead of instances * Change applyPatch to return partial patches instead of binary success * Work towards being able to decode and apply refs * Add helpers for PatchSet assertions * Apply refs in reify, test all cases * Improve diagnostics when patches fail to apply * Stop logging when destroying untracked instances, it's ok * Remove read before setting property in applyPatch * Fix diff thinking all properties are changed
This commit is contained in:
Lucien Greathouse
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GitHub
GitHub
parent
50f0a2bd2e
commit
f66860bdfe
148
plugin/src/Reconciler/diff.lua
Normal file
148
plugin/src/Reconciler/diff.lua
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@@ -0,0 +1,148 @@
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--[[
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Defines the process for diffing a virtual DOM and the real DOM to compute a
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patch that can be later applied.
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]]
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local Log = require(script.Parent.Parent.Parent.Log)
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local invariant = require(script.Parent.Parent.invariant)
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local getProperty = require(script.Parent.getProperty)
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local Error = require(script.Parent.Error)
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local decodeValue = require(script.Parent.decodeValue)
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local function isEmpty(table)
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return next(table) == nil
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end
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local function shouldDeleteUnknownInstances(virtualInstance)
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if virtualInstance.Metadata ~= nil then
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return not virtualInstance.Metadata.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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local function diff(instanceMap, virtualInstances, rootId)
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local patch = {
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removed = {},
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added = {},
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updated = {},
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}
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-- Add a virtual instance and all of its descendants to the patch, marked as
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-- being added.
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local function markIdAdded(id)
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local virtualInstance = virtualInstances[id]
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patch.added[id] = virtualInstance
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for _, childId in ipairs(virtualInstance.Children) do
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markIdAdded(childId)
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end
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end
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-- Internal recursive kernel for diffing an instance with the given ID.
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local function diffInternal(id)
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local virtualInstance = virtualInstances[id]
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local instance = instanceMap.fromIds[id]
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if virtualInstance == nil then
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invariant("Cannot diff an instance not present in virtualInstances\nID: {}", id)
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end
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if instance == nil then
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invariant("Cannot diff an instance not present in InstanceMap\nID: {}", id)
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end
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if virtualInstance.ClassName ~= instance.ClassName then
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error("unimplemented: support changing ClassName")
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end
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local changedName = nil
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if virtualInstance.Name ~= instance.Name then
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changedName = virtualInstance.Name
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end
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local changedProperties = {}
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for propertyName, virtualValue in pairs(virtualInstance.Properties) do
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local ok, existingValueOrErr = getProperty(instance, propertyName)
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if ok then
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local existingValue = existingValueOrErr
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local ok, decodedValue = decodeValue(virtualValue, instanceMap)
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if ok then
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if existingValue ~= decodedValue then
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changedProperties[propertyName] = virtualValue
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end
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else
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Log.warn("Failed to decode property of type {}", virtualValue.Type)
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end
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else
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local err = existingValueOrErr
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if err.kind == Error.UnknownProperty then
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Log.trace("Skipping unknown property {}.{}", err.details.className, err.details.propertyName)
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elseif err.kind == Error.UnreadableProperty then
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Log.trace("Skipping unreadable property {}.{}", err.details.className, err.details.propertyName)
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else
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return false, err
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end
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end
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end
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if changedName ~= nil or not isEmpty(changedProperties) then
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table.insert(patch.updated, {
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id = id,
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changedName = changedName,
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changedClassName = nil,
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changedProperties = changedProperties,
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changedMetadata = nil,
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})
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end
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-- Traverse the list of children in the DOM. Any instance that has no
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-- corresponding virtual instance should be removed. Any instance that
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-- does have a corresponding virtual instance is recursively diffed.
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for _, childInstance in ipairs(instance:GetChildren()) do
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local childId = instanceMap.fromInstances[childInstance]
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if childId == nil then
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-- This is an existing instance not present in the virtual DOM.
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-- We can mark it for deletion unless the user has asked us not
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-- to delete unknown stuff.
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if shouldDeleteUnknownInstances(virtualInstance) then
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table.insert(patch.removed, childInstance)
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end
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else
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local ok, err = diffInternal(childId)
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if not ok then
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return false, err
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end
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end
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end
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-- Traverse the list of children in the virtual DOM. Any virtual
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-- instance that has no corresponding real instance should be created.
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for _, childId in ipairs(virtualInstance.Children) do
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local childInstance = instanceMap.fromIds[childId]
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if childInstance == nil then
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-- This instance is present in the virtual DOM, but doesn't
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-- exist in the real DOM.
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markIdAdded(childId)
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end
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end
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return true
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end
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local ok, err = diffInternal(rootId)
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if not ok then
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return false, err
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end
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return true, patch
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end
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return diff
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